JAHN-TELLER TYPE STRUCTURAL TRANSITION IN KDY(WO4)(2)

The low temperature structural phase transition in the KDy(WO4)(2) sin gle crystal has been first studied by means of both ESR method and spe cific heat C(T). A broad maximum of C(T) with peak at T-c = 6.38 K and lambda-shaped temperature dependence of the ESR line width LVI(T) in the vicinity of transition may be explained as being due to the struct ural phase transition caused by the interaction of the electronic stat es of Dy ions with the lattice vibrations. An analysis of C(T) and Del ta H(T) dependencies show that the second order structural phase trans ition is the transition of Jahn-Teller type and does not occur with a change of point symmetry. (C) 1997 Elsevier Science Ltd.