溶胶-凝胶法制备铥镱共掺杂Y_2Ti_2O_7粉末上转换发光特性研究

Research of Up-conversion Luminescent Properties of Tm^(3+)-Yb^(3+) Co-doped Y_2Ti_2O_7 Powdersby Sol-gel Method

采用溶胶-凝胶(Sol-gel)法制备1 mol%Tm3+、1 mol%Tm3+和10 mol%Yb3+共掺杂Y2Ti2O7粉末。Tm3+掺杂Y2Ti2O7为Y2Ti2O7相和微量TiO2相的混合结构,Yb3+共掺杂不改变Tm3+掺杂Y2Ti2O7相结构。在976 nm半导体激光器(LD)激发下,在430～500 nm和620～750 nm波长范围内获得了蓝色和红外上转换发光,分别对应于Tm3+的1G4→3H6和3H4→3H6跃迁。Yb3+共掺杂显著提高了Tm3+掺杂Y2Ti2O7的上转换发光强度。研究表明:随着LD激发电压增大,Tm3+-Yb3+共掺杂Y2Ti2O7上转换发光强度逐渐增大,且上转换发光强度随LD激发功率增大呈现两阶段变化规律;随着温度升高,Tm3+-Yb3+共掺杂Y2Ti2O7上转换发光强度逐渐降低,这是由无辐射弛豫速率随着温度升高而增加所致。

The 1 mol% Tin^3＋, 1 mol% Tm^3＋ and 10 tool% Yb^3＋ co -doped Y2Ti2O7 powders were prepared by sol- gel method. The Tm^3＋ doped Y2Ti2O7 was composed of mixture of Y2Ti2O7 and tiny TiO2 phases. Yb^3＋ co - doping had no effect on the phase structure of Tm^3＋ doped Y2Ti2O7. The blue and infrared up -conversion emissions in the wavelength range of 430 - 500 nm and 620 - 750 nm were detected by a 980 - nm semiconductor laser diode （LD） excitation, which corresponding to the ^1G4→^3H6 and ^3H4→^3H6 transitions of Tm^3＋. The up -conversion emissions intensity of Tm^3＋ doped Y2Ti2O7 powders was enhanced by Yb^3＋ co -doping. The up -conversion emissions intensity of Tm^3＋ -Yb^3＋ co -doped Y2Ti2O7 increased gradually with increasing the excitation voltage of LD. The two step process was observed for the up - conversion emission intensity with increasing the excitation power of LD. The up - conversion emissions intensity of Tm^3＋ -Yb^3＋ co- doped Y2Ti2O7 was decreased with increasing the temperature, which caused by the increase of rate of nonradiative relaxation rate with temperature.