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Piezoelectric ceramic material including manufacturing method and application
FIELD OF THE INVENTION This invention relates to new piezoelectric ceramic compositions,
methods of preparation of piezoelectric ceramic materials and their specific use. (Prior Art) A
piezoelectric material is a material that generates a voltage when a mechanical stress is applied
thereto. Also, when a voltage is applied to the piezoelectric material, deformation of the material
occurs. The measure of piezoelectric activity includes the "d" factor, which relates to the charge
and strain of the material. It is desirable to maximize this factor. Perhaps the most promising
group of piezoelectric materials is the complex niobate group with perovskite or tungsten bronze
structure. This class of material exhibits excellent electrical properties as a single crystal.
However, using single crystals for many ceramic applications is not practical. To date, no one has
prepared a satisfactory polycrystalline material of ferroelectric probcite which exhibits the best
piezoelectric performance using standard ceramic technology. The reason is that in addition to
the desired perovskite phase, a non-piezoelectric phase harmful to the electrical properties of the
ceramic is formed. Polycrystalline ceramic materials will exhibit a piezoelectric effect if the
material is anisotropic. In practice, polycrystalline piezoelectric materials are fabricated by
heating the polycrystalline material to a temperature not well below the material's Curie
temperature (Tc) and then cooling in the presence of a strong electric field. This procedure
causes the dipoles of polycrystalline material that are otherwise randomly oriented to have a
final distribution of positive and negative charges (i.e., dipoles) within the polycrystalline
material. Well known piezoelectric materials include barium titanate, lead titanate, PZT (lead
zirconate titanate) and lead niobate. The piezoelectric effect was discovered at the end of the
19th century and was observed to occur in naturally occurring crystals such as quartz and
Rochelle salt. However, the polycrystalline ceramic materials described above have attracted the
attention of many researchers, and in recent years there has been continuous improvement to try
to optimize their electrical and physical properties. Polycrystalline ceramic piezoelectric
materials are of interest for acoustic transducers (eg microphones and alarms), high power
ultrasound generators (eg sonar and ultrasonic cleaning), pickups and sensors (eg record
players), It is because it is used for applications, such as a resonator and a filter (for example,
radio and television). The reason for the great interest of polycrystalline ceramic piezoelectric
materials is that such materials are shaped and formed into various shapes and sizes before
being polarized (polarized) and the final desired for polycrystalline ceramic materials. It is easy to
give the orientation of the dipole.
Furthermore, ceramic piezoelectric materials generally incorporate all the mechanical properties
of ceramics, ie high compressive strength, good chemical resistance, etc. PZT is probably best
known among the ceramic materials mentioned above (it is mentioned that PZT is a binary
mixture of lead zirconate and lead titanate). The PZT mixtures are used in all of the various
applications described above, with slight variations in composition to suit each particular
requirement. Attempts have been made to optimize the electrical performance of PZT ceramics as
well as the electrical performance of other ceramic composites. Electrical properties of this type
include dielectric constant (K), aging (ie, degradation of piezoelectric performance over time),
coupling coefficient, and the like. However, it has also been discovered by many others that the
best in one or more of the above properties adversely affects other performance. Therefore,
many researchers are continuing to study optimal polycrystalline ceramic piezoelectric materials.
One of the many important applications of polycrystalline piezoelectric ceramics is as a
hydrophone equipped on submarines for anti-submarine warfare. In particular, piezoelectric
materials are used in metrology and passive hearing devices in submarines. When a piezoelectric
material is used as a hydrophone, gh (voltage coefficient), d33, d31 (piezoelectric strain
coefficient in different crystal axis directions), dh (bulk elastic modulus, where dh = d33 + 2d31),
and dhgh Piezoelectric properties, such as the figure of merit related to sensitivity) are all
important. Also, in the hydrophone, it is desirable to increase the values of dh, dhgh and K as
much as possible. In particular, although efforts have been made to maximize dh, known dh
values of ceramic only are insufficient for use in new sonar hydrophones such as wide-aperture
and towed arrays. Furthermore, gh = dh / ε0 K, and K must be large values. For example, if the
value of K is large and the piezoelectric material is electrically connected to an amplifier, cable or
the like, then an inexpensive (i.e. less complex) preamplifier can be used. However, if the value of
K is relatively small, expensive (i.e., complex) preamplification devices are required. Furthermore,
the figure of merit must also be large enough. Also, gh must also be relatively large, but typical
ceramic compositions can not simultaneously maximize both gh and K. Thus, to enhance both dh
and gh, a composite material must be formed.
