0000000000041570
AUTHOR
S. N. Kallaev
Heat capacity and thermal conductivity of multiferroics Bi1-xPrxFeO3
The heat capacity and thermal conductivity of multiferroics Bi1–xPrxFeO3 (0 ≤ x ≤ 0.50) has been studied in the temperature range of 130–800 K. A slight substitution of praseodymium for bismuth is found to lead to a noticeable shift of the antiferromagnetic phase transition temperature whilst the heat capacity increases. The temperature dependences of the heat capacity and thermal conductivity exhibit additional anomalies during phase transitions. The experimental results suggest that the excess heat capacity can be attributed to the Schottky effect for three-level states. The basic mechanisms of the heat transfer of phonons are highlighted and the dependence of the mean free path on temper…
Electroluminescence of (Pb0.91La0.09)(Zr0.65Ti0.35)O3 relaxor ceramics
Abstract Lanthanum doped lead zirconate titanate (PLZT) relaxor ceramics with (Pb 0.91 La 0.09 )(Zr 0.65 Ti 0.35 )O 3 composition exhibit a repolarization induced by electroluminescence (EL) with a pronounced discrete character of emission. It is established that this behavior is related to the reorientation of nanodimensional polar regions in a strong pulsed electric field in the vicinity of a smeared phase transition. The time and temperature dependences of the EL intensity are studied.
Features of Thermal Properties of Ferroelectric PLZT Ceramics in the Region of Phase Transition
A study of specific heat and thermal expansion of PLZT-9/65/35 ceramics in the 150– 800 K range of temperatures is reported. Specific diffused features in behaviour of heat capacity and thermal expansion are revealed in the 250–650 K and 330–550 K range of temperature, respectively, and shown to be the result of the growth and changes of a system of ordering nano-size polarised regions. The features of heat capacity in the 250–650 K range of temperature are found to be related to two-level states (the Schottky anomaly). Obtained results are discussed together with data of structural and dielectric studies.
Thermal properties of ferroelectric 0.7PbNi1/3Nb2/3O3–0.3PbTiO3ceramics
A study of heat capacity as function of temperature of the 0.7PbNi1/3Nb2/3O3–0.3PbTiO3 solid solution within the 120–800 K range is reported. Broad anomalies on the curve of heat capacity are revealed in the 250–450 K and 450–650 K intervals peaking at 520 K and a λ-anomaly at T ≈ 225 K. Results are discussed with account for dielectric and structural data.
Heat Capacity and Dielectric Properties of the PNN-PT Ferroelectric Ceramics
A study of dielectric permittivity and heat capacity of the (1-х)PbNi1/3Nb2/3O3 – хPbTiO3 solid solution system (x = 0.3, 0.4, 0.5) within the 290–700 K range is reported. Temperatures of phase transitions Tm determined from maximums of dielectric permittivity ϵ depends on the content of PbTiO3. A broad phase transition is shown to proceed in the 0.7PbNi1/3Nb2/3O3–0.3PbTiO3 composition around 312 K. Specific to phase transitions anomalous heat capacity is observed at Т ≈ 520 K in all compositions studied.
Dielectric properties and ac conductivities of Bi1−xSmxFeO3 ceramics
Dielectric permittivity, dielectric losses and ac-conductivity of polycrystalline Bi1−xSmxFeO3 (x = 0; 0.05; 0.1; 0.15; 0.2) are measured in the frequency range 1 kHz–10 MHz and in the temperature range 25–600 °C. Anomalies have been observed at the 200 °C, 300 °C and at the Néel temperature. It has been demonstrated that doping with Sm has enhanced the dielectric properties and increased conduction in the frequency region 1 MHz) and at a certain temperature Tm, depending on the composition Bi1−xSmxFeO3, the conductivity reaches a maximum. The results are discussed with reference to the model of correlated barrier hopping.