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Bi(Fe0.5Mn0.5)O3 is an Mn substituted Bismuth ferrite ferroelectric synthesized following mixed oxide process method of solid-state reaction technique after calcined at 800 °C for 8 h. XRD study approves the development of an orthorhombic single-phase new crystal structure. Electrical characterization of the compound is done by an impedance analyzer. The dielectric and impedance study of the material is investigated in a wide span of frequency (102–106 Hz) and temperature (30–500 °C). The parent compound bismuth ferrite has a higher transition temperature (∼830 °C) which markedly decreases to 470 °C on substitution of Mn is substituted at the B site. Impedance study of the compound exhibits non-Debye type relaxation process. With the rising temperature, the relaxation frequency shifts toward the high frequency side. From the plots of complex impedance, negative temperature coefficient of resistance (NTCR) behavior like semiconductor is noticed. The conductivity is mainly contributed by the grain in the material. [ABSTRACT FROM AUTHOR]

Devices based on ferroelectric hafnium oxide are of major interest for sensor and memory applications. In particular, Si-doped hafnium oxide layers are investigated for the application in the front-end-of-line due to their resilience to high thermal treatments. Due to its very confined doping concentration range, Si:HfO2 layers based on thermal atomic layer deposition often exhibited a crossflow pattern across 300 mm wafer. Here, plasma enhanced atomic layer deposition is explored as an alternative method for producing Si-doped HfO2 layers, and their ferroelectric and pyroelectric properties are compared. [ABSTRACT FROM AUTHOR]

High energy synchrotron X-ray diffraction, in situ with electric field, was carried out on the morphotropic phase boundary composition of the piezoelectric alloy PbTiO3-BiScO3. We demonstrate a strong correlation between ferroelectric-ferroelastic domain reorientation, lattice strain and phase transformation. We also show the occurrence of the three phenomena and persistence of their correlation in the weak field regime. [ABSTRACT FROM AUTHOR]

The phase transitions and domain structure of the promising PbO-free solid solution series, (0.95-x)BiFeO3-xLaFeO3-0.05La2/3TiO3, were investigated. X ray diffraction(XRD) revealed a transition from a ferroelectricR3c to a PbZrO3-like (Pbam) antiferroelectric (AFE) structure at x = 0.15 followed by a transition to a paraelectric (PE, Pnma) phase at x > 0.30. The ferroelastic/ferroelectric twin domain width decreased to 10-20 nm with increasing x as the AFE phase boundary was approached but coherent antiphase tilted domains were an order of magnitude greater. This domain structure suggested the local symmetry (20 nm) is lower than the average structure (R3c, a-a-a-) of the tilted regions. The PE phase (x = 0.35) exhibited a dominant a-a-c+ tilt system with Pnma symmetry but diffuse reflections at ~1/4{ooe} positions suggest that short range antipolar order is residual in the PE phase. The complex domain structure and phase assemblage of this system challenge the conventional interpretation of phase transitions based on macroscopic symmetry. Instead, it supports the notion that frustration driven by chemical distributions at the nanometric level influences the local or pseudo-symmetry as well as the domain structure, with XRD giving only the average macroscopic structure. [ABSTRACT FROM AUTHOR]

The phase transitions and domain structure of the promising PbO-free solid solution series, (0.95-x)BiFeO3-xLaFeO3-0.05La2/3TiO3, were investigated. X ray diffraction(XRD) revealed a transition from a ferroelectricR3c to a PbZrO3-like (Pbam) antiferroelectric (AFE) structure at x = 0.15 followed by a transition to a paraelectric (PE, Pnma) phase at x > 0.30. The ferroelastic/ferroelectric twin domain width decreased to 10-20 nm with increasing x as the AFE phase boundary was approached but coherent antiphase tilted domains were an order of magnitude greater. This domain structure suggested the local symmetry (20 nm) is lower than the average structure (R3c, a-a-a-) of the tilted regions. The PE phase (x = 0.35) exhibited a dominant a-a-c+ tilt system with Pnma symmetry but diffuse reflections at ~1/4{ooe} positions suggest that short range antipolar order is residual in the PE phase. The complex domain structure and phase assemblage of this system challenge the conventional interpretation of phase transitions based on macroscopic symmetry. Instead, it supports the notion that frustration driven by chemical distributions at the nanometric level influences the local or pseudo-symmetry as well as the domain structure, with XRD giving only the average macroscopic structure. [ABSTRACT FROM AUTHOR]

The effects of Mn doping on the structural properties of the topological insulator Bi2Se3 in thin film form were studied in samples grown via molecular beam epitaxy. Extended x-ray absorption fine structure measurements, supported by density functional theory calculations, indicate that preferential incorporation occurs substitutionally in Bi sites across the entire film volume. This finding is consistent with x-ray diffraction measurements which show that the out of plane lattice constant expands while the in plane lattice constant contracts as the Mn concentration is increased. X-ray photoelectron spectroscopy indicates that the Mn valency is 2+ and that the Mn bonding is similar to that in MnSe. The expansion along the out of plane direction is most likely due to weakening of the Van der Waals interactions between adjacent Se planes. Transport measurements are consistent with this Mn2+ substitution of Bi sites if additional structural defects induced by this substitution are taken into account. [ABSTRACT FROM AUTHOR]