If the value of dhgh is too low, the sensitivity of the hydrophone is insufficient for the intended
purpose. The performance factor is particularly important as current submarines are much
quieter than previous generations and use acoustic / magnetic / electrical signature reduction
techniques. For this reason, sensitive acoustic devices are needed as an alternative to submarine
detection. Various manufacturing methods are also known for forming polycrystalline ceramic
piezoelectric materials. Among the production methods of this type, there are conventional
methods of mixing oxides, molten salt synthesis of PZT materials disclosed by Ardent et al. (US
Pat. No. 4,152, 281), and Woodhead et al. Has disclosed a method of producing (US Patent No. 3,
725, 298). However, many researchers continue to study the preferred process for producing the
desired polycrystalline piezoelectric ceramic material. Efforts are also being made to synthesize
single crystal materials such as PZT and PZN-PT (ie lead zinc niobate-lead titanate). However,
although various piezoelectric parameters for PZN-PT single crystals are known, to date, few
studies have been conducted on PZN-PT polycrystalline ceramic materials. SUMMARY OF THE
INVENTION The present invention was made from the above point of view and to overcome the
drawbacks of the prior art. It is an object of the present invention to provide a novel
polycrystalline ceramic piezoelectric composition in which the electrical properties of the
material are the best. It is also a future aim to provide a manufacturing method to obtain the
desired reliable stoichiometric composition of the new piezoelectric material. Still further, a
further object of the invention is the use of the new piezoelectric material in combination with
other materials (eg to form a composite material), whereby hydrophones, robotics, contact
pattern recognition sensors, ultrasound It is to be able to use for applications, such as a
transducer. The main focus of the study was lead zinc niobate-lead titanate (PZN-PT). The solid
solution of PZN-PT can be doped with barium and strontium by replacing lead (P) at the "A"
positive ion location in PZN-PT with a small amount of dopant such as BaTiO3 and SrTiO3. It can
be formed. It is desirable to perform synthesis near the shape boundary in the PZN-PT system.
Furthermore, the conventional oxidation-sintering method to form a new PZN-PT composition is
We will also clarify the sol-gel method for obtaining a novel PZN-PT composition closer to the
type boundary. The desirable use of the sol-gel method is the fine size (small) size of the particles
produced due to organic precursors (usually metal alkoxides) which allow synthesis at low
temperatures and do not have harmful non-piezoelectric phases, and powders Is homogeneous.
Thus, the improved piezoelectric material can be obtained using a sol-gel method. The novel
composition and process make it possible to produce PZN-PT materials based on perovskites
which contain small amounts of barium titanate or strontium titanate as stabilizers. It has been
determined that the composition of PZN-PT can be made very close to the shape boundary,
which allows both the piezoelectric coefficient value and the dielectric constant to be maximized
simultaneously. (Means for solving the problems) a. Composition of New Piezoelectric Material
FIG. 1 shows a ternary phase diagram for the system PZN-PT-BT and the system PZN-PT-ST. The
reference letter "M" indicates the projection of the type boundary of the system. The respective
compositional points represented by the numerical values 1 to 11 are shown in the following
Table 1. <img class = "EMIRef" id = "202827445-00002" /> Barium titanate (BaTiO3) and
strontium titanate (SrTiO3) are the best dopants to be added to the binary component of PZN-PT
to stabilize the system It was confirmed that barium titanate gave slightly better results than
strontium titanate. Experimental Procedure The composition of the ceramic identified in Table 1
and revealed in Figure 1 was obtained by the following procedure. Puratronic grade oxides were
fully ground in a jar and calcined at temperatures of 800 ° C. and 1000 ° C. for 2 hours each.
