Structure and magnetic properties of Sr2NiAO6 (A = W, Te)

Crystal structures and magnetic properties of the B-site ordered perovskites Sr2NiWO6 and Sr2NiTeO6were investigated. Powder X-ray diffraction analysis revealed that Sr2NiWO6 and Sr2NiTeO6 have the tetragonal structure of I4/m (No. 87) and the monoclinic structure of C2/m (No. 12-2), respectively. Magnetic measurement of Sr2NiWO6 and Sr2NiTeO6 revealed that antiferromagnetic transition appears at 54 and 35 K, respectively. Heat capacity measurement gave a different transition temperature of 28 K for Sr2NiTeO6. Analysis of the entropy of the three-dimensional antiferromagnetic transition revealed that local ordering of spins begins at higher temperatures of observed TN, especially in Sr2NiTeO6.