Microstructure and microwave dielectric properties of modified zinc titanates (I)
- Korea Univ., Seoul (Korea, Republic of). Dept. of Material Science and Engineering
- Korea Univ., Seoul (Korea, Republic of). Dept. of Material science and Engineering
- Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Ceramics
Zinc metatitanate, ZnTiO{sub 3}, decomposes into zinc orthotitanate and rutile on heating above 945 C. It was found that this material could be a useful candidate for microwave resonator materials. The substitution of Zn by less than 10 mol% of Ba, Ca, or Sr achieves near zero {tau}{sub f} in spite of the fact that BaTiO{sub 3}, CaTiO{sub 3}, and SrTiO{sub 3} themselves have positive {tau}{sub f}. The origin of the temperature-compensating characteristics of the modified system was found to be in the reduction or elimination of rutile by the formation of new phases such as Ba{sub 3}Zn{sub 7}Ti{sub 12}O{sub 34}, Ca{sub 2}Zn{sub 4}Ti{sub 15}O{sub 36}, and Sr{sub 2}Zn{sub 4}Ti{sub 15}O{sub 36} polytitanates, which have much lower positive {tau}{sub f} than the rutile. It was revealed that zinc orthotitanate grains containing around 0.33 mol excess rutile have Zn{sub 2}Ti{sub 3}O{sub 8} nanosize precipitates in the grain. The precipitates had a structural coherency with the Zn{sub 2}TiO{sub 4} cubic matrix phase. The modified system has microwave dielectric properties of {epsilon}{sub r} = 25--32, Q factor at 10 GHz = 2,300--5,400, and {tau}{sub f} = +56 to {minus}22 ppm/C.
- OSTI ID:
- 638360
- Journal Information:
- Materials Research Bulletin, Vol. 33, Issue 6; Other Information: PBD: Jun 1998
- Country of Publication:
- United States
- Language:
- English
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