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
刊名	Journal of the American Ceramic Society
	2000
卷号	83 期号:2 页码:403-409
关键词	diamond-like carbon cubic bn pressure transition phases silicon
ISSN号	0002-7820
中文摘要	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.
原文出处	://WOS:000085764600023
公开日期	2012-04-14
内容类型	期刊论文
源URL	[http://ir.imr.ac.cn/handle/321006/37050]
专题	金属研究所_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.