High-pressure synthesis of novel hydrides in Mg–RE–H systems (RE = Y, La, Ce, Pr, Sm, Gd, Tb, Dy)
High-pressure synthesis of novel hydrides in Mg–RE–H systems (RE = Y, La, Ce, Pr, Sm, Gd, Tb, Dy)
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DOI：
10.1016/j.jallcom.2005.04.093
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发表时间：
2006-02
影响因子：
6.2
通讯作者：
A. Kamegawa;Y. Goto;H. Kakuta;H. Takamura;M. Okada
中科院分区：
文献类型：
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作者：
A. Kamegawa;Y. Goto;H. Kakuta;H. Takamura;M. Okada
用压砧式高压合成装置合成了Mg-RE-H（RE=Y，La，Ce，Pr，Sm，Gd，Tb，Dy）三元系的新稀土化合物，并对其晶体结构、热稳定性和氢含量进行了研究。在Mg-Y-H体系中，合成了具有FCC型结构的MgY_2Hy_3。在MgH_2-xmol% REH（REH= LaH_3，CeH_2.5，PrH_3）体系中，在GPa量级的高压下，在x=25-33附近合成了具有原始四元结构的新化合物。在x=25时，Mg-La、Ce和Pr体系的晶格常数分别为a=0.8193nm、c =0.5028nm、a= 0.8118nm、c = 0.4979nm和a=0.8058nm、c=0.4970nm。在Mg-La、Ce和Pr体系中，新化合物的氢含量分别为4.1、3.7和3.9mass%，化学式分别为Mg3 LaH 9、Mg3CeH8.1和Mg3 PrH 9。在600 K左右，新化合物分解为Mg和稀土氢化物（Mg_3LaH_9：614 K，Mg_3CeH_8.1：609 K，Mg_3PrH_9：630 K），发生吸热反应。在MgH_2-xmol%hREH（hREH= GdH_3，TbH_3，DyH_3）中，在x=67左右合成了具有FCC型结构的新化合物.
The high-pressure synthesis of new hydrides of Mg–RE–H systems, where RE=Y, La, Ce, Pr, Sm, Gd, Tb and Dy, were conducted by using a cubic-anvil-type apparatus, and their crystal structure, thermal stabilities and hydrogen contents were investigated. In Mg–Y–H system, newly found MgY2Hywith a FCC-type structure has been prepared. In MgH2–xmol% REH (REH=LaH3, CeH2.5and PrH3), new hydrides with primitive tetragonal structure were synthesized around x=25–33 under GPa-order high pressures. The lattice constants were a=0.8193nm, c=0.5028nm, a=0.8118nm, c=0.4979nm and a=0.8058nm, c=0.4970nm at x=25 in Mg–La, Ce and Pr systems, respectively. The hydrogen contents of the novel compounds were 4.1, 3.7 and 3.9mass% in Mg–La, Ce and Pr systems, respectively, and the chemical formulae were found to correspond to Mg3LaH9, Mg3CeH8.1and Mg3PrH9. The new hydrides decomposed into Mg and rare-earth hydride at about 600K (Mg3LaH9: 614K, Mg3CeH8.1: 609K, Mg3PrH9: 630K) with an endothermic reaction. In MgH2–xmol%hREH (hREH=GdH3, TbH3and DyH3), new hydrides with FCC-type structure were synthesized around x=67.