close

Вход

Забыли?

вход по аккаунту

?

j.molstruc.2018.08.057

код для вставкиСкачать
Accepted Manuscript
Enhancement of the red emission of Eu3+ by Bi3+ sensitizers in yttrium alumino
bismuth borosilicate glasses
D.V. Krishna Reddy, Sk. Taherunnisa, A. Lakshmi Prasanna, T. Sambasiva Rao,
N. Veeraiah, M. Rami Reddy
PII:
S0022-2860(18)31006-8
DOI:
10.1016/j.molstruc.2018.08.057
Reference:
MOLSTR 25578
To appear in:
Journal of Molecular Structure
Received Date:
23 March 2018
Accepted Date:
16 August 2018
Please cite this article as: D.V. Krishna Reddy, Sk. Taherunnisa, A. Lakshmi Prasanna, T.
Sambasiva Rao, N. Veeraiah, M. Rami Reddy, Enhancement of the red emission of Eu3+ by Bi3+
sensitizers in yttrium alumino bismuth borosilicate glasses, Journal of Molecular Structure (2018),
doi: 10.1016/j.molstruc.2018.08.057
This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to
our customers we are providing this early version of the manuscript. The manuscript will undergo
copyediting, typesetting, and review of the resulting proof before it is published in its final form.
Please note that during the production process errors may be discovered which could affect the
content, and all legal disclaimers that apply to the journal pertain.
ACCEPTED MANUSCRIPT
1
Enhancement of the red emission of Eu3+ by Bi3+ sensitizers in
yttrium alumino bismuth borosilicate glasses
D.V. Krishna Reddy, Sk. Taherunnisa , A. Lakshmi Prasanna, T. Sambasiva Rao,
N. Veeraiah, M. Rami Reddy*
Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar-522 510, India
*Email.: mramireddy2001@yahoo.co.in
Abstract
Trivalent europium ions doped yttrium alumino bismuth borosilicate glasses
(YABiBS) of the composition are synthesized by the melt - quenching method. The
structural, thermal and spectral properties of the prepared glasses have been investigated by
XRD, EDS, FT-IR, DTA, optical absorption, photoluminescence and decay profiles. XRD
indicated the amorphous nature of the samples. From the DTA traces thermal Parameters like
ΔT, S and H are evaluated to verify the thermal stability of the titled glasses. FTIR spectra
exhibited bands due to various fundamental vibrational units of borate and silicate groups.
The optical absorption spectra exhibited the bands due to 7F0 → 5G4, 7F0 → 5L6, 7F0 → 5D2, 7F0
→7F6,
and 7F1 → 7F6 transitions of Eu3+ ions. In addition the absorption spectra also exhibited
a band due to 1S0 → 1P1 transition of Bi3+ ions. From the absorption spectra, the optical band
gap and Urbach energies and also nephelauxetic ratios were evaluated. The emission spectra
(excited at 392 nm) exhibited five luminescence bands at 577, 590, 612, 651and 700 nm
assigned to 5D0 → 7F0, 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, and 5D0 → 7F4 transitions of Eu3+
ions, respectively. The absorption and emission spectra were characterized using Judd-Ofelt
(J-O) theory and radiative parameters viz., radiative transition probability (AR), branching
ratio (R), and luminescence quantum efficiency (), radiative life time (), stimulated

