High-Density Electron Anions in a Nanoporous Single Crystal: [Ca 24 Al 28 O 64 ] 4 + (4 e - )

• DOI: 10.1126/science.1083842
• Publication Date: 2003-08-01T03:27:13Z
• Authors: Satoru Matsuishi; Yoshitake Toda; Masashi Miyakawa; Katsuro Hayashi; Toshio Kamiya; Masahiro Hirano; Isao Tanaka; Hideo Hosono
• Keywords: 0103 physical sciences; 540; 01 natural sciences; 620

We removed ∼100% of clathrated oxygen ions from the crystallographic cages in a single crystal of 12CaO·7Al 2 O 3 , leading to the formation of high-density (∼2 × 10 21 cm – 3 ) electrons highly localized in the cages. The resulting electron forms a structure that we interpret as an F + center and migrates throughout the crystal by hopping to a neighboring cage with conductivity ∼100 siemens per centimeter, demonstrating that the encaged electron behaves as an anion. The electron anions couple antiferromagnetically with each other, forming a diamagnetic pair or singlet bipolaron. The resulting [Ca 24 Al 28 O 64 ] 4 + (4 e – ) may be regarded as a thermally and chemically stable single crystalline “electride.”