# Siam Physics Congress 2015

20-22 May 2015
Asia/Bangkok timezone
The Centennial Celebration of General Relativity Theory and 80 Years of Thai Physics Graduate

## Effects of Oxygen Vacancies on Dielectric Properties of Na${}_{1/2}$Bi${}_{1/2}$Cu${}_3$Ti${}_4$O${}_{12}$ Ceramics Prepared by a Urea Combustion Method

21 May 2015, 13:00
3h 30m
Board: MNA-11
Poster presentation Material Physics, Nanoscale Physics and Nanotechnology

### Speaker

Mr Wattana Tuichai (Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen, THAILAND 40002)

### Description

The influences of oxygen vacancies on the dielectric and electrical properties of Na${}_{1/2}$Bi${}_{1/2}$Cu${}_3$Ti${}_4$O${}_{12}$ ceramics prepared by a urea combustion method were investigated via annealing in oxidizing atmosphere. Interestingly, a single Na${}_{1/2}$Bi${}_{1/2}$Cu${}_3$Ti${}_4$O${}_{12}$ phase was successfully prepared using a low calcination temperature of 800 ${}^{\circ}$C for 6 h. High dielectric permittivity (${\varepsilon}^{\prime}$) and dense ceramic microstructure were achieved by sintering at a low temperature of 980 ${}^{\circ}$C. The values of ${\varepsilon}^{\prime}$ and tan$\delta$ were reduced by annealing in O${}_2$ atmosphere, which were described to correlate with the decrease in oxygen vacancies at grain boundaries. A decrease in low-frequency tan $\delta$ values can be well explained due to the reduction of DC conduction, which was primarily governed by the enhanced grain boundary resistance due to filling oxygen vacancies. A slight decrease in ${\varepsilon}^{\prime}$ due to the annealing process was attributed to the reduction of grain boundary capacitance. By annealing process, the conduction activation energy at the grain boundaries was significantly enhanced, whereas the conduction activation energy inside the grains did not change. The results clearly indicated the effects of oxygen vacancies at the grain boundaries on the giant dielectric response and correlated grain boundary response.

### Primary author

Mr Wattana Tuichai (Materials Science and Nanotechnology Program, Faculty of Science, Khon Kaen University, Khon Kaen, THAILAND 40002)

### Co-authors

Dr Prasit Thongbai (Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen, THAILAND 40002) Prof. Santi Maensirid (School of Physics, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima, THAILAND 30000) Dr Supamas Danwittayakul (National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani, THAILAND 12120) Dr Teerapon Yamwong (National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani, THAILAND 12120)

### Presentation Materials

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