Production of α-Rhombohedral Boron by Amorphous Boron Crystallization

✍ Scribed by S.O. Shalamberidze; G.I. Kalandadze; D.E. Khulelidze; B.D. Tsurtsumia

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 122 KB
• Volume: 154
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2000.8836

✦ Synopsis

Some characteristic features of the technology of producing -rhombohedral boron by amorphous powder crystallization were considered. Powder samples were heated in a high-temperature resistance furnace at 83C/min to 10003C and then the rate was reduced to 23C/min. After the above heating rates, pyrolytic amorphous boron transforms to -rhombohedral boron when held for 90 min at 11703C in either argon atmosphere or vacuum. Electrolytic amorphous boron starts to crystallize at 11503C to -rhombohedral boron without going through the intermediate -rhombohedral boron phase. The investigation of the in6uence of impurities on the crystallization of amorphous boron showed that carbon was more unfavorable than metallic impurities, preventing the formation of the -rhombohedral boron phase. Though the powders of pyrolytic and electrolytic amorphous boron are distinguished by purity (electrolytic boron is more contaminated), the investigations performed lead to the speculation that the crystallization process is in6uenced by the shortrange order of the atoms of the initial powders rather than by the impurity content.