• journal_title：American Mineralogist
• Contributor：Wansheng Xiao ; Dayong Tan ; Wei Zhou ; Ming Chen ; Xiaolin Xiong ; Maoshuang Song ; Jing Liu ; Ho-Kwang Mao ; Jian Xu
• Publisher：Mineralogical Society of America
• Date：2012-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2012.4021
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：97
• issue：7
• firstpage：1193
• section：Articles

A new cubic perovskite polymorph of PbGeO₃ (Phase II) was synthesized by laser heating in the diamond-anvil cell (DAC) at the pressure of 36 GPa. Fitting the Birch-Murnaghan equation of state against its observed P-V data yields a bulk modulus K₀ of 196(6) GPa and the volume V₀ of 56.70(13) ų when K₀′ is assumed being 4. After the pressure is released, the PbGeO₃ Phase II changes gradually into an amorphous phase, which contains mainly fourfold-coordinated germanium. It indicates that the PbGeO₃ Phase II with a GeO₆ octahedron framework transforms to a GeO₄ tetrahedron network during the amorphization. The existence of PbGeO₃ cubic perovskite Phase II at high pressures indicates that the polarized character of the Pb²⁺ ion induced by its 6s² lone pair electrons would be totally reduced in the environment of major silicate perovskites inside the lower mantle, and thus the Pb atom would substitute the Ca atom to enter the CaSiO₃ perovskite.