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Studie der Kristallisationsbedingungen von Ti‐dotierten, mit der Glaskristallisationstechnik hergestellten Bariumhexaferritpulvern für Mikrowellenanwendungen
Author(s) -
Quiroz P.,
Halbedel B.
Publication year - 2011
Publication title -
materialwissenschaft und werkstofftechnik
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.285
H-Index - 38
eISSN - 1521-4052
pISSN - 0933-5137
DOI - 10.1002/mawe.201100716
Subject(s) - crystallization , materials science , ferrimagnetism , analytical chemistry (journal) , dielectric , doping , barium ferrite , magnetocrystalline anisotropy , annealing (glass) , coercivity , mineralogy , ferrite (magnet) , chemical engineering , magnetization , magnetic anisotropy , metallurgy , chemistry , composite material , condensed matter physics , physics , optoelectronics , chromatography , quantum mechanics , magnetic field , engineering
For microwave applications Titanium doped M‐type hexagonal ferrites have been synthesized by means of glass crystallization technique varying the crystallization parameters and the melt doping concentrations. The chosen melt dopings were x = 5.4 and 7.2 mole‐% TiO 2 with the following basic composition (mole‐%): 40 BaO + 33 B 2 O 3 + (27‐x) Fe 2 O 3 + x TiO 2 . We have studied the dependencies between the magnetic properties, the valence of the iron ions in the glasses and the powders, the formation of new dielectric phases and the microwave absorption. After the Ti 4+ ions substitutions, the magnetocrystalline anisotropy changed, this effect was observed in the static magnetic properties ( J H C and M S ) measured using a vibration sample magnetometer. Furthermore the Ti 4+ ions preferably occupy mainly the 2a as well as slightly the 2b sites in the lattice of the barium hexaferrite, which are studied using Mössbauer spectroscopy. Besides, the X‐ray diffraction studies proved that the formation of the ferrimagnetic (BaFe 12‐x Ti x O 12 ) and dielectric (BaTi 6 O 13 ) phases are dependent on the crystallization parameters. The controlled influencing of lattice sites occupation and of the Fe 2+ content in the ferrimagnetic phase as well as the controlled formation of the dielectric phase rate during the annealing are possibilities to optimize the microwave absorption of Ti‐doped barium hexaferrite powders synthesized by glass crystallization technique.