Microwave assisted preparation of ternary scheelite CaMoO4: Er3+/Yb3+ nano-phosphors for up/down-conversion photoluminescence, temperature sensing and antibacterial properties

Abstract

Due to their exceptional intrinsic optical characteristics, molybdate compounds have aroused significant attention in recent years for their effective up and downconversion luminescence. In the present study, a series of xEr³⁺/Yb³⁺ (x = 0.5 %, 1 %, 2 %, 4 % and Yb³⁺ =15 %) doped CaMoO₄ nanophosphors synthesized through a microwave assisted approach and subsequently the comprehensive analysis of the functionalities such as optical properties, antibacterial traits and their integration with temperature sensing, have been explored. Furthermore, the structural refinement confirms the occurrence of tetragonal scheelite phase of the prepared materials. The morphology of the material was identified by FE-SEM and HR-TEM analysis which reveals particles are in spherical shape. Up-conversion luminescence intensities were found to be dependent on doping concentration, laser excitation power and external temperature upon 980 nm light excitation. The temperature sensing response of the optimized sample was examined based on intensity ratio of two emission bands that involves thermally connected energy levels of Er³⁺ ion. The maximum absolute sensitivity of 10.74 × 10⁻³ K⁻¹ (at 500 K) was found, demonstrating its potential application in high temperature thermometry. The comprehensive analysis and the outcome of the present study suggests the potential prospect of the as-synthesized material in food preservation, medical equipment, water treatment, and as an optical coating agent for solid state luminous devices.