ENGINEERING KNOW-HOW OF TRANSLUCENT CUBIC BORON NITRIDE SINGLE CRYSTALS AND POLYCRYSTALS (BRIEF REVIEW)

Abstract

Based on the fundamental optical characteristics, cubic boron nitride (cBN) should be transparent over the entire frequency range of visible light. At the same time, optical transparency in reality, among the many known cBN materials, is still perceived as an exotic exception, not a rule. In practice, especially among sintered materials for instrumental purposes, absolutely opaque cBN polycrystals and composites BN, predominantly black or dark gray, dominate. Undoubtedly, pure transparent and purposefully doped materials of wide-gap cBN, which, in addition, are superhard and highly heat-conducting, arouse certain practical interest, prompting their use in ultraviolet optoelectronics and semiconductor technology. This paper provides a brief review of the existing experience on the preparation of transparent single and polycrystalline cBN by various methods, such as spontaneous mass crystallization, sintering of final phase powders, and conversion sintering of graphite-like modifications of BN of various origins (online colour at: www.altis-ism.org.ua).