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Very pure lead zirconate titanate ceramics were prepared for an accurate determination of the characteristic values of piezoelectric properties. The ceramics were sufficiently matured by using pulverized calcined powders and by sintering with a gradual rise in temperature. Electromechanical activity of the ceramics became maximum when the ceramics were subected to poling at 100°C with a field intensity of 40 kV/cm for 10 min. Deterioration gave rise to the breakdown of ceramics along grain boundaries when the field intensity and the time of poling increased. Breakdown predominated in the ceramics belonging to tetragonal symmetry.Breakdown seems to be caused by a decrease of intergranular binding strength, and this assumption was confirmed by measurement of the bending strength and observation of the fracture.

For laying the basis of production lapping of lead zirconate-titanate ceramics (one of the piezoelectric ceramics), textures, dynamical properties and lapping characteristics are studied concerning the specimens, A (substituted Sr for a part of Pb), B (added Fe to A) and C (added Nb to A). The results obtained are as follows : (1) The properties are A>C>B in grain size, B>C>A in hardness, C>B>A in bending strength and A>C>B in porosity. (2) Lapping characteristics are B>A>C in lapping quantity and lapping force, while best in B for roughness. (3) It is desirable for intermediate lapping to use No. 1500 abrasives of green silicon carbide or white aluminum oxide at a lapping pressure of 0.06-0.1 kg/cm2, and for final lapping to use No. 3000 abrasives.

The kinetics of the gas–solid reduction reactions of high purity dry hydrogen with selected lead compounds and glasses was investigated. Materials studied were PbO, Pb2SiO4, PbSiO3, PbZrO3, PbTiO3, lead zirconate titanate (54/46, Zr/Ti ratio), lead orthosilicate glass, and lead metasilicate glass. A constant pressure (1 atm) hydrogen flow (2 liters per minute) system was used in reacting the powdered materials at specified constant temperatures. The extent of reduction was quantitatively determined by (1) weight loss of the reacted specimen, and (2) dew point of the reaction atmosphere. Expressions are presented for relating both the weight loss and the dew point to the fraction of reduction, a. The activation energies for the reduction reactions were calculated from plots of log h (reaction rate constant) versus 1/T°K. Activation energies obtained were 18.4, 19.9, 21.0, 34.6, 46.5, and 47.0 kcal per mole, respectively, for the first six compounds. The lead glasses, which reacted below their melting ranges, were reduced appreciably less than the lead compounds.

Disturb pulse and fatigue effects have prevented or limited the use of ferroelectric materials as matrix addressed arrays of light valves suitable for optical memories, page composers, displays and printers. These problems can be optically balanced out by building an array of compensators out of a second piece of ferroelectric and applying to the compensator array the same disturb and polarization reversal history that the light valve array receives. Experimental data obtained on a lanthanum doped lead zirconate titanate ferroelectric ceramic shows the effectiveness of the active compensator technique in balancing out the disturb pulse effect. The optical balancing technique is not limited to ferroelectrics, but can also be applied to other optically active materials which do not have an absolute switching threshold and/or decay. The balancing technique can also be used to overcome the problems of elastic switching, which would normally cause light to escape momentarily from a half selected valve.

Two ferroelectric ceramics, Pb (Zr0.52, Ti0.48)O3 with 1 wt % Nb2O5 and pure BaTiO3, were studied under shock wave loading. Plane shock waves having pressures ranging from 2 to 175 kbar were produced by high‐explosive driving systems. Measurements were made with a streak camera and shock‐detecting ferroelectric wafers. Both ceramic materials showed evidence of a two‐wave structure over a wide range of shock pressures. Results indicate that these two‐wave structures are characteristic of the elastic properties of the materials and are not due to phase transitions from ferroelectric to paraelectric. Pressure‐volume Hugoniot curves are presented for both materials. Electrical charge released to an external load by Pb (Zr0.52, Ti0.48)O3 with 1 wt % Nb2O5 was measured as a function of the pressure of a shock which was moving parallel to the axis of polarization. The primary mechanism in this reduction of polarization by shocks was found to be, not a phase transition or domain switching, but merely a reduction ...

