close

Вход

Забыли?

вход по аккаунту

?

Electrical Conductivity and Formation of Chalcogenide Glasses in GeЦAsЦSe and GeЦSbЦSe Melts.

код для вставкиСкачать
(C6H5)3PO t o solutions of Pb(OCOCH&t in benzcnc Jecomposes when its isolation is attempted. From the analytically determined atomic ratio P b : P = 1.00:0.93 and ligand
Lxchange with H3P04 t o give Pb(HzPO4)j (CsHs)3PO, how3ever, it can be concluded that the yellow primary product is
the 1 : 1 adduct Pb(OCOCH3)4. (CgH5)3PO, which also had
not previously been described.
Received: J u l y 2 3 , 1968
[Z 883 IEI
German version: Angew. Chem. 80, 1031 (1968)
Figure 1 shows the atomic distribution cuIvcs at 620 (supercooled), 670, and 830 "C. Maxima can be recognized at r %
n . 3.03 A where n a 1, 2, 3, 4, 5, and 6; there is also a welldeveloped maximum at r * 1'2 ' 3.03 .&
HoAe/rrann1)1 recently drew attcntion to t h e micellar structure of metallic melts. Accordingly antimony melts may be
composed of double layers of limited extension as they can be
cut out of a primitive cubic structure parallel to (100) (Fig. 2).
[*I Priv.-Doz. Dr. F. Huber and Dipl.-Chem. M.
S. A. El-Meligy
Institut f u r Anorganische Chemie und Elektrochernie
der Technischen Hochschule
51 Aachen, Professor-Pirlet-Strasse1 (Germany)
[l] A . WuIchinson and W. Pollard, J. chem. SOC. (London) 6Y,
212 (1896).
[2] K. Elbs and R . Nubling, 2. Elektrochern. angew. physik.
Chern. 9, 776 (1903).
[3] H. Bode and E. Voss, Elektrochim. Acta 6, 11 (1962).
[4] F. Huber and M . S . A . El-Meligv, Z. anorg. allg. Chem., in
press.
Structure of Molten Antimonyl**I
By H . U . Gruber and H . Krebs[*I
The intensity distribution of Mo radiation scattered at a free
surface of molten antimony has been measured with great
accuracy by a Bragg-Brentano type camera followed by bent
quartz crystal monochromator
and discriminator. The
melt was placed in a quartz cuvette with a lustrous carbon
window capable of being heated. The measured intensities
were normalized by Hosemann's empirical procedure[*].
Fig. 2. Schematic representation of the atomic arrangement in molten
antimony.
The atomatic distances are probably not equal within these
double layers, but they alternate, as in the structures of black
phosphorus or GeSr41. The double layers may be arranged
one on the other, as in GeS, since antimony has a strong
tendency to take part in PO bonds and sp hybridization is
diminished (41. In Figure 2 one possibility of lateral bonding
of the double layers is indicated.
The great mobility of the atoms in the melt probably arises
from the easy exchange between bilateral p a bonding and
unilateral sp hybrid bonding, so that a mesomeric bond is
readily broken on one side and strengthened o n the otherC41.
Received: August 21, 1968
[Z 884a I€]
German version: Angew. Chem. 80, 999 (1968)
~
. . .
[*I Dr. H. U. Gruber and Prof. Dr. H. Krebs
- -"
"Q
11
12
13
1L
15
16
17
18
19
20
Institut fur anorganische Chemie der Universitat
7 Stuttgart N, Schellingstrasse 26 (Germany)
[**I Cf. H. U. Gruber, Dissertation, Universitat Stuttgart 1968;
H. U . Gruber and H. Krebs, 2. Naturforsch., in press.
[l] H. Krebs, H. Weyand, and M . Haucke, Angew. Chem. 70,
468 (1958).
[21 Cf. H. Krebs, N. Bernhardt, H. Thurn, and H. Welte, 2. anorg. allg. Chem. 357, 247 (1968).
[3] R. Husemnnn, unpublished.
141 Cf. H. Krebs: Grundziige der anorganischen Kristallchemie.
Enke, Stuttgart 1968; translated by H . P . L. Walter: Fundamentals of Inorganic Crystal Chemstry. McGraw-Hill, London 1968.
Electrical Conductivity and Formation of
Chalcogenide Glasses in Ge-As-Se and
Ge-Sb-Se Melts[**]
By R. W. Huisty and H . K r e b s [ * ]
Fig. 1. Atom distribution curves f o r molten antimony. For r values
> 1OA only the deviation from the statistical distribution- the scale
increased by a factor of 5 - is shown.
Angew. Chem. internat. Edir. 1 Vol. 7 (1968) / N o . 12
A high-polymeric glass can be formed from a melt only if a
large portion of bivalent atoms (e.g., 0, S , Se, or Te) or
atomic groups (e.g., CH2) with a bond angle < 180'' is
present, allowing a n irregular type of bonding[l21 and thus,
together with slight thermal dissociation, a certain mobility
of the atoms in a viscous melt. If the starting material c o w
tains too many tervalent (e.g., P, As, or Sb) and quadrivalent
atoms (e-g., Si or Ge), dissociation processes d o not lead t o
