Phase transitions in nanostructured K$_{(1-x)}$(NH$_4$)$_{(x)}$H$_2$PO$_4$ (x = 0 – 0.15) solid solutions

Effect of ammonium dihydrogen phosphate admixture on phase transitions in nanostructured solid solutions $(1-x)$KH$_2$PO$_4$-$(x)$(NH$_4$)H$_2$PO$_4$ at $x=0,0.05$ and $0.15$ has been studied by dielectric spectroscopy. The samples have been prepared by embedding of aqueous solutions into porous borosilicate glasses. The X-ray diffraction have shown that the crystal structure at room temperature corresponds to the bulk KDP and the average nanoparticle diameters are 49 (2) nm for the sample with 5 % of (NH$_4$)H$_2$PO$_4$ (ADP) and 46 (2) nm for the nanocomposites with 15 % of ADP. Dielectric response data analysis have revealed the shifts of the ferroelectric phase transition temperature as a function of (NH$_4$)H$_2$PO$_4$ concentration: at $x=0$ $\Delta T_C$ is equal to $\sim$6 K, at $x=0.05$ $\Delta T_C$ $\sim$3 K and at $x=0.15$ $\Delta T_C$ $\sim$2 K.