Transparent Ferroelectric Ceramics Research Articles

Transparent ferroelectric ceramics: Properties and applications

Abstract A review is given concerning up-to-date methods of the transparent ferroelectric ceramics (TFC) production (chemical coprecipitation of raw material, two-stage hot-pressing, etc.), its application in optoelectronic devices (large-aperture modulators, linear light gate arrays, segmented displays) and possible new developments (near IR modulators including). Specific features of the TFC physical properties (optical parameters, photorefraction) are analyzed, the nature of the diffused phase transition in PLZT ceramics and related studies being discussed.

Radiation-induced effects in transparent ferroelectric ceramics

Abstract PLZT and PSN ceramics have been exposed to γ-radiation (energy ≈ 1.15 MeV, dose up to 3 · 109 rad), electron flux (≈4.5 MeV, dose up to 3.1018 electr./cm2) and fast neutrons (≥ 0.1 MeV, dose up to 1018 n/cm2). The irradiated material was used to study radiation effects on dielectric parameters (e and tgδ were measured at frequencies from 1 kHz to 5 MHz), polarization (dielectric hysteresis quasistatic loops) and non-linear optical properties (I2w). The measurements were made in the region of phase transition as well as to examine annealing of radiation-induced defects. As compared to PLZT the PSN ceramics is more resistant to radiation, the most sensitive PLZT compounds being with 7 ≤ × ≤ 9.5 at .% of La. Obtained results are explained by the change of ion charge, redistribution of vacancies in A and B sublattices of PLZT and by possible ion ordering in sublattice B of PSN with account for intrinsic fields in the relevant compounds.

Theory of propagation of electromagnetic waves in transparent ferroelectric ceramics

Abstract Propagation of electromagnetic waves in inhomogeneous dielectrics is considered within the framework of random field theory. We develop a method for solving problems associated with wave scattering by inhomogeneities of permittivity tensor e(r). The method is applicable to the whole wave length range. Although we impose no restrictions on the nature of inhomogeneities, the only examples of inhomogeneous media considered in the paper are polarized segnetoelectrics, mono- and multiphase polycrystals. It is demonstrated that the effects due to coordinate dependence of e can be revealed by analyzing the Fourier transform of effective permittivity tensor e*., Scattering index γ, phase ν* and group 𝒸* velocities are computed using the Bourret approximation with allowance for spatial dispersion. Asymptotic expressions for γ, ν* and 𝒸* are given for the long (compared to the effective dimensions of the scattering regions) wavelength range, short and ultrashort wavelength ranges.

Switching processes and pyroelectric properties of γ-irradiated transparent ferroelectric ceramics

Abstract Pyroelectric and dielectric properties and switching of ferroelectric PLZT ceramics have been studied in the range 290–470 K. The effect of γ-irradiation on pyroelectric coefficient, dielectric permittivity and rate of Barkhausen jumps sequence at polarization switching of PLZT ceramics is found to be most pronounced at phase transition.

Studies on microstructure and microproperties of PLZT ceramics

The microstructure of PLZT transparent ferroelectric ceramics were studied by high-resolution electron microscopy (HREM) and electron diffraction. The following experimental results were obtained: 1. (1) The structure of micro-domains in the cubic α phase is exactly the same as that of the ferroelectric β phase after poling. The ‘fringe’-shaped micro-regions in the HREM micrograph of 7·9/70/30 PLZT is the result of lattice overlapping of the orthorhombic micro-domains and the cubic α phase matrix. 2. (2) A 2 × d 111 superlattice along the 〈111〉 directiion was observed in 7·9/70/30 PLZT ceramics. It is probably the result of gliding or rotation on the {111} plane due to self-regulation of the structure in the presence of point defects. 3. (3) The lattice image micrographs taken near the grain boundary show that the grain boundaries in PLZT ceramics are very fine. Most of their widths are less than 6Å; some are only 2–3 Å. However, in some places the grain boundaries are broadened, and may reach several tens of ångströms. The structure of broadened grain boundaries appears amorphous. In addition, using specially constructed instruments, the electrical and electrooptical properties of single grains in PLZT ceramics were measured and compared with the properties of the ceramic materials.

Laser-induced surface metallization of ceramic PLZT

Hot pressed, optically transparent ferroelectric ceramics of lanthanum modified lead zirconate titanate (PLZT) have been locally reduced and metallized by means of ultraviolet Kr+ laser irradiation in a hydrogen atmosphere. The technique allows maskless single-step metallic patterning of the material.