Single crystals of the lead zirconate-titanate solid solution containing 85 percent and those containing less than 40 percent of lead zirconate have been prepared from a molten solvent of a mixture of KF and PbF 2 , and the measurements of optical birefringence have been made. They are all optically negative. The absolute value of birefringence of the crystal containing less than 20 percent of PbZrO 3 shows a maximum when plotted against temperature and resembles the behavior of PbTiO 3 . Such an anomalous behavior tends to vanish with increasing amount of PbZrO 3 . These phenomena are explained taking account of the effect of covalent bonding, after the method developed by Kobayashi and Yamada. 1) The contribution of the covalent nature increases at first and then decreases gradually with increasing PbZrO 3 content. The crystal containing 85 percent of PbZrO 3 is in rhombohedral phase and has larger anisotropy than in tetragonal phase.

Studies have been made of the dielectric behavior of several ferroelectric ceramic materials when a two-dimensional stress was applied normal to the axis of polarization. It has been shown that the dielectric constant decreases and the dielectric loss increases with increasing stress, part of the change being irreversible and part reversible. Upon application of stress to a sample, the dielectric constant did not change instantaneously but appeared to decrease linearly with the logarithm of time. Mechanisms are suggested for the observed effects.

Production lapping of lead zirconate-titanate ceramics are dealt with lapping rate, parallelism, yield and machining time including cutting-off time, since ceramics are machined as planeparallel, slender, thin plates in using for relay switches. The results obtained are as follows : (1) The order in lapping rate is A (no additive) >D (added Cr) >C (added Nb) >B (added Fe). Strong specimen C has a yield of 95%. (2) The difference in plate thickness within 10μ and the parallelism of 2μ are obtained from plane-parallel lapping, where the motion of specimens is restricted in carriers. (3) The concentration of lapping vehicle influences on lapping rate only by a factor of 5%. Supplying vehicle at a rate of 150 cc/min is desirable for preventing from breakage of plates. (4) Cut-off thickness is chosen as 0.3 mm regardless of the kind of ceramics. The whole machining time in lapping plates of 0.3 mm thick to 0.2 mm thick is shortened by a factor of about 40% than in lapping plates of 0.5 mm thick.

The effects of one‐dimensional pressure parallel to the polar axis of piezoelectric ceramics have been investigated for a cobalt‐modified barium titanate, NRE‐4, two strontium‐modified lead zirconate titanates, AM‐97 and PZT‐4, and a niobium‐modified lead zirconate titanate, PZT‐5. Pressures up to 10 000 psi had little permanent effect on the polarization and coupling factors of AM‐97 and PZT‐4 but permanently reduced those of NRE‐4 and PZT‐5. The low‐field permittivity decreased initially and then increased with increasing pressure for all materials. At fields up to 3 kV/cm on AM‐97 and PZT‐4, the permittivity and dielectric loss increased severely with pressures to 10 000 psi; the field dependence decreased to approximately constant values independent of the magnitude of the pressure after several hundred hours. Similar measurements on NRE‐4 showed that the changes with pressure and time were not so severe. Changes in the high‐field permittivity and loss due to hydrostatic pressure superimposed on a one...

A polarity effect has been observed in dynamically stressed ferroelectric lead zirconate titanate ceramics Pb0.99Nb0.02(Zr0.65Ti0.35)0.98O3, which depends on the motion of the stress wave relative to the direction of remanent polarization. From the observations it is concluded that p‐type mobile charge carriers are being liberated at the stress front, which in turn are acted upon by local internal fields. This action causes dielectric degradation when the stress wave travels opposite to the direction of remanent polarization. The charge liberation is attributed to a combination of ionization and failure mechanisms. Graham has reported a similar effect in alpha quartz, in which electrons are liberated.

An array of electrically addressed light valves, referred to as a page composer or a pattern generator, is an important component of an optical memory. Ferroelectric and related materials, such as nematic liquid crystals, are attractive candidates for this application. This paper details the geometrical and optical characteristics and the various techniques for addressing a page composer for a holographic optical memory. Experimental data obtained on a nematic liquid crystal and single crystal bismuth titanate are presented. This data is compared with that previously reported for ceramic lead zirconate titanate and single crystal gadolinium molybdate. The major conclusions are that the optimum array is one in which the valves are individually addressed light scatterers. This operating mode is most conveniently achieved with a liquid crystal on an integrated semiconductor chip. The semiconductor circuits can also serve as the photodetector array for the optical memory. However, slow switching limits the us...

