Compression behavior and phase transition of β-Si3N4 under high pressure

• 来源期刊: 中国物理B（英文版）
• 关键词: phase transition bulk modulus β-Si3N4 high pressure in situ x-ray diffraction
• 年，卷（期）: 2018,（5）
• 页码范围: 400-404
• 页数: 5页
• 语种: 英文
• DOI: 10.1088/1674-1056/27/5/056101

摘要

The compressibility and pressure-induced phase transition of β-Si3 N4 were investigated by using an angle dispersive x-ray diffraction technique in a diamond anvil cell at room temperature.Rietveld refinements of the x-ray powder diffraction data verified that the hexagonal structure (with space group P63/m,Z =2 formulas per unit cell) β-Si3N4 remained stable under high pressure up to 37 GPa.Upon increasing pressure,β-Si3N4 transformed to δ-Si3N4 at about 41 GPa.The initial β-Si3N4 was recovered as the pressure was released to ambient pressure,implying that the observed pressureinduced phase transformation was reversible.The pressure-volume data of β-Si3N4 was fitted by the third-order BirchMurnaghan equation of state,which yielded a bulk modulus K0 =273(2) GPa with its pressure derivative K'o =4 (fixed)and K0 =278(2) GPa with K'o =5.Furthermore,the compressibility of the unit cell axes (a and c-axes) for theβ3-Si3N4demonstrated an anisotropic property with increasing pressure.