Synthesis of ternary Si clathrates in the A-Al-Si (A = Na and K) system

Motoharu Imai, Shiva Kumar Singh, Mitsuaki Nishio, Takahiro Yamada, Hisanori Yamane

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9 Citations (Scopus)


With the aim of producing functional materials based on earth-abundant elements, we examined the synthesis of the ternary type-I clathrates A8AlxSi46-x (A = Na and K). The type-I Si clathrate K7.9(1)Al7.1(1)Si38.9(4), having a lattice parameter of 10.434(1) A, was successfully synthesized via the direct reaction of K, Al, and Si by optimization of both the synthesis temperature and the molar ratios among the raw ingredients. K8Al7Si39 exhibited metallic conduction: its electrical resistivity increased with increasing temperature. The high pressure synthesis of Na8AlxSi46-x was also examined, using a belt-type apparatus and employing a mixture of NaSi, Al, and Si as the reagents. In this manner, the type-I Si clathrate Na8.7(9)Al0.5(1)Si45(2), having a lattice parameter of 10.211(1) A, was synthesized at 5.5GPa and 1570 K.

Original languageEnglish
Article number07JC02
JournalJapanese Journal of Applied Physics
Issue number7
Publication statusPublished - 2015 Jul 1


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