The high-field losses of adulterated lead zirconate-titanate ceramics were compared on the basis of rates of temperature rise of standard-size samples in the same transducer configuration. Systematic chemical modification in light of the ionic model of the perovskite structure was used to produce ceramics with widely varying high-field behavior. High-field losses could be greatly reduced by adulteration of either cation site with ions of lower than normal valency. At 1 at.% concentration, lowest losses were found with adulterants whose valence was one unit less than normal. The results are explained as stoichiometric effects. Normal air-fired lead zirconate-titanate ceramics are considered to be deficient in metal tons. Adulteration with subvalent cations reduces the iotal oxygen content of the ceramic and brings it toward true ABO3 stoichiometry. Lowest losses are postulated for truly stoichiometric bodies.

Lead zirconate titanate ceramics with certain 3‐ or 5‐valent additions (lanthanum, neodynium, tantalum, and niobium) are found to be characterized by low aging of electrical and mechanical properties, a well‐defined hysteresis loop, and by high electrical and mechanical losses. Experimental investigations are reported on plain lead zirconate titanate and on a low‐aging niobium modification.The experiments included an electron microscope study of the ceramics and a number of electrical measurements. As a result of the study, the changed properties of the substituted material have been explained as being due to domain wall motion under low electric field. The results of electrical measurements supporting this conclusion, and a hypothesis accounting for the effects in terms of lattice vacancies, are presented.The 3‐ or 5‐valent additives described in the foregoing also cause greatly increased volume resistivity in the ceramic. This has not been satisfactorily explained.

Piezoelectric ceramics—a class of oxidic ferro-electric materials with specific modifications—display excellent electro-mechanical properties for use as transducer elements in the production of high voltages, ultrasonics, wave fiilters, radiation detectors and for pressure measurements. The paper gives an account of the efforts made in the direction of indigenous development and production of lead zirconate titanate type of materials at Armament Research and Development Establishment and describes their characteristics and typical uses.

The transverse linear electrooptic effect found in poled plates of ferroelectric ceramic PLZT 12/40,'60 has been utilized in the construction of an optical modulator used for sensing low voltages. The transparency of the La-modified lead zirconate titanate material, the large electrooptic coefficient rc = 1.4 x m/V and index of refraction n = 2.55. and the low birefringence at zero field Ano = -0.0011, make the ceramic convenient for the design of a small optical voltage sensor. This sensor, which is read out using fiber optics, can measure voltages in the range 0-50V to k 1 V with a response time of about 0.5 msec. The sensors can be designed to change transmittance by 0.9%,T. This sensitivity increases considerably with increasing temperature because of concurrent increases in rc and decreases in An,,. Both this thermal behavior and approximate calculations show ro and thus the large sensor sensitivity. to depend on an electrooptic effect intrinsic to the ceramic material rather than on domain realignment.

The electrooptic properties of hot-pressed lead zirconate titanate ceramics and their applications are reviewed. Coarse-grained, bismuth-doped ceramics with average grain size greater than 2 ώm have light scattering properties that can be varied by switching the orientation of the ferroelectric polarization. Fine-grained bismuth-or lanthanum-doped ceramics have an effective birefringence that can be varied either by applying an external electric field (conventional electrooptic effect) or by partially switching the remanent polarization (electrooptic memory effect). Ba, Sn, or La modifications of the lead zirconate titanate system produce materials with improved switching characteristics and electrooptic effects similar to those of fine-grained bismuth-or lanthanum-doped ceramics. Lanthanum modified lead zirconate titanate (PLZT) is significantly more transparent than other electrooptic ceramics. The PLZT system includes materials with electrooptic memory and either linear or quadratic electrooptic effects. The electrooptic properties of modified lead zirconate titanate ceramics, especially PLZT, combined with localized switching and modulation capabilities are particularly suitable for information storage and display devices.

The behavior of the cavity resonance in open tubes of barium titanate and lead zirconate titanate ceramic immersed in water has been studied both experimentally and theoretically for a range of length‐to‐radius ratios (h/a). Particular emphasis is given to tubes of small h/a where the cavity‐resonant frequency is near the ring‐resonant frequency of the tube, and close coupling is observed between the two modes. A coaxial line array of such elements, which has been built and tested, exhibits a high efficiency over a wide frequency band. Since no pressure release is used in its construction, this transducer is promising as a lightweight, high‐power sound source for operation at great depths in the ocean.

