The electrical transport properties of La0.5Sr0.5CrO3 below room temperatures were investigated by dielectric, dc resistivity, magnetic properties and thermoelectric power. Below TC, La0.5Sr0.5CrO3 contains a dielectric relaxation process in the tangent loss and electric modulus. The La0.5Sr0.5CrO3 involves the transition from high temperature thermal activated conduction process to low temperature one. The transition temperature corresponds well to the Curie point. The relaxation mechanism has been discussed in the frame of electric modulus spectra. The scaling behavior of the modulus suggests that the relaxation mechanism describes the same mechanism at various temperatures. The low temperature conduction and relaxation takes place in the ferromagnetic phase. The ferromagnetic state in La0.5Sr0.5CrO3 indicates that the electron - magnon interaction occurs, and drives the carriers towards localization in tandem with the electron - lattice interaction even at temperature above the Curie temperature.

Thermoelectric power, dc conductivity, and the dielectric relaxation properties of La2NiO4.03 are reported in the temperature range of 77 K - 300 K and in a frequency range of 20 Hz - 1 MHz. Thermoelectric power was positive below 300K. The measured thermoelectric power of La2NiO4.03 decreased linearly with temperature. The dc conductivity showed a temperature variation consistent with the variable range hopping mechanism at low temperatures and the adiabatic polaron hopping mechanism at high temperatures. The low temperature dc conductivity mechanism in La2NiO4.03 was analyzed using Mott's approach. The temperature dependence of thermoelectric power and dc conductivity suggests that the charge carriers responsible for conduction are strongly localized. The relaxation mechanism has been discussed in the frame of the electric modulus and loss spectra. The scaling behavior of the modulus and loss tangent suggests that the relaxation describes the same mechanism at various temperatures. The logarithmic angular frequency dependence of the loss peak is found to obey the Arrhenius law with activation energy of ~ 0.106eV. At low temperature, variable range hopping and large dielectric relaxation behavior for La2NiO4.03 are consistent with the polaronic nature of the charge carriers.

완화형 강유전체인 0.9MPb*Mg13/Nb23/)O3-0.1PbTiO3에서 강유전-상유전 상전이에 수반되는 relaxation거동을 살펴보기위해 낮은 전계에서 측정된 유전특성과 높은 전계에서 측정된 전계유기 분극 거동 등을 조사하였다. -50-90˚C의 상전이 온도범위에 걸쳐 1V/mm의 낮은 전계에서 측정된 유전특성의 온도의존성을 구하고 수 kVmm의 강전계하에서 발생된 분극의 온도의존성을 관찰하였다. 이 모든 결과들은 Vogel-Fulcher관계식에 비교적 정확하게 일치되었으며 그 결과 Tf 는 294.6˚K로 나타났다. 본 연구결과를 통하여 Vogel-Fulcher관계식에 의한 주파수 의존성은 낮은 전계하에서의 유전특성 뿐 아니라 강전계하에서의 여러물성들도 동일하게 적용되는 것을 확인할 수 있었다.