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Effect of Sol-gel Coating on Microstructure and Electrical Properties of Microwave Garnets

Published online by Cambridge University Press:  10 February 2011

Yong. S. Cho ,
Leo Brissette  and
Vasantha. R. W. Amarakoon
Yong. S. Cho
Affiliation:
New York State College of Ceramics at Alfred University, Alfred, NY 14802
Leo Brissette
Affiliation:
Electromagnetic Science Inc., Norcross, GA 30092
Vasantha. R. W. Amarakoon
Affiliation:
New York State College of Ceramics at Alfred University, Alfred, NY 14802
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Abstract

Microwave magnetic properties of Gd substituted yttrium iron garnets are known to depend on their microstructural characteristics such as porosity and grain size. Surface coating of the garnet powders through a gelation of Si and Mn organic solution was conducted to inhibit the grain boundary movement during sintering with considerable densification. High density and uniform microstructure were obtained after sintering at 1400°C in O2 atmosphere. Grain growth kinetics were studied with variation in sintering time as a function of grain size. An activation energy of 102.9 kcal/mol was obtained for grain growth of the sol-gel coated sample. Grain boundary region was investigated by using TEM and EDS. A very thin grain boundary layer was observed with Si segregation in the region. Electrical resistivity at 100 Hz was 1.46×109 Ωcm for the sol-gel coated sample sintered at 1400°C for 3hrs in O2. Above results were discussed and compared with those obtained by the conventional batch mixing of additives.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 411: Symposium T – Electricaly-Based Microstructural Characterization , 1995 , 289
Copyright
Copyright © Materials Research Society 1996

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References

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