The calcined powder was ground in a mortar and compressed at 45,000 psi (without binder) on
average. The pellets were sintered in an open crucible at a temperature of 1050 ° C. for 1 hour.
In Figures 2 and 3, for compositions 1, 2, 4 and 5, when these compositions are calcined at 800
° C, they are calcined at 800 ° C when calcined at 1000 ° C. The content of pebroskite formed
when sintered at ° C., and calcined at 1000 ° C. and sintered at 1050 ° C. is indicated.
The dopant used in the case of FIG. 2 was SrTiO 3, and the dopant used in the case of FIG. 3 was
BaTiO 3. Of all the compositions tested, compositions # 4 and # 5 have the highest content of
perovskite and the best electrical properties. The content of pebroskite present was determined
from the following equation. Pebroskite content (%) = Iperov / (Iperov + Ipyro) Here, Iperov is the
intensity of the main X-ray diffraction peak for the perovskite, and Ipyro is the intensity of the
main X-ray diffraction peak for the pyrochlore. Figures 2 and 3 show that as the composition
approaches the shape boundary and thus approaches pure PZN (ie composition # 1 to # 2,
composition # 4 to # 5) the perovskite loses stability during sintering It has been shown to be a
pyrochlore phase. The samples corresponding to the compositions # 1 and # 2 (containing 20
and 10 mol% of the dopant, respectively) had high contents of the perovskite and poor electrical
characteristics. Table 2 shows the values of d33 and K (max) for compositions 1, 2, 4 and 5,
respectively. <img class = "EMIRef" id = "202827445-00003" /> Since the combination of
properties that occurs with compositions # 4 and # 5 is preferred, these compositions were
studied in more detail. For these particular compositions, the study was limited to BaTiO3 as the
dopant. Composition # 4 and # 5 of stoichiometrically mixed starting powders of Puratronic
grade (99.999 +%) PbO, ZnO, Nb2O5, TiO2 and BaCO3 (SrCO3 can be used if Sr is the dopant)
(0.855 PZN-0.095 PT-0.05 BT and 0.873 PZN-0.097 PT-0.03 BT) were obtained. The powder
mixture was wetted with freon until homogeneous and ground. The wet ground powder was then
dried and calcined at 800 ° C. for about 4 hours in a closed platinum crucible. The calcined
powder was then re-wetted and ground to fine grains. The second calcination took about 40
minutes, and the average size of the particles in the material was about 10 microns. Next, 3% by
weight of PVA (manufactured by Air Product # 205) binder was dissolved in distilled water. The
calcined powder was then added to form an aqueous mixture. The mixture of powder and binder
was heated and stirred on a hot plate until all the water was evaporated.
The temperature of the hot plate was about 95 ° C. and the time was about 6 hours. The dried
product was then ground to -100 mesh and die pressed at a pressure of about 5000 psi to finish
into pellets. The pellets were then pressed to an average of about 45,000 pri. The averaged
pressed pellets were compacted to a powder of essentially the same chemical composition as the
pellets. Next, when the powder mixture of pellets is sealed in an alumina crucible and heated, the
atmosphere generated in the alumina crucible is the same in chemical composition as that of the
crucible, whereby lead etc. This step is important because it prevents the evaporation of the
elements of Al and thus the deviation of the composition of the ceramic from the stoichiometric
relationship. The alumina crucible was then heated to reach 600 ° C. at a heating rate of about
40 ° C. per hour to drive off the binder. The pellets were then heated to a temperature of about
1050 ° C. at a heating rate of 900 ° C. per hour. The pellets were maintained at this
temperature of about 1050 ° C. for about 1-2 hours, followed by furnace cooling. The density
range of composition # 4 is 7.45-7.53 g / cm <3>, the density range of composition # 5 is 6.917.10 g / cm <3>, and the theoretical density is about 8.24 g / cm <3> Met. The lower density in
composition # 5 was due to the formation of the picurol phase. The weight loss during sintering
was determined to be about 3.2% by weight, of which 3% by weight was the binder. X-ray
diffraction analysis of the finished material demonstrated that composition # 4 was 100%
perovskite, as shown in FIG. 4 herein. The X-ray diffraction analysis pattern of composition # 5 is
shown in FIG. The sintered pellets were then thinned to a disc having a thickness of 1-4 mm, and
then the disc was coated with silver to form an electrode. The Curie temperature for Composition
# 4 was determined to be 175 ° C., and the Curie temperature for Composition # 5 was
determined to be 160 ° C. The Curie temperature was determined by volumetric measurement
in a silicone oil bath at a temperature range of 25 ° C-200 ° C. SED-EDS analysis was used to
determine the stoichiometry of the sintered pellets corresponding to compositions # 4 and # 5.
