Structure and properties of La-modified Na0.5Bi0.5TiO3 at ambient and elevated temperatures

Abstract

The magnetic phase diagram and large reversible room-temperature magnetocaloric effect in antiperovskite compounds Zn1−xSnxCFe3 (0≤x≤1) J. Appl. Phys. 112, 063904 (2012) Convergent beam electron-diffraction investigation of lattice mismatch and static disorder in GaAs/GaAs1−xNx intercalated GaAs/GaAs1−xNx:H heterostructures Appl. Phys. Lett. 101, 111912 (2012) The role of structural properties on deep defect states in Cu2ZnSnS4 studied by photoluminescence spectroscopy Appl. Phys. Lett. 101, 102102 (2012) Electronic, structural, and elastic properties of metal nitrides XN (X = Sc, Y): A first principle study AIP Advances 2, 032163 (2012) Magnetic tri-axial grain alignment in misfit-layered bismuth-based cobaltitesThe crystal structure and property changes of sodium bismuth titanate (Na 0.5 Bi 0.5 TiO 3 , NBT) piezoelectric ceramics are reported as a function of La modification (0.5-2.0 at. %) and increasing temperature using high resolution x-ray diffraction, permittivity, depolarization, and polarization and strain hysteresis measurements. La substitution is found to decrease the depolarization temperature of NBT (e.g., 1.5 at. % La substitution lowers the depolarization temperature by 60 C relative to the unmodified composition) with little impact on the room temperature polarization and strain hysteresis. The room temperature structures of the various NBT compositions were modeled using a mixture of the monoclinic Cc space group and the cubic Pm 3m phase, where the Pm 3m phase is used to model local regions in the material which do not obey the long range Cc space group. With increasing La substitution, the lattice parameter distortions associated with the Cc phase approached that of the prototypical cubic unit cell and the fraction of the Pm 3m phase increased. The relationship between these crystallographic changes and the depolarization behavior of La-modified NBT is discussed.

Ferroelectric and magnetic properties of magnetoelectric (Na0.5Bi0.5)TiO3–BiFeO3 synthesized by acetic acid assisted sol–gel method

“…The remanent polarization (P r ) and coercive field (E C ) values are 33.5 C/cm 2 and 64 kV/cm agrees well with the previous reports. 21,22 A complete saturation of P-E loop in NBT is not possible due to presence of oxygen vacancies created as a result of the evaporation of volatile sodium and bismuth oxides during high temperature sintering procedure; such charged carriers would act as pinning centers to pin domains nearby. However, the observed P r value clearly suggest the minimal deviation from the expected stoichiometry of Na 0.5 Bi 0.5 .…”

“…19 It is piezoelectric (d 33 ∼ 102 pC/N, K P = 52%) and exhibits higher polarizable limits (remanent polarization, P r = 38 C/cm 2 and Coercive field, E C = 73 kV/cm). [20][21][22] It has dielectric maxima at 320 • C and exhibits interesting phase transitions: an anomaly around 200 • C (ferroelectric-antiferroelectric transition) and Curie temperature (T C ) around 520 • C. Optical birefringence, piezoelectric and dielectric properties of NBT as well as its solid solutions have attracted a substantial research attention. As a non-classic ferroelectric material and due to the frequency dependence of the permittivity at low temperature phase transition around 200 • C, NBT is considered as a relaxor ferroelectric.…”

Electric-field-induced local and mesoscale structural changes in polycrystalline dielectrics and ferroelectrics

“…Processing conditions of BaTiO 3 and SrTiO 3 are described in Supplementary Note 3, whereas those for Na ½ Bi ½ TiO 3 can be found in ref. 31. X-ray total scattering was measured using beamline 11-ID-B of the Advanced Photon Source at Argonne National Laboratory32.…”

Structural evolution of bismuth sodium titanate induced by a-site non-stoichiometry: Neutron powder diffraction studies

“…In addition, recent works report that a doping on perovskite A-and B-site [8][9][10] modifies physical properties such as depolarization temperature, T d and piezoelectric constant (d 33 ). For example, a doping of lanthanide ions 8,11 on the A-site decreases the depolarization temperature, T d . Contrary, the B-site substitution of the iron and the manganese 9,10 enhances the T d .…”