We report structural and magnetic properties of rare earth doped Bi0.95R0.05 FeO3 (R = Y, Ho, and Er) submicron particles. Rare earth doping enhances the magnetization and the magnetization shows an increasing trend with decreasing dopant ionic radii. In contrast to the x-ray diffraction pattern, we have seen a strong evidence for the presence of rare earth iron garnets R3Fe5O12 in magnetization measured as a function of temperature, in selected area electron diffraction, and in Raman measurements. Our results emphasised the role of secondary phases in the magnetic property of rare earth doped BiFeO3 compounds along with the structural distortion favoring spin canting by increase in Dzyaloshinskii-Moriya exchange energy. [ABSTRACT FROM AUTHOR]

Bismuth halide oxide with three halogen elements (P‐BiOXs) catalyst was prepared by a facile precipitation method at room temperature only for 30 min. Several measurement technologies were employed to characterise the structures and morphologies of the obtained samples. Coloured Rhodamine B (RhB), methyl orange (MO), methylene blue (MB) and colourless bisphenol A (BPA) were selected to evaluate the photocatalytic activity of the samples. The experimental results showed the P‐BiOXs thin nanoplates exhibited the most excellent photocatalytic activity among the prepared samples for the degradation of MO under visible light illumination. More importantly, the catalyst P‐BiOXs could effectively degradate RhB, MB and BPA. The P‐BiOXs catalyst displayed good photocatalytic stability by the recycling tests. The highly efficient visible light catalytic properties of P‐BiOXs could be due to the high specific surface area, enhanced light‐harvesting ability, the suitable bandgap energy and the lower recombination rate of the photogenerated electrons and holes. [ABSTRACT FROM AUTHOR]

To investigate the influence of graphene on the photocatalytic activity of bismuth ferrite (BiFeO3), BiFeO3 and flaky BiFeO3@graphene were prepared through the hydrothermal‐synthesis process. The as‐prepared particles were characterised by XRD, TGA, SEM, X‐ray photoelectron spectroscopy, and PL measurements. The results show that the BiFeO3 nanoparticles have a microstructure and homogeneously attached to graphene sheets. Moreover, the flaky BiFeO3@graphene composites exhibited higher photocatalytic efficiency than pure BiFeO3, especially under visible light irradiation. The synergistic effects of graphene and BiFeO3 of composites were proposed to guide the further improvement of their photocatalytic activity. [ABSTRACT FROM AUTHOR]

Doping is an effective way to enhance photocatalytic activity. Herein, the authors have synthesised a series of BiFe1−xTixO3 (x = 0, 0.05, 0.10, 0.15, 0.20) nanocrystals through sol–gel methods. X‐ray diffraction, Raman spectra, high‐resolution transmission electron microscopy images and X‐ray photoelectron spectroscopy characterisations indicate doping could facilitate the formation of Bi2Fe4O9 phase at low content, while inhibiting this formation at high content. Interestingly, the appearance of Bi2Fe4O9 improved the photocatalytic activity, which may be attributed to the spontaneous formation of heterostructure between Bi2Fe4O9 and BiFeO3 phases. The staggered energy bands between these two phases could effectively separate electrons and holes, resulting in enhanced photocatalytic performance. [ABSTRACT FROM AUTHOR]

The mixed‐phase BiVO4 nanosheet with different ratios of solvents was prepared by a one‐step hydrothermal method. The viscosity of ethylene glycol helps form a homogeneous thin nanosheet, which can be compared with the microstructure of BiVO4 with different ratios of solvents (deionised water and ethylene glycol). Also, both XRD and Raman diagrams indicate that the synthesis of BiVO4 nanosheet constitutes with a mixture of two crystal types. The mixed‐phase BiVO4 possesses higher photocurrent density, smaller electron transport resistance and longer lifetime. Enhanced photoelectrochemical performance can be attributed to the mixed‐phase BiVO4 has a large specific surface area, as well as o‐BiVO4 (orthorhombic BiVO4) and s‐BiVO4 (monocline BiVO4), form heterogeneous junction to promote photogenerated carries separation and reduce the recombination of photogenerated electron–hole. [ABSTRACT FROM AUTHOR]

We have prepared thin films of BiFe1-xZrxO3 (x=0.0–0.15) by chemical solution deposition on Pt/Si substrates. Structural characterization of the films using x-ray diffraction and Raman spectroscopy suggests lattice distortion upon doping for x<0.15. This also appears to be the limit for pure phase formation. Ferroelectric measurements reveal that Zr doping leads to reduction in the remnant polarization and an increase in the coercive field, attributed to lattice distortion. Dielectric measurements indicate that the doped compositions exhibit absence of low frequency relaxation, usually associated with defects and grain boundaries. Absence of Fe2+ in our films was verified using x-ray photoelectron spectroscopy. Role of Zr in controlling the film’s properties has been explained in terms of changes in the bond strength. [ABSTRACT FROM AUTHOR]

