Absorption spectra peculiarities at the jahn-teller ordering in KDy(MoO₄)₂

Abstract The absorption spectra of KDy(MoO4)2 are studied in the region of the low-temperature phase transition of cooperative Jahn-Teller ordering type. Theparameters of the fine structure components of the absorption spectrum manifest anomalies of different type in the temperature region 20-8K. Possible low-temperature phases accompanied with the doubling of the unit cell of initial rhombic phase D2h 14 are analysed. It is shown that the Jahn-Teller pseudoeffect occurs in KDy(MoO4)2 due to the interaction between the electron states of Dy3+ ions and the strains in the “pre-transition” temperature region.