A distortion of pseudotetramers coupled with the Jahn-Teller effect in the geometrically frustrated spinel system CdV2O4

For the geometrically frustrated spinel system CdV2O4 With V3+ (S = 1) that undergoes structural and magnetic transitions at T-cl = 97 K, and may exhibit a transition to the antiferromagnetic state at T-c2 = 35 K, the crystal structures at 299 and 85 K have been determined with space groups Fd (3) over barm and 14(1)/amd, respectively, by means of x-ray four-circle diffraction. At 85 K, the VO6 octahedron is distorted due to the Jahn-Teller effect with contraction of the V-O bond along the tetragonal c axis, and the network of V ions is achieved by the linkage of a distorted V-4-tetrahedron block with two kinds of V-V bonds. On the basis of these structural properties, magnetic susceptibilities at temperatures between T-cl and T-c2 are explained in terms of the tetragonally distorted pseudotetramer model.