Structural and optical properties of nanocrystalline mayenite Ca₁₂Al₁₄O₃₃ powders synthesized using a novel route

In this article, mayenite Ca₁₂Al₁₄O₃₃ nanoparticles have been synthesized using oxalate precursor technique based on low cost starting materials for the first time. As a consequence, the effect of synthesis conditions on the crystal structure, crystallite size, microstructure, surface area S_BET and optical properties was studied. The results confirmed that well crystalline cubic mayenite phase was formed at low annealing temperature 800 °C for 1 h. The crystallite size was strongly depending on the temperature and time. Completely, it was in the range from 70.3 to 131.5 nm. Besides, lattice constant and unit cell volume were decreased whereas theoretical bulk density was increased with increasing the temperature and time. Meanwhile, the microstructure of the formed mayenite sample annealed at 800 °C was exhibited as sliced- leaves shape which was transformed to platelet like structure with raising the temperature. Meanwhile, the N₂ adsorption–desorption isotherm specific surface area (S_BET) was 5.00 m²/g. Ultraviolet–visible-Near IR spectroscopy evinced that optical band gap energy using Kubelka–Munk function based on Tauc’s plot was found to decrease with evaluation temperature and time. Moreover, the room temperature photoluminescence spectra measurement at excitation band 248 nm of pure mayenite nanoparticles was displayed an intense emission band centred at 360 nm.