emission cross-section () were evaluated. The values of radiative parameters are found to
be the highest for the transition 5D0→7F2 of 0.6mol% Eu3+ doped YABiBS glass (BE0.6). The
co-doping of Bi3+ ions (10.0mol %) caused a substantial enhancement (nearly three times) in
ACCEPTED MANUSCRIPT
2
the intensity of this red emission. These results suggested the energy transfer between Bi3+
ions and Eu3+ ions. The energy transfer efficiency has been explained in terms of structural
modifications taking place in the glass network.
Keywords: YABiBS glasses; Eu3+ ions; Photoluminescence; Bi3+ ions; Energy transfer.
1. Introduction
For more than two decades extensive research is being carried out on borosilicate
glasses, which are the influential glasses offering attractive applications in the fields of
optoelectronics, solar energy technology, as sealants and on nuclear waste immobilization
etc. The wide applications of these glasses are due to their high refractive index, softening
temperature, resistance to chemical attack; low thermal expansion, dispersion, and
mechanical strength [1]. The sesquioxide Y2O3 participates in the glass network with
tetrahedral (YO4) and octahedral (YO6) occupancy. The tetrahedral yttrium ions join with
SiO4 groups, while octahedral yttrium ions act as modifiers [2, 3]. Similarly, the
incorporation of Al2O3 into borosilicate causes the phonon energy decreases due to de-cluster
the RE3+ (Rare Earth) and improves the luminescence efficiency by minimizing emission
losses due to cross relaxation [4]. Among Heavy metal oxides, Bi2O3 is known as
luminescence stimulator for rare earth ions. Presently researchers are attracted towards the
behaviour of Bi3+ ions as sensitizers in various glass matrices [5, 6], activate the luminescent
ions present in the glass matrix. Mostly Bi3+ ions act as modifier in the borosilicate glasses
and by de-polymerize the host glass network and the reduce emission losses [7]. The
enhancement of the luminescence is possible with the Bi3+ ions as sensitizers in these glasses,
for wide applications in the fields of solid state lasers, optical electronic devices, thermal
sensors and optical fiber amplifiers etc. [8]
ACCEPTED MANUSCRIPT
3
Now-a-days, most of the research work on glass materials have been ardent towards
trivalent lanthanide (Ln) based materials for the development of bulk lasers, optical
amplifiers, optical detectors, optical waveguides, optical devices such as photoelectric display
devices and field emission displays etc. [9-11]. Among the rare earth ions, triply ionized
europium (Eu3+) ions are one of the useful candidates for its use in photonic applications as in
the display devices as efficient red emitting laser medium due to the narrow and
monochromatic nature of the 5D0 → 7F2 transition at around 612 nm. Such materials have
commercially-recognized applications in tricolor lamps, cathode ray tubes, luminescent probe
for biochemical and biomedical applications, and optical storage materials etc. [12-13].
Recently, Hegde et al., and several other authors have carried out commendable work on
emission features of Eu3+ ions in several glasses and glass ceramics [14-17].
In the present investigation we have studied and characterized the influence of Bi3+
ions on the luminescence efficiency of Eu3+ ions in Y2O3 mixed borosilicate glasses. The
observed intensification of the red emission of Eu3+ ions is discussed in terms of energy
transfer between Bi3+ and Eu3+ ions.
2. Materials and methods
Eu2O3 doped Y2O3-Al2O3-Bi2O3-B2O3-SiO2 (YABiBS) glasses are prepared by the
melt quenching method. The chemical compositions and the labels of the prepared glasses are
as shown in Table 1. Analytical grade reagents of Y2O3, Al2O3, Bi2O3, B2O3, SiO2 and Eu2O3
(with 99.9% purity) powders are used to prepare the glasses. Appropriate quantities of
chemicals were taken and were ball milled for 2 h to obtain homogeneous mixture. The
mixture is taken in platinum crucible and heated for about 20minutes in an automatic
temperature controlled furnace at a temperature 1420 oC. The melt is quickly poured into
ACCEPTED MANUSCRIPT
4
preheated brass mould so as to obtain the required shape. The obtained samples were
immediately transferred to the muffle furnace of 400 oC temperature for annealing. The
muffle furnace containing samples was switched off immediately and left to cool at room
temperature at a rate of 25 oC/ h to avoid thermal stress and to get the structural stability.
Later the samples were ground and optically polished to final dimensions of 1.0 cm x 1.0 cm
x 0.2 cm.
The refractive index of the glasses is measured (at the wavelength of 589.3 nm) using
Abbe’s refractometer with monobromo naphthalene as a contact layer between the glass and
the refractometer prism. The density of the glasses is measured by Archimedes’ principle
with O-xylene as immersion liquid using ViBRA HT modal kit to an accuracy of 0.001
g/cm3.The X-ray diffraction patterns are recorded on XRD-6100 SHIMADZU diffractometer
in the scanning range of 90-10o(2θ) operated at 40 kV, 30 mA, using Cu Kα radiation of
wavelength 1.5406 Å at room temperature. The energy dispersive spectroscopy
measurements were conducted on a Thermo Instruments Model Noran System 6 attached to
scanning electron microscope. The Fourier transform infrared analysis is carried out using
SHIMADZU-IRAffinity-1S FT-IR spectrophotometer with the resolution of 0.1cm-1 in the
spectral range 400-4000 cm-1 using KBr pellets (300 mg) containing a pulverized sample (1.5
mg). Differential thermal analysis of powder sample is performed on SHIMADZU DTG60H.The optical absorption (UV–Vis) spectra are recorded on JASCO, V-570
spectrophotometer from 200 to 2400 nm with spectral resolution of 0.1 nm. The emission,
excitation, and decay measurements are carried out using FLS-980 Fluorescence
spectrometer at room temperature by using xenon flash lamp as an excitation source.
ACCEPTED MANUSCRIPT
5
3. Results and discussion
3.1 Physical parameters
The prepared YABiBS glasses doped with Eu3+ ions were found to be transparent
without bubbles and strain. Using measured values of density (d) and refractive index (n)
other related physical parameters like molar volume (VM), Eu3+ ion concentration (Ni),
polaron radius (rp), inter-ionic distance (ri), and field strength (Fi) [18,19] are evaluated and
tabulated in Table 2.
Fig. 1 shows the variations of density and molar volume with the concentration of
Eu3+ ions. It can be observed that density of the samples is increased with increase of Eu2O3
concentration. This is because in the glass composition we have replaced Al2O3 (M.W.
101.96 g/mole) by Eu2O3 (M.W. 351.926 g/mole) and the molar volume as expected
exhibited a decreasing trend [20].
3.2 X-ray diffraction pattern (XRD)
The XRD patterns of Eu3+ ions doped with YABiBS glasses are shown in the Fig. 2.
In these patterns no sharp peaks have been observed indicating the prepared samples are of
amorphous in nature.
3.3 Energy dispersive spectroscopy (EDS)
Fig. 3 EDS spectrum of 1.0mol% Eu2O3 of doped YABiBS glass is presented. The
spectrum indicates all the expected elements like silicon (Si), oxygen (O), Aluminum (Al),
Yttrium(Y), Bismuth (Bi) and Europium (Eu) are present in the glass matrix.
ACCEPTED MANUSCRIPT
6
3.4 Differential Thermal Analysis (DTA)
The thermodynamic properties of the Eu2O3 doped YABiBS glasses are presented by
the DTA thermograms in Fig. 4.The transition temperature (Tg), onset crystallization
temperature (Tx) and crystallization temperature (Tc) of these glasses were derived by
marking the intersection of two tangents respectively. The temperature difference value
(ΔT=Tg- Tx) can be considered as a criterion to measure glass thermal stability. Using DTA
traces, two other thermal parameters viz., S-Parameter and weighted thermal stability
parameter (H) is evaluated by using Saad-Poulain criterion [21-23]. The parameter S that
gives more information on thermal stability and the resistance to devitrification after the
formation of the glasses is evaluated using,
S=
(Tx - Tg)(Tc - Tx)
Tg
.
(1)
The parameter related to thermal stability is defined as
H=
∆T
Tg
(2)
These parameters evaluated for the titled glasses and compared with the other silicate
glasses reported in the literature (Table 4). The comparison indicated the highest values for
the titled glasses in this work. Further, the glass doped with 0.6 mol% Eu2O3 is observed to
have highest values of the parameters ΔT, S and H. Hence, this glass is predicted to have
good thermal stability against devitrification and useful for drawing optical fibres.
ACCEPTED MANUSCRIPT
7
3.5 FT-IR Spectra
The FT-IR spectroscopy involves in the twisting, bending, rotational and vibrational
motions in molecules upon the interaction of IR radiation; portions of the incident radiation
are absorbed as particular wavelength. The IR spectrum recorded in the spectral region 4001600cm-1 for Eu2O3 doped YABiBS glass samples reveal a series of bands presented in Table
5; a band at about 450 cm-1[24, 25] due to the bending and rocking vibrations of Si-O-Si /
AlO6 units and vibrations of the Bi-O-Bi/ BiO6 units, intensity of this band decreases with the
increase in the concentration of Eu3+. Another band at around 688-696 cm-1 due to
symmetrical bending vibrations of Si-O-Si and deformation of the Si-O-B linkages is also
observed[26].A band in the region 801-807 cm-1 band identified as being due to the vibrations
of metal–oxygen of Y-O and Al-O vibrations of AlO4 structural units [27, 22]. Further, a
