A research group at Kanagawa Academy of Science and Technology and Tokyo Institute of Technology succeeded in synthesizing lead perovskite-type oxide cobalt (PbCoO3), and both lead and cobalt are charge-ordered (periodic arrangement of the same element ions with different valences). It was discovered that an unprecedented charge distribution was realized.In addition, Osaka Prefecture University, Waseda University, Chuo University, Gakuin University, Kyushu University, and various research institutes participate in the research group.
Perovskite-type oxide is a typical crystal structure of a metal oxide having an elemental composition represented by the general formula ABO3, and has been actively studied because it has various functions. It is well known as a ferroelectric substance that it was established as a perovskite-type oxide containing lead (Pb) at the A site of ABO3 and a metal element (4d transition metal) of the 3th period of the Periodic Table of the elements at the B site. It was only lead titanate.
In recent years, the research team has found that in various perovskite oxides, the valence of lead (Pb) at site A increases as the periodic table of elements moves from titanium (Ti) to nickel (Ni) at site B to the right. However, it was becoming clear that the valence of transition metals was decreasing, but PbCoO3 had not been synthesized so far.
今回の研究では、超高圧（15万気圧）を用いることで、世界で初めてPbCoO3の合成に成功した。さらに、放射光Ｘ線と中性子線を用いた研究で、ペロブスカイト型構造の、AサイトにPb2+とPb4+が1：3で、BサイトにCo2+とCo3+が1：1で秩序配列した、四重ペロブスカイトと呼ばれる特殊な電荷分布を持つことが明らかになった。
Quadruple perovskite is a group of substances that are attracting attention because they have various functions such as huge permittivity, magnetoresistive effect, negative thermal expansion, and oxygen reduction / oxygen generation catalyst.It is expected that these functions will be manifested by modifying PbCoO3 in the future.
(Note) In the text, 3 of O3 is a subscript, and 2+ such as Pb2 + is a superscript.
Published paper information:[Journal of the American Chemical Society] A-site and B-site charge orderings in an sd level controlled perovskite oxide PbCoO3 (English)
