Multi-functionalities of photoluminescence, X-ray excited luminescence and optical temperature sensing in Er3+ and Er3+/Yb3+ doped Gd2Zr2O7 phosphors

Abstract

A series of Er3+-doped and Er3+-Yb3+ co-doped Gd2Zr2O7 phosphors were synthesized via hydrothermal method, and their multifunctional properties were studied in detail. The Raman spectra indicated that the products were the ordered pyrochlore phase of Gd2Zr2O7, which exhibited a good radiation resistance. The up-conversion (UC), down-conversion (DC) photoluminescence (PL) and X-ray excited luminescence (XEL) spectra of the Er3+: Gd2Zr2O7 samples showed the similar spectra profiles, which were composed of the prominent green (2H11/2/4S3/2→4I15/2) and weak red (4F9/2→4I15/2) emissions. The co-doping of Yb3+ ions was beneficial for the improvement in UC PL but led to the reductions in DC PL and XEL. Besides, the X-ray induced green emissions demonstrated a high-sensitivity to the dose rate and a long-term stability against the continuous X-ray irradiation. Moreover, using the fluorescence intensity ratio (FIR) technique, the temperature sensing behaviors were analyzed based on the thermally coupled levels (TCLs) 2H11/2 and 4S3/2 of Er3+. The FIRs were found to be insensitive to the excitation power variation, and the optimal relative sensing sensitivity reached ~1.1%K−1 at 298 K. These characteristics may enable the studied system applicable for optical thermometry, X-ray detection and X-ray imaging.