Phase transitions in thin layers of solid solutions К$_x$Na$_{1-x}$NO$_2$

Thin layers of the К$_x$Na$_{1-x}$NO$_2$ system have been obtained from a melt using special techniques. It is shown that a ferroelectric phase transition disappears when the content of К$^+$ ions reaches $x=0,1$. The dielectric constant, pyroelectric current and conductivity diminish with an increase of $x$. These data demonstrate that phase transition temperature goes down when the concentration of impurity grows. A phase diagram of the system under consideration has been plotted.