Structural Phase Transition and Dielectric Properties of ZnCr 2 O 4

Normal spinel ZnCr 2 O 4 undergoes an antiferromagnetic transition at T N =12.5 - 0.5 K. Dielectric constant makes a jump at T N , indicating that an abrupt change in the lattice structure is accompanied with the magnetic transition. X-ray powder diffraction shows that a probable symmetry below T N is an orthorhombic( Fddd ) or its subgroup.