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Superconducting Materials Synthesis Group

We have synthesized various superconducting materials and investigated their physical properties. We also have searched for Si compounds, silicides, with suitable physical properties for solar-photovoltaic and thermoelectric applications, and have examined their properties in detail.

Objective

We have focused on the following three themes: (1) search for new superconducting materials and investigation of the physical properties of known superconductors, (2) search for and investigation of physical properties of semiconducting silicides with appropriate physical properties for photovoltaic and thermoelectric applications, (3) development of a novel chemical process for functional ceramics synthesis.

"Electrical resistivity, magnetization, and specific heat of superconducting material SrPt2Sb2 as a function of temperature. (M. Imai et al., Supercond. Sci. Technol. 26, 075001 (2013).)" Image

Electrical resistivity, magnetization, and specific heat of superconducting material SrPt2Sb2 as a function of temperature. (M. Imai et al., Supercond. Sci. Technol. 26, 075001 (2013).)


"Crystal structure of Zintl-phase solar cell material BaSi2. The red and blue spheres represent Ba and Si atoms." Image

Crystal structure of Zintl-phase solar cell material BaSi2. The red and blue spheres represent Ba and Si atoms.




Selected Recent Results

Discovery of superconducting 122 antimonides, superconducting antimonides structurally related to iron-based superconducting materials

The discovery of superconductivity with a superconducting critical temperature (Tc) of 26 K in LaFeAs(O,F) has stimulated studies on superconducting iron pnictides, and various systems such as 1111, 122, and 11 have been discovered. However, superconducting materials that are structurally related to iron-based superconductors are limited to phosphides and arsensides. In this study, we have synthesized superconducting antimonide that is structurally related to iron-based superconductors, SrPt2Sb2 (Tc = 2.1 K). This is the first report of a superconducting antimonide structurally related to iron-based superconducting materials. We also found that a novel material BaPt2Sb2 shows superconductivity (Tc = 1.8 K).

"Crystal structure of BaPt2Sb2" Image

Crystal structure of BaPt2Sb2


"Electrical resistivity of BaPt2Sb2 as a function of temperature." Image

Electrical resistivity of BaPt2Sb2 as a function of temperature.




Synthesis and physical properties of ternary Si clathrate K8ExSi46-x (E = Al or Ga)

Ternary Si clathrates that encapsulate alkaline-earth atoms have been reported to be metallic. We have demonstrated that a ternary Si clathrate with encapsulated alkaline atoms, K8Ga8Si38, is a semiconducting material with an energy gap of approximately 1.2 eV, suggesting that it has a potential for photovoltaic applications. A potential of K8ExSi46-x for thermoelectric applications was also examined.

"Crystal structure of ternary Si clathrate K8ExSi46-x (E = Al or Ga)" Image

Crystal structure of ternary Si clathrate K8ExSi46-x (E = Al or Ga)


"Optical absorption coefficient of K8Ga8Si38 as a function of photon energy." Image

Optical absorption coefficient of K8Ga8Si38 as a function of photon energy.




Group Leader

"Motoharu IMAI" Image

Motoharu IMAI


Group Member

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Superconducting Materials Synthesis Group
1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047 JAPAN
TEL. +81-29-859-2814
E-Mail: IMAI.Motoharu=nims.go.jp(Please change "=" to "@")
National Institute for Materials Science (NIMS)
1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JAPAN
TEL.+81-(0)-29-859-2000
FAX.+81-(0)-29-859-2029