A study of the nuclear reactor irradiationinduced changes in the electrical and lattice properties of ferroelectric Pb(Zr0.65Ti0.35)O3+ 1 wt% Nb2O5 revealed that these changes in properties are caused by different damage centers. The changes observed in electrical properties were: (1) Pr decreased but P3 remained constant, (2) double (antiferroelectric-type) hysteresis loops were formed, (3) an increase by a factor of 5 in grain size did not affect the radiation damage rate in the ceramics, (4) an increase in irradiation temperature of 100°C above room temperature doubled the damage rate, (5) EC for unpoled ceramics was insensitive to irradiation until integrated fast neutron fluxes of lo18 nvt (and the associated γ-dose) were exceeded and thereafterECincreased exponentially, (6) aging of the radiation-induced damage did not occur at room tem perature, (7) the damage centers which affected the electric properties were temperature annealed, the annealing temperature depending on the particular material, (8) the introduction of lattice strain, as observed by changes in the longitudinal wave velocity (phonon mean free path length), did not appear to be related to changes in electrical properties. These changes in electrical and thermal properties are consistent with the published data for irradiated triglycine sulfate, Rochelle salt, barium titanate, and guanidinium aluminum sulfate and it is suggested that a common damage model may be constructed for all these ferroelectric materials.

Acoustoelectric amplification, in the linear approximation, is considered for a system containing several types of carriers in the two limiting cases of fast and slow carrier equilibration. The pertinent expressions are first derived for a piezoelectric semiconductor and then expanded to the more practical case of a layered system containing one or more semiconducting layers coupled to a piezoelectric element. An experimental example is given in the form of a guided elastic plate wave in lead zirconate titanate coupled to a plate of near‐intrinsic Ge.

Continuing studies on the improvement of the optical quality of lanthanum modified lead zirconate titanate (PLZT) ceramics have shown that (1) bulk residual porosity and (2) chemical inhomogeneity are primary factors contributing to optical losses in thick plates of the material. This paper describes methods by which both of these major faults in the ceramic can be virtually eliminated. In addition, the optical and electrooptic properties of the improved material are presented and compared with those of previously available materials. Successful methods of eliminating residual porosity and enhancing chemical homogeneity resulted from studies which led to improved hot-pressing techniques and chemical preparation of the PLZT powders. Essentially all of the residual porosity was eliminated by introducing an oxygen atmosphere during the hot-pressing process. Chemical homogeneity was improved significantly by using high purity liquid solutions for preparing the PLZT powders. A combination of lead oxide and solutions of lanthanum acetate, zirconium alkoxide and titanium alkoxide was found to yield consistently good results. Optical tranhmission measurements were made on one-millimeter thick polished plates of representative PLZT composit~ons. Three sets of plates were prepared from (1) mixed oxides conventionally hot-pressed, (2) mixed oxides hot-pressed in an oxygen environment, and (3) chemically co-precipitated powders hot-pressed in an oxygen environment. For each composition measured, the optical transmission increased progressively for materials (1). (2). and (3). Moreover. materials (2) and (3) were progressively more homogeneous than (1) when viewed between crobsed polarizers. Electrooptic measurements for materials prepared by the three techniques discussed above showed no significant differences in electrooptic properties.

It is pointed out that responsivity can be improved by mechanical resonances. The enhancement factor of responsivity of a trigricyne sulphate (TGS) pyroelectric detector is measured as 40 ∼ 50 at the mechanical resonances whose modes are assigned to dilational modes of a rectangular-plate vibrator. Also, a pyroultrasonic parametric amplifier is demonstrated, which can show further improvement of responsivity of the pyroelectric detector by amplifying the strain that accompanies pyroelectricity. Gain and an equivalent circuit are derived using a simplified parametrically coupled multimode vibrator model. A pyroultrasonic parametric amplifier using lead zirconate titanate (PZT) ceramic is demonstrated, and an improvement of about 5 dB is shown. Obtaining the gain stability is one of the serious problems of a pyroultrasonic parametric amplifier.

Measurements are described of the switching currents in polycrystalline lead zirconate titanate as a function of time and applied electric field. Samples of three compositions were investigated: Pb(Zr0·65 Ti0·35)0·99 Nb0·01 O3, Pb(Zr0·52 Ti0·48)0·99 Nb0·01 O3 and Pb Zr0·55 Ti0·45 O3. The results of these measurements show that the switching current has an exponential dependence on the reciprocal of the applied electric field, in a manner similar to that measured previously for single-crystal ferroelectric materials, and that the materials have no true coercive field. Activation fields and switching currents have been measured. A theoretical treatment of switching in polycrystalline materials is given and good agreement between the experimental data and the theory has been obtained by considering the polycrystalline material to be an assembly of randomly oriented single crystals. For low electric fields the currents through all the lead zirconate titanate materials showed an intermittent switching behaviour which was probably due to the statistical nature of the nucleation process in the different regions of the ceramic material.

