Crystal structure, thermal expansion and electrical conductivity of Pr(Ga_(1-x)Co_x)_(0.9)Mg_(0.1)O_(3-δ) (x=0, 0.1, 0.2, 0.3)

摘要

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.