Thermal equation of state of aluminum-enriched silicate perovskite

Inferences of the chemical homogeneity of Earth's mantle depend on comparin g laboratory-derived equations of state of mantle phases with seismically d etermined properties of the material in situ, A uniform chemical compositio n of the entire mantle has been found to be consistent with measurements, t o date, of these properties for the end-member MgSiO3 perovskite phase. New pressure-volume-temperature data for silicate perovskite containing 5 mole percent Al2O3 has yielded different values of the equation of state parame ters, with the bulk modulus being significantly smaller at lower mantle con ditions than for aluminum-free perovskite, thus requiring adjustments in ot her components to match seismic observations.