HRTEM and EELS studies on the amorphization of hexagonal boron nitride induced by ball milling

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	HRTEM and EELS studies on the amorphization of hexagonal boron nitride induced by ball milling
	J. Y. Huang; H. Yasuda; H. Mori
	2000
发表期刊	Journal of the American Ceramic Society
ISSN	0002-7820
卷号	83 期号:2 页码:403-409
摘要	We present a new approach, namely ball milling, to synthesize amorphous boron nitride (a-BN), The amorphization kinetics are revealed by X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), and electron energy loss spectroscopy (EELS), HRTEM investigations indicate that, in the early stage of milling, the thick sp(2) layers are sliced into many thinner sheets because of cleavage;along the basal planes, In the intermediate stage of milling, deformation is accommodated primarily by simultaneous shearing along the basal planes. As a result of sustained shearing, a number of defects, such as stacking faults, (0002) [11 (2) over bar 0] twinning, simultaneous shearing of lattice planes, and half Frank loops with Burgers vectors of 1/2[0001], are introduced in the hexagonal BN (h-BN) grains. Simultaneous shearing also causes significant change in the lattice symmetry of most grains. In the final stage of milling, the fiberlike tightly bonded sp2 sheets are broken and refined further, until a nanocrystalline and amorphous mixture is formed. XRD of the sample mined for 180 b exhibits an amorphous halo pattern; nevertheless, HRTEM demonstrates that the end product is essentially a nanocrystalline and amorphous mixture. The grain sizes of the nanocrystals are <3 nm, and their stacking is turbostratic. EELS investigations of the a-BN indicate that bonding is :primarily sp2, but a small fraction of sp(3) a-BN is also found, which is assumed to be the nuclei of the cubic phase (c-BN) in the high-pressure and high-temperature experiments and thus facilitates the hexagonal to cubic transition, The present a-BN fabrication method can provide an effective way to facilitate the synthesis of sintered bulk c-BN materials.
部门归属	osaka univ, res ctr ultrahigh voltage electron microscopy, suita, osaka 565, japan. chinese acad sci, inst met res, atom imaging solids lab, shenyang 110015, peoples r china.;huang, jy (reprint author), univ calif los alamos natl lab, div mat sci & technol, los alamos, nm 87545 usa
关键词	Diamond-like Carbon Cubic Bn Pressure Transition Phases Silicon
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WOS记录号	WOS:000085764600023
引用统计	被引频次：97[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.imr.ac.cn/handle/321006/37050
专题	中国科学院金属研究所
推荐引用方式 GB/T 7714	J. Y. Huang,H. Yasuda,H. Mori. HRTEM and EELS studies on the amorphization of hexagonal boron nitride induced by ball milling[J]. Journal of the American Ceramic Society,2000,83(2):403-409.
APA	J. Y. Huang,H. Yasuda,&H. Mori.(2000).HRTEM and EELS studies on the amorphization of hexagonal boron nitride induced by ball milling.Journal of the American Ceramic Society,83(2),403-409.
MLA	J. Y. Huang,et al."HRTEM and EELS studies on the amorphization of hexagonal boron nitride induced by ball milling".Journal of the American Ceramic Society 83.2(2000):403-409.