Shear induced phase transition in PbO under high pressure

✍ Scribed by Hubertus Giefers; Felix Porsch

• Publisher: Elsevier Science
• Year: 2007
• Tongue: English
• Weight: 427 KB
• Volume: 400
• Category: Article
• ISSN: 0921-4526
• DOI: 10.1016/j.physb.2007.06.033

✦ Synopsis

We have studied the structural behavior of lead monoxide (PbO) as a function of pressure via angular dispersive X-ray diffraction employing two different pressure transmitting media that were quasi-hydrostatic (N 2 ) and non-hydrostatic (MgO), respectively. Besides litharge (a-PbO) and massicot (b-PbO), which are both stable at ambient pressure, there is an orthorhombic g-PbO phase which appears upon application of pressure to a-PbO. We have found that the orthorhombic g-PbO phase is favored by shear stress under nonhydrostatic conditions. a-PbO shows strong anisotropy in compressibility. The a-axis is rather incompressible with a linear stiffness coefficient of K a0 ¼ 540(30) GPa whereas the c-axis stiffness is K c0 ¼ 25(1) GPa. The bulk modulus of a-PbO is K 0 ¼ 23.1(3) GPa and its derivative K 0 0 ¼ 7:0ð3Þ.