Disorder of O2- ion and incorporation of O- and O-2(-) radicals in nanoporous crystal 12CaO center dot 7Al(2)O(3) studied by low-temperature heat capacity measurements

Kohama Y; Tojo T; Kawaji H; Atake T; Matsuishi S; Hosono H

Chemical Physics Letters, Vol.421, No.4-6, 558-561, 2006

DOI10.1016/j.cplett.2006.02.016 Export Citation

Disorder of O2- ion and incorporation of O- and O-2(-) radicals in nanoporous crystal 12CaO center dot 7Al(2)O(3) studied by low-temperature heat capacity measurements

Kohama Y, Tojo T, Kawaji H, Atake T, Matsuishi S, Hosono H

Heat capacity of nanoporous crystal, 12CaO center dot 7Al(2)O(3) (C12A7), was measured between 8 5 mK and 5 K under magnetic field up to 9 T. The heat capacity under zero magnetic field did not fit to the T-3 law; the deviation was discussed in terms of the disorder of the O2-ions in the subnanometer-sized cages in C12A7 lattice. Under magnetic field, the heat capacity showed a Schottky-type anomaly due to the Zeeman splitting of O- and O-2(-) radicals (S = 1/2) incorporated in the cages. The total concentration of O- and 02 radicals in the crystal was estimated to be 4.4 x 10(18) cm(-3) (2.3 x 10(21) mol(-1), 3.8 x 10(-3) mol mol(-1)). (c) 2006 Elsevier B.V. All rights reserved.