PNNL

Abstract

This work reports the discovery of room-temperature ferromagnetism in 5 - 9 nm sized Ce1-xNixO2 nanoparticles (0.01 = x = 0.10) prepared using a sol-gel based chemical method at room temperature and under ambient conditions. Particle induced x-ray emission studies were used to determine the dopant concentrations. Magnetic measurements of the chemically synthesized Ce1-xNixO2 samples at room temperature showed coercivity in the 40 - 120 Oe range, and the saturation magnetization showed a maximum of 1.21 memu/g (8.59×10-4 µB/Ni ion) for x = 0.04. Average crystallite sizes and lattice parameters estimated from x-ray diffraction and transmission electron microscopy studies showed a gradual decrease with x in the entire doping range while the lattice strain showed a minimum for x = 0.04. Optical studies revealed direct band gap energies ranging from 3.23 to 3.99 eV with a minimum for x = 0.04. A high Curie temperature of TC = 550 K was obtained for x = 0.04.