Dual-functions of non-contact optical thermometry and anti-counterfeiting based on La2MgGeO6: Bi3+, Er3+ phosphors

Here, La2MgGeO6: Bi3+, Er3+ samples were synthesized by the high-temperature solid-phase method, and the up/down-conversion luminescence properties were investigated with the excitation of near-infrared light (980 nm and 1550 nm) and ultraviolet light (322–378 nm). Under the excitation of ultraviolet light, the sample can exhibit the characteristic broadband blue emission (Bi3+ ions) and green emission (Er3+ ions). When excited with near-infrared light, the sample has only typical green and orange up-conversion emission bands. The green and orange luminescence could be achieved by adjusting the excitation wavelength. In addition, the sample can present multicolor luminescence with the change of pump power and temperature. At the same time, the temperature measurement performance of the phosphor was explored by using the fluorescence intensity ratio technique based on the Er3+ ion thermal coupling energy level (2H11/2/4S3/2) and non-thermal coupling energy level (2H11/2/4F9/2). The maximum temperature sensitivity reached 1.23 %K−1 and 0.99 %K−1, respectively. Therefore, La2MgGeO6: Bi3+, Er3+ samples could be candidates for multicolor anti-counterfeiting and temperature sensors material.