symmetric vibration of B-O-Si units are observed at 907 cm-1 and tri, tetra, penta borate and
diborate groups belonging to BO4 groups are assigned to 1053-1060 cm-1[28]. The band
observed at about 1200 cm-1 is assigned to the asymmetric vibrations of Si-O-Si [29]. B-O
stretching vibrations of BO3 triangles are observed at 1380-1389cm-1 and stretching modes of
Si-OH are located at 1497-1507 cm-1[30].
In the Fig. 5, the intensity of the asymmetrical bands viz., due to BO3 and AlO6
structural units is observed to increase at the expense of symmetrical vibrational bands of
BO4, SiO4 and AlO4 structural units with the gradual increase of Eu2O3 concentration up to
0.6mol% and there after a reversal trend is observed. There are several reports suggesting that
the octahedral Al3+ ions do act as modifiers similar to conventional modifiers like
alkali/alkaline oxides and induce structural defects like non-bridging oxygen’s (NBO’s) and
dangling bonds and this results an increase in the intensity of asymmetrical vibrational bands
[31, 32].
ACCEPTED MANUSCRIPT
8
3.6 Optical absorption spectra and nephelauxetic effect
The optical absorption spectra of Eu2O3 doped YABiBS glasses in UV-Vis-NIR
regions recorded at room temperature are shown in Figs. 6(a) & 6(b). The spectra exhibited
absorption bands at 370, 393,463, 2096, and 2202 nm corresponding to 7F0 → 5G4, 7F0 → 5L6,
7F
0
→ 5D2, 7F0 →7F6, and 7F1 → 7F6 transitions of Eu3+ ions respectively [33]. Among these
one broad hump is observed at 471 nm, it is absent in the bismuth free YABiBS glass (B0E0)
(inset of the Fig. 6(a)). This clarifies that the Bi3+ ions are active in this host matrix. The Bi3+
ion which exhibit different electronic transitions from ground state 1S0 to its four excited
states 3P0, 3P1, 3P2 and 1P1. The intensity of these absorption bands strongly depend on the
host matrix. When the Bi3+ ion is exposed to UV light, the electrons in Bi3+ ion, usually
transfer from the 1S0 to the 3P1 or 1P1 level, but not to the 3P0 and 3P2 excited states, because
the 1S0→3P0 and 1S0→3P2 transitions are forbidden [34], hence the absorption spectra of Bi3+
doped glasses are expected to exhibit the bands due to 1S0→1P1 and 1S0→3P1 transitions only.
However, in the present study we have observed only one band at 471nm identified as being
due to 1S0 →1P1 transition of Bi3+ ions [35-37].
From the observed optical edge, we have evaluated the optical band gap (Eo) of these
glasses by drawing Tauc plot between (αhν) 1/2, (αhν) 2as a function of hν as per the equation
α(ν)hν = C (hν- Eo)n
(3)
In Eq. (3), C is a constant and the exponent (n) can take values 1/2 and 2 for indirect,
direct transitions, respectively [38]. Tauc plots for direct transition are shown in Fig. 7(a) and
for the indirect transition are shown in Fig. 7(b). From the extrapolation linear portion of
these plots the values of optical band gaps are estimated and presented in Table 6.
The values of E0 are found to be the minimal for the glass BE0.6 while these values
have exhibited a slight increasing tendency for further increase in the concentration of Eu2O3.
ACCEPTED MANUSCRIPT
9
In the IR spectra we have observed a gradual increase in the intensity of band due to
the vibrations of AlO6 structural units with increase in the concentration of Eu2O3 from 0 to
0.6 mol%. Such increase suggests an increase in the concentration of octahedral Al ions in
the glass network.
Such changes lead to decrease in the optical band gap, as we have observed.
However, in the samples containing higher concentration of the Eu2O3 (>0.6 mol %), an
increment in the optical band gap is visualized. This is probably due to the fact that in this
concentration range of Eu2O3, the concentration of BO4 and AlO4 seems to prevail over the
concentration of BO3 and AlO6 structural units and thereby an increase in the degree of
polymerization of the glass network takes place. This leads to increase in the optical band gap
from the glass BE0.6 to BE1.0 as reported in Table 6.
The Urbach energy (∆E) corresponds to the width of the localized states which is used
to characterize the degree of disorders in the amorphous materials [39]. The changes in these
values are due to the formation of defects in the titled glass. The value of E is calculated by
taking the reciprocal of the slope of the linear portion of ln(α) versus hν plot (Fig. 8.) These
values are found to be 0.275, 0.283, 0.288, 0.292, 0.291, and 0.290 eV for the BE0, BE0.2,
BE0.4, BE0.6, BE0.8 and BE1.0 glasses, respectively. It can be observed that ∆E values
increases slightly up to BE0.6 glass, where as optical band gap values are decreases, hence
urbach energy values change inversely with the optical band gap values, due to increase in
the NBO’s. Similar result was reported by Kesavulu et al., [40].
The nephelauxetic effect is a key probe to identify the bonding nature of the RE3+ ions
with the surrounding ligands. The nephelauxetic ratio β is calculated using the expression
νc
β=ν
a
(4)
ACCEPTED MANUSCRIPT
10
where ν the observed wave number (in cm−1) of a particular is transition of the
Europium ion and ν is the wave number (in cm−1) for the corresponding transition of the
aquo-ion. The bonding parameter δ values were determined from the relation given below
[41].
δ=
1-β
β
× 100
(5)
where  is the average value of the nephelauxetic ratio. The calculated δ values of the
titled glasses were presented in Table 7 along with the observed absorption band transitions.
The nature of the bonding between the Eu3+ ions and the surrounding ligand anions
could be predicted either as covalent or ionic depending upon the positive or negative sign of
the bonding parameter (δ) values. The positive δ values observed for these glasses indicate
the Eu3+ ions exist in covalent nature.
3.7 Excitation and emission spectra
The excitation spectrum of Eu3+ doped YABiBS glasses recorded monitored at
emission wavelength 612 nm is shown in Fig. 9. The spectrum reveals eight bands at 362,
375, 381, 392, 414, 464, 532 and 578 nm corresponding to the 7F0→5D4, 7F0→5G2, 7F1→5L7,
7F
0→
5L , 7F →5D , 7F →5D 7F →5D ,
6
1
3
0
2,
0
1
and 7F0→5D0 transitions of Eu3+ ions, respectively
[42]. Among these excitation transitions, the 7F0→5L6 transition (392 nm) is the most intense
and hence same has been used for recording the emission spectra.
The photoluminescence spectra of titled glasses are recorded at room temperature at
excited wavelength 392 nm in region 450 –750 nm. The emission spectra of Eu3+ doped
glasses exhibited five emission bands as 577, 590, 612, 651and 700 nm due to 5D0 → 7F0,
ACCEPTED MANUSCRIPT
11
5D
0
→ 7F1, 5D0 → 7F2, 5D0 → 7F3 and 5D0 → 7F4 transitions of Eu3+ ions [43] .The
luminescence spectra is expected to exhibit a broad band in the spectral region 600-630 nm
due to the transition from the 3P1 excited state to the 1S0 ground state of Bi3+ ions [5, 44-46].
Comparison of emission spectra of the B0E0.6 and BE0.6 glasses (insert of the Fig. 10)
shows the intensity of the band due to 5D0 →7F2 transition of 0.6mol% Eu2O3 glass
containing Bi3+ ions is approximately three times larger when compared with Bi3+ free glass.
This increase is attributed to the transfer of energy from the 3P1→1S0 emission transition of
Bi3+ to the 5D0→7F2 of Eu3+ because the energy of these transitions is nearly equal, the
intensity increase of the transition 5D0 → 7F2 shows radiative energy transfer from the state
3P
1
to 5D0 and relaxes down to 7F2 level gradually.
The intensity of emission bands increases with increasing of Eu3+ ion concentration in
the host matrix up to 0.6 mol% and for further increase of Eu3+ concentration a reverse trend
is observed. A Plot drawn between the concentrations of Eu3+ ions versus relative emission
intensity of the transition 5D0 →7F2 (Fig. 11) clearly shows concentration quenching beyond
0.6 mol% of Eu3+ ions.
The higher asymmetry (or) lower symmetry possessed by the Eu3+ ions is confirmed
through the luminescence intensity ratio (R/O) of the electric dipole transition (5D0 → 7F2)
and the magnetic dipole transition (5D0 → 7F1) [47]. The higher R/O ratio gives higher
asymmetry of Eu3+ ions and it can decide the quality of the host matrix suitability for laser
action. The R/O ratio values of the prepared glasses are found to be 3.29, 3.72, 3.95, 3.82 and
3.76 for BE0, BE0.2, BE0.4, BE0.6, BE0.8 and BE1.0 glasses respectively from these values
it can be concluded that BE0.6 glass posses the highest R/O value when compared with other
glasses, which is suggestive for applications of this material for photonic devices.
ACCEPTED MANUSCRIPT
12
3.8 Judd –Ofelt analysis and radiative parameters
The conventional least square fitting for the trivalent europium ion is not appropriate
for evaluating Ω because of the Zero magnitude of some of the reduce matrix elements for
all the absorption transitions. Further, the 7F0 ground state and the first excited 7F1 state in the
Eu3+ ion lie very close to each other with the a small energy difference ( 265 cm-1). Hence it
is difficult to study J-O parameters from absorption transitions. Hence, we have evaluated the
J-O parameters for the Eu3+ ions from the emission spectra [48] using the energies of 5D0→
7F
2,
7F
4
and 7F6 electric dipole transitions. However, Ω6 is negligibly small for 5D0→7F6
transition since the band corresponding to this transition could not be visualized. Hence, we
have evaluated Ω2 and Ω4 parameters by using the following relation [49, 47].
S
[
5 →7
0
5 →7
0
]
2,4
1
=
2
2
3
2
 2,4 ( + 2)
Ω2,4
3
 
