Dehydrogenation properties and crystal structure analysis of Mg(BH4)(NH2)
Dehydrogenation properties and crystal structure analysis of Mg(BH4)(NH2)
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DOI：
10.1016/j.jallcom.2013.03.081
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发表时间：
2013-12
影响因子：
6.2
通讯作者：
T. Noritake;K. Miwa;M. Aoki;Mitsuru Matsumoto;S. Towata;Haiwen Li;S. Orimo
中科院分区：
文献类型：
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作者：
T. Noritake;K. Miwa;M. Aoki;Mitsuru Matsumoto;S. Towata;Haiwen Li;S. Orimo
用热分析和同步辐射X射线衍射法研究了双阴离子络合物氢化物Mg(BH4)(NH2)的脱氢性能和晶体结构。将化学计量比的镁(BH4)2和镁(NH2)2的混合物球磨后，加热到453K形成Mg(BH4)(NH2)晶体。在513K和688K下，Mg(BH4)(NH2)的脱氢反应分两步进行，反应顺序为：Mg(BH4)(NH2)→MGH2+BN+2H2(失重率7.3%)→Mg+BN+3H2(总失重率为11.0%)。Mg(BH4)(NH2)的脱氢温度比另一种双阴离子络合物Li2(BH4)(NH2)的脱氢温度低约50K。通过300K下的晶体结构测定(晶系：四方晶系，空间群：I41-1(第80号)，晶格常数：a=5.792(1)，c=20.632(4))，确定了该化合物的晶体结构。在Mg(BH4)(NH2)晶体中，阳离子(Mg2+)和阴离子(BH4-和NH2-)沿c轴方向交替堆积。镁离子与两个BH4-阴离子和两个NH2-阴离子以四面体配位。
Dehydrogenation properties and crystal structure of the double anion complex hydride Mg (BH 4)(NH 2) were studied by thermal analyses and synchrotron X-ray diffraction. The stoichiometric mixture of Mg (BH 4) 2 and Mg (NH 2) 2 were ball-milled and then heated to 453 K to form Mg (BH 4)(NH 2) crystal. The dehydrogenation of Mg (BH 4)(NH 2) occurs in two-stage at 513 K and 688 K. The following reaction sequence is suggested by the results of thermal analyses; Mg (BH 4)(NH 2)→ MgH 2+ BN+ 2H 2 (7.3 mass% weight loss)→ Mg+ BN+ 3H 2 (11.0 mass% weight loss in total). The dehydrogenation temperature of Mg (BH 4)(NH 2) is approximately 50 K lower than that of the other double anion complex Li 2 (BH 4)(NH 2). The crystal structure of Mg (BH 4)(NH 2) was determined by the measurement at 300 K (crystal system: tetragonal, space group: I4 1 (No. 80), lattice constants: a= 5.792 (1), c= 20.632 (4) Å at 300 K). In the crystal of Mg (BH 4)(NH 2), the cation (Mg 2+) and the anions (BH 4-and NH 2-) are stacked alternately along the c-axis direction. The Mg 2+ cation is tetrahedrally coordinated with two BH 4-anions and two NH 2-anions.