1. P. Suthanthirakumar, C. Basavapoornima, and K. Marimuthu, J. Lumin. 392, 187 (2017).
2. V.K. Rai, S.B. Rai, and D.K. Rai, Spectrochim. Acta Part A Mol. Biomol. Spectrosc. 302, 62 (2005).
3. D. Manzani, D. Pabœuf, S.J. Ribeiro, P. Goldner, and F. Bretenaker, Opt. Mater. 383, 35 (2013).
4. R.T. Karunakaran, K. Marimuthu, S.S. Babu, and S. Arumugam, Solid State Sci. 1882, 11 (2009).
5. A. Dehelean, S. Rada, I. Kacso, and E. Culea, J. Phys. Chem. Solids 1235, 74 (2013).