(1 − x)Na0.5Bi0.5TiO3–xCdTiO3 solid solutions in the whole concentration range (0.0 ≤ x ≤ 1.0) were studied by means of X-ray diffraction, dielectric spectroscopy and polarization measurements. The study was mainly focused on crystalline structure of the compositions, depending on their place in the phase diagram. The solid solution system exhibits at least four different phases at room temperature, giving rise to paraelectric, ferroelectric and relaxor ferroelectric behaviour. There were proposed appropriate space groups for each of these phases, using Rietveld refinement method for analysis of the X-ray diffraction patterns and taking into account polarization measurement results. Unexpected and unusual octahedral tilt systems—a+a+a+ and a+b+c+—were found in certain CdTiO3 concentration ranges. The tilt system a+b+c+, which was detected in the ferroelectric phase, was evidenced for the first time, as it has been theoretically predicted, but never experimentally observed before in any material. It was shown that ferroelectricity in (1 − x)Na0.5Bi0.5TiO3–xCdTiO3 solid solutions arises not only from the Ti+4 displacements, but also from the polar distortions in square planar and cubooctahedral cation A-sites. Upon heating, at a phase transition from the ferroelectric to the paraelectric state, a+b+c+ tilt system transforms into a+a+a+. The studied compositions were compared with (1 − x)Na0.5Bi0.5TiO3–xCaTiO3 solid solution system, as CdTiO3 and CaTiO3 are crystallographically very similar. It was revealed that both constituents behave very differently. CaTiO3 in (1 − x)Na0.5Bi0.5TiO3–xCaTiO3, even in low concentrations, stabilizes solid solutions in its Pnma space group, unlike its counterpart CdTiO3 in the studied materials.
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
This is a preview of subscription content, log in to check access.
This work has been supported by National Research Program in the framework of project “Multifunctional Materials and composites, photonics and nanotechnology (IMIS2)”.
Rao BN, Olivi L, Sathe V, Ranjan R (2016) Electric field and temperature dependence of the local structural disorder in the lead-free ferroelectric Na0.5Bi0.5TiO3: an EXAFS study. Phys Rev B 93:024106. doi:10.1103/PhysRevB.93.024106CrossRefGoogle Scholar
Aksel E, Forrester JS, Kowalski B, Jones JL, Thomas PA (2011) Phase transition sequence in sodium bismuth titanate observed using high-resolution X-ray diffraction. Appl Phys Lett 99:222901. doi:10.1063/1.3664393CrossRefGoogle Scholar
Jones GO, Thomas PA (2002) Investigation of the structure and phase transitions in the novel A-site substituted distorted perovskite compound Na0.5Bi0.5TiO3. Acta Crystallogr Sect B 58:168–178. doi:10.1107/S0108768101020845CrossRefGoogle Scholar
Dorcet V, Trolliard G, Boullay P (2008) Reinvestigation of phase transitions in Na0.5Bi 0.5TiO3 by TEM. Part I: first order rhombohedral to orthorhombic phase transition. Chem Mater 20:5061–5073. doi:10.1021/cm8004634CrossRefGoogle Scholar
Birks E, Dunce M, Ignatans R, Kuzmin A, Plaude A, Antonova M, Kundzins K, Sternberg A (2016) Structure and dielectric properties of Na0.5Bi0.5TiO3–CaTiO3 solid solutions. J Appl Phys 119:074102. doi:10.1063/1.4942221CrossRefGoogle Scholar
Moriwake H, Kuwabara A, Fisher CAJ, Taniguchi H, Itoh M, Tanaka I (2011) First-principles calculations of lattice dynamics in CdTiO3 and CaTiO3: phase stability and ferroelectricity. Phys Rev B 84:104114. doi:10.1103/PhysRevB.84.104114CrossRefGoogle Scholar