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Ceramics Surface and Interface Group

Ceramics have surface, interface and grains. Especially, the surface and interface (grain boundary) in ceramics show the electrical properties. Our group focuses on the surface and interface as reaction field during the sintering to fabricate the oxide with poor sinterability and stability in air. In order to achieve above purpose, we used soft-chemical method, solid-state reaction method, and ion beam techniques. By the integration of the information on ceramics fabrication, we proceed with a basic ceramics science.

Research target

The research target is to fabricate the dense ceramics such as SnO2, La2O3, In2O3 and Ga2O3 etc. These materials are well known as the semiconductor and dielectric materials. For example, SnO2 and In2O3 are the sensor materials, and show the poor sinterability. La2O3 has a problem on the stability under the humidity atmosphere. We synthesize the dense ceramics and use them the target for rf- sputtering and PLD methods. Finally, we measure the gas sensor property for hydrogen and ethanol of these thin films.


We are developing oxide-based gas sensor materials. However, it is difficult to obtain a high-density target for thin films that has an optimum resistance value. Therefore, we are evaluating the gas sensor by synthesizing SnO2 and In2O3, which are difficult to sinter, and using them as targets to form thin films by sputtering method.


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The group evaluates hydrogen and oxygen defects in densified ceramics. These are help to understand the deterioration mechanism. We are also evaluating the gas sensor characteristics of thin films and powder films. In order to understand the characteristics, we evaluate structure and chemical composition on the surface layer, and develop it into the study of the reaction mechanism of the gas at the surface.


Facilities

This is a secondary ion mass spectrometry (SIMS). This is helpful to detect light element, isotope and impurities.(Fig. 1)

This is ion implantor. This is useful the surface modification. We also use to make a standard sample for SIMS analysis.(Fig. 2)

"Fig. 1" Image

Fig. 1


"Fig. 2" Image

Fig. 2




Selected Recent Results

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Zinc oxide has been studied as a gas sensor. When Al is ion-implanted and diffusion annealing is performed, the impurity Li diffuses into zinc oxide and forms a solid solution. The presence of Al allows most of Li to form a solid solution with ZnO.


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This figure shows the temperature dependence of oxygen diffusion obtained by diffusing 18O tracer in Al-implanted and pre-annealed samples. The pre-annealed sample showed a large change in the temperature dependence of oxygen diffusion.


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This figure is a gas sensor evaluation of SnO2 thin film synthesized by the sputtering method. The response of 10 ppm acetone gas was evaluated. The response was 67.5, confirming sufficient sensitivity.



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Ceramics Surface and Interface Group
1-1 Namiki, Tsukuba, Ibaraki, 305-0044 JAPAN
TEL: +81-29-860-4434
E-Mail: SAKAGUCHI.Isao=nims.go.jp(Please change "=" to "@")