ISSN:
1432-2021
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
,
Geosciences
,
Physics
Notes:
Abstract Crystal field spectra have been obtained from K2Co2(SO4)3 at a number of temperatures from 20 K to room temperature. The transition to the 4 T 1g(P) excited state is found to be split at all temperatures owing to the trigonal distortion of the Co site. Below the P213-P212121 phase transition temperature an excess splitting is observed owing to the additional distortion of the site in the orthorhombic phase. This excess distortion is found to be a linear function of temperature with no first order step at T c. Thus on a local scale the transition appears to be second order. The trigonal splitting increases with increasing temperature above Tc; this is not expected from the Speer-Salje model of the transition mechanism, which predicted decreasing distortion of the oxygen octahedra with increasing temperature. We propose that the apparent increase of asymmetry is due to the off centring of the Co atom in the high temperature phase in a more regular environment.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00202212
