  The compression behavior of zircon-type samarium orthovanadate, SmVO4, has
been investigated using synchrotron-based powder x-ray diffraction and
ab-initio calculations up to 21 GPa. The results indicate the instability of
ambient zircon phase at around 6 GPa, which transforms to a high-density
scheelite-type phase. The high-pressure phase remains stable up to 21 GPa, the
highest pressure reached in the present investigations. On pressure release,
the scheelite phase is recovered. Crystal structure of high-pressure phase and
equations of state (EOS) for the zircon- and scheelite-type phases have been
determined. Various compressibilities such as bulk, axial and bond, estimated
from the experimental data are found to be in good agreement with the results
obtained from theoretical calculations. Calculated elastic constants show that
the zircon structure becomes mechanically unstable beyond the transition
pressure. Overall there is good agreement between experimental and theoretical
findings.
