Zhang Zhanwen, Li Xinfang, Wang Changjian, Qiao Xvsheng
Civil Aviation Flight University of China Luoyang College, Luoyang 471001, China.
State Key Laboratory of Silicon Materials & School of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China.
Phys Chem Chem Phys. 2019 Aug 21;21(31):17047-17053. doi: 10.1039/c9cp03929e. Epub 2019 Jul 30.
Quadrivalent Cr theoretically exhibits great potential to achieve higher photo-luminescence (PL) lifetime based temperature sensitivity than the commonly utilized trivalent Cr, but the problem is how to stabilize the anomalous quadrivalent chemical state of Cr. Here we propose a type of glass-ceramic phase structure with a precipitated ZnAlO crystalline sub-phase and a residual ZnO-SrO-SiO glassy sub-phase, where Cr can be well stabilized in the residual glassy sub-phase. From PL spectra, Cr or Cr was found to be located at T (tetrahedral crystal filed) or O (octahedral crystal filed) sites with a relatively high crystal field strength. The thermally coupled E(D)/T(F) states of Cr or the E(G)/T(F) states of Cr were revealed as competitive energy level pairs suitable for PL lifetime based temperature sensing. Quadrivalent Cr had a particular PL lifetime ratio of E(D)/T(F) up to 10, which was much higher than that (10) of trivalent Cr:E(G)/T(F). This supported Cr to eventually achieve a higher temperature sensitivity (1.72% K) one order of magnitude higher than that of Cr (0.83% K). This provides the possibility of utilizing Cr-doped glass to develop a type of temperature sensor with high precision and sensitivity.
