Effects of annealing temperature on the phase formation, optical, photoluminescence and magnetic properties of sol-gel YFeO3 films

Abstract

YFeO 3 (YFO) thin films were deposited onto quartz substrates via sol-gel spin-coating technique and annealed at different temperature ranged between 650 and 900 °C. The impact of annealing temperature on the phase formation, microstructural, optical, photoluminescence (PL) and magnetic properties of the films were systematically investigated. X-ray diffraction analysis revealed an amorphous structure in film annealed at 650 °C and formation of hexagonal-YFO ( h -YFO) phase in films annealed at 750–800 °C. The films annealed at 850–900 °C exhibited an orthorhombic-YFO ( o -YFO) structure. Atomic force microscopy images of h -YFO films showed homogeneous surface with uniform particles size and shape. The particle size increased and had irregular shape in o -YFO films. The average particle size was 44 and 117 nm, while the root square roughness was 1.38 and 2.55 nm for h - and o -YFO films annealed at 750 and 850 °C, respectively. The optical band gap ( E g ) was 2.53 and 2.86 eV for h - and o -YFO films annealed at 750 and 850 °C, respectively. The PL spectra of h -YFO films were red-shifted compared with that of o -YFO films. The PL emission related to near band edge was observed at 459.0 and 441.9 nm for h - and o -YFO films annealed at 750 and 850 °C, respectively. The magnetization was enhanced with the increasing of annealing temperature and has the value of 4.8 and 12.5 emu/cm 3 at 5000 Oe for h - and o -YFO films annealed at 750 and 850 °C, respectively.