Crystal structure, thermal expansion and electrical conductivity of Pr(Ga1-xCox)0.9Mg0.1O3-δ (x=0, 0.1, 0.2, 0.3)

Pr(Ga1-xCox)0.9Mg0.1O3–δ(x=0, 0.1, 0.2, 0.3) was synthesized using solid-state reaction technique to study the effects of Co doping on their structure and properties. Room and high temperature XRD, DSC and electrical conductivity measurement with D.C. four-probe technique were adopted in the study. The results indicated its orthorhombic-distorted perovskite structure at room temperature. PrGa0.9Mg0.1O3–δ maintained its orthorhombic-distorted structure between 298 and 1173 K. For Pr(Ga0.7Co0.3)0.9Mg0.1O3–δ, such structure existed below 873 K. From 873 to 1173 K, it possessed tetragonal structure. The transformation from orthorhombic to tetragonal structure at 873 K was of second order. The intrinsic volume thermal expansion of tetragonal structured Pr(Ga0.7Co0.3) 0.9Mg0.1O3–δ was about 50% higher than those of PrGa0.9Mg0.1O3–δ. The electrical conductivity increased with Co content. The activation energies of conduction for Pr(Ga1–xCox)0.9Mg0.1O3–δ are in range from 0.197 to 0.246 eV, much lower than 1.543 eV for PrGaO3.