Preparation by sol–gel method and characterization of Zn-doped LaCrO3 perovskite

Abstract

A new perovskite solid solution system of LaCr1−xZnxO3 (0 ≤ x ≤ 0.3) was synthesized through sol–gel method. The effect of Zn doping on the lanthanum chromite prepared was investigated. Thermal decomposition of the dried gel of LaCr0.8Zn0.2O3 was characterized by TG/DTA thermal analysis. The synthesized powders were characterized by means of X-ray diffraction (XRD), infrared spectra (IR), and scanning microscope (SEM). Finally, electrical properties were characterized by the standard four-probe technique. From the preceding analysis, it can be shown that the amorphous powders crystallize in the orthorhombic structure with Pbnm (62) space group (JCPDS card 24-1016), where the crystallite size ranges from 29.46 to 53.21 nm. The oxides LaCr1−xZnxO3 (0 ≤ x ≤ 0.3) have the comportment of semiconductors in the working temperature range 25–350 °C. The electrical conductivity increases with the degree of substitution x, whereas the maximum electrical conductivity obtained is ~13.8 S/cm at 350 °C for LaCr0.3Zn0.3O3 where the electrical conduction occurs by a thermal activated of small polarons hopping. At higher temperature, the electrical behavior is similar to that of pure metal.