抄録
The isostatic compression of cordierite revealed a displacive phase transition occuring at 7 GPa accompanied by a orthorhombic-to-triclinic symmetry breaking. The static elasticity of the orthorhombic low-P form of cordierite is evidences anomalous softening as indicated by the pressure derivative of the bulk modulus (dK/dP = -0.6) on approaching the critical transition pressure between 6.9 and 7.4 GPa. In-situ XRD and Raman spectroscopy reveal that the compression is independent on the pressure media, and molecular species in the structural channels remain unchanged. The study in the DAC shows that neither P-induced de- nor overhydration occurs under the given pressure conditions.