The effect of Nd modification on ferro-, piezo-, and dielectric properties of intergrowth Bi4Ti3O12-SrBi4Ti4O15 ceramics was investigated. X-ray diffraction and Raman scattering were used to identify the crystal phase and to distinguish the doping sites. With increasing Nd content up to 0.50, both remanent polarization (2Pr) and piezoelectric coefficient (d33) were found to increase and reach the maximum value of 33.2 μC/cm2 and 14 pC/N, respectively, which gained an enlargement over 1.7 times in 2Pr and a desirable 75% increment in d33 value. However, further Nd modification starts to deteriorate the ferro- and piezoelectric behavior. Impedance spectroscopy shows the activation energy of conductivity increased with increasing Nd content, which can be regarded as direct proof of the restraint of oxygen vacancies. The thermal variations of dielectric permittivity and loss tan δ with Nd content show the characteristic of diffuse phase transformation while the convincible defect-related relaxation phenomenon was not found. Interestingly, in contrast to La modification, Nd modification does not induce the relaxor behavior even at very high doping content. [ABSTRACT FROM AUTHOR]

The effect of Nd modification on ferro-, piezo-, and dielectric properties of intergrowth Bi4Ti3O12-SrBi4Ti4O15 ceramics was investigated. X-ray diffraction and Raman scattering were used to identify the crystal phase and to distinguish the doping sites. With increasing Nd content up to 0.50, both remanent polarization (2Pr) and piezoelectric coefficient (d33) were found to increase and reach the maximum value of 33.2 μC/cm2 and 14 pC/N, respectively, which gained an enlargement over 1.7 times in 2Pr and a desirable 75% increment in d33 value. However, further Nd modification starts to deteriorate the ferro- and piezoelectric behavior. Impedance spectroscopy shows the activation energy of conductivity increased with increasing Nd content, which can be regarded as direct proof of the restraint of oxygen vacancies. The thermal variations of dielectric permittivity and loss tan δ with Nd content show the characteristic of diffuse phase transformation while the convincible defect-related relaxation phenomenon was not found. Interestingly, in contrast to La modification, Nd modification does not induce the relaxor behavior even at very high doping content. [ABSTRACT FROM AUTHOR]

• Bismuth chalcogenide single crystals were synthesized by floating zone technique. • A comparison among different growth procedures were described. • Different compounds Bi 2 Te 3 , Bi 2 Se 3 , Bi 2 Se 0.9 Te 2.1 and Bi 1.85 Sb 0.15 Se 3 , were grown. • Stoichiometric and very well oriented single crystals were isolated. • Crystals range from a few mm to tens of millimeters, with different thicknesses. In this paper, two procedures for the growth of both binary and ternary single crystals of bismuth chalcogenides by optical floating zone technique are described. Detailed characterization has been carried out on a series of samples, i.e. Bi 2 Se x Te 3-x , with x = 0 and 0.9, and Bi 2-x Sb x Se 3 , with x = 0 and 0.15, to isolate high quality single crystals, essential for an accurate study of the physical properties of the materials. Systematic compositional and structural analysis on the samples grown by the two different procedures have been compared to infer the optimal growth parameters to obtain the largest possible single crystals. The c -axis lattice parameter of Bi 1.85 Sb 0.15 Se 3 is reported here for the first time. [ABSTRACT FROM AUTHOR]

The dramatically enhanced polarizations and saturation magnetizations observed in the epitaxially constrained BiFeO3 (BFO) thin films with their pronounced grain-orientation dependence have attracted much attention and are attributed largely to the constrained in-plane strain. Thus, it is highly desirable to directly obtain information on the two-dimensional (2D) distribution of the in-plane strain and its correlation with the grain orientation of each corresponding microregion. Here the authors report a 2D quantitative mapping of the grain orientation and the local triaxial strain field in a 250 nm thick multiferroic BFO film using a synchrotron x-ray microdiffraction technique. This direct scanning measurement demonstrates that the deviatoric component of the in-plane strain tensor is between 510-3 and 610-3 and that the local triaxial strain is fairly well correlated with the grain orientation in that particular region (22 References).

