Title :
Atomic migration in CoGaxFe2-xO4
Author :
Lee, Seung Wha ; Kim, Dong Hoi ; Sung Real Hong ; Kim, Sam Jin ; Kim, Woo Chnl ; Kim, Sung Baek ; Kim, Chul Sung
Author_Institution :
Sch. of Electron. Eng., Chungbuk Nat. Univ., Cheongju, South Korea
fDate :
9/1/1999 12:00:00 AM
Abstract :
Co-Ga ferrite has been studied with X-ray diffraction, vibrating sample magnetometer and Mossbauer spectroscopy. The crystal structure for this system is spinel and lattice constants is in accord with Vegard´s law. The Neel temperature decreases linearly with Ga concentration suggesting the superexchange interaction Co-O-Fe link is stronger than that for the Ga-O-Fe link. Atomic migration of CoGa0.1Fe1.9O4 starts near 350 K and increases rapidly with increasing temperature to such a degree that 73% of the ferric ions as the A sites have moved to the B site by 700 K. The temperature dependence of the magnetic hyperfine field and magnetization of CoGa0.1Fe1.9O4 is explained by the Neel theory of ferrimagnetism using three superexchange integrals: JA-B=-11.5 kB, JA-A=9.8 kB, JB-B=21.3 kB
Keywords :
Mossbauer effect; Neel temperature; X-ray diffraction; cobalt compounds; crystal structure; diffusion; ferrites; lattice constants; magnetisation; superexchange interactions; 350 K; 700 K; Co(GaFe)2O4; Co-Ga ferrite; CoGaxFe2-xO4; Mossbauer spectroscopy; Neel temperature; Vegard´s law; X-ray diffraction; crystal structure; lattice constants; magnetic hyperfine field; magnetization; superexchange interaction; Absorption; Annealing; Erbium; Iron; Lattices; Mass spectroscopy; Powders; Sealing materials; Temperature dependence; X-ray diffraction;
Journal_Title :
Magnetics, IEEE Transactions on
