Exploration of the Temperature Sensing Ability of La₂MgTiO₆:Er³⁺ Double Perovskites Using Thermally Coupled and Uncoupled Energy Levels

Abstract

This work aimed to explore the temperature-sensing performance of La2MgTiO6:Er3+ double perovskites based on thermally coupled and uncoupled energy levels. Furthermore, the crystal structure, chemical composition, and morphology of the samples were investigated by powder X-ray diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy, respectively. The most intense luminescence was observed for the sample doped with 5% Er3+. The temperature-dependent emission spectra of La2MgTiO6:5% Er3+ were investigated in the wide range of 77–398 K. The highest sensitivity of the sample was equal to 2.98%/K corresponding to the thermally coupled energy level 2H11/2 → 4I15/2 and 4S3/2 → 4I15/2 as compared to 1.9%/K, obtained for the uncoupled energy level 2H11/2 → 4I15/2 and 2H9/2 → 4I15/2. Furthermore, the 300 K luminescent decay profiles were analyzed using the Inokuti–Hirayama model. The energy transfer among Er3+ ions was mainly regulated by the dipole–dipole mechanism. The critical transfer distance R0, critical concentration C0, energy transfer parameter Cda, and energy transfer probability Wda were 9.81 Å, 2.53×1020 ions·cm−3, 5.38×10−39 cm6·s−1, and 6020 s−1, respectively.

Keywords

• double perovskites
• La₂MgTiO₆
• erbium
• luminescence
• luminescent thermometry