TEMPERATURE DRIVEN TUNING OF THE STRUCTURE AND MAGNETIC PROPERTIES OF OXIDES OF ERBIUM AND CHROMIUM AT NANOSCALE

Oimang Borang, S. Srinath, S. N. Kaul, Y. Sundarayya

Abstract: We report the synthesis of homogeneous single phase nanoparticles of ErCrO4 and ErCrO3 by a modified sol-gel hydrothermal method. Temperature dependent annealing results in the formation of ErCrO4 and ErCrO3 phases at low and high temperatures. Analysis of the X-ray diffractograms reveal that ErCrO4 crystallizes into tetragonal structure with space group I41/amd and ErCrO3 into orthorhombic structure with space group Pnma. Morphological analysis confirms uniformly distributed nanoparticles of ErCrO4 with size 20 nm and ErCrO3 with 70 nm. DC magnetic measurements show that ErCrO4 undergoes a paramagnetic-antiferromagnetic transition at 16 K, the Néel temperature (TN) due to the superexchangeEr–O–Cr–O– Erantiferromagnetic interactions and that the Er3+ ions alone carry a magnetic moment while Cr exists in Cr5+ (3d0 ) valence state. And ErCrO3 undergoes paramagnetic-antiferromagnetic transition at 137 K (TN), due to Cr–O–Cr superexchange interaction, with canting of spins at Cr sites below Néel temperature, attributed to antisymmetric Dzyaloshinsky-Moriya (DM) exchange interaction between neighbouring spins.

Keywords: Sol-gel processing, Nanocrystalline materials, Antiferromagnetics

DOI: https://doi.org/10.15623/ijret.2017.0613004