9
1
( )
|⟨5 │U
2,4
D0
|7F2,4⟩|
2
(6)
In Eq. (6) Smd is the line strength of 5D0→7F1 transition, 1 is the wavenumber of the
5D
7F
0→
1
transition, 2,4 are the wavenumbers of the 5D0→7F2, and 7F4 transitions,
|⟨ │
2,4
respectively, n is the refractive index, 5D U
0
[
(taken from the literature [50]), and S
5 →7
0
0
]
2,4
5 →7
1
|7F2,4⟩|
2
are the reduced matrix values
is the emission intensity ratio of
corresponding transitions.
The Ω2 parameter is related to the short-range effect such as polarizability of the
metal-ligand bonds; Ω4 parameter is related to the long-range effect such as viscosity and
rigidity of the glass. The JO parameters of the prepared glasses have been calculated and
compared with similarly reported values for other glasses [51-53] (Table 8).These parameters
ACCEPTED MANUSCRIPT
13
follow the trend as Ω2 > Ω4, uniformly for all the prepared glasses. Higher Ω2 values are often
an indication of higher asymmetry and higher covalency around the Eu3+ ions which is also
confirmed by R/O values.
The J-O parameters have been used to determine the radiative properties such as
radiation transition probability (AR),total radiative probability(AT),stimulated emission cross

section(), branching ratio(R),radiative lifetime(R), gain band width ( × ∆λeff), and

figure of merit( × R) of the prepared glasses following the expressions reported in the
literature [54] as follows.
Radiation transition probability (AR) can be expressed as
AR(5D →7F )
0
J
2
4 3
n(n + 2)
64π ν
= 3h(2J + 1)
9
(
2
)
3
Sed + n Smd ,
(7)
where Sed is the electric-diploe line strength of the 5D0→7F2, 4, 6 and Smd is the
magnetic-diploe line strength of the 5D0→7F1 can be expressed as follows.
(
‖ Ψ'J')
λ
Sed = ∑λ = 2,4,6Ωλ ΨJ‖U
2
2 2
Smd =
e h
2
Ωλ|〈ΨJ‖L + 2S‖Ψ'J'〉|
(8)
2
2 2
16π m c
(9)
Total radiative probability (AT) can be expressed as summation of all possible radiative
transition probabilities (AR).

