We present a comprehensive study, combining experimental and theoretical approaches, to assess the hydrogen evolution reaction (HER) efficiency of BiFeO3-based solid solutions. Initially, we investigate the electronic and optical properties of these compounds, with a particular focus on band edge alignment relative to water redox potentials. Our findings show that the materials exhibit optimal band gaps of approximately 2.0 eV, indicative of enhanced visible light absorption and favorable energetic alignment to drive efficient hydrogen generation. To corroborate our theoretical predictions, we perform photoelectrochemical measurements on selected BiFeO3 based compounds synthesized via the solid-state method. Our experimental results reveal a high hydrogen yield, with BiFeO3-SrTiO3 achieving a production rate of similar to 114 mu mol/L in 30 min, outperforming BiFeO3-BaTiO3 (similar to 70 mu mol/L) and pristine BiFeO3 (similar to 61 mu mol/L). These findings validate our theoretical assumptions and demonstrate the superior HER performance of BiFeO3-SrTiO3, positioning it as a highly promising candidate for sustainable hydrogen production.

In this study, we have performed investigations on the structural stability, elec-tronic band structures, magnetic exchange couplings, and half-metallic performance of CrxCa1-xSe materials using computational methods of density functional theory via GGA-WC, GGA-PBE and, TB-mBJ exchange-correlation potentials. The CrxCa1–xSe compounds are thermodynamically stable and synthesizable owing to their negative formation energies. The structural parameters of CrxCa1–xSe with GGA-WC and GGA-PBE approximations appear to be in excellent concordance compared to the experi-mental data and recent theoretical calculations. According to GGA-PBE and TB-mBJ calculations, the CrxCa1–xSe compounds revealed integral magnetic moments and a half-metallic behavior with better half-metallic gaps, and spin-polarization of 100%. The CrxCa1–xSe alloys appear to be better materials for use in spintronic devices.

Nanostructured BaTi1-xSnxO3 (x = 0, 0.05 & 0.075) were successfully synthesized using the modified Pechini processing method. The phase purity and symmetry were examined by X-ray diffraction and Raman spectroscopy. Tetragonal symmetry was obtained for BaTiO3 (BT) while orthorhombic symmetry for Sn doped BT. BT exhibits an up-shift of the Curie temperature towards high temperatures (TC = 139 ?C). In contrast, a down-shift was recorded for Sn doped BT. Then, indirect electrocaloric (EC) adiabatic temperature change delta T and the energy storage performances were determined based on ferroelectric hysteresis loops. Interestingly, large EC responsivity of delta T/delta E = 0.81 x 10(-6) K m/V was obtained for the BT accompanied with a moderate stored energy of 23 mJ/cm(3) but with a high energy efficiency of 67%. The incorporation of Sn in BT was found to broaden the EC responsivity and to improve the energy efficiency up to 90%, recorded for the 5% Sn doped BT.

The ab initio calculations based on the density functional theory (DFT) using the self-consistent Full potential linearized augmented plane wave (FPLAPW) method were performed to explore the electronic structures, thermodynamic and thermoelectric properties of new rattling Full Heusler alloys Ba2AgZ (Z = As, Sb, Bi). Results showed that the AlCu2Mn-type structure state is energetically the most stable structure. The results show that the electronic property of these cubic Rattling Heusler alloys have a semiconducting behavior with indirect band gaps Eg (L-D). The predicted band gaps were found to be 0.566, 0.548 and 0.433 eV for Z = As, Sb and Bi, respectively. The thermodynamic properties comprising the thermal expansion coefficient, heat capacity, entropy and Debye temperature parameter were evaluated at various pressures from 0 to 15 GPa. Thermoelectric properties of the Ba2AgZ (Z= As, Sb, Bi) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds exhibit ultralow thermal conductivity, good Seebeck coefficients and large high power factors, thus resulting they are suitable for use in thermoelectric device applications.

