Mechanism of unique self-powdering phenomenon in ferroelastic crystals and development of materials with giant internal stress

2014 Fiscal Year Final Research Report

• Project/Area Number: 25630277
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Inorganic materials/Physical properties
• Research Institution: Nagaoka University of Technology
• Principal Investigator: KOMATSU Takayuki 長岡技術科学大学, 工学(系)研究科(研究院), 教授 (60143822)
• Project Period (FY): 2013-04-01 – 2015-03-31
• Keywords: 機能性セラミックス材料 / 自己微粉化現象 / 強弾性結晶 / ガラス結晶化 / 内部応力

Outline of Final Research Achievements

The mechanism of the self-powdering phenomenon of β'-RE2(MoO4)3 crystals (RE: Rare-earth), which is the breaking of crystals into small pieces during the crystal growth in RE2O3-MoO3-B2O3 based glasses, was examined using polarized optical microscope observations in a heating stage. The crack formation radiating out from the center part was clearly observed in the inside of crystals (diameter >40 micron), and it was found that the crack formation behavior depends largely on the kind of RE2O3. The base glasses have larger densities at room temperature when compared with β'-RE2(MoO4)3 crystals formed, which is a unique feature in the RE2O3-MoO3-B2O3 system. Such differences in the density might induce the accumulation of extremely large stresses in the inside of crystals, eventually causing the breaking of crystals. Bulky crystallized glasses were synthesized through the sintering of glass powders, having a potential for the development of materials with giant internal stresses.

Free Research Field

材料工学