sufficient mobility of the atoms t o permit a molten liquid
state. In this case the melting process must be connected with
a complete change in the bonding system. As in molten
germanium, the coordination number 6 should be approached,
since then, as with germanium, mesomeric p a bonding is
possible. As a result metallic conductivity should occur and,
in addition, the atoms then would be highly mobile, since by
947
local conversion into unilaterally binding sp hybrid quantum
states bonds can be broken easily while others are strengthened[2,31. The high mobility of the electrons, and thus of the
atoms themselves, should lead to great reactivity of the
atoms and hence to crystallization of the melt.
These relations were verified experimentally for thc systcms
Ge- Sb-Se and Ge--As-%. The electrical conductivity
could be measured up t o high temperatures by a new, very
rapid, electrodeless method 141.
Figure 1 shows the glass-forming region for slow and rapid
cooling in the system Ge-Sb-Se. Glass-forming melts are
Far
semiconducting, with a wide forbidden zone (symbol 0).
Ge
[*I Dr. R. W. Hnisty
Texas Instruments Inc.
Dallas, Texas 75222 (USA)
Prof. Dr. H. Krebs
Institut fur anorganische Chemie der Universitat
7 Stuttgart N,Schellingstrasse 26 (Germany)
I**]
Ct'. R. W . Ifaisty, Dissertation, Universitat Stuttgart, 1968;
R . W. Haisty and H . Krebs, J. non-cryst. Solids, in press.
111 H. Krebs, Angew. Chem. 78, 577 (1966); Angew. Chern. internat. Edit. 5, 544 (1966).
[2] H. Krebs: Grundziige der anorganischen Kristallchemie.
Enke, Stuttgart 1968; translated by H. P . L. Walter: Fundamentals of Inorganic Chemistry. McGraw-Hill, London 1968.
[ 3 ] H . Krebs, V. B. Lnzarev and H. Winkler, Z. anorg. allg.
Chem. 352, 277 (1967).
[4] R. W. Haisty, Rev. sci. Instruments 38, 262 (1967); 39, 778
(1968).
[ 5 ] R. J . Patterson and J . M . Brau, Paper, Electrochem. SOC.
Meeting, Cleveland, Ohio, 1966.
Formation of Electron-donor-acceptor Complexes
as a Basis for Specific Adsorption
By H. Stetter and J. Schroeder [ *I
Fig. I . Glass-forming region in the system Ge-Sb-Se on slow (-)[51
and rapid (- - -) cooling. Typical electrical conductivity curves for the
compositions 1,2,3, and 4 are reproduced in Fig. 2.
We have begun a study of whether the formation of electrondonor-acceptor complexes can be used for specific adsorption
in the chromatography of compounds of high molecular
weight [I]. The most suitable substrates proved t o be cellulose
esters of 3-(pentamethylpheny1)- (1) and 3-(9-phenanthryl)propionic acid (2) [*I, which can be prepared from mercerized
cellulose and the chlorides of the two acids [31. Each glucose
unit could be erterified with 2-3 equivalents of the acid.
outside the glass-forming region the melts have metallic conHowever, relatively high but non-metallic conductivity .).(
ductivity (@) i s found in a transition region; there the melts
seem to be biphasic in microregions, containing metallic
lo7,
-
-
1000800 600
t I"C1
400 300
200
The new cellulose esters permit appreciably better separation
of aromatic nitro compounds and of quinones than is possible
on commercial cellulose powder or silica gel (Figs. 1 and 2).
I
/
do'o,
10-l
I"
0
0
OO
00
0 0 0 0 0
a
Fig. 2. Electrical conductivity of Ge-Sb-Se
compositions 1,2,3, and 4 (cf. Fig. 1).
melts - curves for the
conducting micelles (enriched in Ge and Sb) within a semiconducting matrix (enriched in Se). Crystallization of antimony-containing selenium melts is made easier by a catalytic
influence of the antimony.
IZ 884b IEI
Received: August 21, 1968
German version: Angew. Chem. 80,999 (1968)
948
0 0 0 0 0
b c d e l i a b c d e
2
3
Fig. I .
Thin-layer chromatogram of (a) rn-nitrotoluene. (b) p-nitrotoluene, (c) 2.4-dinitrotoluene, (d) 2,4,6-trinitrotoluene. (e) mixture.
1 = M N silica gel, 2 = cellulose estel of ( I ) , 3 = cellulose ester of ( 2 ) .
Eluant: etherllight petroleumlacetone 50:40: 10. Color of the complexes:
yellow-red.
Moreover the position of the substances o n the plate can b e
easily determined by the color of the donor-acceptor complexes formed. We consider this principle of specific adsorption 10 be capable of extension.
Angew. Chem. internat. mit. Vol. 7 (19681 / N O .12
Документ
Категория
Без категории
Просмотров
0
Размер файла
201 Кб
Теги
geцsbцse, chalcogenide, geцasцse, melt, formation, glasses, electric, conductivity
1/--страниц
Пожаловаться на содержимое документа