Tetragonal Phase Change by Copper Solution in Nickel Oxide

Abstract

Nickel copper oxide ((Ni_1-xCu_x)O) thin films, where the Cu content x was changed in the range from 0 to 1, were prepared by pulsed laser deposition. The copper content of the thin films was determined by energy-dispersive X-ray analysis with scanning electron microscopy. Transmission electron microscope observations of the thin film with x=0.52 revealed that the unit cell was distorted from cubic to tetragonal according to the Jahn-Teller effect by Cu²⁺ ions dissolved in the NiO lattice.