In particular, in Table 3 listed here, theoretical values and average values are shown together
with the analysis results obtained at 10 different points of the pellet. <img class = "EMIRef" id =
"202827445-00004" /> <img class = "EMIRef" id = "202827445-000005" /> Next, all the
samples are samples in a light inert oil such as silicone oil And heated in the typical manner of
heating to
The sample was exposed to an electric field of about 2 kV / mm for 20 to 60 minutes. The
samples were then aged for several days. The peak value of d33 measured for composition # 4
immediately after polarization was 745 × 10 <-12> C / N, and for composition # 5 was 549 ×
10 <-12> C / N. The electrical data obtained after appropriate aging are shown in Table 4. In
composition # 4, a high dielectric constant value of 3252 was obtained. <img class = "EMIRef" id
= "202827445-000006" /> Also, the electrical properties of the novel compositions # 4 and # 5
have been raised here in comparison to the known electrical properties of other materials It is
shown in 5. <img class = "EMIRef" id = "202827445-000007" /> As apparent from Table 5, the
composition obtained this time, in particular, composition # 4 has an electrical property superior
to that of the known composition. ing. In particular, for composition # 4, the hydrostatic
piezoelectric strain coefficient (dh) is far superior to that of the known composition, and both the
coefficient of performance (dhgh) and d33 (piezoelectric strain coefficient) are extremely good.
Therefore, although the novel composition # 4 has 10 times the sensitivity of the PZT material,
the high dielectric constant also reduces the loss of electrical signal when connected to a
preamplifier or cable. Thus, composition # 4 has properties superior to any of the previously
known composite ceramic materials. ロ. Preparation of New Piezoelectric Material by Sol-Gel
Method It was discovered that the sol-gel method treatment of the above-mentioned piezoelectric
material can produce almost 100% perovskite PZN-PT structure from 30 mol% PT (without
doping). It was previously known that such a 100% perovskite structure was present at only 50
mole% PT. The reason why this difference of about 20% by mole of the present amount of PT is
made possible is that only conventional oxide sintering techniques were used before. Therefore,
it is apparent that the amount of the perovskite phase can be improved by using the sol-gel
processed powder. Since this was confirmed, it was tried to adjust the parameters such as
sintering temperature, sintering time, heating rate and addition of dopant to make the ratio of the
existing perovskite as large as possible.
It was surprising that this 100% probscite was found, since ordinary skilled workers would
normally expect not less pyrochlore to be present at concentrations of lead titanate (PT).
