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Vol.52, No.5, 379 ~ 385, 2014
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| Title |
| Microstructure and Structural Analysis of the x(Na0.5K0.5)NbO3-(1-x)BaTiO3 Ceramics for MLCCs |
| 하주연 Joo Yeon Ha , 김진성 Jin Seong Kim , 이희수 Hee Soo Lee , 최연규 Youn Kyu Choi , 이연숙 Yeon Sook Lee |
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| Abstract |
| The doping effect of (Na0.5K0.5)NbO3(NKN) on the crystal structure, microstructure and electrical properties of BaTiO3 (BT) ceramics was investigated as alternatives for rare-earth elements. x(Na0.5K0.5) NbO3-(1-x)BaTiO3 ceramics with 0.00 ≤ x ≤ 0.10 were synthesized by a solid-state reaction method. The dielectric constant and the insulation resistance (IR) of the sample with x=0.05 were about 43% and 45% higher, respectively, than those of the undoped one, and the temperature coefficient of capacitance (TCC) met the X7R specification. The sample with x=0.05 had the lowest tetragonality among the four compositionsand had the finest grain size of < 2 um. The sample doped over the solubility limit (x=0.10) showed the lowest dielectric properties by the presence of a secondary phase with a needle shape. Although the addition of NKN decreased the tetragonality, the electrical properties were enhanced by the formation of the defect dipole and conduction electron, which are caused by the compensation of oxygen vacancy and electron. The addition of x=0.05 NKN to BaTiO3 improved the electrical properties due to the substitution behavior that resulted in making the defect dipole and conduction electron. |
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| Key Words |
| dielectrics, powder processing, electrical properties, X-ray diffraction, substitution behavior |
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