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Dielectric spectra of ceramic samples of Ca[sub 1-x]Pb[sub x]TiO[sub 3] (0 ≤ x ≤ 0.4) solid solutions were studied at frequencies between 10 Hz and 1 MHz in a temperature range of 4.2-300 K. A ferroelectric phase transition was observed at x=0.3 with transformation to a relaxor type behavior at x>0.3. The transition temperature T[sub c] follows a linear dependence T[sub c] ∞ (x-x[sub c]) with x[sub c]=0.28 contrary to a square-root dependence T[sub c]∞(x-x[sub c])[sup 1/2] predicted by the theory for incipient ferroelectrics. The critical concentration essentially exceeds the x[sub c] values for SrTiO[sub 3] and KTaO[sub 3] incipient ferroelectrics. [ABSTRACT FROM AUTHOR]

Transient currents in SrRuO[sub 3]//Ba[sub 0.8]Sr[sub 0.2]TiO[sub 3]//SrRuO[sub 3] thin film capacitors, in the time interval 0.05-2.5 s after the step voltage switching on and off, have been investigated. The origin of these currents is proposed, including two components: charging (discharging) of near-electrode potential barriers and oxygen vacancy migration. It has been established that transient current of capacitor charging is mainly determined by the barrier component, and transient current of capacitor discharging is due to both components. The parameters of potential barriers were determined giving a good agreement of the calculated time dependences of transient currents with the experimental data. [ABSTRACT FROM AUTHOR]

The results of measurements by the ac heater-probe method of the specific heat and thermal conductivity of polycrystalline BaTiO[sub 3] films with thickness between 1 and 0.1 µm in a temperature range 120-440 K are presented. In the heating and cooling runs, the phase transition anomalies of the thermal properties in the region of each phase transition in the sequence of symmetry change m3m-4mm-mm2-3m have been observed. A temperature hysteresis is observed, which is the signature of the first order phase transitions. As film thickness decreases, anomalies shift to lower temperatures and became smeared. [ABSTRACT FROM AUTHOR]

Capacitance relaxation in Ba[sub 0.8]Sr[sub 0.2]TiO[sub 3] thin film structures has been investigated. Slow decrease of the capacitance after a bias voltage switching on is explained by suppressing the film dielectric permittivity by the field of a p-n junction originated as a result of the oxygen vacancy migration in the bias field. After the bias switching off, the p-n junction gradually disappears due to the vacancy diffusion, and the capacitance increases. The relation determining capacitance increase after the bias switching off has been obtained in agreement with experimental data. The proposed relaxation mechanism is considered as a certain type of the size effect when the p-n junction depleted region spreads over the film thickness. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Dielectric properties of ceramic samples of (1-x)SrTiO[sub 3]-xSrMg[sub 1/3]Nb[sub 2/3]O[sub 3] and (1-x)SrTiO[sub 3]-xSrSc[sub 1/2]Ta[sub 1/2]O[sub 3] solid solutions were studied at x≤15% and x≤10%, respectively. The real and imaginary parts of the dielectric constant were measured at frequencies between 10 Hz and 1 MHz and in a temperature range of 4.2-300 K. Remarkable relaxation was found between 80 and 300 K. The relaxation was suggested to be due to local charge compensation processes. The activation energy for these processes was determined to be (0.25±0.05) eV with τ[sub 0]=(10[sup -12]...10[sup -13]) s. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]