Dynamical Jahn–Teller distortion in single crystals of Cu(II) doped magnesium potassium phosphate hexahydrate: a variable temperature EPR study

Single crystal electron paramagnetic resonance (EPR) studies on Cu(II)-doped magnesium potassium phosphate hexahydrate have been carried out at room temperature. The temperature dependence of g and A values has been obtained for the polycrystalline sample and the ground state is unambiguously identified. These results indicate the existence of a dynamic Jahn–Teller distortion for Cu(II) ion. The g and A tensor direction cosines are evaluated and compared with Mg–O directions, which confirms that Cu(II) enters substitutionally in the lattice.