Site preference and the optical thermometry strategy by different temperature response from two sites environment of Mn2+ in K7ZnSc2B15O30

Abstract

A novel optical thermometry strategy based on different temperature response from two sites environment of Mn2+ in K7ZnSc2B15O30:Mn2+ had been reported. The color tunable Mn2+ doped K7ZnSc2B15O30 luminescence materials were successfully prepared, and the photoluminescence properties were studied. Using density functional theory, the electronic structure was estimated. The calculated result showed that K7ZnSc2B15O30 was a direct-band gap material with the energy gap of 4.22 eV. Upon the excitation of UV light, the photoluminescence spectra of K7ZnSc2B15O30:Mn2+ phosphors demonstrated two emission bands centered at 584 nm and 675 nm attributed to the substitution of Zn2+ and Sc3+ sites with Mn2+ respectively. Depending on the concentration of Mn2+, the emitting color can be tunable from yellow to red in the Mn2+ doped single-phase phosphors. The temperature-dependent luminescence properties of K7ZnSc2B15O30:Mn2+ was anlysized range from 300 K to 520 K. The results indicated that the thermal quenching properties of Mn2+ at the two kinds of lattice sites are different. When Mn2+ occupied the position of Sc3+, the luminescence intensity decreased significantly with the increasing of temperature, on the contrary, when Mn2+ occupied the position of Zn2+, the luminescence intensity decreased slightly with the rise of temperature. This situation caused a significant change in the fluorescence intensity ratio of the two emission bands. Further study showed that the typical phosphor had a high relative and absolute sensitivity respectively with maximum value of 1.84% K−1 and 0.0311 K−1 at 520 K, and the temperature resolution is about 0.8 K. These results indicated that the single Mn2+ doped K7ZnSc2B15O30 materials showed a potential application for optical thermometry.