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Preparation and structures of the La1−xKxCo1−xNbxO3 (x = 0–l) system |
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| Authors: | Tzu-Wei Huang Yee-Shin Chang Guo-Ju Chen Yen-Hwei Chang |
| Affiliation: | aDepartment of Material Science and Engineering, National Cheng Kung University, Tainan, Taiwan, ROC bInstitute of Electro-Optical and Materials Science, National Formosa University, Yunlin, Taiwan, ROC cDepartment of Material Science and Engineering, I-Shou University, Kaohsiung, Taiwan, ROC |
| Abstract: | The La1−xKxCo1−xNbxO3 system was performed by conventional solid state reaction technique using metal oxides. By DSC analysis, the activation energy of crystallization of the powders with x = 0.3 is 388.4 kJ/mol. The crystal structure of the compound reveals a transition from rhombohedral to cubic, and then to orthorhombic structure as the amount of the potassium niobate (KNbO3) increases. It is found that the structure of the samples with x < 0.3 is similar to that of lanthanum cobaltate (LaCoO3), while at the compositions with 0.7 ≥ x ≥ 0.3, the structure transforms to cubic. Finally, with x ≥ 0.7, the structures were similar to that of KNbO3. According to the results of selected-area-diffraction (SAD) patterns and X-ray diffraction (XRD) identifications, the lattice parameters were calculated. The direction of superlattice structure along 2 1 0] was found for x = 0.5 as identified from SAD patterns. The dielectric constants were measured with cubic structure. Dielectric constant (K) decreases with increasing x. |
| Keywords: | X-ray diffraction Thermal analysis Crystal structure and symmetry |
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