Electrical Transports of LaFe1-xTixO3(x≤0.10)

Electrical transports of LaFe 1- x Ti x O 3 ( x ≤0.10) containing ligand holes (3 d 5 L ) were investigated by dielectric properties, ac and dc conductivities. A dielectric relaxation peak appeared with the activation energy which increased from 0.49 eV to 0.56 eV with increasing the amount of Ti ions. A thermal activation in the intensity of the peak was observed with the activation energy of 0.02 eV for LaFeO 3 and 0.05 eV for Ti-doped specimens. These energies corresponded well to those obtained in dc conductivities. Compensation of holes by electrons introduced by substitutions of Ti 4+ for Fe 3+ was confirmed. The ac conductivity was found to obey an equation of σ(ω)= A ω s , ω being the angular frequency. There were three temperature ranges in the plots of β(=1- s ) vs T ; the low temperature range where β≃0, the intermediate range where Pike's theory holds and the high temperature range where holes can hop over large energy barriers. These behaviours have been discussed in terms of small polarons of ligand holes.