0000000000018322
AUTHOR
V. V. Efremov
Comparative Acoustic and Contact Studies of Elasticity of Ferroelectric LixNa1 - xTa0.1Nb0.9O3Solid Solutions at Nanometer Spatial Resolution
Comparative acoustic and contact studies of elastic properties of the Li x Na 1−x Ta 0.1 Nb 0.9 O 3 (x = 0.015–0.135) ferroelectric solid solution ceramics are reported. A good agreement is obtained between the values of elastic modules determined by acoustic and contact methods at nano-scale spatial resolution.
Dielectric Dispersion and Ion Conductivity in High-Pressure LixNaw1-xNbO3Solid Solutions
Thermal behaviour and dispersion of dielectric permeability and thermal behaviour of conductivity measured in ferroelectric ceramic solid solutions of Li x Na 1−x NbO 3 (x = 0.17, 0.25) synthesized at high pressure and possessing extended region of homogeneity are reported. The Li x Na 1−x NbO 3 (x = 0.17, 0.25) solid solutions of perovskite structure are found to be super-ionic conductors at rather low temperatures O ≥ 400 K. Dielectric dispersion and anomalous behaviour of dielectric permeability are observed in the thermal range of super-ionic conductivity corresponding to structural transformations in the high-pressure solid solutions.
The Effect of Grain Size of the Stock on Electrical Characteristics of the Li0.03Na0.97Ta0.05Nb0.95O3Perovskite Ceramics
The microstructure and electrical properties of two samples of the ferroelectric Li0.03Na0.97Ta0.05Nb0.95O3 ceramic solid solution prepared from initial charge stocks of different dispersity by conventional ceramics technology are compared. The average size of grains and concentration of pores in the samples are found to be of little difference while the electrical properties of the ceramics are strongly affected by the grain size of the initial mixture. The difference in properties is due to conditions at the diffusion stage of the solid-phase synthesis caused by differences in composition of larger grains rather than the grain size itself.
Microstructure and Mechanical Properties of High-Pressure LixNa1-xTayNb1-yO3Solid Solution Perovskite Ceramics
The effects of the temperature of synthesis and component concentration on microstructure of high-pressure LixNa1-xTayNb1-yO3 solid solution perovskite ceramics (х = 0.12, 0.17; у = 0; у ≥ 0.5) were studied. Original results of elastic properties of high-pressure LixNa1-xTayNb1-yO3 (х = 0.17; 0 ≤ у ≤ 0.5) solid solutions measured by contact probe techniques are reported. The observed decrease of the modulus of elasticity with increasing the sintering temperature of Li0,17Na0,83TayNb1-yO3 solid solutions is assumed to be related to conditions of re-crystallisation of disordered solid solutions at synthesis under high pressure.
Dielectric Permittivity and Conductivity of Li0.07Na0.93Ta0.1Nb0.9O3and Li0.07Na0.93Ta0.111Nb0.889O3Solid Solutions
Results of studies of dielectric properties and conductivity in 290–700 K range of temperature and frequencies from 25 to 106 Hz in ferroelectric perovskite solid solutions Li0.07Na0.93Ta0.1Nb0.9 O3 and Li0.07Na0.93Ta0.111Nb0.889 O3 are reported. A first-order ferroelectric phase transition proceeds in both studied compositions within the observed range of temperature. The co-precipitated Ta2yNb2(1-y)O5 pentoxides being used for synthesis of Li0.07Na0.93Ta0.111Nb0.889O3 the Curie point shifts by ∼75 K to a lower temperature while compared with Li0.07Na0.93Ta0.1Nb0.9O3 synthesised from mechanical mixture of the Ta2O5 and Nb2O5 oxides the high-frequency dielectric permittivity and ion conduct…
The Effects of Thermo-Baric Synthesis on the Structure and Properties of the Ferroelectric Li0.125Na0.875NbO3Solid Solution
ABSTRACTResults of X-ray diffraction, dielectric, and Raman studies of the ferroelectric Li0.125Na0.875NbO3 solid solution obtained under hot-pressing conditions (6 GPa, 1400 and 1800 K) are compared with those of the same compound synthesized by conventional ceramics technology. The thermo-barometric synthesis is found to improve the ordering of cations and to increase the value of dielectric permittivity and ion conductivity of the ceramics.