Structural and physical properties of microwave synthesized orthorhombic perovskite erbium chromite ErCrO_3

摘要

Rare-earth chromite ErCrO_3 powder was synthesized from metal nitrate precursors using microwave synthesis. (Micro-) structural characterizations were performed using X-ray diffraction, Rietveld refinement, High Resolution Transmission Electron Microscopy and Electron Micro-Diffraction. Magnetization vs. temperature measurements revealed anti-ferromagnetism with T_(Neel) ≈ 135 K. An anti-fcrrimagnetic moment of ≈ 0.4 μ_B was determined from magnetization vs. applied field measurements. Temperature dependent impedance spectroscopy (IS) indicated 3 dielectric relaxation processes: electrode interface, grain boundary and bulk. The intrinsic bulk activation energy was found to be 0.27 eV and the dielectric permittivity ε_r was ≈ 23 in excellent agreement with Clausius-Mossotti predictions and showed no perceptible temperature dependence. This and the low ε_r value suggested that ErCrO_3 is a dielectric rather than ferroelectric compound. IS measurements with applied dc bias revealed the signs of an unconventional type of Schottky barrier at the metallic Au electrode/ceramic ErCrO_3 interface.