Phase Behavior in the LiBH4鈥揕iBr System and Structure of the Anion-Stabilized Fast Ionic, High Temperature Phase

详细信息    查看全文

• 作者：Irene Cascallana-Matias ; David A. Keen ; Edmund J. Cussen ; Duncan H. Gregory
• 刊名：Chemistry of Materials
• 出版年：2015
• 出版时间：November 24, 2015
• 年：2015
• 卷：27
• 期：22
• 页码：7780-7787
• 全文大小：386K
• ISSN：1520-5002

文摘

The fast ionic, high temperature (HT) phase of LiBH₄ can be stabilized by Br炉 substitution. Lithium borohydride bromide compounds, Li(BH₄)_1鈥?i>xBr_x, have been synthesized mechanochemically, with and without thermal treatment and the resulting phase behavior determined as a function of composition. Single phase materials exist for 0.29 鈮?x 鈮?0.50 with conductivity 2 orders of magnitude higher than LiBH₄ at 313 K. Powder neutron diffraction has been used to resolve the details of the crystal structure of one such compound. These demonstrate that ⁷Li(¹¹BD₄)_0.667Br_0.333 retains the HT structure (hexagonal space group P6₃mc, a 鈮?4.2 脜, c 鈮?6.7 脜) from 293 to 573 K. The borohydride bromide exhibits considerable static and dynamic disorder, the latter invoking complex rotational motion of the (BH₄)炉 anions.