Transition between orbital orderings in YVO3.

Evidence has been found for a change in the ordered occupation of the vanadium d orbitals at the 77 K phase transition in YVO3, manifested by a change in the type of Jahn-Teller distortion. The orbital ordering above 77 K is not destroyed at the magnetic ordering temperature of 116 K, but is present as far as a second structural phase transition at 200 K. The transition between orbital orderings is caused by an increase in octahedral tilting with decreasing temperature.