Stimulated emission cross-section  can be expressed as
4
λPAR
E
σP =
2
8πcn Δλeff
(10)
ACCEPTED MANUSCRIPT
14
where λP is the band intensity of corresponding peak , AR s the radiation transition
probability, ∆λeff is the effective line width, c speed of light.
Branching ratio(R) can be expressed as
AR
βR = A
(11)
T
Radiative lifetime(R) can be expressed as
τR = [AT]
‒1
(12)
The radiative parameters of the studied glasses are determined for the transitions
5D
7F
0→
0,
7F
1,
7F
2,
7F
3,
and 7F4 and listed in Table 9.

The higher  value is an indicative of high gain with low threshold. In the present

work BE0.6 glass exhibited higher value of  for the transition 5D0→7F2 (11.69 x 10-22 cm2)
suggesting studied material is a probable laser medium. The R is the important laser
parameter in the design of new luminescent devices. The higher value of this can be predicted
the higher luminescence efficiency of the glass. In the titled glasses BE0.6 possesses
relatively higher R value corresponding to the 5D0→7F2 transition as 0.701.
The calculated lifetimes (R) of the prepared glasses are found to be 3.092, 2.963,
2.860, 2.910, 2.989 ms for the BE0, BE0.2, BE0.4, BE0.6, BE0.8 and BE1.0 glasses
respectively. Other important parameters to characterize the laser materials by using the
stimulated emission cross-section are optical gain band width (σ × Δλeff) and figure of merit
(FOM, σ × τ) are higher for the transition 5D0→7F2 for BE0.6 glass; these values are found to
be 163.54 × 10−28 cm3 and 33.43 × 10−24 cm2, respectively.
ACCEPTED MANUSCRIPT
15
3.9 CIE color chromaticity diagram and Correlated color temperatures
The emission spectra of the Eu3+ doped YABiBS glasses have been characterized with
the CIE 1931 color chromaticity diagram to explore the dominant characteristic emission
color [55]. The color chromaticity coordinate values (x,y) of the prepared glasses BE0.2,
BE0.4 BE0.6, BE0.8 and BE1.0 are found to be (0.605,0.339), (0.617,0.330), (0.661,0.301),
(0.647,0.312), and (0.635,0.318), respectively.
The correlated color temperatures (CCT) have also been calculated using the (x, y)
chromaticity coordinate values following the McCamy's approximation formula [56] in order
to check the quality of the emitted light. In general, CCT is one of the significant
characteristic features which describe the temperature corresponding to the closest Planckian
black-body radiator to the operating point in the CIE diagram. It can be expressed as
CCT = −449d3+ 3525d2− 6823d + 5520.33
(13)
where d is the inverse slope line determined using the color chromaticity co-ordinates
and epicenter value which is given as d = (x − xe) / (y − ye) and the value of epicenter (xe , ye)
is equal to (0.332,0.186).
The calculated CCT values for the BE0.2, BE0.4, BE0.6, BE0.8, and BE1.0 found to be
1996.1 K, 2341.1 K, 4276.2 K, 3430.5 K, and 2960.4 K, respectively. These values suggest
that the glasses are promising candidates for red emitting source applications.
3.10 Decay curve analysis
ACCEPTED MANUSCRIPT
16
Another important parameter to examine the usefulness of the glass as a lasing medium is
the decay lifetime of the excited state. The decay curves of the 5D0 upper level recorded at exc for
the glasses mixed with and without Bi2O3 doped with 0.6 mol% of Eu2O3 are presented in Fig. 13.
The curves appeared to be fitting into double-exponential as per the following expression [52].
-
It = I0 + A1e
()
t
τ
1
-
+ A2e
()
t
τ
2
(14)
In Eq. (14), I0 and It are the emission intensities at time t=0 and t, respectively, 1 and
2 represent slow and fast decay life components, A1, A2 are the fitting constants.
The average lifetime (avg) can be expressed as
2
2
A1τ1 + A2τ2
τavg = A
1τ1 + A1τ2
(15)
The average decay time of 5D0 excited level of BE0.2, BE0.4, BE0.6, BE0.8 and BE1.0
glasses are found to be 1.515, 1.506, 1.497, 1.484, and 1.421ms, respectively. The values of
radiative life times evaluated from the JO theory are shown in Table 10.
The total decay rate of the 5D0 level is the combination of both radiative and nonradiative processes. The radiative transition is accredited due to the Eu3+- Eu3+ ions
interaction and is included in all the emission transitions. The non-radiative decay is due to
the interaction of Eu3+ ions with the vibration of the host matrix and it reaches the lower
energy state with the emission of multiple phonons called ‘multi-phonon relaxation process’
and is expressed using the following expression[13].
ACCEPTED MANUSCRIPT
17
WNR =
1
τavg
-τ
1
(16)
rad
The WNR (s−1) for the 5D0 level is found to be 336.6, 326.5, 318.3, 330.2, and 369.1
corresponding to BE0.2, BE0.4, BE0.6, BE0.8 and BE1.0 glasses, respectively.
The energy gap between the 5D0 fluorescent and the next lower level 7F6 is 12536
cm-1. Due to this large energy gap, the multi phonon relaxation for the 5D0 level is quite
small. The deviation in the experimental and calculated lifetime values was caused by the
non-radiative decays like quenching, multi-phonon relaxation caused by the OH- units. The
value of WNR for 5D0 level of BE0.6 glass is found to be the minimum indicating the low
emission loses due to cross relaxation.
The ratio of a number of photons emitted to the number of photons absorbed is
defined as the luminescence quantum efficiency (). In the case of RE3+ ion incorporated
systems, it is equal to the ratio of the average lifetime to the calculated lifetime for the
corresponding levels and is given by [57].
η=
τavg
τrad
(17)
The  values for the 5D0 level is found to be 48.99%, 50.82%, 52.34%, 50.99% and
47.54% for the BE0.2, BE0.4, BE0.6, BE0.8 and BE1.0 glasses, respectively.
From the titled glasses, BE0.6 glass possesses the highest quantum efficiency
(52.34%) corresponding to the 5D0→7F2 transition. This observation suggests that 0.6 mol%
of Eu2O3 is the optimal concentration in the titled glass system for getting the highest
luminescence efficiency indicating such material is a potential candidate for red laser
applications.
ACCEPTED MANUSCRIPT
18
4. Conclusions
Eu3+: YABiBS glasses are prepared by the melt-quenching method. The values of thermal
parameters ΔT, S and H are found to be the highest for the glass BE0.6 indicating such glass
possess highest thermal stability and hence useful in developing optical fibre devices. The
positive magnitude of the bonding parameter (δ) values reveals the covalent nature of the
Eu3+ environment in the prepared glasses. From the optical absorption edges, ∆E values
change inversely with the optical band gap values. The decrease in the optical band gap
values and increase in the asymmetric nature of AlO6 and BO3 structural units of IR spectra
are response to the increase in NBO’s in the glass network. Ω2 > Ω4 is the trend observed for
the J-O parameters calculated from the emission spectra of the titled glasses, higher Ω2
Values and R/O values indicate the Eu3+ ions environment is highly asymmetric and covalent

