Upconversion thermal enhancement of 2H11/2→4I15/2 of Er3+ and blue emission of impurity Tm3+ in Sr3(PO4)2:Er3+/Yb3+

Abstract

AbstractA series of Sr2.99‐x(PO4)2:.01Er3+/xYb3+ (x = .02, .04, .06, .08, .10) phosphors in the presence of impurity Tm3+ were synthesized by high temperature solid‐state method, and X‐ray diffraction results show that these samples are pure R‐3 m(166) space group phase. The upconversion luminescence (UCL) of Er3+ and impurity Tm3+ under 980‐nm laser excitation were investigated, and the results show that the intense blue UCL of impurity Tm3+ and thermal enhancement of 2H11/2→4I15/2 of Er3+ simultaneously exist. When Er3+ doping concentration is kept at .01, both the blue UCL intensity of impurity Tm3+ and green and red UCL intensity of Er3+ reach the maximum at Yb3+ doping concentration of .08. The thermal enhancement effect of 2H11/2→4I15/2 of Er3+ was observed as high as 3.27 times from 303 to 723 K, which is because of lattice distortion and phonon‐assisted transition. In addition, the optical temperature performance of Sr2.91(PO4)2:.01Er3+/.08Yb3+ sample was studied, and the maximum absolute temperature sensitivity was calculated as .00623 K−1 at 538 K. This study suggests that Sr3(PO4)2:Er3+/Yb3+ phosphors in the presence of impurity Tm3+ have a promising application prospect as optical temperature sensor at high temperature.