An explicit and novel structure, lattice dynamics, and photoemission of La-doped nanocrystalline SrZrO3 perovskite

Abstract

As no complete and comprehensive studies have been previously reported for La-doped nanocrystalline SrZrO3 (SZO), we researched herein a detailed investigation for pure and La-doped samples. A modified solid-state reaction process, including successive cycles of milling and sintering at high temperature, was followed to produce SZO and Sr0.9La0.1ZrO3 (SLZO) powdered ingots. Rietveld analysis of X-ray diffractometer data predicts that the two samples exhibit orthorhombic structure with an increase in crystallite size by ~25% for doped sample. A great reduction in Raman modes intensity (~60%) and an annihilation of several vibration modes were detected using Raman spectroscopy. The degree of ordering on the B-site was recorded to be higher in La-doped sample. According to ultraviolet–visible (UV–Vis) absorption, a decrease in the optical gap width (E g) from 4.40 eV to 4.21 eV was achieved by La incorporation due to the presence of additional defect states such as oxygen and Sr vacancies at the band edge. The process of electron–hole recombination was studied using photoluminescence (PL) spectroscopy. Deconvolution of PL spectra yielded four emission bands: one green band, one blue band, and two violet bands. Highly intense violet emission at λ = 393 nm approximately five times greater than that detected for pure SZO is realized as La3+ substitutes for Sr2+. Such property nominates SLZO for technological applications requiring highly intense violet emission, e.g., light-emitting diodes.