The Crystallization of BN and the Synthesis of cBN at High Pressure and Temperature
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摘要: 研究了非晶BN、二维有序BN和低有序度六方BN(G.I=6.1)在高温高压下的结晶行为及不同有序度的BN对立方BN合成的影响。研究结果表明,低有序度BN向高有序度六方相转化,但不同有序度的BN原料向立方BN转化的行为不同。少量B掺杂下的立方氮化硼的合成实验发现B的掺入阻碍立方BN的生成。低有序度BN不易向立方BN的主要原因可以认为是它们存在较多的N空位,高温高压下随着BN的结晶化,B以杂质析出并阻碍了立方BN的合成。Abstract: The crystallization of amorphous, turbostratic and low crystalline degree hexagonal BN was found at high pressure and temperature and the conversion behavior of various BN with different crystallinity to cBN were studied. Results show that the synthesis of cBN is getting difficult as the crystallinity of starting BN material becomes worse (i.e. G.I value increase). When synthesizing cBN using hexagonal BN doped with B, we found that B can hinder the conversion to cBN. The existence of high nitrogen vacancies in low crystallinity BN may explain why it is difficult to transform to cBN. When BN crystallizes at high pressure and temperature, boron escapes which hinders the conversion of hBN to cBN.
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Key words:
- BN /
- high pressure and temperature /
- crystallization /
- cBN /
- nitrogen vacancy
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