Structure, microstructure, dielectric and piezoelectric properties of solid solution ceramics of a six-component system $(1-y-a-z)$ (Na$_{0.5}$K$_{0.5}$NbO$_3$) - $y$LiNbO$_3$ - $a/2$CdNb$_2$O$_6$ - $z$Pb(Zr$_{0.5}$Ti$_{0.5}$)O$_3$

For the first time, solid solutions of two sections of a six-component system KNN-LN-PZT-CdNbO6 of the form $(1-y-a-z)$ (Na$_{0.5}$K$_{0.5}$NbO$_3$) - $y$LiNbO$_3$ - $a/2$CdNb$_2$O$_6$ - $z$Pb(Zr$_{0.5}$Ti$_{0.5}$)O$_3$: were prepared by two-stage solid- phase synthesis followed by sintering using conventional ceramic technology: section I with $y$ = 0.05, $a$ = 0.025, 0.15 $\le z<$ 0.50; section II with $y$ = 0.10, $a$ = 0.050, 0.15 $\le z<$ 0.50. X-ray diffraction revealed that all the studied experimental samples have pseudocubic symmetry. The microstructure of ceramic solid solutions is characterized by extreme inhomogeneity. An analysis of the dielectric, piezoelectric, and elastic properties (macroresponses) of the experimental samples allowed for the identification of a group of compositions with high relative permittivity values, which are promising for low-frequency applications. A conclusion is made about the feasibility of utilizing the proposed compositions in the design of electronic devices.