Magnetic and crystallographic properties of LnCrO(4) (Ln = Nd, Sm, and Dy)

Zircon-type compounds LnCrO(4) (Ln = Nd, Sm, and Dy) were prepared. Their p recise crystal structures at room temperature were determined from X-rav di ffraction measurements. These compounds have a tetragonal system with space group 14(1)/amd. Magnetic susceptibility and specific heat measurements ha ve been performed for all the compounds in the temperature range between 1. 8 and 300 K. For NdCrO4, an antiferromagnetic transition was found at 25.2 K. SmCrO4 and DyCrO4 show magnetic transitions at 15.0 and 22.8 K, respecti vely. In addition, structural phase transitions were observed at 58.5 and 3 1.2 K, respectively. For DyCrO4, the crystal structure below the transition temperature was determined by low-temperature powder X-ray diffraction mea surements to be orthorhombic with space group Imma. (C) 2001 Academic Press .