KINETICS OF STRUCTURAL PHASE TRANSFORMATIONS IN K0.945Ag0.055NO* and K0.945Cs0.055NO* MONOCRYSTALS

Summary: In this work have been presented the result of investigation of K0,945Ag0,055NO3 and K0,945Cs0,055NO3 single crystals were grown from aqueous solution of KNO3, AgNO3 and CsNO3 using isothermal crystallization method. Then, structural and phase transformations in samples were studied by X-ray and optical microscopy methods. It has been determined that in K0,945Ag0,055NO3 monocrystal at T393K temperature, in K0,945Cs0,055NO3 monokrystal at T455K temperature the rhombic (II)  hexagonal (III) transformation occurs with the formation and growth of the III - modification crystal embryo within II – modification. The results obtained from the kinetic studies were determined that the temperature dependence of the conversion rate of II  III in K0,945Ag0,055NO3 and K0,945Cs0,055NO3 single crystals can be expressed by an empirical formula of υ=(aΔT+bΔT^2+cΔT^3)⋅10^(-2) cm/sec. ΔT=T_t-T_0 is temperature delay, T_t- is transformation temperature and is equilibrium temperature between interconverting modification crystals. Based on the results of velocity measurements, the activation energy of IIIII polymorphic transformations were calculated.