Specific solid state features of transparent ferroelectric ceramics

Characteristic features of chemical composition, structure and properties of transparent ferroelectric ceramics (TFC) are revealed from the analysis of the known materials. From considerations of the microstructure of TFC, it is shown that practically no space charge accumulates on the grain boundaries. Essential physical and technological factors responsible for light transmittance are analyzed, and criteria that can be used for the search for new TFC compositions proposed. Some TFC properties are explained in terms of highly doped and compensated ferroelectrics. Specific features of TFC in comparison with electrooptic single crystals and opaque ferroelectric ceramics are discussed.

Investigations of some crystal-chemical possibilities of transparent ferroelectric ceramics modification

Obligatory and auxiliary conditions for successful searching of new transparent ferroelectric ceramic (TFC) types are formulated. Typical members of three structural groups as potential TFC are present.

Dielectric properties of PLZT transparent ferroelectric ceramics at low and infra-low frequencies

Anomalous behaviour of the complex dielectric constant ε* at Tt was revealed in thermally depoled samples of PLZT X/65/35 ferroelectric ceramics with X = 9.25 and 10 by means of infra-low-frequency dielectric spectroscopy in ultra-weak fields (E∼ = 0.1 V/cm). It was observed that the value of the additional maximum ε' in the Tt region increased for diminishing measuring field frequencies and tended to drift towards lower temperatures. The frequency-temperature dependence ε* of samples affected by biasing electric fields was investigated. The emergence and evolution of polar regions in the ferroelectric ceramics in a quasipolar phase was investigated by measuring the light depolarisation due to the longitudinal effect of light scattering.

Application of electrooptic shutters in photorecording systems to visualize liquid films

Visual investigation of a liquid film in a light emitting gas flow was carried out by means of synchronous photoexcitation and photorecording of fluorescence. The undesired exposure of the photorecording medium to the gas radiation was suppressed by a rapid electrooptic (EO) shutter made out of transparent ferroelectric ceramics of lanthanum modified lead zirconate-titanate (PLZT).

Peculiarities of production of transparent ferroelectric ceramics based on lead-scandium niobate

Major problems in the production of transparent ferroelectric ceramics based on lead-scandium niobate Pb(Sc0.5NB0.5)03 with regard to the improvement of both the reproductibility and quality can be solved by increasing the degree of homogeneity and dispersion of the initial mixture of raw materials.The necessity to introduce an extra amount of lead oxide into the initial mixture of raw materials and the optimum conditions for its removal from the final product during hot pressing are discussed.Physical properties of ferroelectric ceramics (FEC) have been analyzed.

Irradiation effects on the structure, properties and phase transition in PLZT and PSN ferroelectric ceramics

PLZT and PSN transparent ferroelectric ceramics have been subjected to γ-irradiation (energy ≈ 1;15 MeV; power of the dose 1050 r/s; doses up to 3 × 109 rad), electron irradiation (energy ≈ 4.5 MeV; power of the dose ≈ 1012 electr./cm2 · s: doses up to 1018 electr./cm2) and direct irradiation in a thermal reactor channel (neutron energy ≥ 0.1 MeV; flow density from 1.8 × 1011 to 2.4 × 1012 n/cm2 s: the dose up to 1018 n/cm2).Results of complex X-ray, dielectric, and optical studies of the irradiated ceramics are interpreted in terms of radiation-induced defect interaction with the real structure defects of the initial material taking into account the chemical and phase constitution, as well as the defectness and ordering of structural elements at different levels of the latter.

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.

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

Semiconductor properties and general applications op optical ceramics

Abstract The electron and hole processes in transparent ferroelectric ceramics (TFC) are considered. The basic concepts about the defects and their relation to the electric conductivity in TPC are analyzed. Results of the studies of electrical properties of the surface and specific features of hologram forming are presented. The basic applications of electron-hole processes in TPC are discussed.

Transparent ferroelectric ceramics: Phase transitions and new materials

Abstract The phase transition in PLZT X/65/35 solutions is considered as a diffuse transformation characterized by the two processes comprising it—distortion of the symmetric structure and domain formation. Transparent PSN ceramics are reported to be a promising material in matrix addressing devices due to a low operating voltage and a high P t/P t, ratio.

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.