Transparent PLZT Ceramics Research Articles

Hot-pressed transparent PLZT ceramics from low cost chemical processing

Lanthanum-modified lead zirconate titanate (PLZT) ceramics were obtained with high transmittance in the visible range by a combination of an inexpensive chemical processing and hot pressing. Optical, microstructural, pyroelectric, ferroelectric and dielectric properties characterized in this study attested the applicability of the employed method in the production of PLZT transparent ferroelectric ceramics. In fact, the corresponding analyzed physical parameters are in very good agreement with those obtained in samples traditionally prepared by other methods. Furthermore, due to high sample quality, a phenomenological analysis of the PLZT 10/65/35 relaxor features was performed in these ceramics.

Microstructural Evolution of Transparent PLZT Ceramics Sintered in Air and Oxygen Atmospheres

Transparent lanthanum‐doped lead zirconate titanate (PLZT) ceramics were fabricated by air‐pressure sintering. When the PLZT (9/65/35) specimens were sintered in air, the microstructure was not uniform throughout the body; the outer region near the surface was completely dense, while the inner region of the body was porous. The thickness of the outer dense layer increased parabolically with sintering time. When the specimen was sintered in air at 1200°C for 8 h, the thickness of the dense layer was ∼0.25 mm. Therefore, when the specimen had a thickness of <0.5 mm, it was dense and transparent. This difference in microstructure was attributed to the formation of lattice vacancies as a result of PbO evaporation from the surface. The sintering atmosphere also was important in determining the thickness of the dense layer. The thickness was strongly dependent on the oxygen partial pressure of the atmosphere. The oxygen‐gas trapped in pores was deemed to migrate easily through the lattice vacancies. By sintering in an oxygen‐gas atmosphere at 1200°C for 8 h, a transparent PLZT with thickness up to 2 mm was fabricated.

Controlled Oxygen Partial Pressure Sintering of (Pb,La)(Zr,Ti)O3 Ceramics

Transparent PLZT(7/60/40) ceramics with large piezoelectric coefficients were obtained using a two‐step sintering process with controlled oxygen partial pressure. Specifically, low‐oxygen‐pressure and low‐temperature sintering were used in the first step, followed by a high‐oxygen‐pressure, high‐temperature sintering cycle. High‐density ceramics with small grain sizes of about 3 µm were prepared. As a result, kp= 0.71, k33= 0.78, d33= 850 × 10‐12 C/N, and a transparency of 15% (λ= 610 nm, thickness of 1 mm) have been achieved; 20% improvement of d33 was gained compared to conventional processed PLZT ceramics (d33= 710 × 10‐12 C/N).

Invitation to chiral physics

Although measurement of the optical activity of solids had been impossible for 170 years since its discovery by Arago (1811), we have developed a method called HAUP (high accuracy universal polarimeter), which enables one to measure simultaneously optical activity, birefringence, and rotation of the indicatrix of any crystals, even those belonging to the monoclinic and triclinic systems. Thus the HAUP has opened a new research field in condensed matter physics. This article reviews our applications of the HAUP method to studies on several unsolved problems in this science. It includes an understanding of the origin of structurally incommensurate phases, a revelation of the twinning mechanism of the ferroelectric domains, the first exploration of optical properties of monoclinic crystals, the determination of correct crystal symmetries of transparent PLZT ceramics, first measurements of anisotropic gyrations of helical polymers, and measurements of reciprocal and non-reciprocal optical activity of high temperature superconductors. It is important to note that these problems could be solved only by making use of the crucial property of optical activity. Summing up the present study, we should like to emphasize the necessity of the new research field, ‘chiral physics’where axial tensors like gyration can play major roles.

Development of novel method for measuring optical activity of solids and its applications

Although measurement of the optical activity of solids has been impossible for the 180 years since its discovery by Arago (1811), we have developed a method called HAUP (high accuracy universal polarimeter), which enables one to measure simultaneously optical activity, birefringence, and rotation of the indicatrix of any crystals, even those belonging to the monoclinic and triclinic systems. Thus HAUP has opened new research fields in condensed matter science. This article reviews our applications of the HAUP method to studies on several unresolved problems in this science. It includes an understanding of the origin of structurally incommensurate phases of some ferroelectrics, the determination of the correct crystal symmetries of the transparent PLZT ceramics, first measurements of anisotropic gyrations in helical polymers, and optical activity of HTSC. It is important to note that these problems could be solved only by making use of the crucial property of optical activity.

Elastic light scattering as a probe for detail in situ investigations of domain and phase evolution

Abstract The new complex method is proposed and used for in situ studying of kinetics of different phase transformations. It is based on real-time registration of elastic light scattering and original mathematical treatment of experimental data in terms of geometrical transformations and phase transitions of percolation type. The angle distribution of transmitted/reflected laser beam intensity was registered with high time resolution. The domain kinetics during polarization reversal in PLZT transparent ceramics, the evolution of the heterophase structure near transition point in single crystals of Gd2(MoO4)3 and kinetics of crystallite growth during rapid thermal annealing in amorphous thin films of Pb5Ge3O11 were examined.

PLZT laser beam modulator

Abstract Laser beam modulator on transparent electrooptic PLZT ceramics are developed for the use in teaching process in schools and universities. Characteristics of the modulator and its electronic control unit are given.

