0000000000024797
AUTHOR
V. Efremov
FRACTAL STRUCTURES IN SINGLE CRYSTALS OF FERROELECTRIC LITHIUM NIOBATE GROWN UNDER STRONGLY UNSTABLE CONDITIONS
Atomic force microscopy studies of lithium niobate single crystals containing heterogeneously distributed lanthanide (Gd) admixture and a regular domain structure of 100 nm to 1 μm steps obtained under conditions of severe thermal instability have revealed fractal structures of the size of 10 to 100 nm within regions of the regular domain structures. A super-structure of clustered defects with 1–2 nm steps explaining results of Raman spectra analysis is supposed to exist in the cation sub-lattice and formation of periodic fractal structures of the size of ∼1 nm–100 μm is suggested to take place in lithium niobate single crystals containing lanthanide admixture.
Dielectric and Elastic Parameters of LixNa1-xTa0.1Nb0.9O3 Ferroelectric Solid Solution Ceramics
Results of the studies of electric and elastic parameters as functions of concentration in ferroelectric LiхNa1-хTa0.1Nb0.9O3 (x = 0–0.16) solid solutions and comparative studies of the elastic properties by acoustic and contact probe techniques are reported. The electric and elastic properties of LiхNa1-хTa0.1Nb0.9O3 solid solutions are shown to be rather sensitive to structural distortion at concentration-induced structural phase transitions. The values of elastic modules obtained from acoustic measurements are found to be in good agreement with those obtained by contact probe techniques.
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.