Pure and (8%, 12% and 16 wt%) Co-doped BiFeO3 (BFO) samples were synthesized by the gel-combustion method. The obtained samples were subjected to the powder XRD, FE-SEM, EDX, TEM, VSM, and hemocompatibility studies. The structural changes (pure crystalline phase to mixed crystalline phase) were observed in BFO with increased Co concentration in the XRD studies. The FE-SEM and TEM images showed the morphology of the samples, which indicates that spherical/bricks shaped particles were formed. According to the VSM analysis, a change in ferromagnetic behaviour was observed increasing the Co concentration BFO. BFO and doped BFO nanoparticles samples have good biocompatibility has been from the hemocompatibility test analysis. The electrochemical behaviour of BFO and doped BFO was also studied by the cyclic voltammetry (CV) analysis. [ABSTRACT FROM AUTHOR]

In this research work, the Ni, Mg, and Ni–Mg co-doped BiFeO3 nanoparticles were synthesized via a sol–gel method. X-ray diffraction analysis confirmed that all samples had a rhombohedral distorted perovskite structure. The field emission scanning electron microscopy images revealed a change in the particle size and shape in the Ni, Mg, and Ni–Mg co-doped BiFeO3 samples compared with the undoped sample. Optical investigation showed an increase in the dielectric constant with substitution of Ni and/or Mg at the Fe sites but the value for the co-doped sample was smaller than the values for the other two samples. The calculated direct band gaps for the undoped and co-doped samples were 1.94 and 2 eV, respectively. The results obtained from the magnetic hysteresis loop measurements at room temperature indicated a ferromagnetic behavior for the doped samples. The higher magnetization value with the optical band gap value in the visible light range, make the Ni–Mg co-doped BiFeO3 multi-ferroic material a promising candidate for opto-electromagnetic applications. [ABSTRACT FROM AUTHOR]

Abstract In this work a series of Bi 25 FeO 40 − Fe 3 O 4 − Fe 2 O 3 composite samples were prepared directly through the solid state reaction process using bismuth and iron based minerals. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV–visible spectroscopy. A series of samples was prepared, varying the calcination temperature between 550 ∘ C and 750 ∘ C. XRD results show the formation of composites, consisting of the phases Bi 25 FeO 40 , magnetite ( Fe 3 O 4 ) and hematite ( Fe 2 O 3 ). The percentage of the Bi 25 FeO 40 phase in the samples ranged from 60% to 85% according to the calcination temperature. SEM micrographs show that the particles making up these materials have lamellar, spherical and cylindrical structures. Magnetic measurements show that the saturation magnetization decreases with the percentage of magnetite. The coercive field ( H C = 210 Oe) remains constant for all samples calcined in the temperature range between 550 − 700 ∘ C. The sample calcined at 750 ∘ C presents an atypical behavior, with an increase of 3× in the value of the coercive field and a low saturation magnetization value, M s = 0.40 emu/g. UV–visible spectroscopy results show that samples calcined between 550 − 750 ∘ C show absorption of ultraviolet and visible light. These results indicate that the powders of the composite Bi 25 FeO 40 − Fe 3 O 4 − Fe 2 O 3 have photocatalytic properties which can be easily recycled by magnetic separation. Highlights • Solid state reaction process used to produce sillenite-magnetite-hematite composites. • Fabrication procedure starts from the bismuth-iron ores instead of chemical reagents. • Bi 25 FeO 40 -Fe 3 O 4 -Fe 2 O 3 show strong absorption in the ultraviolet and visible regions. • Composites can have photocatlytic applications and are recycled by magnetic separation. [ABSTRACT FROM AUTHOR]

The photovoltaic (PV) properties of polycrystalline Bi1−xLaxFeO3 (x = 0–0.3) films have been explored. The X-ray diffraction study reveals that there is a gradual phase transition with the increase in La doping. The composition x = 0.25 is found to be the morphotropic phase boundary (MPB), beyond which the system turns into the non-/antipolar orthorhombic phase. The polarization measurements reveal improved ferroelectric properties with the maximum remanent polarization observed for the x = 0.25 film. A systematic study on the direct and indirect bandgaps of the films has shown a decreasing trend with composition. Interestingly, the PV studies exhibit a maximum open-circuit voltage of 1.30 V for the x = 0.25 film which is three times larger than the value observed for pure BiFeO3 (BFO) (0.47 V). The enhanced PV response in La-doped BFO correlates with the polarization and the change in direct/indirect bandgaps associated with structural instability near the MPB composition. The approach used in this work for enhancing the PV performance in ferroelectric BFO through the combined effects of polarization, bandgaps and competing structures provides a better pathway for improving the ferroelectric PV effect. [ABSTRACT FROM AUTHOR]

Abstract We investigated the growth characteristics and multiferroic properties of BiFeO 3 (BFO) and Yb-doped BiFeO 3 (Bi 0.85 Yb 0.15 FeO 3 , YBFO) thin films grown on Pt/Ta/glass substrates. X-ray diffraction experiments showed that both BFO and YBFO thin films had preferentially (111)-oriented polycrystalline structures. Yb doping of BFO thin films led to enhanced multiferroic properties in terms of the ferroelectricity (remanent polarization of about 41.5 μC/cm2) and ferromagnetism (remanent magnetization of about 1.91 emu/cm3). According to piezoresponse force microscopy experiments, the YBFO thin films possessed larger ferroelectric domain structures than the BFO thin films due to the higher domain wall energy of the YBFO thin films. Highlights • Yb-doped BiFeO3 (Bi0.85Yb0.15FeO3, YBFO) thin films are deposited on Pt/Ta/glass substrates. • Yb doping enhances the multiferroic properties substantially. • The YBFO thin films possess larger ferroelectric domain structures than the BFO thin films. [ABSTRACT FROM AUTHOR]

