Development of needle-like nitride crystals for optical functional materials synthesized by nitridation of metalic melts under ordinary pressures

Research Project

Project/Area Number	18K18959
Research Category	Grant-in-Aid for Challenging Research (Exploratory)
Allocation Type	Multi-year Fund
Review Section	Medium-sized Section 26:Materials engineering and related fields
Research Institution	Tokyo City University
Principal Investigator	KOBAYASHI Ryota 東京都市大学, 工学部, 准教授 (30548136)
Co-Investigator(Kenkyū-buntansha)	宗像文男東京都市大学, 工学部, 教授 (50386356)
Project Period (FY)	2018-06-29 – 2020-03-31
Project Status	Completed (Fiscal Year 2019)
Budget Amount *help	¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000) Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2018: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000)
Keywords	窒化アルミニウム / ウィスカー / 発光挙動 / 窒化ケイ素 / 結晶成長 / 蛍光特性
Outline of Final Research Achievements	In this study, we investigated various process parameters in direct nitridation process of metal melts under ordinal pressure, and achieved to control crystal morphology and luminescence properties in the synthesis of needle-like single crystals of Aluminum Nitride (AlN) and Silicon Nitride (Si3N4). In particular, for AlN, whiskers with high aspect ratio were synthesized and their unknown fluorescent properties were evaluated, and further control of fluorescent properties of AlN whiskers by doping of impurities, further growth and purification by heat-treatment of AlN whiskers, were achieved.
Academic Significance and Societal Importance of the Research Achievements	耐環境性の窒化物の針状結晶において、合成プロセス制御による結晶形態や格子欠陥の制御が可能であることを示したことにより、従来の蛍光材料よりも高い耐久性を有し、形状の異方性を生かした光機能材料や微小機械システム用のLEDやレーザー素子、センサーなどのデバイス開発につながることが期待される。また、デバイスとしてこれまで応用が広く検討されてきた窒化物の板状単結晶と比べて未解明の点が多い針状単結晶において、それらの成長機構や結晶欠陥、発光メカニズムの一端を明らかにしてきた点で大きな学術的な意義があると考えられる。