However, special treatment steps have to be taken to get 100% probscite. Metal organic
precursors for producing solid solutions of PZN-PT, including those doped with barium,
strontium and BaTiO3 (BT), include lead acetate, zinc acetate, niobium isopropoxide (niobium
isopropoxide) and isopropoxide titanium ( prepared by the scientific reaction between titanium
isopropoxide). Reagent grade lead acetate, zinc acetate and titanium isoproxide were purchased
from commercial sources. Isoproxide titanium was prepared by reacting niobium pentachloride
with isopropanol in the presence of anhydrous ammonia. Solutions of barium and strontium were
made by dissolving these pure metals in 2-methoxyethanol. The appropriate molar amounts of
lead acetate and zinc acetate were dissolved in 2-methoxyethanol in a reaction flask and remelted
at a temperature of 120 ° C. with constant stirring for about 2 hours. Instead of remelting it can
also be heated in an open vessel. The main purpose of this heating is to drive off all water and
acetic acid. However, when heating in an open vessel, it may be necessary to add 2methoxyethanol so that the mixture does not dry out. A typical heating time is 1-2 hours under
constant stirring conditions, and the mixture is heated to approximately the boiling point of the
alcohol (ie, 120 ° C.). It is important to perform the heating (i.e., remelting and heating in the
open vessel) for a sufficient amount of time to remove all the acetate from the mixture. It is
desirable to add isopropanol if either remelting or heating in the open container. If all acetate is
removed and not placed at this point, undesirable intermediates result and prevent the formation
of the desired ceramic composition. After removing all the acetate, the solution is cooled to about
room temperature and appropriate amounts of isopropoxide niobium and titanium are added to
the mixture. The resulting solution is clear and must be remelted at 120 ° C. for about two more
hours and then cooled to room temperature. When using a barium or strontium dopant, it is
important to add the barium or strontium after the reaction mixture is cooled, as heating after
the addition of barium or strontium results in undesirable precipitation.
The mixture is then gelled by slow addition of a mixture ranging from 7: 3 to 8: 2 by volume ratio
of 2-methoxyethanol and water. The clear gel is then air dried for 1-2 weeks and then placed in
vacuum at 50 ° C. The dried gel is then broken up into powder and heated slowly to 500 ° C.600 ° C. to decompose and remove all organic matter. The powder is then finely ground and
compacted into pellets which are then sintered in air for 15 minutes to 2 hours at a temperature
of 900 ° C.-1100 ° C. The composition of the phase of the pellet is then determined by X-ray
diffraction. The sintered pellets are then cut into wafers of about 1.5 cm diameter and 0.7-2 mm
thickness. The wafer is then ground to a flat, silvered and electroded, and polarized in a silicone
oil bath for about 15 minutes with a 1-2 kV DC electric field. The electrical properties such as
d33 and dielectric constant (K) are then measured using a d33 meter and an impedance analyzer,
respectively. It should be noted that the relative amount of perovskite was determined from the
ratio of the peak of perovskite (110) and the peak of pyrochlore (222) as described above. FIG. 6
shows four different X-ray diffraction patterns for different compositions of PZN-PT-XT (where X
= Ba or Sr). In addition, Table 6 lists the amounts of lead and substituted dopants in solid solution
of composition 0.9 PZN-0.1 PT. The x-ray diffraction image is taken before the wafer is polarized.
<img class = "EMIRef" id = "202827445-000008" /> As can be seen from this table, the
substitution of 5 mol% of barium for lead in PZN results in about 90% of prosquikite, so A
composition virtually free of pyrochlore is obtained. The same tendency is seen when lead is
replaced with strontium. As shown in Table 7 below, PZN-PT materials containing the abovedescribed optimized compositions # 4 and # 5 can also be used as PZN-PT-BT materials if the
sintering temperature, sintering time and heating rate are different. Both have different effects.
<img class = "EMIRef" id = "202827445-000009" /> As apparent from Table 7, in each of the
compositions # 4 and # 5, about 100% of the perovskite phase can be obtained.