Pairs of ultrasonic elements (piezo-electric ceramics of lead zirconate titanate) were implanted in the myocardium with 0.8–1.2 cm between the elements. Measurements of mural thickness or distance variations along the muscle layers, myocardial chord length (MCL), were performed in anesthetized and conscious dogs. Mural thickness varied reciprocally to MCL during the heart cycle, both with amplitudes of 8—15 per cent of end-diastolic lengths. Shortening usually started in the apical and interventricular parts, whereas shortening of the myocardium close to the base was often delayed. This asynchrony may reflect differences in end-diastolic myocardial fibre lengths. During the isovolumic phase, dimensional changes were small or absent. Comparative measurements with mercury-in-rubber gauges revealed that the considerable isovolumic expansion produced by this technique was an artefact due to stretching of the muscle fibres by the gauges.

A small experimental transducer array was designed, constructed, and tested to demonstrate the feasibility of enclosing the elements in a liquid‐filled housing that requires no pressure‐release materials. The transducer consists of four dumbbell‐type lead zirconate titanate transducer elements that are set in close‐fitting cavities in a high ρc metal block. The entire housing is filled with a silicone fluid and provision is made to maintain the inside pressure equal to the pressure on the outside at all times. Presentation of frequency‐response curves, electrical input impedances, and efficiencies demonstrates that the transducer characteristics are relatively insensitive to ambient pressures up to 1000 psi, the maximum pressure available for test. The transducer is further characterized by high power capability, good efficiency, a low Q, and a high effective electromechanical‐coupling coefficient. [Research sponsored by the USN Bureau of Naval Weapons.]

Sintering and the electrical properties of lead zirconate titanate (PZT) containing excess amount of PbO over the Stoichiometric composition have been presented.(1) The formation and sintering of PZT were nearly complete at about 900°C, as examined by X-ray diffraction analysis, dilatometry and electron microscopy.(2) Abnormal expansion was observed between 400°C and 700°C. Well-defined ceramics have been obtained by heating slowly at this temperature range.(3) An electro-mechanical coupling coefficient comparable to that of BaTiO3 has been obtained by firing at temperatures as low as 900°C.

In order to predict the performance of certain types of deeply submerged underwater transducers, measurements have been made of the properties of piezoelectric ceramics as a function of pressure, time, and electric field. Planar compressive stresses up to 35 000 psi were imposed on barium titanate and lead zirconate titanate ceramic by subjecting thin hollow spheres to uniform external pressure. With increasing stress, the dielectric constant, piezoelectric constant, coupling factor, and elastic compliance decreased by as much as 70%, part of the change being permanent but most of it reversible. The stability of the ceramic properties with duration and number of cycles of the imposed stress varied widely with ceramic composition. Large increases in high‐field dielectric loss were observed at high stress in ceramics usually considered suitable for high‐power projectors. The results indicate that transducers that utilize ceramic under planar stress may suffer significant degradation in performance when deep...

Ceramic disks of barium titanate and lead zirconate titanate, when heated above 100°C, exhibit current discharges which cannot be attributed to the ferroelectric polarization of the material. These discharges are largest in the temperature interval 300°–600°C and depend primarily on the electrode material and its method of application. Discharges of several millicoulombs at voltages up to one‐half volt have been obtained from a ceramic disk one‐half inch in diameter and 30 mils thick having a silver electrode and an indium counterelectrode. Although thermoelectric, pyroelectric, and electret effects are observed in these samples, these phenomena contribute only a very small portion of the total discharge. At constant temperature near 350°C the discharge decays with time as the sum of two exponentials, falling to half‐maximum in periods of the order of one‐half hour. At higher temperatures the decay rate increases, while temperature cycling produces a voltage cycling superimposed on the decay. These findin...

