Equation of state and high-pressure irreversible amorphization in Y3Fe5O12
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The change of crystal structure in yttrium iron garnet Y3Fe5O12 was studied at room temperature at high pressures up to ∼55 GPa by the x-ray diffraction technique in diamond anvil cells. At a pressure of about ∼50 GPa, a drastic change in the x-ray diffraction pattern was observed indicating the transition into an amorphouslike state. When the pressure was increased, the bulk modulus of YIG was found to be 193 ± 4 GPa. It was also found that the amorphous state was retained after decompression down to ambient pressure. From the shape of x-ray patterns in the “amorphous” phase, it was concluded that the local atomic structure consists of iron-oxygen FeO6 octahedral complexes with disordered orientations of local axis and of randomly arranged others ion fragments with the overall Y3Fe5O12 composition. For the amorphous phase, it was evaluated that the bulk modulus of FeO6 octahedral complexes is about 260 GPa.
PACS numbers61.50.Ks 64.30.+t 71.30.+h 81.40 Vw
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