NaGd(WO 4)2∶Yb^3+,Ho^3+,Cr^3+微米晶的上转换发光与温度特性

采用水热法制备了NaGd(WO4)2(NGW)∶Yb^3+,Ho^3+,Cr^3+微米晶。研究了Cr^3+离子掺杂浓度对样品的晶体结构、微观形貌、上转换发光及温度传感特性的影响。在980 nm激光激发下,所有样品均发射以546 nm为中心的较弱绿光和以660 nm为中心的强红光,分别对应于Ho^3+离子的5F4,5S2→5I8和5F5→5I8能级跃迁。随Cr^3+离子掺杂量增加,绿光发射峰强度逐渐减弱,而红光发射先增大后减小,在10%时达到最大,样品色坐标逐渐向红色区域偏移。样品的变温光谱表明,NGW∶Yb^3+,Ho^3+,10%Cr^3+微米晶具有很好的温度特性,其测温灵敏度在486 K时达到最大,约为0.0337 K^-1,比NGW∶Yb^3+,Ho^3+的灵敏度提高近1倍。

Up-conversion Luminescence and Temperature Characteristics of NaGd(WO4)2∶Yb^3+,Ho^3+,Cr^3+Micro-crystals

NaGd(WO4)2(NGW)∶Yb^3+,Ho^3+,Cr3+micro-crystals were synthesized through a hydrothermal method.The effects of Cr^3+doping concentrations on the crystal structure,micro-morphology,upconversion luminescence and temperature sensing properties of the samples were investigated.Under the excitation of 980 nm laser,all of the samples show weak green(centred at 546 nm)and strong red(660 nm)emissions,which corresponding to the energy transition of 5F4,5S2→5I8 and 5F5→5I8 of Ho^3+,respectively.With the increase of Cr3+contents,the intensity of green emission decreases gradually,while the red emission increases firstly and then decreases,reaching the maximum at 10%,and the color coordinates of the samples shift gradually towards the red region.The spectra of temperature dependence of luminescence indicate that NGW∶Yb^3+,Ho^3+,10%Cr^3+micro-crystals exhibit excellent temperature characteristic,and the sensitivity reaches the maximum at 486 K with the value of 0.0337 K^-1,which is nearly doubled compared with that of NGW∶Yb^3+,Ho^3+micro-crystals.