We use the first-principles-based density functional theory with full potential linearized augmented plane wave method in order to investigate the structural, elastic, electronic, magnetic and thermoelectric properties of RhCrZ (Z= Si, Ge, P, As) Half-Heusler compounds. The preferred configurations of the RhCrZ alloys are all type a. The structural parameters are in good agreement with the available theoretical results. The Young’s and shear modulus, Poisson’s ratio, sound velocities, Debye temperature and melting temperature have been calculated. Furthermore, the elastic constants Cij and the related elastic moduli confirm their stability in the cubic phase and demonstrate their ductile nature. The compounds RhCrSi, RhCrGe, RhCrP and RhCrAs are found to be half-metallic ferrimagnets (HMFs) with a half-metallic gap EHM of 0.37, 0.35, 0.25 and 0.02 eV, respectively. The half-metallicity of RhCrZ (Z= Si, Ge, P, As) compounds can be kept in a quite large hydrostatic strain and tetragonal distortion. The Curie temperatures of RhCrSi, RhCrGe, RhCrP and RhCrAs compounds are estimated to be 952, 1261, 82 and 297 K, respectively, in the mean field approximation (MFA). Thermoelectric properties of the RhCrZ (Z= Si, Ge, P, As) materials are additionally computed over an extensive variety of temperatures and it is discovered that RhCrAs demonstrates higher figure of merit than RhCrSi, RhCrGe and RhCrP. The properties of half-metallicity and higher Seebeck coefficient make this material a promising candidate for thermoelectric and spintronic device applications

The ab initio calculations based on the density functional theory (DFT) using the self-consistent full potential linearized augmented plane wave (FPLAPW) method were performed to explore the electronic structures, magnetic and thermoelectric properties of quaternary alloys RbCaCZ (Z = P, As, Sb) with quaternary Heusler structure. Results showed that FM-Y3 is the most favorable atomic arrangement. All the compounds are found to be half-metallic ferromagnetic materials with an integer magnetic moment of 2.00 μB, which predominantly derives from the strong spin polarization of p channels of C hybridized with Z elements. The predicted minority (half-metallic) band gaps were found to be 1.86 (0.87), 1.72 (0.78), and 1.78 (0.71) eV for Z = P, As, and Sb, respectively. Thermoelectric properties of the RbCaCZ (Z = P, As, Sb) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds demonstrates higher figure of merit. The half-metallic structures of these compounds with large band gaps and adequate Seebeck coefficients mean that they are suitable for use in spintronic and thermoelectric device applications.

Investigation of band structure and thermo-physical response of the d 0 new quaternary Heusler compounds KSrCZ (Z = P, As, Sb) within the frame work of density functional theory with full potential linearized augmented plane wave method has been analyzed. Results showed that type-Y3 is the most favorable atomic arrangement. All the compounds are found to be half-metallic ferromagnetic materials with an integer magnetic moment of 2.00 μ B and a half-metallic gap E HM of 0.292, 0.234, and 0.351 eV, respectively. The half-metallicity of KSrCZ (Z = P, As, Sb) compounds can be kept in a quite large hydrostatic strain. Thermoelectric properties of the KSrCZ (Z = P, As, Sb) materials are additionally computed over an extensive variety of temperature and it is discovered that all compounds demonstrates higher figure of merit. The properties of half-metallicity and higher Seebeck coefficient makes these materials a promising candidates for thermoelectric and spintronic device applications.

Abstract Lattice dynamic and mechanical properties of hypothetical RbC and SrC compounds were investigated using the ab-initio pseudopotential method and a linear response scheme. The lattice dynamics was studied in the framework of the density functional perturbation theory (DFPT). The dynamical and mechanical stability of the hypothetical RbC and SrC compounds was proved in their equilibrium B1 structure. In addition, the same stability was confirmed in the B3 phase. The thermodynamic properties were also investigated. They exhibited the same trend in both phases, and followed the Debye model. These results were confirmed in the ferromagnetic state, which makes the investigated compounds promising candidates in the spintronic field.

The electronic structure and magnetic properties of CoRuFeZ (Z = Si, Ge, and Sn) quaternary Heusler compounds were investigated using the full-potential linearized augmented plane wave (FPLAPW) method in framework of the density functional theory (DFT). The results showed that CoRuFeZ (Z = Si, Ge, and Sn) compounds were stable in Y-typel structure. By use the GGA-mBJ, the CoRuFeGe and CoRuFeSn compounds were true half-metallic (HM) ferromagnets. The CoRuFeSi had a nearly HM characteristic. The minority band gaps were 0.557 eV, 0.444 eV and 0.428 eV for CoRuFeSi, CoRuFeGe and CoRuFeSn, respectively. The total magnetic moments of CoRuFeGe and CoRuFeSn compounds were obtained 5 mu(B) per formula unit, which were in agreement with Slater-Pauling rule M-tot = (Z(tot) - 24). CoFeTiSi alloy can transform from a nearly half-metallic to a half-metallic alloy by employing a little expansion stress (+1.725% relatively to the equilibrium lattice constant a(0)). The half-metalliciy characteristic exists in relatively wide ranges of 5.9-6.9 angstrom, 5.825-6.063 angstrom and 5.921-7.187 angstrom for CoRuFeSi, CoRuFeGe and CoRuFeSn compounds, respectively, which makes them promising candidates in spintronics. (C) 2016 Elsevier B.V. All rights reserved.