Abstract The Bi 1.5 Zn 1.0 Nb 1.5 O 7 /BaTi 0.85 Sn 0.15 O 3 heterolayer thin films are deposited on Pt-Si substrates by radio frequency magnetron sputtering and pulsed laser deposition. X-ray diffraction and atomic force microscopy investigations show that the heterolayer thin films with good crystallinity have crack-free and uniform surface morphology. Experimental results suggest that the BZN layer plays a positive role in enhancing the tunable performance of heterolayer thin films. For the heterolayers, the dielectric constant is ~ 312, calculations of tunability and figure of merit display a high value of ~ 51.7% and ~ 104.7 at 424 kV/cm, respectively. The improvement of figure of merit can be attributed to the boundary introduced by the heterolayer structure. [ABSTRACT FROM AUTHOR]

In the present work Bi 0.5 Na 0.5 TiO 3 (BNT) and CoMn 0.2 Fe 1.8 O 4 (CMFO) composites, (1-x) BNT/(x) CMFO with x = 0.10, 0.20, 0.30, 0.40 and 0.50 have been synthesized using solid state reaction method. X-ray diffraction exhibits the peaks akin to constituent BNT and CMFO phases suggesting the effective development of the desired composites. The variation of dielectric constant with temperature reveals their diffuse phase transition behaviour and existence of two dielectric anomalies in vicinity of ferroelectric to antiferroelectric and from antiferroelectric to paraelectric transition temperatures. Remnant polarization (2P r) and Coercive field (2E C) found to decrease with addition of CMFO. Furthermore, magnetization vs. magnetic field (M-H) hysteresis loops shows an increment in magnetization with increase in CMFO content. Complex impedance spectroscopy confirms the existence of grain (bulk) effect and temperature dependent electrical relaxation processes in the composites. Magnetoelectric analysis shows maximum magnetoelectric voltage coefficient, α ME for x = 0.10 and the value of, α ME decreases from 6.765 mV/cm-Oe to 2.780 mV/cm-Oe for the composites x = 0.10 to 0.50. [ABSTRACT FROM AUTHOR]

Abstract 4-aminopyridinium analogue, [4-NH 2 PyH] 7 [BiCl 6 ] 2 Cl , has been synthesized and characterized by single-crystal X-ray diffraction at 100 K, calorimetric, dilatometric and dielectric studies. The crystal structure is centrosymmetric with the monoclinic space group, P 2 1 / n. It consists of two discrete [BiCl 6 ]3- octahedra, one loose Cl− anion and seven, partially disordered, 4-aminopyridinium cations. The compound reveals a reversible first-order phase transition (I→II) at 305/304 K of the 'order-disorder' type. The dielectric studies disclosed a relaxation process in the kilohertz frequency region, assigned to the dynamics of organic cations, described well by the Cole-Cole relation. The 1H NMR spin–lattice relaxation time measurements indicate a complex cations motion over the Phase II. The possible mechanism of the I → II phase transition in [4-NH 2 PyH] 7 [BiCl 6 ] 2 Cl is discussed. Highlights • A new hybrid organic-inorganic material; [4-NH 2 C 5 H 4 NH] 7 [BiCl 6 ] 2 Cl. • The molecular mechanism of the phase transition is of an "order-disorder" type. • The libration motions of cations characterized by a low activation energy are postulated below 125 K. In the high temperature region, the pseudo C′6-type reorientation of the whole cations takes place. [ABSTRACT FROM AUTHOR]

