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

For the geometrically frustrated spinel system CdV 2 O 4 with V 3+ ( S = 1) that undergoes structural and magnetic transitions at T c1 = 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 m and I 4 1 / amd , respectively, by means of x-ray four-circle diffraction. At 85 K, the VO 6 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 c1 and T c2 are explained in terms of the tetragonally distorted pseudotetramer model.