in nature. BE0.6 glass exhibits higher , R and  values of the 5D0→7F2 transition as 11.69
x 10−22 cm2, 0.701 and 52.34%, respectively. From emission spectra it is understood that
intensity of the 5D0→7F2 of BE0.6 glass is increased by three times when the glass is codoped with Bi2O3. Such result indicates Bi3+ ions are acting as possible sensitizers and are
enhancing the PL red emission (5D0→7F2) of Eu3+ ions. CIE color chromaticity coordinates
(x,y) move towards red region with increase in the concentration of Eu2O3 up to 0.6 mol%.
Overall analysis of the results suggests that 0.6 mol% of Eu2O3 is the optimal concentration
so as to get the highest luminescence efficiency in the red region and hence such glasses may
be considered as suitable for the red laser operated devices.
ACCEPTED MANUSCRIPT
19
Acknowledgements
The author, D.V. Krishna Reddy wishes to thank University Grants Commission (UGC),
New Delhi, for sanctioning BSR fellowship (F.No.25-1/2014-15(BSR)/7-2/2007(BSR)), to
carry out this work.
M. Rami Reddy wish to thank to University Grants Commission (UGC), New Delhi and
Department of Science and Technology (DST New Delhi) for the financial assistance to the
Physics Department, ANU, to carry out this work under UGC-DSA1 (F.530/11/DSAI/2015(SAP-I)) and FIST (F. No. SR/FST/PSI-163/2011(C)) programmes, respectively.
The authors acknowledge MoU-DAE-BRNS Project (No.2009/34/36/BRNS/3174),
Department of Physics, S.V. University, Tirupathi, India for extending the experimental
facility.
ACCEPTED MANUSCRIPT
20
References
[1] M.Hasanuzzamana, M. Sajjia, A. Rafferty, A.G. Olabia, “Thermal behaviour of
zircon/zirconia-added chemically durable borosilicate porous glass” Thermochim.
Acta 555 (2013) 81-88.
[2] G. Kaur, M. Kumar, A. Arora, O.P. Pandey, K. Singh, “Influence of Y2O3 on
structural and optical properties of SiO2-BaO-ZnO-xB2O3-(10-x) Y2O3 glasses and
glass ceramics” J. Non- Cryst. Solids 357 (2011) 858-863.
[3] N. Ch. Ramesh Babu, Ch. Srinivasa Rao, M. G. Brik, G. Naga Raju, I. V. Kityk, N.
Veeraiah, “Manifestation of up-conversion in Yb3+/Tm3+ doped Li2O-Y2O3-SiO2 glass
system” Appl. Phys. B 110 (2013) 335-344.
[4] K. Swapna, Sk Mahamuda, A. Srinivasa Rao, S. Shakya, T. Sasikala, D. Haranath,
G. Vijaya Prakash. “Optical studies of Sm3+ ions doped zinc alumino bismuth borate
glasses” Spectrochim. Acta Mol. Biomol. Spectrosc.125 (2014) 53-60.
[5] B.Suresh, N.Purnachand,Ya. Zhydachevskii, M.G.Brik, M.Srinivasa Reddy,
A. Suchocki, M. Piasecki, N. Veeraiah “Influence of Bi3+ ions on the amplification of
1.3 μm emission of Pr3+ ions in lead silicate glasses for the applications in second
telecom window communications” J. Lumin. 182 (2017) 312-322.
[6] B.Suresh, Ya. Zhydachevskii , M.G. Brik “Amplification of green emission of Ho3+
ions in lead silicate glasses by sensitizing with Bi3+ ions” J. Alloys Compd. 683
(2016) 114-122.
[7] Y.Gandhi, MV Ramachandra Rao, Ch Srinvasa Rao, T. Srikumar, I. V. Kityk, N.
Veeraiah. “Influence of aluminum ions on fluorescent spectra and upconversion in
codoped CaF2-Al2O3-P2O5-SiO2:Ho3+ and Er3+ glass system.” J. Appl. Phys. 108, no.
2 (2010) 023102.
[8] V.Thomas, R. G.S.Sofin, M.Allen, H.Thomas, P. R. Biju, G. Jose, N.V.Unnikrishnan.
“Optical analysis of samarium doped sodium bismuth silicate glass.” Spectrochim.
Acta Mol. Biomol. Spectrosc.171 (2017) 144-148.
ACCEPTED MANUSCRIPT
21
[9] R. M. Macfarlane, R. M. Shelby “Measurement of optical dephasing of Eu3+ and
Pr3+ doped silicate glasses by spectral holeburning” Opt. Commun. 45 (1983) 46-51.
[10] Edward G. Behrens, Frederic M. Durville, Richard C. Powell, Douglas H. Blackburn
“Properties of laser-induced gratings in Eu-doped glasses” Phys. Rev. B 39 (1989)
6076.
[11] C.R. Kesavulu, K. Kiran Kumar, N. Vijaya, Ki-Soo Lim, C.K. Jayasankar “Thermal,
vibrational and optical properties of Eu3+-doped lead fluorophosphate glasses for red
laser applications” Mater. Chem. Phys. 141(2013)903-911.
[12] M. Dhamodhara Naidu, D. Rajesh, A. Balakrishna, Y.C. Ratnakaram “Kinetics of
fluorescence properties of Eu3+ ion in strontium-aluminium-bismuth-borate glasses”
Journal of rare earths, 32 (2014) 1140.
[13] Ch. Srinivasa Rao, K. Upendra Kumar, C.K. Jayasankar “Luminescence properties of
Eu3+ ions in phosphate-based bioactive glasses” Solid-State Sci. 13 (2011) 1309-1314.
[14] Vinod Hegde, CS Dwaraka Viswanath, Vyasa Upadhyaya, K. K. Mahato, and Sudha
D. Kamath. "Red light emission from europium doped zinc sodium bismuth borate
glasses." Physica B: Condensed Matter 527 (2017) 35-43.
[15] Vinod Hegde, Akshatha Wagh, Hemanth Hegde, CS Dwaraka Vishwanath, and Sudha
D. Kamath. "Spectroscopic investigation on europium doped heavy metal borate
glasses for red luminescent application." Applied Physics A 123, no. 5 (2017) 302
[16] Zeng Huidan, Zhao Liu, Qing Yu, Guorong Chen, Zhaofeng Wang, and Luyi Sun.
"Enhanced Luminescence of Europium Doped Glass Ceramics Containing Ca5 (PO4)
3F Nanocrystals." Science of Advanced Materials 8, no. 11 (2016): 2054-2058.
[17] Borak Beata, Justyna Krzak, Maciej Ptak, Wiesław Strek, and Anna Lukowiak.
"Spherical nanoparticles of europium-doped silica–calcia glass and glass-ceramic:
Spectroscopic characterization." Journal of Molecular Structure 1166 (2018) 48-53.
[18] J.E. Shelby, J. Ruller, “Properties of Barium Gallium Germanate Glasses.” Phys.
Chem. Glasses” 28 (1987) 262-268.
[19] Andrzej Kłonkowski “Non-monotonic variations of some parameters in vitreous R20SiO2 and R20-A1203-SiO2 systems.” J. Non-Cryst. Solids 72 (1985) 117-137.
[20] M. Anand Pandarinath, G. Upender, K. Narasimha Rao, and D. Suresh Babu.
"Thermal, optical and spectroscopic studies of boro-tellurite glass system containing
ZnO." Journal of Non-Crystalline Solids 433 (2016) 60-67.
ACCEPTED MANUSCRIPT
22
[21] Xiaozhe Han, Yuhua Li, Tiecheng Ma, Zhiqiang Wang, Xin Zhaoa and Hai Linb
“Thermodynamic Properties of Rare-earth Ions Doped Lithium-yttrium- Aluminiumsilicate Glasses.” Advanced Materials Research, 651 (2013) 232-236.
[22] A. Prnová, A. Domanická, R. Klement, J. Kraxner , M. Polovka, “Er and Nd doped
yttrium aluminosilicate glasses: Preparation and characterization.” Opt. Mater. 33
(2011) 1872-1878.
[23] Deepika, K.S. Rathore, and N. S. Saxena. “Kinetics of glass transition and thermal
stability of Se58Ge42− x Pbx (9≤ x≤ 20) glasses.” Appl Phys A 98 (2010) 441-448.
[24] T. Srikumar, Ch. Sinivasa Rao , Y. Gandhi , N. Venkatramaiah, V. Ravikumar, N.
Veeraiah, “Microstructural, dielectric and spectroscopic properties of Li2O–Nb2O5–
ZrO2–SiO2 glass system crystallized with V2O5” J. Phys. Chem. Solids, 72 (2011)
190-200.
[25] R. Iordanova,V. Dimitrov , y. Dimitriev , D. Klissurski “Glass formation and structure
of glasses in the V205-MoO3-Bi203 system” J. Non-Cryst. Solids 180 (1994) 58-65.
[26] A.M. Efimov “Quantitative IR spectroscopy: Applications to studying glass structure
and properties” J. Non-Cryst. Solids 203 (1996) 1-11.
[27] E.I. Kamitsos, A.P. Patsis, M.A. Karakassides, G.D. Chryssikos “Infrared reflectance
spectra of lithium borate glasses” J. Non-Cryst. Solids 126 (1990) 52-67.
[28] A.K. Hassan, L. Borjesson, L.M. Torell “The boson peak in glass formers of
increasing fragility” J. Non-Cryst. Solids 172-174 (1994) 154-160.
[29] Xiaomeng Zhu, Chengle Mai, Mingyu “Li Effects of B2O3 content variation on the Bi
ions in Bi2O3–B2O3–SiO2 glass structure” J. Non-Cryst. Solids 388 (2014) 55-61.
[30] G. Srinivasarao, N. Veeraiah “Characterization and Physical Properties of PbOAs2O3 Glasses Containing Molybdenum Ions” J. Solid State Chem. 166 (2002) 104117.
[31] Y. Gandhi, M.V. Ramachandra Rao, Ch. Srinivasa Rao, I.V. Kityk and N. Veeraiah
“Role of Al2O3 in upconversion and NIR emission in Tm3+ and Er3+codoped calcium
fluoro phosphorous silicate glass system” J. Luminescence 131 (2011) 1443–1452.
[32] Y.Gandhi, M. V. Ramachandra Rao, Ch. Srinivasa Rao, T. Srikumar, I.V. Kityk and
N. Veeraiah “Influence of aluminium ions on fluorescent spectra and upconversion in
co-doped CaF2−Al2O3−P2O5−SiO2: Ho3+ and Er3+ glass system” Journal of Applied
Physics (AIP)108 (2010) 023102.
ACCEPTED MANUSCRIPT
23
[33] N. Vijaya, C.K. Jayasankar “Structural and spectroscopic properties of Eu3+-doped
zinc fluorophosphate glasses” J. Mol. Struct. 1036 (2013) 42-50.
[34] Atul D.Sontakke, AnalTarafder, Kaushik Biswas, K.Annapurna “Sensitized red
luminescence from Bi3+ co-doped Eu3+: ZnO–B2O3 glasses” Physica B 404 (2009)
3525-3529.
[35] C. Lei, J. Yang, Z. Guo-Bin, W. Can, Y. Guang-Tao, W. Chun, L. Guo-Hua
“Concentration and Temperature Dependences of YBO3:Bi3+ Luminescence under
