Relaxation of dynamically disordered tetragonal platelets in the relaxor ferroelectric 0.964Na1/2Bi1/2TiO3−0.036BaTiO30.964\mathrm{Na}_{1/2}\mathrm{Bi}_{1/2}\mathrm{TiO}_3-0.036\mathrm{BaTiO}_3

The local dynamics of the lead-free relaxor $0.964\mathrm{Na}_{1/2}\mathrm{Bi}_{1/2}\mathrm{TiO}_3-0.036\mathrm{BaTiO}_3$ (NBT-3.6BT) have been investigated by a combination of quasielastic neutron scattering (QENS) and ab initio molecular dynamics simulations. In a previous paper, we were able to show that the tetragonal platelets in the microstructure are crucial for understanding the dielectric properties of NBT-3.6BT [F. Pforr et al., Phys. Rev. B 94, 014105 (2016)]. To investigate their dynamics, ab initio molecular dynamics simulations were carried out using $\mathrm{Na}_{1/2}\mathrm{Bi}_{1/2}\mathrm{TiO}_3$ with 001 cation order as a simple model system for the tetragonal platelets in NBT-3.6BT. Similarly, 111-ordered $\mathrm{Na}_{1/2}\mathrm{Bi}_{1/2}\mathrm{TiO}_3$ was used as a model for the rhombohedral matrix. The measured single crystal QENS spectra could be reproduced by a linear combination of calculated spectra. We find that the relaxational dynamics of NBT-3.6BT are concentrated in the tetragonal platelets. Chaotic stages, during which the local tilt order changes incessantly on the timescale of several picoseconds, cause the most significant contribution to the quasielastic intensity. They can be regarded as an excited state of tetragonal platelets, whose relaxation back into a quasistable state might explain the frequency dependence of the dielectric properties of NBT-3.6BT in the 100 GHz to THz range. This substantiates the assumption that the relaxor properties of NBT-3.6BT originate from the tetragonal platelets.Comment: 27 pages, 9 figure

Structural origins of relaxor behavior in a 0.96(Bi1/2Na1/2)TiO3-0.04BaTiO(3) single crystal under electric field

Diffuse x-ray scattering intensities from a single crystal of 0.96(Bi1/2Na1/2TiO3)-0.04(BaTiO3) have been collected at room temperature with and without application of an electric field along the [100] direction. Distinct features in the diffuse scattering intensities indicate correlations on a nanometer length scale. It is shown that locally correlated planar-like structures and octahedral tilt-domains within the room temperature rhombohedral R3c phase are both electrically active and are irreversibly affected by application of an electric field of 4.3 kV/mm. The field dependence of these nanoscale structures is correlated with the relaxor behavior of the material by macroscopic permittivity measurementsopen221

Flufenacet an interesting mix partner for Viper™ Compact and GF-1546 against grass weeds in autumn

ViperTM Compact herbicide consists of the three active ingredients penoxsulam (15 g/L), florasulam (3.75 g/L) and diflufenican (100 g/L). It is a broad-spectrum herbicide used to control loose silky-bent (Apera spica venti), mono- and dicotyledonous weeds in winter wheat, winter barley, winter rye and winter triticale in the autumn. Penoxsulam and florasulam belong to the HRAC group B (ALS inhibitor), diflufenican to the HRAC group F1. Many loose silky-bent populations have a high risk of developing resistance to herbicides in the HRAC group B. For an effective resistance management, it is necessary to use herbicides from low resistance risk groups as mixing partner. A common mixing partner is the active substance flufenacet from the HRAC group K3. In 2015, mixtures of ViperTM Compact (0.5 - 0.75 L/ha) with flufenacet (125-240 g/ha) were tested in field trials. While ViperTM Compact is able to control sensitive grass populations, the addition of flufenacet was able to successfully control less sensitive Apera spica-venti (APESV) biotypes. Furthermore, with the increased flufenacet application rate of 240 g/ha + ViperTM Compact, blackgrass was also controlled successfully. Overall the mixture was selective in the tested cultures. The tank mix of ViperTM Compact + flufenacet thus offers a high effectiveness against grasses and weeds, while at the same time reducing the risk of resistance development

trans-Bis(acetato-κO)bis­(2-amino­ethanol-κ2 N,O)nickel(II)

In the title compound, [Ni(CH3CO2)2(C2H7NO)2], the NiII cation, located on an inversion center, is N,O-chelated by two 2-amino­ethanol mol­ecules and further coordinated by two monodendate acetate anions in a slightly distorted octa­hedral geometry. The latter is stabilized by intra­molecular O—H⋯O hydrogen bonds involving the non-coordinated O atom of the acetate and the H atom of the hy­droxy group of the 2-amino­ethanol ligand. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into a three-dimensional supra­molecular framework that involves (a) the coordinated acetate O atom and one of the H atoms of the amino group and (b) the non-coordinated acetate O atom and the other H atom of the amino group