Abstract Bi 1-x Nd x Mn2O5 with (x = 0, 0.1 and 0.2) samples prepared by sol gel method, have been investigated for its structural and dielectrics properties. Crystallographic studies using X-ray diffraction and Rietveld Refinement techniques showed the formation of single-phase samples for all compositions, crystallizing in a mullite-type orthorhombic perovskite structure, space group Pbam (Z = 4). The SEM techniques confirmed the formation of single-phase materials with excellent mapping distribution. Scanning electron microscopy (SEM) revealed that the grains are irregularly spherical-like shaped confirmed the formation of single-phase materials with excellent mapping distribution, with mean sizes of 107 , 103 and 92 for (x = 0, 0.1 and 0.2) respectively. The Dc conductivity expresses a semi-conductor dependence on temperature for the three samples all over the explored range of temperature. In addition to that, the substitution of Bi by Nd enhances the conductivity. The evolution of Dc conductivity versus temperature obeys to Mott and Davis law, which proves that the thermally activated small polaron hopping is the appropriate model of conduction at high temperature. Then it switches to variable range hopping at low temperature for BiMn 2 O 5 and Bi 0.9 Nd 0.1 Mn 2 O 5. The Ac conductivity is governed by the Jonsher law and its analysis shows that the correlated barrier hopping is the appropriate model of conduction for the two doped samples (Bi 0.9 Nd 0.1 Mn 2 O 5 and Bi 0.8 Nd 0.2 Mn 2 O 5) while the overlapping large polaron tunneling is the suitable model for the undoped one. The impedance analysis is in good coherence with the conductivity analysis and emphasizes the undoubtedly contribution of grain boundaries in the transfer properties. Dielectric analysis allows to notice the heavy increase of ε ' with the increase of the mount of Nd. Besides, the evolution of ε ' with temperature suggest a relaxor behavior and is distinguished by the occurrence of peaks attributed to the existence of polar nanoregions. Graphical abstract Image 1 Highlights • The series of multiferroic materials BiMn2O5 doped by Neodyme has been prepared by a sol-gel method at low temperature. • All compositions, crystallizing in a orthorhombic perovskite structure, space group Pbam. • The evolution of Dc conductivity vs temperature that proves that the thermally activated small polaron hopping is the appropriate model of conduction at high temperature. • The evolution of Dc conductivity that proves that the SPH is the appropriate model of conduction at high temperature. • The impedance analysis emphasizes the undoubtedly contribution of grain boundaries in the transfer properties. [ABSTRACT FROM AUTHOR]

Abstract 3D structured flower-like bismuth tungstate/magnetic-graphene nanoplates (Bi 2 WO 6 /mag-GNPs) composite was first synthetised for degradation of ciprofloxacin (CIP). The morphological properties of Bi 2 WO 6 /mag-GNPs were characterized by SEM, XRD and DRS. The results revealed the synthesized Bi 2 WO 6 /mag-GNPs had the enhanced photocatalytic activity because of the synergistic effects of Bi 2 WO 6 , graphene and Fe 3 O 4. The photocatalytic degradation rate of Bi 2 WO 6 /mag-GNPs toward CIP was almost 6.0 times of mag-GNPs, 2.0 times and 1.7 times of Bi 2 WO 6 and Bi 2 WO 6 /GNPs, respectively. Moreover, the Bi 2 WO 6 /mag-GNPs particles could be easily separated and recycled. The construction of Bi 2 WO 6 /mag-GNPs effectively resolved the separation of photocatalyst and improved the photocatalysis activity of Bi 2 WO 6. Graphical abstract Unlabelled Image Highlights • A novel visible-light 3D structured flower-like Bi 2 WO 6 /mag-GNPs was synthesized. • The synergistic effect of Bi 2 WO 6 and mag-GNPs enhanced the photocatalyst activity. • Bi 2 WO 6 /mag-GNPs can use sunlight to effectively degrade ciprofloxacin. • Bi 2 WO 6 /mag-GNPs showed good reusability and stability. [ABSTRACT FROM AUTHOR]

Abstract Compositional and temperature evolution of crystal structure and magnetic properties of the BiFeO 3 -based compounds co-doped with Ca and transition metal ions - Mn, Ti or Nb was studied with X-ray diffraction and vibrating sample magnetometer techniques. It has been shown that the chemical substitution allows to vary structural parameters, thus modifying magnetic state of the parent cycloidal antiferromagnet. Regardless the type of transition elements, the changes in chemical composition result in a lattice compression, reduce rhombohedral distortions and stabilize a non-polar orthorhombic structure specific to the paraelectric state of BiFeO 3. In all the systems, the co-doping gives rise to the disruption of the spatially modulated antiferromagnetic structure, thus providing the formation of a non-collinear antiferromagnetic order. In the Ca|Ti and Ca|Nb series, the chemical substitution leads to the stabilization of the weak ferromagnetic polar state with remnant magnetization up to 0.25 emu/g. Magnetic properties of the compounds co-doped with Ca and Mn ions are characterized by maximal remnant magnetization of about 0.07 emu/g. The factors driving the structural evolution and modification of magnetic behavior are discussed. Highlights • Crystal structure is studied as a function of the dopant ions and temperature. • Magnetic properties are analyzed depending on the dopant ions. • Remanent magnetization is discussed considering different type of exchange interactions, structural distortion and defects. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The F- Bi 2 MoO 6 can be easily synthetized by a hydrothermal method. • F- Bi 2 MoO 6 show much higher photocatalytic activity than pure Bi 2 MoO 6. • F doing can increase the band gap of Bi 2 MoO 6 and concentration of OH radicals. • The enhanced photocatalytic activity is due to higher charge separation efficiency. Abstract The fluorine substitution on Bi 2 MoO 6 (F-Bi 2 MoO 6) can be easily synthesized by a hydrothermal method. Based on the XRD result, it could be speculated that fluorine ion can substitute oxygen ion in the crystal lattice of Bi 2 MoO 6. The photodegradation activity of F-Bi 2 MoO 6 almost is 1.9 times as high as the single Bi 2 MoO 6 for degradation of RhB and 1.7 times for decomposition of 2, 4-CDP under the visible light. The enhanced catalytic activity of F-Bi 2 MoO 6 should be attributed to the wider band gap, the more positive VB potential and the higher concentration of OH radicals due to the F doping. Additionally, F doping formed the donor state below the Fermi energy, which can trap the electrons and increase the efficiency of charge separation remarkably. [ABSTRACT FROM AUTHOR]

