Optical and photoluminescence response driven by sintering temperature in LaFeO3 nano-perovskites

In this report, we synthesized LaFeO3 nano-perovskite compounds using conventional sol-gel techniques at three different sintering temperatures of 550, 650, and 750 degrees C. This study investigated how sintering temperature affects various properties, including structural, microstructural, vibrational, optical, and photoluminescence properties. Rietveld-fitted X-ray diffraction study confirmed that all reported compounds exhibited orthorhombic symmetry, with Pbma space group, and no identifiable impurity or secondary phase. The lattice parameters increased with rising sintering temperature, as estimated using the Hall-Williamson method for crystalline size determination. Scanning electron microscopy (SEM) images revealed the formation of particles with a spherical shape/size and a flake-like grain structure. The particle size distribution results were similar to the crystalline size. Fourier transform infrared (FTIR) spectroscopy techniques were utilized to explore the vibration modes of Fe-O and the presence of distinct functional groups. Tauc's plot was also used to analyze the absorbance and optical band gap using UV-vis absorption spectroscopy. The optical band gap increased with the rising sintering temperature. We conducted a photoluminescence study to recognize oxygen vacancies and defects of the synthesized compounds. These imperfections cause lattice disorder and a shift in the energy band gap from the ultraviolet to the visible spectrum region, which affects electronic transitions. The synthesized compounds exhibited CIE (Commission Internationale de l'eclairage) chromaticity coordinates in the blue region, making them potentially useful in optical and display devices.