Green Synthesis of Tb3+-Doped CaMoO4 Nanothermometers Using Plant Extract: Enhanced Optical Properties for Temperature Sensing Applications

Abstract

Luminescent temperature sensors enable precise thermal monitoring at cellular levels, facilitating cancer treatment approaches and industrial process monitoring across wide temperature ranges. These sensors, when constructed from inorganic matrices incorporating specific luminescence-activating centers, allow temperature estimation through their emission characteristics. This work investigates the optical properties of Tb³⁺-doped CaMoO₄ crystals synthesized via an environmentally friendly coprecipitation method using an extract from the leaves of the Tabebuia aurea tree. Spectroscopic characterization confirms the formation of the CaMoO₄ crystalline phase and successful incorporation of Tb³⁺ ions into the crystal lattice. Particle morphology was examined using scanning electron microscopy. Temperature-dependent luminescence measurements reveal exceptional performance as an optical sensor, with a calculated relative sensitivity of 2.8% K^–1 at 363 K, surpassing previously reported values for other Tb³⁺-doped materials. This green synthesis approach demonstrates that environmentally sustainable methods can produce nanothermometers with enhanced sensing capabilities, surpassing conventionally synthesized alternatives, and with significantly reduced organic residues, which correlates with a superior radiative lifetime and excellent stability and reproducibility for practical applications.