基于Er3+的两个热耦合能级发光强度测量的荧光强度比测温技术由于不受光谱损失和激发强度波动的影响, 故能够提供准确的非接触式温度测量。但目前通用的荧光强度比技术都是基于上转换激发, 而上转换材料效率较低, 测温不准确。考虑到Er3+能级可通过不同激发源来布居, 本文利用高能光子激发的高效下转换光学测温方法, 来解决上转换发光带来的问题, 并以具有高测温灵敏度的钨酸盐NaGd(WO4)2为基质。研究发现, NaGd(WO4)2可成功用于下转换测温, Yb3+/Er3+共掺样品比Er3+单掺拥有更高的测温灵敏度, 且下转换测温灵敏度要高于上转换, 在掺杂浓度为20%Yb3+/1%Er3+时, 测温灵敏度高达3446×10-4 K-1。这证明了NaGd(WO4)2∶Yb3+/Er3+是理想的测温材料, 也很好地验证了其在高灵敏度下转换测温的可行性, 为荧光强度比技术的应用开辟了新的前景。

The fluorescence intensity ratio(FIR) thermometry based on the measurement of luminous intensities of two thermal coupling energy levels of Er3+ provides high precision for the non-contacted thermometry due to its independency of the spectral loss and excitation intensity fluctuations. However, the common FIR technology is based on the up-conversion(UC) excitation, and its low up-conversion efficiency makes the temperature measurement inaccurate. Considering that the thermalization of population in Er3+ can be achieved by different excitation sources, we utilize the efficient down-conversion(DC) optical temperature measurement with a high-energy photon excitation. A tungstate material of NaGd(WO4)2 with high temperature sensitivity is used as the matrix material. It is found that NaGd(WO4)2 can be successfully applied for the DC thermometry, and the temperature sensitivity of Yb3+/Er3+ co-doped sample is higher than that of Er3+ single-doped one. In addition, the DC thermometry possesses higher sensitivity than UC, and the temperature sensitivity of 20%Yb3+/1%Er3+ doped sample is up to 3446×10-4 K-1, which demonstrates that NaGd(WO4)2∶Yb3+/Er3+ is an ideal temperature measuring material. More importantly, it further proves the feasibility of highly sensitive DC thermometry and opens up new prospects for the utilizations of FIR technology.