Transparent polycrystalline cubic silicon nitride

Norimasa Nishiyama, Ryo Ishikawa, Hiroaki Ohfuji, Hauke Marquardt, Alexander Kurnosov, Takashi Taniguchi, Byung Nam Kim, Hidehiro Yoshida, Atsunobu Masuno, Jozef Bednarcik, Eleonora Kulik, Yuichi Ikuhara, Fumihiro Wakai, Tetsuo Irifune

Research output: Contribution to journalArticlepeer-review

Abstract

Glasses and single crystals have traditionally been used as optical windows. Recently, there has been a high demand for harder and tougher optical windows that are able to endure severe conditions. Transparent polycrystalline ceramics can fulfill this demand because of their superior mechanical properties. It is known that polycrystalline ceramics with a spinel structure in compositions of MgAl2O4 and aluminum oxynitride (γ-AlON) show high optical transparency. Here we report the synthesis of the hardest transparent spinel ceramic, i.e. polycrystalline cubic silicon nitride (c-Si3N4). This material shows an intrinsic optical transparency over a wide range of wavelengths below its band-gap energy (258 nm) and is categorized as one of the third hardest materials next to diamond and cubic boron nitride (cBN). Since the high temperature metastability of c-Si3 N4 in air is superior to those of diamond and cBN, the transparent c-Si3 N4 ceramic can potentially be used as a window under extremely severe conditions.

Original languageEnglish
Article number44755
JournalScientific reports
Volume7
DOIs
Publication statusPublished - 2017 Mar 17
Externally publishedYes

ASJC Scopus subject areas

  • General

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