Li^(+)增强NaGd(WO_(4))_(2)∶Yb^(3+)/Er^(3+)荧光粉的上转换发光和温度传感性能

Upconversion Luminescence and Temperature Sensing Properties of NaGd(WO_(4))_(2)∶Yb^(3+)/Er^(3+)Phosphors Enhanced by Li^(+)

采用水热法制备了NaGd(WO_(4))_(2)∶0.05Yb^(3+)/0.005Er^(3+)/xLi^(+)(x=0,0.01,0.02,0.03,0.05)荧光粉。通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和光致发光(PL)谱等手段分析了样品的晶体结构、形貌和上转换发光性能。结果表明,Li的掺杂并未改变NaGd(WO_(4))_(2)∶Yb^(3+)/Er^(3+)荧光粉的四方相晶体结构,但在波长980nm激光二极管(LD)激发下,样品的上转换发光强度发生明显改变。随着x的增加,Er^(3+)的绿光和红光发光强度均呈现先升高后降低的趋势,当x=0.03时,发光强度达到最大值。上转换发光强度与泵浦功率的依赖关系表明,绿光和红光发射都属于双光子吸收过程。此外,采用基于Er^(3+)热耦合能级的荧光强度比(FIR)测温技术,研究了+NaGd(WO_(4))_(2)∶0.05Yb^(3+)/0.005Er^(3+)/0.03Li^(+)荧光粉在298~573K温度范围内的温度传感性能。该结果表明NaGd(WO_(4))_(2)∶0.05Yb^(3+)/0.005Er^(3+)/0.03Li^(+)荧光粉相对灵敏度(SR)在298K时达到最大值0.0119K^(-1),表明其在光学温度传感领域具有潜在的应用价值。

NaGd(WO_(4))_(2)∶0.05Yb^(3+)/0.005Er^(3+)/xLi^(+)(x=0,0.01,0.02,0.03,0.05)phosphors were prepared by hydrothermal method.The crystal structures,morphologies and upconversion luminescence properties of the samples were analyzed by X-ray diffraction(XRD),scanning electron microscope(SEM)and photoluminescence(PL)spectrum.The results indicate that the doping of Li^(+)does not change the tetragonal crystal structure of NaGd(WO_(4))_(2)∶Yb^(3+)/Er^(3+)phosphors,but the upconversion luminescence intensity of the spmples is obviously changed under the excitation of laser diode(LD)with 980 nm wavelength.With the increase of x,the green light and red light luminescence intensities of Er^(3+)show a trend of first increasing and then decreasing.When x=0.03,the luminescence intensity reaches the maximum.The dependence of upconversion luminescence intensity on pump power indicates that both green emission and red emission belong to two-photon absorption process.In addition,the temperature sensing properties of NaGd(WO_(4))_(2)∶0.05Yb^(3+)/0.005Er^(3+)/0.03Li^(+)phosphor were investigated by the fluorescence intensity ratio(FIR)temperature mearsurement technique based on thermally coupled energy levels of Er^(3+)in the temperature range of 298-573 K.The results show that the relative sensitivity(SR)of NaGd(WO_(4))_(2)∶0.05Yb^(3+)/0.005Er^(3+)/0.03Li^(+)phosphor reaches maximum value of 0.0119 K^(-1) at 298 K,indicating its potential application value in the field of optical temperature sensing.