The effect of static and dynamic stress on the mechanical loss of a piezoelectric ceramic has been measured. Static stress was applied pneumatically along the axis of a radially polarized tube of lead zirconate titanate measuring 2.54 cm long by 0.317 cm wall thickness. It was found that immediately after applying a static compressive stress of 3000 psi, the mechanical loss, proportional to the reciprocal mechanical quality factor Qm−1 increased from 1.27×10−3 to 4.54×10−3. The mechanical loss of the ceramic was determined by measuring the Q factor of the ceramic and its support, and correcting for the support losses. A similar tube was statically biased with a stress bolt by incorporating the tube as the active element in a small model transducer. The transducer was then coupled to a high‐power ultrasonic driver by means of which large dynamic stresses were generated in the ceramic. A dynamic stress of 3000‐psi peak was superposed on a static biasing stress estimated at 5000 to 10 000 psi. The bias alone...

A two component piezoelectric skin-friction force transducer has been developed for a hypersonic flow tunnel which has a run time of approximately 70 milliseconds. Skin-friction forces acting on a sensing diaphragm are transferred to a transducer element which is constructed of lead zirconate titanate composition ceramic beams. The transducer converts a force into two charge signals which correspond to orthogonal components of the force parallel to the skin-friction force sensing diaphragm. The diameter of the sensing element is 0.940 inch and the overall transducer dimensions are 1 inch diameter and 0.625 inch high.

The disadvantages of ceramics based on barium titanate has limited many of the possible applications of this type of piezoelectric material. The Curie point is low and it is inefficient in electromechanical conversion. The discovery of the piezoelectric properties of the solid solution ceramics based on lead zirconate and lead titanate has stimulated increasing interest in transducer design. The paper describes the properties and characteristics of this new range of materials in terms of their ferroelectric and piezoelectric effects.

The crystal chemistry of point defects in lead zirconate-titanate is discussed. The results are used to interpret sintering and grain-growth behavior. Lattice vacancies are created thermally, by substitutional impurities with incorrect valences, and by changes in stoichiometry. Charged O vacancies are introduced when Al3+ replaces Ti4+, and charged Pb vacancies occur when Nb5+ replaces Ti4+. These vacancies are believed to be associated with the impurity ions and cause them to be adsorbed at grain boundaries. This behavior retards grain growth and thereby expedites densification. Aluminum ions (deficient valence) compensate for niobium ions (excess valence). These “paired” defects are not associated with vacancies and are not adsorbed; thus, they do not impede grain growth. Sintering follows Coble's model of bulk diffusion of vacancies from pores to grain boundaries. Oxygen vacancies are believed to be the slowest-moving species. Aluminum: niobium compensation is confirmed by ferroelectric measurements. Doping with Al decreases the mobility of ferroelectric domain boundaries, whereas Nb increases it. Doping with both ions produces ferroelectric properties similar to those of the undoped material.

Poled specimens of barium titanate (BT) and lead zirconate titanate (PZT) ceramics have been successfully recovered after shock loading antiparallel to the polarization vector (short‐circuit configuration) in the 3‐ to 23‐kbar range. It has been shown that permanent depoling as a result of phase transitions or of domain switching can occur within the microsecond time scale of a shock experiment. Results of dynamic charge release measurements made during shock transit in PZT 52/48 tend to corroborate the findings of other investigators. Techniques for recovery of shock‐loaded specimens are discussed.

The optical and electrical switching characteristics of a lead zirconate titanate ferroelectric ceramic 'with Bi or La doping were studied for possible application in a high speed light valve array. Of particular interest were the requirements for coincident voltage selection and stable operation for at least 1010 switching cycles. Excitation aging was found to decrease the contrast achievable when the ceramic is used as an electrically controlled retarder. A more pronounced result of aging is a large increase in the degree of partial switching caused by half-select pulses. Such effects could be temporarily reversed by appropriate cycling to higher temperatures. Little variation in aging with different electrode materials was observed.

Представлены разные датчики, использованные при измерениях на тренмерных сейсмических моделях. Для двух типов источииков и одного приемника подробно описаны характеристики направленности. Во второй части работы рассмотрена рапота приемника неправильной формы. Эксперименты показывают, что приемник пишет правильную форму всех волновых групп в случае, когда расстояние электрод в приемнике меньше длины волны.

