In an antiperovskite oxide Sr3SnO, an anionic state is naively expected for tin such as (Sr2+)3Sn4-O2-. Since tin is a metallic element and tends to be cations like Sn2+ and Sn4+, the “charge-inverted” state Sn4− is unusual and very rare in oxides. However, it has not been experimentally investigated how many electrons tin actually possesses in antiperovskite oxides.
We made use of the Mössbauer effect to investigate the ionic state of tin. In Mössbauer spectroscopy, the state of tin can be deduced by examining γ ray with what wavelength a material absorbs. (γ ray is the light with a wavelength much shorter than that of ultraviolet.) As a result, we confirmed that Sn4− is realized in Sr3SnO (Figure). Furthermore, we revealed that inside Sr3−xSnO with less strontium, tin atoms neighboring the vacancy of strontium (indicated by ‘x‘ of 3−x) are in yet another state than Sn4−. This is the first observation of anionic states of tin in oxides. Through this discovery, we expect that antiperovskite oxides, with unusual metallic anions, will obtain more attention.
This research is a collaboration with Prof. Seto’s laboratory at the Institute for Integrated Radiation and Nuclear Science, Kyoto University. The article information is listed below, but those who are not researchers or have not subscribed to Physical Review B can also view the article from Kyoto University Repository for Navigating Academic Information (KURENAI).