Crystal growth and spectroscopic properties of Cr3+- doped CaGdAlO4

Publication date: Available online 2 February 2017
Source:Journal of Crystal Growth
Author(s): Zhu Zhang, Yisheng Huang, Lizhen Zhang, Shijia Sun, Feifei Yuan, Zhoubin Lin
A Cr³⁺:CaGdAlO4 single crystal with dimensions of Ø 21 × 33 mm³ was grown successfully by Czochralski method for the first time. Its spectral properties including polarized absorption spectra, polarized fluorescence spectra, excitation spectrum and fluorescence decay curves were investigated in detail. The absorption cross-sections at around 573 nm corresponding to the ⁴A2→⁴T2 transition of Cr³⁺ ions are 4.75 × 10^-20 and 2.56 × 10^-20 cm² for σ- and π- polarizations, respectively. The excitation spectrum shows two broad and intense absorption bands at about 390 nm and 570 nm, which are associated with the ⁴A2→⁴T1 and ⁴A2→⁴T2 transitions of Cr³⁺ ions, respectively. The emission band with peak at around 744 nm is ascribed to the ²E→⁴A2 transition of Cr³⁺ ions, with the emission cross-sections of 5.55 × 10^-22 and 5.41 × 10^-22 cm² for σ- and π- polarizations, respectively. The fluorescence lifetime is 4.35 ms at room temperature. The Dq/B value is 2.72, which means that Cr³⁺ ions occupy the lattice sites with strong crystal field strength. The results show that Cr³⁺:CaGdAlO4 crystal can be regarded as a potential laser gain medium.