The influence of Mn substitution on the local structure of Na0.5Bi0.5TiO3 crystals: Increased ferroelectric ordering and coexisting octahedral tilts

Abstract

The ferroelectric domain structure of pure Na 1/2 Bi 1/2 TiO 3 (NBT) and 1 at.% Mn-doped NBT (Mn-NBT) crystals was investigated by piezoresponse force microscopy. The correlation length of the polar regions was found to increase upon Mn substitution. High resolution transmission electron microscopy revealed that the coherency of the lattice across the domain boundaries between polar regions was also enhanced. Selected area electron diffraction showed that Mn favored coexisting 1/2 (ooo) and 1/2 (ooe) oxygen octahedral tiltings, over only 1/2 (ooo) for pure NBT. V C 2012 American Institute of Physics. [http://dx

Evidence for the suppression of intermediate anti-ferroelectric ordering and observation of hardening mechanism in Na1/2Bi1/2TiO3 ceramics through cobalt substitution

“…Though there are few reports at B-site substitution in NBT with Mn and Fe, no specific change in the AFE ordering/behavior was observed or reported. 19,20 …”

Optical dispersion and bandgap of pure and Mn‐doped 0.92Na0.5Bi0.5TiO3‐0.08K0.5Bi0.5TiO3 lead‐free single crystals

“…As shown in the domain structures (Figure ), the domain size in the pure crystal is 35‐52 μm, which is larger than the size 13‐28 μm in the Mn‐doped crystal. The density of domain walls increases after doping Mn ions, enhancing the domain wall scattering, which makes an impedance on the light transmission . Moreover, the Mn ions in NBT‐8KBT possess a fluctuating valence state between +2 and +4, which acts as acceptors in the crystal and form trapping centers in the bandgap .…”

“…In addition, small amounts of dopants are generally considered as an effective method to improve and enhance the performance of materials. For example, Mn dopant have a substantial impact on enhancing piezoelectric response and reducing dielectric loss of NBT solid solutions …”

“…For example, Mn dopant have a substantial impact on enhancing piezoelectric response and reducing dielectric loss of NBT solid solutions. [10][11][12] NBT-based materials, similar to most oxygen-octahedral ferroelectrics, show excellent optical behaviors. [13][14][15] Compared to the ceramics, the crystals normally have better optical performance because the crystal particle arrangement in space is long-range ordered with no grain boundaries.…”

Direct Determination of Cationic Disordering in Sodium Bismuth Titanate

“…In addition, homovalent solid solutions, such as Ba(Ti 1-x Zr x )O 3 and Ba(Ti 1-x Sn x )O 3 , also exhibit a relaxor characteristic with compositional disorder (Sciau et al, 2000;Simon et al, 2004;Yasuda et al, 1996). However, in case of NBT, the origin of relaxor ferroelectricity is still controversial; the relaxor ferroelectricity is said to be induced by the polar nanoregions (PNRs) just like in the lead-based perovskites (Tai & Lereah, 2009;Yao et al, 2012), while third-party phase, such as a modulated orthorhombic phase mediating between rhombohedral and tetragonal, is reported to plays a crucial role in the relaxor property (Dorcet et al, 2008a(Dorcet et al, , 2008bLevin & Reaney, 2012). To unveil the mysterious ferroelectricity in NBT, it is indispensable to firstly verify the existence of a superlattice, where chemical ordering of A-site species (Na and Bi) occurs, since the cationic ordering at room temperature more likely gives rise to the ferroelectricity rather than relaxor property.…”