Magnetic and crystallographic properties of LnCrO4 (Ln = Nd, Sm, and Dy)

Zircon-type compounds LnCrO(4) (Ln = Nd, Sm, and Dy) were prepared. Their precise crystal structures at room temperature were determined from X-rav diffraction measurements. These compounds have a tetragonal system with space group 14(1)/amd. Magnetic susceptibility and specific heat measurements have 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, respectively. In addition, structural phase transitions were observed at 58.5 and 31.2 K, respectively. For DyCrO4, the crystal structure below the transition temperature was determined by low-temperature powder X-ray diffraction measurements to be orthorhombic with space group Imma. (C) 2001 Academic Press.