Pressure-induced phase transitions of lanthanide monoarsenides LaAs and LuAs with a NaCl-type structure

✍ Scribed by I. Shirotani; K. Yamanashi; J. Hayashi; N. Ishimatsu; O. Shimomura; T. Kikegawa

• Book ID: 104166264
• Publisher: Elsevier Science
• Year: 2003
• Tongue: English
• Weight: 129 KB
• Volume: 127
• Category: Article
• ISSN: 0038-1098
• DOI: 10.1016/s0038-1098(03)00491-5

✦ Synopsis

By use of synchrotron radiation the powder X-ray diffraction of lanthanide monoarsenides LaAs and LuAs with a NaCl-type structure has been studied up to 60 GPa at room temperature. First-order phase transitions with the crystallographic change were found at around 20 GPa for LaAs, and 57 GPa for LuAs. The high-pressure form of LaAs is a tetragonal structure and can be viewed as a distorted CsCl-type structure. The atoms in the tetragonal structure are located at La: 0, 0, 0; As: 1/2, 1/2, 1/2. The space group is P4=mmm: The structural change to the tetragonal structure occurs with the volume collapse of about 10%. The structure of these high-pressure phases of LuAs is unknown. The volume vs. pressure curves for LaAs and LuAs are fitted by a Birch equation of state. The bulk moduli of both arsenides are 92 ^6 GPa for LaAs and 85 ^3 GPa for LuAs. The highpressure structural behavior of LaX (X ¼ P, As and Sb) and LnAs (Ln ¼ lanthanide) with the NaCl-type structure is discussed.