Cr^(3+)在SrTiO_3晶体中的晶场能级

CRYSTAL-FIELD ENERGY LEVELS OF Cr^(3+) IN SrTiO_3 CRYSTAL

由激发光谱及荧光光谱的测量,运用Tanabe-Sugano能量矩阵计算了Cr^(3+)在SrTiO_3晶体中的晶场能级.

Excitation and fluorescence spectra of SrTiO3 :Cr3+ crystal were measured at 63 K and 9 K respectively. The crystal-field energy levels of Cr3+ in SrTiO3 crystal were calculated according to Tanobe-Sugano energy matrices and the experimental results.The sample was grown in reduction atmosphere using melt method, which contains nominally 0.01 Wt. % Cr2O3. A l-mm-thick , polished sample, which was annealed at 660℃ for one to two minutes in air , was used in the experiment. Annealing the sample in air reduces the oxygen vacancies and increases Cr4+ concentration.The crystal-field strength parameter D9 and Racah parameters B and C obtained were 1 626, 471 and 2 992 cm-1 respectively. The ratio Dq/B = 3.46>2.3cm--1 means that SrTiO3 crystal belongs to strong field material. The red shift of R line ralative to other Cr3+ -doped crystals is about 100 nm. So large red shift was explained to be due to the strong covalence of the SrTiO3 crystal.