Abstract：By far, the most efficient up-conversion nanocrystals luminescence materials BaGd2ZnO5∶4%Yb3+,1%Er3+, with stable chemical performance, were prepared by using Sol-gel method. XRD pattern shows that the sample is pure phase, belongs to the orthogonal crystals, and space group is Pbnm; SEM micrograph shows that the prepared sample of the morphology sized around 150 nm is evenly distributed. Samples with 971 nm semiconductor laser excitation produce a strong green emission, visible to the naked eye, and up-conversion strength and pump energy relation n=1.22 is two-photon for the realization of the up-conversion emission. They originated from Er3+ ions 2H11/2→4I15/2 and 4S3/2→4I15/2 transition emission, Er3+ ions main excited state absorption (ESA) process is: 4I15/2→4I11/2→2F7/2→2H11/2, 4S3/2, Yb3+ was added because of its large absorption cross section (104 cm-1) so that it is easy to transfer excitation energy to the Er3+ ions which enhance the layout particles number and the energy state of the 2F7/2, thereby enhancing the intensity of the peaks of the spectrum. Fluorescence intensity ratio (FIR) technique based on the green up-conversion emission of the sample has been studied because the Er3+ ions 2H11/2 and 4S3/2 energy level spacing is small. The electrons at the two levels conform to the Boltzmann distribution which is a function of temperature, and thus the fluorescence intensity ratio of two levels can be used to measure the temperature of the substrate material. This method does not interfere with temperature field of the measured object, and can eliminate the uncertainty of the accuracy; the test has a wide temperature range and reasonable temperature resolution, the pump source used is simple, convenient and inexpensive, and has more commercial values. The temperature range of the samples is from 350 to 800 K, and the highest temperature measuring sensitivity can reach 0.003 1 K-1. At the same time, under low excitation density, it can produce higher conversion transmission power, making it become ideal material for distance non-contact temperature measurement.
Key words：Optical temperature sensor;Up-conversion;Fluorescence intensity ratio (FIR)
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