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FTIR Spectra, Lattice Shrinkage, and Magnetic Properties of CoTi‐Substituted M‐Type Barium Hexaferrite Nanoparticles
Author(s) -
Zhao WenYu,
Wei Ping,
Cheng HaiBin,
Tang XinFeng,
Zhang QingJie
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2007.01690.x
Subject(s) - materials science , coercivity , spinel , fourier transform infrared spectroscopy , scanning electron microscope , microstructure , analytical chemistry (journal) , calcination , transmission electron microscopy , nanoparticle , magnetization , barium , chemical engineering , nanotechnology , composite material , chemistry , metallurgy , magnetic field , condensed matter physics , biochemistry , physics , chromatography , quantum mechanics , engineering , catalysis
Single‐phase BaCoTiFe 10 O 19 (BaCoTi‐M) nanoparticles were prepared by a modified sol–gel process, using metallic chlorides as starting materials. The physical chemistry process of BaCoTi‐M formation, the interdependences between composition, technological conditions, microstructure, and magnetic properties were studied by X‐ray diffraction (XRD), Fourier transform‐infrared (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), and vibrating sample magnetometer (VSM). XRD and FTIR results show that BaCoTi‐M nanoparticles formed directly from γ‐Fe 2 O 3 , spinel ferrite, and barium salts without the formation of α‐Fe 2 O 3 and BaFe 2 O 4 . The lattice shrinkage of BaCoTi‐M nanoparticles that occurred on increasing the calcining temperature from 973 to 1173 K under holding for 2 h or on increasing the holding time in the range 0–2 h at 1173 K was discovered by analyzing the dependences of lattice parameters on the heat‐treatment conditions. The shrinkage led to a relatively higher concentration of magnetic Fe 3+ cations in the unit cell, and resulted in an increase of specific saturation magnetization under the corresponding conditions. Microstructural characterization shows that the evolutions of coercivity, remnant magnetization, and squareness ratio depended on the crystal growth and the reduction of structural defect as well as a decrease of grain boundary.