Pressure-induced disordering and anomalous lattice expansion in La2Zr2O7 pyrochlore.

ABSTRACT

Pressure-induced cation and anion disordering in La2Zr2O7 pyrochlore is quantitatively analyzed by Rietveld refinement of in situ x-ray diffraction patterns, Raman, and infrared measurements. An anomalous lattice expansion and obvious change of the pressure dependence of the vibrational modes occur at ∼10 GPa. The pressure-induced water incorporation in the La2Zr2O7 pyrochlore structure may be related to a previously noted photoelectrochemical effect.