Vacuum Ultraviolet Excitation” Chinese Phys. Lett. 25 (2008) 1884.
[36] Dong Hoon Son, Seung Ho Lee and Won-Taek Han “Pump-wavelength Dependence
of the Emission Properties for Er-Yb-Bi Triply-doped Borosilicate Glasses” J. Korean
Physical Society. 61 (2012) 1700-1703.
[37] B.N. Mahalley, S.J. Dhoble, R.B. Pode1, G. Alexander “Photoluminescence in
GdVO4:Bi3+, Eu3+ red phosphor” Appl. Phys. A, 70 (2000) 39-45.
[38] T.G.V.M. Rao, A. Rupesh Kumar, K. Neeraja, N. Veeraiah, M. Rami Reddy “Optical
and structural investigation of Dy3+-Nd3+ co-doped in magnesium lead borosilicate
glasses” Spectrochim. Acta Mol. Biomol. Spectrosc.118 (2014) 744-751.
[39] F. Urbach “The Long-Wavelength Edge of Photographic Sensitivity and of the
Electronic Absorption of Solids” Phys. Rev. 92 (1953) 1324-1326.
[40] C. R. Kesavulu, K. Kiran Kumar, N. Vijaya, Ki-Soo Lim, and C. K. Jayasankar.
"Thermal, vibrational and optical properties of Eu3+- doped lead fluorophosphate
glasses for red laser applications." Materials Chemistry and Physics 141, 2-3 (2013)
903-911.
[41] S. Selvi, K. Marimuthu, G. Muralidharan “Structural and luminescence studies of
Eu3+: TeO2-B2O3-AO-AF2 (A = Pb, Ba, Zn, Cd, Sr) glasses” J. Mol. Struct. 1144
(2017) 290-299.
[42] M. Murali Mohan, L. Rama Moorthy, D. Ramachari, C.K. Jayasankar “Spectroscopic
investigation and optical characterization of Eu3+ ions in K–Nb–Si glasses”
Spectrochim. Acta, Part A. 118 (2014) 966-971.
[43] P. Vijaya Lakshmi, T.G.V.M. Rao, K. Neeraja, D.V. Krishna Reddy, M. Rami Reddy
“Investigation of optical, structural properties of Eu3+ by Mn2+ in barium alumino
borosilicate glasses” J. Mol. Struct. 1125 (2016) 136-143.
ACCEPTED MANUSCRIPT
24
[44] P.Yasaka, K.Boonin, P. Limsuwan, W. Chewpraditkul, N. Pattanaboonmee J.
Kaewkhao Physical “Structural and luminescence Properties of ZnO-Bi2O3-B2O3
Glass System” Applied Mechanics and Materials. 431 (2013) 8-13.
[45] Anxiang Guan, Fuwang Mo, Peican Chen, Yue Geng, Qian Chen, and Liya Zhou
“Photoluminescence Properties and Energy Transfer of Eu, Bi Co-Doped CaYPO
Phosphors” Journal of display technology, 12 (2016) 136-142.
[46] H. D. Ju, J. Liu, B. L. Wang, X. T. Tao, Y. H. Ma, and S. Q. Xu, Bi -Doped Sr Al O
“An unusual color- tunable phosphor for solid state lighting” Ceram. Int. 39 (2013)
857-860.
[47] Lidia Zur, Marta Sołtys, Tomasz Goryczka, Joanna Pisarska, Wojciech A. Pisarski
“Influence of PbF2 concentration on thermal, structural and spectroscopic properties
of Eu3+-doped lead phosphate glasses” J. Mol. Struct. 1075 (2014) 605-608.
[48] S. Selvi, K. Marimuthu, N. Suriya Murthy, G. Muralidharan “Red light generation
through the lead boro-telluro-phosphate glasses activated by Eu3+ ions” J. Mol. Struct.
1119 (2016) 276-285.
[49] R. Balakrishnaiah, R. Vijaya, P. Babu, C.K. Jayashankar, M.L.P. Reddy,
“Characterization of Eu3+-doped fluorophosphate glasses for red emission” J. NonCryst. Solids 353 (2007)1397-1401.
[50] P. Babu, C.K. Jayasankar “Optical spectroscopy of Eu3+ ions in lithium borate and
lithium flouoroborate glasses” Physica B 279 (2000) 262-281.
[51] J. Kaewkhao, K. Boonina, P. Yasakaa “Optical and luminescence characteristics of
Eu3+ doped zinc bismuth borate (ZBiB) glasses for red emitting device” Mater. Res.
Bull. 71 (2015) 37-41.
[52] T. Kalpana , M.G. Brik , V. Sudarsan , N. Veeraiah “Influence of Al3+ ions on
luminescence efficiency of Eu3+ ions in barium boro-phosphate glasses” J. Non-Cryst.
Solids 419 (2015) 75-81.
[53] K. Swapna, Sk.Mahamuda, A. Srinivasa Rao “Luminescence characterization of Eu3+
doped Zinc Alumino Bismuth Borate glasses for visible red emission applications” J.
Lumin. 156 (2014) 80-86.
[54] K. Annapoorani, K. Marimuthu “Spectroscopic properties of Eu3+ ions doped Barium
telluroborate glasses for red laser applications” J. Non-Cryst. Solids 463 (2017) 148157.
ACCEPTED MANUSCRIPT
25
[55] Kaushal Jha, M.Jayasimhadri “Spectroscopic investigation on thermally stable
Dy3+ doped zinc phosphate glasses for white light emitting diodes” J. Alloys Compd.
(2016) 833-840.
[56] S. S. McCamy “Correlated color temperature as an explicit function of chromaticity
coordinates” Color. Res. Appl.17 (1992) 142-144.
[57] K. Bhargavi, V. Sudarsan, M.G. Brik, M. Sundara Rao, Y. Gandhi, P. Nageswara
Rao, N. Veeraiah “Influence of Al declustering on the photo luminescent properties
of Pr3+ ions in PbO–SiO2 glasses” J. Non-Cryst. Solids 362 (2013) 201-206.
Figure captions
Fig. 1 Density and molar volume changes with the Eu2O3 concentration in YABiBS glasses.
Fig. 2 XRD Spectrum of Eu3+ doped YABiBS glass.
Fig. 3 EDS Spectrum of 1.0 mol% Eu3+ doped YABiBS glass.
Fig. 4 DTA curve of Eu3+ doped YABiBS glasses.
Fig. 5 FT-IR spectra of Eu3+ doped YABiBS glasses.
Fig. 6(a) Optical absorption spectra of Eu3+ doped YABiBS glasses in UV-VIS region.
Fig. 6(b) Optical absorption spectra of Eu3+ doped YABiBS glasses in NIR region.
Fig. 7(a) Tauc plots to evaluate direct band gap of Eu3+ doped YABiBS glasses.
Fig. 7(b) Tauc plots to evaluate in-direct band gap of Eu3+ doped YABiBS glasses.
Fig. 8 Plots of ln (α) and hν for Eu3+ doped YABiBS glasses.
Fig. 9 Excitation spectra of Eu3+ doped YABiBS glasses.
Fig. 10 Luminescence spectra of Eu3+ doped YABiBS glasses.
Fig. 11 Concentration Vs Luminescence Intensity curve of Eu3+ doped YABiBS glasses.
Fig. 12 Chromaticity diagram of Eu3+ doped YABiBS glasses.
Fig. 13 Decay Curves of Eu3+ doped YABiBS glasses.
ACCEPTED MANUSCRIPT
26
Fig. 14 Energy level diagram of 0.6 mol% Eu2O3 doped YABiBS glasses.
Table captions
Table 1 The chemical compositions of the prepared glasses.
Table 2 Various physical properties of Eu3+ doped YABiBS glasses.
Table 3 Characteristic temperatures of Eu3+ doped YABiBS glasses.
Table 4 Comparison of Thermal parameters of several optical glasses.
Table 5 FT-IR spectra assignment of Eu3+ doped YABiBS glasses.
Table 6 The cutoff wavelength, optical band gaps, Urbach energy of Eu3+ doped YABiBS
glasses.
Table 7 Bonding parameters (β, δ) of Eu3+ doped YABiBS glasses.
Table 8 Comparison of the luminescence intensity ratio (R/O) and JO parameters of the Eu3+
doped YABiBS glasses and other reported Eu3+ glasses.
Table 9 Emission band position (λp, nm), Effective bandwidth (Δλeff, nm), radiative transition
probability (A, s−1), branching ratio (βR), stimulated emission cross-section (σ × 10−22 cm2),
of the 5D0 → 7FJ (J= 0, 1, 2, 3 and 4) of the Eu3+ doped glasses YABiBS glasses.
Table 10 Experimental (avg), Calculated (cal) lifetimes, Quantum efficiency (η) and Nonradiative relaxation (WNR) of the Eu3+ doped glasses YABiBS glasses.
ACCEPTED MANUSCRIPT
27
Table 11 The CIE 1931 chromaticity color coordinate (x, y), and Correlated Color
Temperature (CCT, K) of the Eu3+ doped YABiBS glasses.
ACCEPTED MANUSCRIPT
Fig. 1: Density and molar volume changes with the Eu2O3 Concentration in YABiBS glasses.
Fig. 2: XRD Pattern of Eu3+ doped YABiBS glass
ACCEPTED MANUSCRIPT
Exo
Fig. 3: EDS Spectrum of 1.0 mol% Eu3+ doped YABiBS glass
Heatflow(W/g)
Tg
Tc
Tx
BE0
Endo
BE1.0
BE0.6
30
230
430
630
830
Temperature (oC)
Fig. 4: DTA thermographs of Eu3+ doped YABiBS glasses
ACCEPTED MANUSCRIPT
Fig. 5: FT-IR spectra of Eu3+ doped YABiBS glasses
ACCEPTED MANUSCRIPT
Fig. 6(a): Optical absorption spectra of Eu3+ doped YABiBS glasses in UV-VIS region.
ACCEPTED MANUSCRIPT
Fig. 6(b): Optical absorption spectra of Eu3+ doped YABiBS glasses in NIR region.
ACCEPTED MANUSCRIPT
Fig. 7(a): Tauc plots to evaluate direct band gap of Eu3+ doped YABiBS glasses.
ACCEPTED MANUSCRIPT
Fig. 7(b): Tauc plots to evaluate in-direct band gap of Eu3+ doped YABiBS glasses.
ACCEPTED MANUSCRIPT
Fig. 8: Plots of ln(α) and hν for Eu3+ doped YABiBS glasses
ACCEPTED MANUSCRIPT
Fig. 9: Excitation spectra of Eu3+ doped YABiBS glasses
ACCEPTED MANUSCRIPT
5
D0
7
F2
5
1200000
D0
7
F2
Intensity(a.u)
Intensity(a.u)
1000000
800000
BE0.6
600000
7
7
F1
5
D0
5
200000
BE0.8
D0
5
0
570
590
BE1.0
exc= 392nm
BE0.2
5
D0
570
7
D0
7
630
5
610
630
D0
650
670
690
710
5
D0
7
F4
650
7
F3
Wavelength(nm)
670
F4
F3
F1
F0
590
610
7
D0
7
D0
Wavelength(nm)
BE0.4
5
B0E0.6
400000
5
BE0.6
F0
690
Fig. 10: Photoluminescence spectra of Eu3+ doped YABiBS glasses
710
ACCEPTED MANUSCRIPT
Fig. 11: Concentration Vs Luminescence Intensity curve of Eu3+ doped YABiBS glasses
ACCEPTED MANUSCRIPT
Fig. 12: Chromaticity diagram of Eu3+ doped YABiBS glasses
ACCEPTED MANUSCRIPT
Fig. 13: Decay Curves of Eu3+ doped YABiBS glasses.
ACCEPTED MANUSCRIPT
Fig.14: Energy level diagram of 0.6 mol% Eu2O3 doped YABiBS glasses.
ACCEPTED MANUSCRIPT
Highlights

