SYMMETRY ANALYSIS OF KD3(SEO3)2-SEO2- ESR-SPECTRA

The symmetry analysis of KD3(SeO3)2:SeO2BAR ESR spectra, in previous publications, is incompatible with C2h symmetry of the low temperature phase. Such incompatibility motivated a suggestion that KD3(SeO3)2 might go to a pyroelectric phase at low temperature. The present work demonstrates that the correlated rotations of SeO2 groups, induced in the phase transition, transform according to the representation B3g of group D2h, the same symmetry of the order parameter. Therefore, the ESR spectra are in harmony with the symmetry change in the transition D2h --> C2h and the crystal cannot be pyroelectric.