Markedly different behaviors were reported for isostructural Gd2Ti2O7 and Gd2Zr2O7 pyrochlores at pressures of up to 44GPa, in which the substitution of Ti for Zr significantly increased structural stability. Upon release of pressure, the Gd2Ti2O7 became amorphous. In contrast, the high-pressure phase of Gd2Zr2O7 transformed into a disordered defect-fluorite structure. First-principles calculations for both compositions revealed that the response of pyrochlore to high pressure was controlled by the intrinsic energetics of defect formation.

Phase Stability and Pressure Dependence of Defect Formation in Gd2Ti2O7 and Gd2Zr2O7 Pyrochlores. F.X.Zhang, J.W.Wang, J.Lian, M.K.Lang, U.Becker, R.C.Ewing: Physical Review Letters, 2008, 100[4], 045503