Thus, it has been shown that the formation of the perovskite phase is greater than anything
previously done by sol-gel processing of PZN-PT solid solutions. Phase stability is further
enhanced by replacing part of the lead with barium or strontium. It can be seen that the electrical
properties correlate with the amount of perovskite phase and depend on the nature and amount
of the dopant. By optimizing the parameters of sol-gel treatment, sintering treatment and amount
of dopant, a solid solution of PZN-PT without pyrochlore near the typical phase boundary is
obtained here. ハ. Composite Piezoelectric Hydrophone The above-mentioned piezoelectric
material can be used for use as a passive sonar passive hearing device (hydrophone) for a
submarine. If this piezoelectric material is to be used in a wide aperture array (WAA) or a new
conformal sonar array (ACSAS) for submarines, it is desirable to combine the piezoelectric
material with a polymer material. A typical WAA is shown in FIG. 7 by the numeral 4 while a
typical ACSAS is shown by the numeral 5 in FIG. The use of a composite hydrophone is highly
desirable because the ceramic piezoelectric materials described above have high values of dh and
d33. Furthermore, because of the high dielectric constant, the final electrical constant, ie, the
capacitance of the composite structure, can be placed fairly sparsely without being significantly
reduced. The large anisotropy already present in the piezoelectric strain coefficient (d33, dh) can
be further enhanced with the appropriate connectivity of the composite. This new material shows
the best behavior in the 3-1 connection number by Newman notation. In this type of composite,
the active phases (ie PZN-PT) are connected in one dimension, ie in the direction of thickness,
while the polymer matrix is connected in three dimensions. A 3-1 composite is shown in FIG. 9,
where the composite is indicated by the numeral 1, the ceramic piezoelectric material by the
numeral 2, and the polymer (ie the polymer matrix) by the numeral 3. 3When -1 connection is
used, the electrical properties of the composite can be determined by the following equation.
Kavg =% ceramic x K ceramic d33 avg = d33 ceramic d31 avg =% ceramic x d31 ceramic dh avg =
d33 avg + 2 (% ceramic x d33 ceramic) gh avg = dh avg /% ceramic x Kavg Formation procedure
of these 3-1 composites It will be as follows if it says. 3Two different procedures for -1
composites were developed primarily by studies conducted at the Materials Research Laboratory
at Pennsylvania State University.
In one approach, piezoelectric bars were extruded and the bars were presintered but not
polarized. Varying the location and number of holes as well as the diameter of the rods were
used to vary the proportion of the volume of the active phase in the composite. This approach
required great effort and was required to extrude and heat treat the ceramic bars before making
the composite. The well known technique known as "dice and fill" is well suited to the fabrication
of laboratory scale prototypes, and was used here. In the die and fill method, a block made of a
single sintered ceramic material was tacked to a machined metal block using a “crystal bond”
resin, which was a resin that softened at about 90-120 ° C. . Typical dimensions of the
cylindrical ceramic block were in the range of 10-20 mm in diameter and about 4 mm in
thickness. The sample was first rotated 90 ° into the block using a high speed precision grinder
and a thin diamond impregnated blade to make a one-dimensional cut in the direction
perpendicular thereto. This cutting was to leave about 1 mm of solid ceramic to support the bar
being sheared off most of the thickness of the material. Diamond blades of various widths were
used, and the position between each cut, ceramic bar, or "pillar" was changed to perform various
steps of polishing so that various thicknesses and intervals remained. The sample was cut into
ceramic pillars between 0.5 and 1 mm wide at intervals of about 0.5 to 2 mm using a blade
between 0.015 and 0.05 inches in thickness. These changes were realized by changing the
volume fraction of the active piezoelectric in the inert polymer matrix. After grinding the ceramic
block, it was removed from the tacked metal block and was rinsed and then ultrasonic cleaned
first in acetone and then in freon to remove any crystal bonds. This procedure thoroughly
degreased the ceramic (ie, removed the cutting oil during high speed polishing). ) The ceramic
was then dried at about 100 ° C in an oven. Heating should be minimized if the ceramic block is
polarized prior to grinding, in which case the sample should be peeled off by immersion in
acetone rather than by heating, and samples that have been cut will be vacuum furnaces It
should be dried for several hours at a temperature of about 60 ° C. The ground ceramic is then
placed in a metal or plastic mold and epoxy powder is poured around the sample. Spurrs epoxy, a
material that was originally used to cast biological samples, can change its compliance primarily
by changing its component ratio due to its low viscosity (ie 4 part epoxy) Because of this, it was
successfully used as a matrix material.
