Thermal expansion in zircon and almandine: Synchrotron x-ray diffraction and lattice dynamical study

X-ray diffraction data are obtained on polycrystalline samples of zircon (ZrSiO₄) and almandine (Fe₃Al₂Si₃O₁₂) from 100 to 300 K using x-ray diffraction beam line at Elettra synchrotron source. The observed thermal expansions in zircon and almandine, which differ by a factor of 2--3, are found to be in good agreement with the predictions from our lattice-dynamical calculations. The calculations also enabled a microscopic interpretation of the available experimental data.