M.R. Jisha, Yun Ju Hwang, Jae Sun Shin, Kee Suk Nahm, Prem Kumar, K. Karthikeyan, N. Dhanikaivelu, D. Kalpana, N.G. Renganathan and A. Manuel Stephan
Materials Chemistry and Physics 115 ( 1 ): 33 - 39 , 2009