The sample and the uncured epoxy were placed in a vacuum chamber and the system was
evacuated until no bubbles came out of the ceramic pieces (ie, the ceramic was impregnated with
epoxy). The epoxy was then cured at approximately 60 ° C. for about 6 hours according to the
manufacturer's instructions. The hardened epoxy block with the ceramic pieces was scraped until
the ceramic rods came out, and the solid ceramic base holding the rods was cut or scraped off. A
combination of techniques including rock sectioning, low speed diamond sawing and abrasive
grit handling was used to cut off excess epoxy. 3The -1 polymer-ceramic material is now coated
with a silver-containing paint on the surface to make it electrode, then it is polarized if it is not
polarized before cutting. As a result of measuring the piezoelectric constant, d33, it was found
that the ceramic rod embedded in the composite had a lower value of d33 as compared to a
single piece of ceramic which was similarly polarized. Values for ceramics in composites tend to
be only about 75% of the values for solid pieces. Several theories are thought to be able to
explain this behavior, among which there is an unexpected voltage gradient of the electric field
during polarization in the composite and that the piezoelectric element is subjected to
confinement stress from epoxy Although it is conceivable, the detailed mechanism that produces
this behavior is not yet understood. It is known that the best hydrostatic piezoelectric properties
are obtained when the top and bottom surfaces of the composite (i.e. the electrode end faces
perpendicular to the rod) are clamped with a thin metal plate. The brass plate was then glued to
the composite using silver-plated conductive epoxy. A greater improvement was seen as this
procedure improved the dh coefficient and the volume fraction of the ceramic decreased. For
example, when using a brass plate, the value of dh for a 35% by volume composite increased
from 55 to 85 pC / N, and from 15 to 15% by volume from 5 to 160 pC / N. Table 8 shows the
electrical properties of the simple substance and the composite material into which 5%, 15% and
35% of PZN-PT corresponding to composition # 4 is added. 10A and 10B show composites
containing ceramic piezoelectric materials corresponding to composition # 4 of 35% and 15%,
respectively. <img class = "EMIRef" id = "202827445-000010" /> It is clear that the 15% ceramic
3-1 composite has the highest dhgh and dh values among the three composites. .
Furthermore, when the value of dhgh is compared with the known value of the piezoelectric
material alone currently used in hydrophones, the value of dhgh is four times larger and the
relative dielectric constant K is twice that of the known one. Thus, a 3-1 composite containing
15% ceramic yields very desirable properties. 3-1 The exact mechanism by which the composites
enhance the electrical properties is not well defined and further research is needed. Variables
affecting the composite material include the degree of adhesion of the polymer to the ceramic
rod, the stiffness of the polymer matrix, the volume fraction of the active element and the
inactive stiffening element including internal elements such as metal electrodes and glass rods.
While the present invention has disclosed preferred embodiments thereof, the present invention
is not limited to the details of the content set forth herein, and various modifications may be
made without departing from the scope of the invention as defined in the appended claims.
Modifications, modifications and improvements that can be made by those skilled in the art are
also included. BRIEF DESCRIPTION OF THE DRAWINGS The details of the invention are explained
by the attached drawings. FIG. 1 is a ternary state diagram of the system PZN-PT- (BT or ST). FIG.
2 shows the relationship between the perovskite formed when SiTiO3 is used as a dopant and the
other composition in percentage. FIG. 3 shows the relationship between the perovskite formed
when BaTiO3 is used as a dopant and the other composition in percentage. FIG. 4 shows an X-ray
diffraction pattern of composition # 4 when BaTiO3 is used as a dopant. FIG. 5 shows an X-ray
diffraction pattern of composition # 5 when BaTiO3 is used as a dopant. FIG. 6 shows four
different X-ray diffraction patterns when X = Ba or Sr with four different PZN-PT-XT
compositions. Referring to FIG. 7, a representative gauge wide-aperture array (WAA) sonar for a
submarine is shown. FIG. 8 shows a new conformal array sonar (ACSAS) for typical hearing in a
submarine. FIG. 9 shows a 3-1 composite material according to the present invention. FIG. 10a
shows a 3-1 composite comprising 35% of ceramic and in FIG. 10b a 3-1 composite comprising
15% of ceramic.
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