Order parameter behavior in the vicinity of antiferroelectric phase transition in K1−x(NH4)xH2PO4 mixed crystals

The dielectric permittivity ε11 have been studied for antiferroelectric (AFE) compounds of mixed crystals K1−xH2(NH4)xPO4 to determine the order parameter behavior. It has been found that the crystals under study undergo first-order phase transitions (PT). The decrease of ammonium concentration leads to the reduction of the order parameter “jump” in the vicinity of corresponding PT temperatures as well as to the increase of PT diffusiveness.