Piezoelectricity and rotostriction through polar and non-polar coupled instabilities in bismuth-based piezoceramics

Coupling of order parameters provides a means to tune functionality in advanced materials including multiferroics, superconductors, and ionic conductors. We demonstrate that the response of a frustrated ferroelectric state leads to coupling between order parameters under electric field depending on grain orientation. The strain of grains oriented along a specific crystallographic direction, 〈h00〉, is caused by converse piezoelectricity originating from a ferrodistortive tetragonal phase. For 〈hhh〉 oriented grains, the strain results from converse piezoelectricity and rotostriction, as indicated by an antiferrodistortive instability that promotes octahedral tilting in a rhombohedral phase. Both strain mechanisms combined lead to a colossal local strain of (2.4 ± 0.1) % and indicate coupling between oxygen octahedral tilting and polarization, here termed “rotopolarization”. These findings were confirmed with electromechanical experiments, in situ neutron diffraction, and in situ transmission electron microscopy in 0.75Bi$_{1/2}$Na$_{1/2}$TiO$_{3}$-0.25SrTiO$_{3}$. This work demonstrates that polar and non-polar instabilities can cooperate to provide colossal functional responses

Revealing the solid‐state processing mechanisms of antiferroelectric AgNbO₃ for energy storage

AgNbO₃ is one of the prominent lead‐free antiferroelectric (AFE) oxides, which readily exhibits a field‐induced AFE to ferroelectric phase transition and thus a high energy storage density. The solid‐state synthesis of AgNbO₃ is considered difficult and an oxidizing atmosphere is typically employed during AgNbO₃ processing, on the premise that oxygen can prevent possible decomposition of the silver oxide at high temperatures. However, details about the influence of processing parameters on the functional properties of AFE AgNbO₃ are insufficiently understood. In this work, the solid‐state reaction of a stoichiometric AgO and Nb₂O₅ mixture was investigated. We found that ball milling can convert AgO into metallic Ag, which is beneficial for lowering the reaction temperature for the formation of the perovskite phase to 500‒600℃. Moreover, the influence of the processing atmosphere (air, O₂, and N₂) was investigated by thermal analysis and in situ X‐ray diffraction. Since the reaction between Ag and Nb₂O₅ to form AgNbO₃ requires oxygen uptake, AgNbO₃ was only found to form in air and O₂, whereby the kinetics were faster in the latter case. All the sintered AgNbO₃ samples exhibited a similar crystallographic structure, although the samples processed in O₂ had a lower oxygen vacancy concentration. Despite this, well‐defined AFE double polarization loops were obtained in all cases. Our results indicate that decomposition of sliver oxide during ball milling is beneficial for the solid‐state reaction, while a pure O₂ atmosphere is not essential for the synthesis of high‐quality AgNbO₃. These findings may simplify the processing and facilitate further research of AgNbO₃‐based antiferroelectrics

Геоэкологическая характеристика и элементный состав листьев тополя территории г. Тюмень

Работа направлена на изучение элементного состава листьев тополя как биогеохимического индикатора состояния окружающей среды городов с выраженной специализацией. Исследование проведено на примере города Тюмень.The work is directed at studying the elemental composition of poplar leaves as a biogeochemical indicator of the state of the environment of cities with a pronounced specialization. The study was conducted on the example of the city of Tyumen

Piezoelectricity and rotostriction through polar and non-polar coupled instabilities in bismuth-based piezoceramics

Coupling of order parameters provides a means to tune functionality in advanced materials including multiferroics, superconductors and ionic conductors. We demonstrate that the response of a frustrated ferroelectric state leads to coupling between order parameters under electric field depending on grain orientation. The strain of grains oriented along a specific crystallographic direction,〈h00〉, is caused by converse piezoelectricity originating from a ferrodistortive tetragonal phase. For〈hhh〉oriented grains, the strain results from converse piezoelectricity and rotostriction, as indicated by an antiferrodistortive instability that promotes octahedral tilting in a rhombohedral phase. Both strain mechanisms combined lead to a colossal local strain of (2.4 ± 0.1) % and indicate coupling between oxygen octahedral tilting and polarization, here termed “rotopolarization”. These findings were confirmed with electromechanical experiments, in situ neutron diffraction and in situ transmission electron microscopy in 0.75Bi1/2Na1/2TiO3-0.25SrTiO3. This work demonstrates that polar and non-polar instabilities can cooperate to provide colossal functional responses