Submitted on: 17 January 1998.
Revised on: 22 February 1998.
Accepted on: 07 March 1998.
Materials Today Physics---ELSEVIER
http://reply.papertrans.cn/3/215/21407/21407-22.png
Submitted on: 26 August 2017.
Revised on: 27 September 2017.
Accepted on: 11 October 2017.
Materials Today Physics
http://reply.papertrans.cn/3/215/21407/21407-24.png
Submitted on: 17 May 2018.
Revised on: 12 June 2018.
Accepted on: 30 June 2018.
Materials Today Physics
http://reply.papertrans.cn/3/215/21407/21407-26.png
Submitted on: 20 October 2015.
Revised on: 01 December 2015.
Accepted on: 26 December 2015.
Materials Today Physics---ELSEVIER
Submitted on: 07 November 2012.
Revised on: 21 November 2012.
Accepted on: 04 December 2012.
Materials Today Physics
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