Dependence of electro-optic properties of PLZT upon the chemical compositions

Abstract The characteristics of the ferroelectric and the electro-optic properties was investigated on the transparent PLZT ceramics, which had a slim D-E loop. The coercive force Ec was 0.24 × 106 V/m and the remnant polarization Pr was 7.9 × 10−2 C/m2 for the typical composition of PLZT (9/65/35), applying AC 2 kV/mm at 50 Hz. Transmittance of a PLZT electro-optic shutter was studied. The shutter was fabricated by PLZT wafer with a pair of slot electrode sandwiched between artificial polarizers under crossed Nicols. In order to evaluate the electro-optic hysteresis, the ratio of the half width to the applied voltage was employed, and was about 20% for PLZT (9/65/35), 13% for PLZT (10/65/35) and 8% for PLZT (9/69/31), in giving the maximum light intensity. The hysteresis of transmittance were decreased with increment of both La and Zr content, although the quadratic electro-optic coefficient was decreased.

Electrooptical and electrostrictive PLZT ceramics light modulators for infrared

Abstract The studies of modulators for infrared made of transparent PLZT ceramics are reported. Two types of light modulators are discussed: 1) using the transversal electrooptic effect and 2) using the longitudinal electrooptic (EO) effect and electrostriction. The latter has been made as an electric field controllable Fabry-Perot interferometer. The characteristics of the modulators are provided.

Optical and dielectric properties of transparent PLZT ceramics with various defects

Abstract The optical transmitance, crystallographic structure and dielectric properties for PLZT 8/65/35 samples either containing a number of various dopands (Mn, Fe, Co, Eu), or subject to neutron or electron irradiation have been studied.

Fabrication of Transparent PLZT Ceramics with a High Transmittance and Their Application to Optical Light Shutter

Lanthamun-modified lead zirconate titanate (PLZT) powders were produced by chemical preparation method and these powders were sintered by ordinal atmosphere sintering method with O2-gas flow. As a result of combination both high quality powder and atmosphere sintering, high transparent PLZT ceramics with a transmittance as high as 67% at the wavelength of 600 nm were obtained. Optical light shutters were produced using these PLZT ceramics and proved to be applicable for commercial use.

Self-focusing and self-deflection of laser beams in transparent plzt ceramics

We report measurements of the self-focusing and self-deflection of argon ion laser light for PLZT 11/65/35 ceramic samples. The results are interpreted in terms of a nonlinear refractive index and a thermal lens model. The far-field patterns of a thermal lens and self-deflected light beams are presented.

Vacuum sintering of transparent piezo-ceramics

Abstract Transparent PLZT ceramics were fabricated by a new vacuum-atmosphere sintering method combining vacuum sintering and atmosphere sintering. Cold pressed powders were first sintered in vacuum for 15 – 30 minutes at 1150 – 1180°C and then heated in air for 60 – 90 hours with atmosphere powder. By this process, highly transparent PLZT ceramics were obtained. The production of nearly colourless small grain - size samples is possible.

The effect of random field on electronic processes, phase transitions and hologram writing in transparent ferroelectric PLZT ceramics

Abstract The ferroelectric phase transitions, photovoltaic effect and some peculiarities of hologram writing in PLZT are explained on the basis of the theory of highly doped and compensated ferroelectrics.

Electric and Optical Properties of PLZT Ceramic Shutter Array

This paper is concerned with a light-shutter array of PLZT transparent ceramics utilizing newly-developed electrode structure. Relationships between shutter characteristics and electrostrictive effect of the PLZT are investigated. The electrode structure plays significant roles on the reliability of the shutter characteristics. Thus, by introducing a double layer electrode structure coated with resin, the highly stable light-shutter array is obtained to a long time drive. Furthermore, small temperature dependent shutter array can be also realized by controlling each width of the electrode and light-shutter aperture.

Influence of irradiation and periunent magnetic field on physical proplrties of PLZT and PSN transparent ferroelectric ceramics

Abstract Physical parameters of the γ-and electron irradiated transparent ferroelectric PLZT and PSN ceramics have been presented. Influence of the permanent magnetic field on PLZT and PSN dielectric properties have been observed.

Influence of permanent magnetic field on dielectric properties of transparent ferroelectric PLZT ceramics

Influence of permanent magnetic field on dielectric properties of transparent ferroelectric PLZT ceramics

The mechanism of applied-field-induced remanent birefringence in transparent ferroelectric PLZT ceramics

The mechanism of applied-field-induced remanent birefringence in transparent ferroelectric PLZT ceramics

The mechanism of applied-field-induced remanent birefringence in transparent ferroelectric plzt ceramics

Abstract It is shown that the remanent domain reorientation and space charge fields are responsible for the remanent birefringence in PLZT 10/65/35 and PLZT 8.5/65/35. A more detailed study of the space charge effects and suggestions how to eliminate the remanent birefringence have been presented

Thermal and spectral studies of photorefraction and photoconductivity in transparent ferroelectric PLZT ceramics

The thermal effects in PLZT-x ceramics with a La concentration of x = 7-13 at.% have been studied while spectral studies have been performed with PLZT-10 at room temperature. It was observed that each process causing a rise in photoconductivity is followed by an increase in sensitivity of the photorefraction effect. The experimental results for quasiferroelectric and paraelectric phases are qualitatively explained by the one-dimensional space-charge model.