Title :
Atomic migration and superexchange interaction in Ni0.1Cu0.9Fe2O4
Author :
Kim, Woo Chul ; Kim, Sam Jin ; Lee, Seung Wha ; Ji, Sang Hee ; Kim, Chul Sung
Author_Institution :
Dept. of Phys., Kookmin Univ., Seoul, South Korea
fDate :
9/1/2000 12:00:00 AM
Abstract :
Ni0.1Cu0.9Fe2O4 was studied with X-ray diffraction and Mossbauer spectroscopy. The crystal structure was found to be a cubic spinel with the lattice constant a0=8.386±0.005 Å. The Neel temperature was determined to be TN=755 K for a heating rate of 5 K/min. The Mossbauer spectra consisted of two six-line patterns corresponding to Fe 3+ at the tetrahedral (A) and octahedral (B) sites. Debye temperatures for A and B sites were found to be 568±5 K and 194±5 K, respectively. Atomic migration of Ni0.1Cu0.9Fe2O4 starts near 350 K and increases rapidly with increasing temperature to such a degree that 71% of the ferric ions from the A sites moved to the B sites at 550 K. The temperature dependence of the magnetic hyperfine field of Ni0.1Cu0.9Fe2O4 was explained by the Neel theory of ferrimagnetism using three superexchange integrals: JA-B=-29.2 kB, JA-A=-21.9 k B, JB-B=0.5 kg
Keywords :
Debye temperature; Mossbauer effect; Neel temperature; X-ray diffraction; antiferromagnetic materials; copper compounds; crystal structure; ferrites; hyperfine interactions; nickel compounds; self-diffusion; superexchange interactions; Debye temperatures; Fe3+; Mossbauer spectroscopy; Neel temperature; Ni0.1Cu0.9Fe2O4; X-ray diffraction; atomic migration; crystal structure; cubic spinel; ferric ions; ferrimagnetism; ferrite; heating rate; lattice constant; magnetic hyperfine field; superexchange interaction; temperature dependence; Atomic measurements; Copper; Ferrites; Heating; Iron; Lattices; Physics; Spectroscopy; Temperature; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
