Pyroxenes: Structural transformations,local fields,and effects of short-range ordering of cations

To reveal the physical nature of the structural transformations caused by changes in temperature, pressure, or composition, the topological stability of five pyroxene structures of Si-Ge solid solutions was investigated by powder X-ray diffraction. Four structural transformations were provoked by selective substitution of cations, the corresponding changes in local fields in the key structural position M1 were investigated by Mössbauer spectroscopy.