La2NiBi was synthesized by heating a cold pressed pellet of the elements in a sealed and evacuated silica tube at 1070 K. The structure was determined via powder and single crystal X‐ray diffraction. La2NiBi crystallizes orthorhombically, in the space group Pnma: a = 838.88(6), b = 455.61(11), c = 1210.4(2) pm and V = 0.46261(14) nm3 (wR = 0.1002, 1001 F2 values, 26 variables, Z = 4). La2NiBi represents a higher congener of La2NiSb and adopts a ternary ordered version of the Bi3Ni structure type. Similar to La2NiSb, the nickel atoms form infinite zigzag chains (259 pm Ni–Ni) with trigonal‐prismatic lanthanum coordination. One rectangular face of the lanthanum prism is capped by a bismuth atom (333.08–364.74 pm La–Bi, 281.18 pm Ni–Bi). These zigzag chains run along the b axis. DFT based band structure calculations and DOS representations suggest metallic behavior. This was confirmed via temperature dependent impedance spectroscopic measurements. A Seebeck coefficient of –10 μV·K–1 in the temperature range up to 873 K substantiates this finding. Thermal analyses show that the compound is stable up to 873 K under inert gas conditions and degrades at higher temperatures. The magnetic measurements show almost no grain boundary nickel impurities characterizing La2NiBi as a weak Pauli paramagnet. [ABSTRACT FROM AUTHOR]

Abstract Polycrystalline sample of 0.3Bi 1-x Y x FeO 3 -0.7Ba 0.8 Sr 0.2 TiO 3 (0.05 < x < 0.15) are prepared via solid state route. The analysis of x-rays diffraction shows that the prepared ceramics crystallize in a tetragonal structure. Moreover, Raman measurement confirms the tetragonal structure of all samples. From the temperature dependence of dielectric constant, we deduced that the samples show a relaxor behavior. So as to look into the electrical properties a complex impedance spectroscopy is highlighted. The conductivity spectrum exhibits a semi conducting behavior. At low frequency the dominant conduction process is the small polarons jump mechanism while for high frequency the charges carriers moves according to the correlated barrier hopping model. Nyquist plots show that the most adequate equivalent circuit is composed by a grain resistance in series with a parallel combination between a grain boundary resistance and capacitance. Graphical abstract Image 1 Highlights • Yttrium doped 0.3Bi 1-x Y x FeO 3 -0.7Ba 0.8 Sr 0.2 TiO 3 were successfully prepared through solid state solution. • Structural and vibrational analysis confirms the tetragonal structure of the prepared samples. • The composite BYFO-BST shows a relaxor ferroelectric behavior. • The σ AC conductivity obeys the universal Jonscher law. • The Nyquist plot reveals the presence of bulk grain and grain boundary contribution in the impedance analysis. [ABSTRACT FROM AUTHOR]

Abstract The sintering mechanism of BiFeO 3 has been investigated in-situ by energy dispersive X-ray diffraction (ED-XRD) using a high-energy white collimated X-ray beam from the Advanced Photon Source (Argonne National Laboratories). Such radiation is very penetrating thereby allowing measurements of the sample even when placed inside the flash sintering set up. Additionally, the fast ED-XRD measurements permit monitoring the flash sintering process by providing information about phase composition and sample temperature in real time. Moreover, profile scans, obtained by moving the stage vertically while recording the ED-XRD spectra, permit investigating the homogeneity of the flash for the entire length of the sample. All experiments have been complemented by ex-situ studies. It has been concluded that flash sintering of BiFeO 3 is a homogeneous process without any directionality effects. Furthermore, flash sintering takes place at quite low temperatures (below the Tc ≈ 830 °C), which may be related to the high quality of the samples, as pure, highly insulating ceramics without evidence of secondary phases with a homogenous nanostructured grain size distribution are obtained by this technique. Moreover, it is also evidenced that the rapid heating of the sample does not seem to justify, at least by itself, the densification process. Therefore, it appears that the electric current should play a role in the enhanced mobility during the sintering process. [ABSTRACT FROM AUTHOR]

