0000000000335403
AUTHOR
V. A. Sandler
Effects of VTE Treatment on Composition of Lithium Tantalate Single Crystals
The vapour transport equilibration (VTE) is used to change the Li/Ta ratio in lithium tantalate single crystals of different crystallographic orientations (Z-cut and Y/128°-cut). Treatment by VTE is shown to provide thin layers in lithium tantalate plates composition of which is close to stoichiometric while the values of the coercive field are different, much smaller compared with congruent single crystals. There are several mechanisms of diffusion of the Li+ ions in LiTaO3 under conditions of VTE the contribution of each being dependent on the crystallographic orientation of the sample.
Dielectric Properties and Conductivity of Ferroelectric LixNa1-xTa 0.1Nb0.9O3 Solid Solutions
Results of a study of dielectric properties and conductivity of ferroelectric perovskite solid solutions of the LixNa1-xTa0.1Nb0.9O3 (х = 0.03–0.135) series with the 290–700 K thermal range and frequencies from 25 to 106 Hz are reported. The charge in this kind of materials is shown to be transferred by Li+ ions the contribution from bulk transport of ions dominating. A first order phase transition close to the second order transitions proceeds in LixNa1-xTa0.1Nb0.9O3 solid solutions within the thermal range examined. The increase of Li concentration enhances the features of the second order transition.
Dielectric properties of lithium niobate single crystals doped with gadolinium
In this paper dielectric properties of LiNbO3:Gd single crystals at temperatures ~ 290–490 K at narrow frequency range (0.5–106 Hz) are presented. The influence of growth conditions was also investigated. The anomalies on dielectric plots depend on the development of the micro- and nano-domain structure.
Anomalies of dielectric properties and conductivity in single domain LiNbO3:Zn crystals
ABSTRACTA study of the temperature dependence of dielectric constant, conductivity, and piezoelectric modulus in the single-domain state of LiNbO3 crystals modified by Zn admixture at threshold concentration is reported. Unipolarity of the LiNbO3:Zn crystals is observed to increase after treatment of brand-new samples by high-temperature electro-diffusion annealing and by subsequent high-temperature annealing of short-circuited samples. The observed effects are explained as a result of meta-stable residual domains collapsing at high temperature the collapse being assisted by disintegration of charged clusters stabilizing domain walls. The rise of unipolarity is accompanied by anomalies on t…
Formation of Layers of Diverse Stoichiometric and Phase Composition in Lithium Tantalate Crystals at Treatment by Vapour Transport Equilibration
Layers from tens to hundreds of microns thick of a different phase composition and stoichiometry are shown to form in lithium tantalate crystals subjected to treatment by vapor transport equilibration in lithium vapour. The 500 microns thick stoichiometric (Li/Ta ≈ 1) layers have ten times lower values of the coercive field compared with congruent lithium tantalate. As electrical measurements suggest, a new polar structure of phase transition at ∼120°C is possibly formed within a thin (30 μm) surface layer of the lithium tantalate sample after vapour transport equilibration treatment.