  Through powder x-ray diffraction we have investigated the structural behavior
of SmVO3, in which orbital and magnetic degrees of freedom are believed to be
closely coupled to the crystal lattice. We have found, contrary to previous
reports, that SmVO3 exists in a single, monoclinic, phase below 200 K. The
associated crystallographic distortion is then stabilized through the
magnetostriction that occurs below 134 K. The crystal structure has been
refined using synchrotron x-ray powder diffraction data measured throughout the
structural phase diagram, showing a substantial Jahn-Teller distortion of the
VO6 octahedra in the monoclinic phase, compatible with the expected G-type
orbital order. Changes in the vanadium ion crystal field due to the structural
and magnetic transitions have then been probed by resonant x-ray diffraction.
