Elastic constants of NaBH4 and LiBH4: Instability of β-LiBH4 Xiao-Dong Zhang, Zhu-Feng Hou, Zhen-Yi Jiang and Yu-Qing Hou EPL, 88 3 (2009) 36005 Published online: 17 November 2009 DOI: 10.1209/0295-5075/88/36005