An accurate X-ray fluorescence spectrometric method is described for the determination of lead, zirconium and titanium in lead zirconate-titanate ceramics. Careful matching of samples and standards by a borax fusion method resulted in a relative standard deviation of about 0.2% for the major constituents. The determination, after separation, of the unreacted oxide of lead by atomic absorption spectrometry, and of the unreacted oxides of zirconium and titanium by X-ray fluorescence spectrometry is also described. An X-ray fluorescence spectrometric method is proposed for the determination of dope elements (K, La, Sm, Yb) with internal standards (Ca, Ce, Cr, Ni respectively). The magnesium dope is determined by atomic-absorption spectrometry with standard addition.

The differential energy spectrum of a flash x-ray source or other pulsed radiation sources may be measured using the ferroelectric radiation detector. The detector, consisting of the poled ceramic lead zirconate titanate, exhibits a pulse charge output which is proportional to the absorbed dose. The spectrorneter system itself employs a filtration technique where a set of energy-selective metal filters is positioned in front of a corresponding set of ferroelectric detectors, and the radiation induced charge output of each detector is measured. From this data the spectrum of the pulsed radiation source is deduced by the use of a numerical unfolding technique. Experimentally, the concept of the ferroelectric spectrometer system was verified by measuring the spectrum of a 0.6 MVP flash x-ray machine. Since the ferroelectric detector exhibits a dynamic response to the incident radiation pulse, the same spectrometer concept is used to measure the spectrum as a function of time. The time-dependent character of tnle flash x-ray machine spectrum was detected experimentally and tne results showed that the energy spectrum is harder during the first portion of the pulse.

A statistical approach is used to determine the effect of porosity in ceramic materials on their dielectric breakdown strength. The calculated drop in dielectric strength is in good agreement with the experimental data for lead zirconate titanate ceramics. The theory shows that the measured dielectric strength in porous materials is a function of the porosity, the void size, and of the dimensions of the test sample.

Lanthanum-doped lead zirconate titanate (PLZT) ceramics of composition 8/65/35 and 9/65/35 have been studied by electrical, optical and thermal means. The results obtained have been used to elucidate the nature and extent of the phases occurring and the phase transitions between them. Phase α is obtained by thermally depoling a ceramic. It is converted into phase β by the application of electric fields or stress. On removal of the electric field, phase β is retained below a temperature TD while it reverts back to phase α if the temperature is above Tt. If phase β is heated, it transforms into α at Tt, but there is no reverse transformation on cooling. The transition at Tt can be sharp for chemically homogeneous material. Phase α is found to be non-birefringent, even in a single grain. It has linear dielectric and elastic properties. Phase β is birefringent, ferroelectric and ferroelastic. The properties of the two phases and the transitions between them can be used to explain the effects of electric field...

Large area PZT detectors with D∗ (500 K, 1, 1,) = 7 × 108 cm Hz12/W and fast detectors with a response time of at least 5 nsec have been fabricated. The pyroelectric coefficient of 27 nCcm2 K and a materials figure of merit of 2.8 × 10−9 C cmJ have been measured for these devices.

Solid-state substitution of Bi and Nb ions in the perovskite crystal structure of Pb(Ti0.47Zr0.53)O3 was investigated by sample weight changes at 1150°C in an “equilibrium” PbO atmosphere. A model is discussed that includes the effect of charge neutralization, requiring weight losses for A-site substitutions and weight gains for B-site substitutions. Experiments support the substitution of Bi as Bi3+ on the Pb2+ A site and Nb as Nb5+ on the (Ti,Zr)4+ B site of lead zirconate-titanate. For each mole of BiO1.5 added to a specimen, 1.5 moles of PbO are lost; for each mole of NbO2.5 added, 0.5 moles of PbO are gained. These results agree with the proposed model and with ionic size arguments. The weight changes were time-dependent during the first 30 to 40 h at 1150°C. This behavior is accounted for by the presence of transient second phases.

Electrooptic effects observed so far in ferroelectric lead zirconate titanate ceramic materials are transverse electrooptic effects (linear, quadratic, and memory), strain-biased longitudinal electrooptic memory effect, and electrically controlled scattering. The electrooptic memory effects are related to variations of ceramic birefringence with remanent polarization. All the above electrooptic effects are found in Ba, Sn, and La modified lead zirconate titanate ceramics except electrically controlled scattering. Both the character and magnitude of these effects are strongly dependent on the composition and grain size of the ceramic material as well as on the temperature and light wavelength of observation. The results for the La modified ceramics, which can be made highly transparent, are discussed in the greatest detail. The various electrooptic effects are shown to arise either from orientation of ferroelectric domains or from field-enforced ferroelectric distortion of certain para-electric materials.