Abstract:
In solid solutions of Na$_{1/2}$Bi$_{1/2}$TiO$_{3-x}$BaTiO$_3$, the question of the relationship between the concentration of BaTiO$_3$$(x)$ and the presence of relaxor properties, as well as at what value of $x$ these properties disappear, was studied. For this purpose, dielectric measurements of polarized and unpolarized compounds were carried out in a wide range of concentrations $x$ 0.05 $<x<$ 0.45. Ceramic and monocrystalline samples were studied. It was found that relaxation properties exist in the studied concentration range $x$ and the normal ferroelectric state cannot be achieved. This contradicts a number of literature data in which relaxor properties disappear already at $x$ = 0.18. It is suggested that different values of $x$ at which relaxor properties are lost may be associated with different sizes and numbers of polar nanoregions in the cubic ergodic phase resulting from the synthesis of ceramics due to different sintering temperatures and sample densities. It is concluded that the value of $x$, at which the relaxor properties disappear, is not constant for all NBT–$x$BT compounds and may vary depending on the synthesis conditions.
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