Structural and optical study of optimized undoped and Cu-doped LaAlO3

Abstract

Different compositions of undoped and Cu-doped LaAlO${}_3$ samples were synthesized using the solid-state reaction method with variable single-stage and double-stage heat treatments to obtain the monophasic LaAlO${}_3$. The monophasic LaAlO${}_3$ sample is formed via double stage heat-treatment, i.e., 1100°C (2 h) followed by 1450°C (4 h). Their structural, morphological, and optical properties are characterized using X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, Field emission scanning electron microscopy with an attached energy dispersive spectroscopy, UV–Visible and Photoluminescence spectroscopy. Copper probably occupied the Al-O sites in the rhombohedral crystal structure, as confirmed by FTIR band shifting in the doped system. The optical band could be functionalized by Cu dopant, and it decreased in the Cu-doped LaAlO${}_3$. The bandgap is in the semiconductor range, i.e., 2.4–1.8 eV. The developed materials may find applications in energy conversion devices as cathode materials in intermediate temperature solid oxide fuel cell applications.