Eu3+ doped YABiBS glass with and without Bi2O3 was prepared by using meltquenching method.

Enhancement of the red intense emission transition (5D0→7F2) of Eu3+ sensitized by
Bi3+ for red laser applications.

Thermal Parameters calculated from DTA curves shows thermal satiability of title
glasses to develop the optical fibre devices.

The decrease in the optical band gap values represents the increase in non-bridging
oxygen’s in the glass network. ∆E values change inversely with the optical band gap
values.
ACCEPTED MANUSCRIPT
Table-1: The chemical compositions of the prepared glasses
Y2O3
Glasses mol %
Al2O3
mol %
Bi2O3
mol %
B2O3
mol %
SiO2
mol %
Eu2O3
mol %
B0E0
5
10
-
30
55
-
BE0
5
10
10
20
55
-
BE0.2
5
9.8
10
20
55
0.2
BE0.4
5
9.6
10
20
55
0.4
BE0.6
5
9.4
10
20
55
0.6
B0E0.6
5
9.4
-
30
55
0.6
BE0.8
5
9.2
10
20
55
0.8
BE1.0
5
9.0
10
20
55
1.0
Table-2: Various physical properties of Eu3+ doped YABiBS glasses
Physical Parameters
Density, d (g/cm3)
(±0.004)
Molar Volume, MV (cm3/mol)
(±0.002)
Ion concentration, Ni
(1020ions/cm3)(±0.005)
Interionic distance, ri
(Å)(±0.005)
Polaron radius, rp
(Å) (±0.005)
Field strength, Fi
(1015cm-2) (±0.005)
Refractive index, n
(±0.001)
BE0.2
BE0.4
BE0.6
BE0.8
BE1.0
3.685
3.709
3.734
3.758
3.783
31.354
31.286
31.210
31.144
31.070
0.399
0.795
1.190
1.574
1.957
0.292
0.232
0.203
0.185
0.172
1.178
9.374
8.200
7.473
6.954
2.158
3.413
4.471
5.389
6.230
1.638
1.647
1.650
1.644
1.641
ACCEPTED MANUSCRIPT
Table -3: Characteristic temperatures of Eu3+ doped YABiBS glasses
S.No
Glass
Tg
Tx
Tc
1
BE0
552
770
795
2
BE0.6
546
771
797
3
BE1.0
533
774
798
Table - 4: Comparison of Thermal parameters of several optical glasses.
Composition
∆T
S (oC)
Y2O3 -Al2O3-Bi2O3-B2O3-SiO2 [This Work]
218
9.87
0.394
Y2O3-Al2O3-Bi2O3-B2O3-SiO2-0.6Eu2O3 [This Work]
241
10.85
0.452
Y2O3-Al2O3-Bi2O3-B2O3-SiO2-1.0Eu2O3 [This Work]
225
10.71
0.412
Li2O3-Y2O3-Al2O3-SiO2- Tm2O3-Yb2O3[14]
177
8.34
0.238
Li2O3-Y2O3-Al2O3-SiO2- Sm2O3[14]
194
10.94
0215
Y2O3-Al2O3-SiO2-Nd2O3[15]
64
1.07
0.082
Y2O3-Al2O3-SiO2-Er2O3[15]
71
1.10
0.073
H
ACCEPTED MANUSCRIPT
Table 5: FT-IR spectra assignment of Eu3+ doped YABiBS glasses
S.No
BE0
BE0.2
BE0.4
BE0.6
BE0.8 BE1.0
Band assignments
1
452
461
458
464
460
460
Bending and rocking motion of Si–O–
Si/ AlO6 units, Vibrations of the Bi-OBi bands of BiO6 units.
Symmetrical bending vibrations of Si–
O–Si, deformation of the Si-O–B
linkages.
Characteristic metal–oxygen Y–O and
Al–O vibrations and AlO4 structural
units.
Symmetric vibration of B–O–Si units.
2
688
696
696
698
696
688
3
807
807
804
801
801
804
4
918
904
907
910
904
907
5
1058
1060
1056
1053
1056
1052
Tri, tetra, penta borate and diborate
groups belonging to BO4 groups.
6
-
1168
1171
1168
1168
1160
7
1389
1382
1388
1385
1385
1380
8
-
1507
1507
1499
1500
1497
Asymmetric vibrations of Si–O–Si and
BO3 units.
B–O stretching vibrations of BO3
triangles and other borate groups.
Stretching modes of Si–OH.
Table 6: The cutoff wavelength, optical band gaps, Urbach energy of Eu3+ doped YABiBS
glasses
Glass
Cutoff
samples wavelength
(nm)
Optical band gaps (eV)
Indirect Urbach energy
band gap
(E)
3.637
0.275
BE0
340
Direct
band gap
3.648
BE0.2
351
3.536
3.529
0.283
BE0.4
357
3.478
3.466
0.288
BE0.6
362
3.430
3.419
0.292
BE0.8
360
3.441
3.432
0.291
BE1.0
359
3.456
3.449
0.290
ACCEPTED MANUSCRIPT
Table 7: The empirical energy levels (in cm-1) and bonding parameters (β, δ) of Eu3+ doped
YABiBS glasses
S. No
1.
2.
3.
4.
_
_
Transitions
from
Eu3+ ions
7F → 5L
0
6
7F → 5D
0
2
7F → 7F
0
6
7F → 7F
1
6
BE0.2
BE0.4
BE0.6
BE0.8
BE1.0
Aquo-ion
[34]

25445
21551
4768
4539
0.987
25445
21551
4766
4535
0.985
25510
21598
4768
4537
0.986
25510
21551
4773
4541
0.984
25445
21551
4766
4539
0.987
25400
21519
4798
4630
_
δ
1.317
1.522
1.626
1.419
1.317
_
Table 8: Comparison of the luminescence intensity ratio (R/O) of 5D0→7F2 to 5D0→
7F transitions and JO parameters of the Eu3+ doped YABiBS glasses and other reported Eu3+
1
glasses.
GLASS
SAMPLES
BE0.2
R/O
3.29
JO Parameters
Ω2
Ω4
5.601
1.805
BE0.4
3.72
5.585
1.911
BE0.6
3.95
5.524
1.810
BE0.8
3.82
5.743
1.977
BE1.0
3.76
5.764
1.867
ZBiB[44]
2.80
-
-
BBP[45]
3.13
5.870
2.70
ZAlBiB[46]
2.78
2.28
1.54
ACCEPTED MANUSCRIPT
Table -9: Emission band position (λp, nm), Effective bandwidth (Δλeff, nm), radiative
transition probability (AR, s−1), branching ratio (βR) %, stimulated emission cross-section
E
(σP × 10−22 cm2), of the 5D0 → 7FJ (J= 0, 1, 2, 3 and 4) of the Eu3+ doped glasses YABiBS
glasses
Transition
Parameter
BE0.2
BE0.4
BE0.6
BE0.8
BE1.0
5D
λP
Δλeff
AR
E
σP x10-22
576
6.46
0
0
577
8.41
0
0
577
3.76
0
0
577
4.99
0
0
577
4.10
0
0
βR
E
σP x Δλeff
0
0
0
0
0
0
0
0
0
0
σP x τR
λP
Δλeff
AR
E
σP x10-22
βR
E
σP x Δλeff
0
0
0
0
0
589
13.31
60.28
2.80
590
15.35
63.40
2.43
588
11.74
67.51
3.15
588
17.17
64.60
2.14
589
16.36
63.64
2.26
18.5
37.26
18.7
37.30
19.3
36.98
19.0
36.74
18.6
36.97
σP x τR
λP
Δλeff
AR
E
σP x10-22
8.65
7.20
9.00
6.22
6.75
611
14.55
230.43
9.53
611
14.95
239.27
9.72
612
13.99
245.03
11.69
611
14.14
243.27
9.74
612
14.04
236.18
9.86
βR
E
σP x Δλeff
68.7
138.66
69.4
145.31
70.1
163.54
69.9
137.72
69.1
138.43
σP x τR
λP
Δλeff
AR
E
σP x10-22
29.46
28.80
33.43
28.34
29.47
653
12.62
0
0
651
14.35
0
0
651
12.12
0
0
651
15.71
0
0
650
14.85
0
0
βR
E
σP x Δλeff
0
0
0
0
0
0
0
0
0
0
σP x τR
λP
Δλeff
AR
E
σP x10-22
βR
0
0
0
0
0
697
15.83
32.65
2.58
698
23.43
34.78
2.86
700
14.05
36.89
8.35
701
16.16
35.89
2.84
699
17.71
34.63
2.36
10.0
10.3
10.5
10.3
10.0
7F
0→
0
E
5D
7F
0→
1
E
5D
7F
0→
2
E
5D
7F
0→
3
E
5D
7F
0→
4
ACCEPTED MANUSCRIPT
σP x Δλeff
E
40.84
67.00
117.31
45.89
41.79
σP x τR
E
7.97
8.47
23.88
8.26
7.05
Table -10: Experimental (avg), Calculated (rad) lifetimes, Quantum efficiency (η) and
Non- radiative relaxation (WNR) of the Eu3+ doped glasses YABiBS glasses.
Glass
Sample
BE0.2
τavg(ms)
τrad (ms)
η (%)
WNR
1.515
3.092
48.99
336.6
BE0.4
1.506
2.963
50.82
326.5
BE0.6
1.497
2.860
52.34
318.3
BE0.8
1.484
2.910
50.99
330.2
BE1.0
1.421
2.989
47.54
369.1
Table-11: The CIE 1931 chromaticity color coordinate (x, y), and Correlated Color
Temperature (CCT, K) of the Eu3+ doped YABiBS glasses
The chromaticity
coordinates
CCT(K)
BE0.2
x
0.605
y
0.339
1996.19
BE0.4
0.617
0.330
2341.18
BE0.6
0.661
0.301
4276.27
BE0.8
0.647
0.312
3430.56
BE1.0
0.635
0.318
2960.45
Glass
Документ
Категория
Без категории
Просмотров
1
Размер файла
2 237 Кб
Теги
molstruc, 057, 2018
1/--страниц
Пожаловаться на содержимое документа