Graphical abstract (a) Electric field amplitude (E 0) dependence of P - E hysteresis loops measured at 0.1 Hz. The inset (b) shows hysteresis area < A > of the hysteresis loops with variation E 0. (c), (d) are the plots of ln P r , ln E c , ln< A > and dln< A >/dln E 0 versus ln E 0. Here, the polarization reversal and dynamic hysteresis were investigated in (Bi 1/2 Na 1/2)TiO 3 (BNT) ceramics. The scaling behaviors were presented by studying the dependence of hysteresis loops on the field amplitude E 0. New feature of polarization responses and scaling behaviors were obtained. The exponent α in an equation of the hysteresis loop area < A >∝ E 0 α displayed large values in high- E 0 stage. Highlights • The exponent α in the hysteresis loop area < A >∝ E 0 α equation shown large values in high- E 0 stage. • The < A > displayed abnormal increase with temperature. • A near frequency-invariant coercive field E C , accompanied by a weakly dependent P r and < A > was observed. Abstract The excellent electrical properties and potential applications of ferroelectric ceramics are intrinsically correlated with the dynamic polarization response under applied electric field. However, the lack of clarity with regard to global polarization reversal process has hindered the understanding of the functional properties. Here, the polarization reversal and dynamic hysteresis were investigated in (Bi 1/2 Na 1/2)TiO 3 (BNT) ceramics. The scaling behaviors were presented by studying the field amplitude E 0 , frequency f 0 and temperature T 0 dependence of hysteresis loops. Three new features of polarization responses and scaling behaviors were obtained. First, the exponent α in the hysteresis loop area < A >∝ E 0 α equation displayed large values in high- E 0 stage. Then, the < A > displayed an abnormal increase with increasing temperature. Finally, a near frequency-invariant coercive field E C , accompanied by a weak dependent P r and < A >, was observed. The correlation between these new features and polarization extension/rotation as well as complex domain structure and field-induced phase transition was demonstrated. [ABSTRACT FROM AUTHOR]

Presents information on a study which examined the phase decomposition in a high quality bismuth compound single crystal annealed in air, using x-ray diffraction and scanning electron microscopy. Methods; Results; Discussion.

Presents a study that examined the stability of bismuth-lead-strontium-carbon-copper-oxygen phase contained in silver-sheathed oxide-powder-in-tube specimens. Use of x-ray diffraction, transmission electron microscopy and energy dispersive x-ray analysis; Effect of silver cladding on lead stability and microstructure; Discussion on the transmission electron microscopy micrographs of a sample annealed in the single phase region.

Presents information on a study which investigated the effect of temperature and atmosphere on stability of the high-T phase in bismuth superconductors using alternating current susceptibility, x-ray diffraction and Raman measurements. Methods; Results; Discussion.

Focuses on the synthesis of single-phase material of the (bismuth-lead) strontium-calcium-copper-oxygen oxide ceramic superconductor. Use of powder x-ray diffraction patterns; Change of the crystal structure with progressing reaction; Calculation of lattice constants using a least square fit.

Three‐dimensional Bi2S3 with different morphology of flower‐like, waxberry like and hydrangea like on the tin‐doped indium oxide substrate has been produced from one‐step aqueous solution at low temperature (40–70°C) and fixed pH of 0.81 for 24 h. The UV–vis measurement showed that the absorption spectrums of obtained Bi2S3 crystals were occurred blue shift compared to the bulk orthorhombic Bi2S3(1.3 eV). With the increase in temperature, the crystallinity of Bi2S3 films was gradually improved. When the temperature went to 55°C, the best conductivity was obtained. [ABSTRACT FROM AUTHOR]

Abstract A study of structure and oxide-ion conductivity in the Bi 4 Nb 1 − x Y x O 8.5 − x solid solution using X-ray and neutron powder diffraction and a.c. impedance spectroscopy is presented. Slow cooled samples are typically biphasic, exhibiting a mixture of cubic/pseudo-cubic and orthorhombic or tetragonal fluorite based phases. Single phase cubic and pseudo-cubic materials can be isolated by quenching from high temperatures. The defect structure in these quenched phases has been determined by neutron diffraction and shows an oxide-ion distribution that is compositionally dependent. This distribution is correlated with the compositional variation of the low temperature activation energy for total conductivity, whereas the activation energy for high temperature conductivity decreases with increasing value of x , reflecting the reduction in dopant-vacancy interaction with increasing yttrium content, as well as a change from a tetragonally ordered type III phase for low x -value compositions to a fully disordered δ-Bi 2 O 3 type phase at x = 0.4. Ordering phenomena are proposed to account for the appearance of a linear intermediate temperature region with high activation energy in Arrhenius plots of conductivity at x ≥ 0.4. Conductivities in the order of 10−1 S cm−1 are achieved at 700 °C in these materials. Graphical abstract Unlabelled Image Highlights • A full solid solution range is obtained in the system Bi 4 Nb 1 − x Y x O 8.5 − x. • The oxide-ion distribution is compositionally dependent. • Bi 6 s 2 is stereochemically active with Bi coordination numbers between 4.35 and 4.85. • Conductivity increases with increasing vacancy concentration. • Conductivity in the order of 10−1 S cm−1 at 700 °C. [ABSTRACT FROM AUTHOR]