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(La3+ Mg2+) codoped BiFeO3 nanopowders: Synthesis, characterizations, and giant dielectric relaxations |
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| รหัสดีโอไอ | |
| Creator | 1. Pornsawan Kum-onsa 2. Narong Chanlek 3. Masaki Takesada 4. Pornjuk Srepusharawoot 5. Prasit Thongbai |
| Title | (La3+ Mg2+) codoped BiFeO3 nanopowders: Synthesis, characterizations, and giant dielectric relaxations |
| Publisher | Faculty of Engineering, Khon Kaen University |
| Publication Year | 2564 |
| Journal Title | Engineering and Applied Science Research |
| Journal Vol. | 48 |
| Journal No. | 6 |
| Page no. | 766-772 |
| Keyword | Dielectric permittivity, Dielectric relaxation, Electron hopping, Interfacial polarization |
| URL Website | https://www.tci-thaijo.org/index.php/easr/index |
| Website title | Engineering and Applied Science Research |
| ISSN | 2539-6161 |
| Abstract | A new strategy to improve the dielectric properties of BiFeO3 is proposed by codoping with La3+ and Mg2+ to control the ceramic microstructure and increase the dielectric permittivity (??), respectively. The main phase of BiFeO3 is obtained in nanocrystalline powders of LaxBi1-xFe1-xMgxO3 (x = 0, 0.05 and 0.1), which are prepared by a chemical co-precipitation method. The particle size of the codoped LaxBi1-xFe1-xMgxO3 is smaller than that of the BiFeO3. A dense ceramic microstructure without porosity is obtained by sintering at 800 ?C for 3 h. The mean grain size of the BiFeO3 ceramics decreases with increasing codoping (La3+?Mg2+) concentration. The primary roles of La3+ and Mg2+ are to suppress the grain growth and enhance the densification rate, respectively. At 1 kHz, the ?? of the LaxBi1-xFe1-xMgxO3 with x = 0.1 increased significantly compared to that of the BiFeO3, while the loss tangent (tan?) was lower than that of the BiFeO3. In addition, another role of Mg2+ is to increase the ?? without any effect on the tan?. Two dielectric relaxations are observed in low-frequency (150-250 K) and high-temperature (250-400 K) ranges. An X-ray photoelectron spectroscopy shows that the Fe2+/Fe3+ ration in the codoped LaxBi1-xFe1-xMgxO3 increased compared to that of the BiFeO3, corresponding to the increase in ??. Thus, a low-temperature dielectric relaxation is attributed to the electron hopping between Fe2+?O?Fe3+. On the other hand, a high-temperature dielectric relaxation is caused by interfacial polarization relaxation. |
