In the present study, the dielectric, ferroelectric, and voltage-tunable characteristics of the Na0.5Bi0.5TiO3-Li0.45La0.52 square(0.03) TiO3 homogeneity range were investigated, together with the associated microstructural properties. The results revealed the polarization characteristics of the investigated samples, which enabled us to propose their possible structure at the microscopic and nanoscopic levels. With increases in the Li0.45La0.52 square(0.03) TiO3 concentration, the Na0.5Bi0.5TiO3, which is macroscopically ferroelectric, first changes to a morphotropic composition with ferroelectric regions distributed within the nonpolar matrix. A further increase in the Li0.45La0.52 square 0.03TiO3 concentration reduces the size and the fraction of the polar regions, while at a certain concentration the sample becomes paraelectric. The applicability of the investigated samples for voltage-tunable and other devices is also discussed.