Exploration of the Temperature Sensing Ability of La(2)MgTiO(6):Er(3+) Double Perovskites Using Thermally Coupled and Uncoupled Energy Levels

This work aimed to explore the temperature-sensing performance of La(2)MgTiO(6):Er(3+) 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% Er(3+). The temperature-dependent emission spectra of La(2)MgTiO(6):5% Er(3+) 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 (2)H(11/2) → (4)I(15/2) and (4)S(3/2) → (4)I(15/2) as compared to 1.9%/K, obtained for the uncoupled energy level (2)H(11/2) → (4)I(15/2) and (2)H(9/2) → (4)I(15/2). Furthermore, the 300 K luminescent decay profiles were analyzed using the Inokuti–Hirayama model. The energy transfer among Er(3+) ions was mainly regulated by the dipole–dipole mechanism. The critical transfer distance R(0), critical concentration C(0), energy transfer parameter C(da), and energy transfer probability W(da) were 9.81 Å, [Formula: see text] ions·cm(−3), [Formula: see text] cm(6)·s(−1), and 6020 s(−1), respectively.