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Experimental data demonstrate that LiNaTaNbO ( y ≠ 0) ferroelectric solid solutions near special concentration points ( x = 0.125 and 0.25), which have increased degrees of short- and long-range order, undergo a superionic transition. In the Raman spectra of LiNaTaNbO, the superionic transition shows up as a predominant 'melting' of the alkali metal sublattice and broadening of the corresponding lines into a Rayleigh line wing, whereas the other sublattices in the structure remain relatively 'rigid.' The temperature of the superionic transition can be tuned by varying the degree of static disorder of structural units in the Nb/Ta sublattice. [ABSTRACT FROM AUTHOR]

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 conductivity of relatively low value of activation enthalpy increases. [ABSTRACT FROM PUBLISHER]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The microstructure of ceramic samples of high-pressure ferroelectric LiNaNbO ( x = 0.17, 0.25) perovskite solid solutions has been studied in relation to synthesis temperature and composition. The elastic properties (Young's modulus) of the high-pressure LiNaNbO ( x = 0.125, 0.17, 0.25) solid solutions have been studied for the first time by a contact technique. The results demonstrate that, with increasing sintering temperature, the Young's modulus of the high-pressure LiNaNbO solid solutions at singular concentration points ( x = 0.125 and 0.25, Li/Na = 1/7 and 1/3) increases considerably, whereas that of LiNaNbO decreases markedly, which seems to be related to the recrystallization behavior of ordered and disordered solid solutions at high pressures. [ABSTRACT FROM AUTHOR]

We have studied the electrical and elastic properties of Li xNa1 − xTa0.1Nb0.9O3 ( x = 0–0.16) ferroelectric ceramic solid solutions. The results demonstrate that these properties of the Li xNa1 − xTa0.1Nb0.9O3 solid solutions are rather sensitive to the lattice distortions resulting from compositional structural phase transitions. The elastic constants determined by acoustic and contact techniques agree well. [ABSTRACT FROM AUTHOR]

Thermal behaviour and dispersion of dielectric permeability and thermal behaviour of conductivity measured in ferroelectric ceramic solid solutions of LixNa1-xNbO3 (x = 0.17, 0.25) synthesized at high pressure and possessing extended region of homogeneity are reported. The LixNa1-xNbO3 (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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The dielectric permittivity of Li xNa1 − xNbO3 ferroelectric solid solutions prepared at high pressures has been measured as a function of temperature and frequency, and their structural properties have been studied. The results demonstrate that ceramics samples of the Li xNa1 − xNbO3 ( x = 0.17, 0.25) ferroelectric perovskite solid solutions exhibit superionic conduction at relatively low temperatures ( T ≥ 400 K). In the temperature range of superionic conduction, we observe significant dielectric dispersion and anomalies in permittivity, corresponding to structural transformations of the high-pressure solid solutions. [ABSTRACT FROM AUTHOR]