High-Pressure Behavior\nof Ca₂SnO₄, Sr₂SnO₄, and\nZn₂SnO₄

Abstract

The pressure-induced structural evolution of Ca₂SnO₄, Sr₂SnO₄, and Zn₂SnO₄ has been characterized by powder X-ray diffraction\nup to\n20 GPa using the ALBA synchrotron radiation source and density functional\ntheory calculations. No phase transition was observed in Ca₂SnO₄ and Zn₂SnO₄ in the investigated\npressure range. The observation in Zn₂SnO₄ solves\ncontradictions existing in the literature. In contrast, a phase transition\nwas observed in Sr₂SnO₄ at a pressure of 9.09\nGPa. The transition was characterized as from the ambient-condition\ntetragonal polymorph (space group <i>I</i>4/<i>mmm</i>) to the low-temperature tetragonal polymorph (space group <i>P</i>4₂/<i>ncm</i>). The linear compressibility\nof crystallographic axes and room-temperature pressure–volume\nequation of state are reported for the three compounds studied. Calculated\nelastic constants and moduli are also reported as well as a systematic\ndiscussion of the high-pressure behavior and bulk modulus of M₂SnO₄ stannates.