基质VO_(4)^(3+)与掺杂离子Pr^(3+)荧光强度比的新型高灵敏度光学测温研究

Novel high-sensitivity optical thermometry based on fluorescence intensity ratio ofVO_(4)^(3+) to Pr^(3+)

目前,光学测温技术在传感、治疗、诊断和成像等领域取得了重大突破.但是,基于传统热耦合能级荧光强度比测温的灵敏度较低,限制了其进一步的发展.本文基于基质与掺杂离子间不同的温度依赖行为,提出了一种新型的具有高灵敏度的测温方案.首先,采用固相法成功合成了YVO_(4):Pr^(3+)荧光粉.然后,采用X射线衍射(XRD)、扫描电子显微镜和荧光分光光度计对样品的结构与发光特性进行表征.XRD结果表明Pr^(3+)成功掺入YVO_(4)基质.SEM结果表明样品为长方体形状微米晶颗粒,平均颗粒大小约为2.1μm.在320 nm激发下,YVO_(4):Pr^(3+)主要呈现出在440 nm附近的蓝光发射和606 nm的红光发射,发光峰不存在明显的重叠.基于VO_(4)^(3+)与Pr^(3+)的发光对温度的不同响应,实现了新的荧光强度比测温方案.测温范围为303—353 K,最大绝对灵敏度和相对灵敏度分别为0.651 K–1和3.112×10^(–2) K^(–1)@353 K,远高于传统的热耦合能级测温方案.这为设计具有优异温度灵敏度和信号可辨别性的自参考光学测温材料提供了一种有前景的途径.

It is noteworthy that since 2010,the number of published and cited scientific papers on optical thermometry has increased exponentially.Optical thermometry technology is about to make a significant process in sensing,therapy,diagnosis,and imaging.The current research mainly focuses on optical thermometry that is developing towards high-sensitivity thermometry.In this work,a new thermometry strategy is proposed based on the different temperature-dependent behaviors between the host ions and the doped ions.Firstly,YVO_(4):xPr^(3+)(x=0%–1.5%)phosphors are successfully synthesized by the solid-state method.Then,the structure and luminescence properties of the samples are characterized by X-ray diffraction(XRD),scanning electron microscope(SEM)and fluorescence spectrophotometer.The XRD results show that Pr^(3+)ions are successfully incorporated into the YVO_(4) host,and the sample has a tetragonal phase crystal structure with space group I41/amd.The SEM results show that the samples are rectangular-shaped micron particles with smooth surfaces,and the average grain size is about 2.1μm.Under the excitation of 320 nm,the sample mainly exhibits broadband blue emission around 440 nm and red emission at 606 nm,which are attributed to the charge transfer transition of VO_(4)^(3+)and the 1D2→3H4 transition of Pr^(3+),respectively.The relationship between the luminescence of the sample and the concentration of Pr^(3+)is studied.It is found that the optimal doping concentration of Pr^(3+)is 0.5%,and a higher doping concentration will cause concentration to be quenched.The reason for quenching concentration is the electric dipole-quadrupole interaction.The luminescence peak position of the temperature-dependent spectrum of YVO_(4):0.5%Pr^(3+)is consistent with that at room temperature.As the temperature increases,the total luminescence intensity gradually decreases,which is caused by thermal quenching,and the mechanism of thermal quenching is analyzed.Since the temperature-dependent behaviors of luminescence of VO_(4)^(3+)and Pr^(3+)are significantly different from each other,a new fluorescence intensity ratio thermometry strategy is realized.Temperatures range is 303–353 K,and the maximum absolute sensitivity and relative sensitivity are 0.651 K–1 and 3.112×10^(–2) K^(–1) at 353 K,respectively,much higher than the traditional thermally coupled level thermometry strategy.In addition,there is no obvious overlap between the emission peaks of VO_(4)^(3+)and Pr^(3+),which provides a good discrimination capability for signal detection.The above results show that this work provides a promising path for designing self-reference optical thermometry materials with excellent temperature sensitivity and signal discrimination.