Crystal growth and structure refinement of a new higher boride NaAlB14

• Published in: Journal of alloys and compounds 2005-05, Vol.395 (1-2), p.231-235
• Main Authors: OKADA, Shigeru, TANAKA, Takaho, SATO, Akira, SHISHIDO, Toetsu, KUDOU, Kunio, NAKAJIMA, Kazuo, LUNDSTRÖM, Torsten
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; Physics
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2004.10.057

Boron-rich compounds containing B12 icosahedral structures are of great interest because of their remarkable physical and chemical properties, which may be of potential application to thermoelectric materials and photodetectors. Single crystal of a new ternary boride NaAlB14 was grown from a high temperature Al solution using Na2B4O7 and crystalline boron powders as raw materials under an Ar atmosphere. The crystals obtained showed a plate-like or a trapezoidal shape with well-developed {010} faces, and were reddish black with a metallic luster. The largest crystal prepared in the present work attained maximum dimensions of approximately 7.3 mm x 3.2 mm x 2.8 mm. The crystals were examined by powder X-ray diffraction and chemical analyses, and the crystal structure of NaAlB14 was refined using data of single crystal X-ray diffractometry. The structure refinement converged at an Rl (F2) value of 0.025 with 29 parameters for 381 independent reflections [F0 > 4sigma(F0)] and 0.027 for all 426 independent reflections. The crystal structure is orthorhombic with the space group Imma (number 74), and lattice constants are a= 1.0465(1), b =0.5844(1), and c=0.8231(1) nm; V=0.5034(l)nm3; Z=4.