The Rh-catalyzed hydroformylation of the CC double bonds of triglycerides (T) was performed in aqueous medium through the formation of supramolecular complexes resulting from the inclusion of the alkenyl chains of T into the cavity of modified cyclodextrins (CDs).

AbstractSingle phase Pd5As is prepared by heating stoichiometric amounts of the elements (evacuated silica tubes, 973 K, 4 d).

Using the full-potential linearized augmented plane-wave (FP-LAPW) calculations with generalized gradient approximation functional (GGA), we investigated the structural, electronic and magnetic properties of the family compounds AlP as ternary diluted semiconductors (DMS)s Al1−x(TM=Cr,V)xP with concentration of 0.25 and 0.125 in zinc blende phase (B3). The interaction of 3d orbital of transition metal with the 3p states of the four phosphorus atoms who occupy the summits of the tetrahedron resulting from SP3 hybridization, stabilize more the phenomena of magnetization by the effect of Zener's p–d exchange. The analyses of electronic and magnetic properties using the total and partial density of state and bands structure show that Al1−xCrxP and Al1−xVxP are spin-polarized with a half-metallic band gap. We seem that these materials will be among the good candidates for spintronic applications.

AbstractIn this work, first-principles calculations of the structural, electronic and magnetic properties of Heusler alloys CoMnYAl, CoMnYGa and CoMnYIn are presented. The full potential linearized augmented plane waves (FP-LAPW) method based on the density functional theory (DFT) has been applied. The structural results showed that CoMnYZ (Z = Al, Ga, In) compounds in the stable structure of type 1+FM were true half-metallic (HM) ferromagnets. The minority (half-metallic) band gaps were found to be 0.51 (0.158), 0.59 (0.294), and 0.54 (0.195) eV for Z = Al, Ga, and In, respectively. The characteristics of energy bands and origin of minority band gaps were also studied. In addition, the effect of volumetric and tetragonal strain on HM character was studied. We also investigated the structural, electronic and magnetic properties of the doped Heusler alloys CoMnYGa1−xAlx, CoMnYAl1−xInxand CoMnYGa1−xInx(x = 0, 0.25, 0.5, 0.75, 1). The composition dependence of the lattice parameters obeys Vegard’s law. All alloy compositions exhibit HM ferromagnetic behavior with a high Curie temperature (TC).

Using the full-potential linearized augmented plane-wave method of first-principles calculations of density functional theory, we have performed a systematic investigations on the structural, electronic, and magnetic properties related to the spintronic applications for gallium phosphide GaP doped with 3d transition metal (TM) atoms such as vanadium (V), chromium (Cr), and manganese (Mn) as ternary GaGa−x TM x P diluted magnetic semiconductors (DMSs) in zinc-blende phase at concentrations x = 0.0625, 0.125, and 0.25. The analysis of electronic and magnetic properties with various concentrations (x) of TM revealed that GaGa−x V x P at (x = 0.0625, 0.125, and 0.25) and Ga−x TM x P (TM = Cr and Mn) at (x = 0.0625 and 0.125) are half-metallic ferromagnets (HMF) with spin polarization of 100 %. The HMF character destroyed for GaGa−x Cr x P and GaGa−x Mn x P at higher concentration x = 0.25 of Cr and Mn. The half-metallic gap increases with decreasing in concentration of impurity, and therefore, the GaGa−x TM x P, GaGa−x Cr x P, and GaGa−x Mn x P DMSs at low concentrations appear to be better candidates for spintronic applications.

The structural, electronic, and half-metallic ferromagnetic properties of ordered zinc blende Al 1−x Mn x P diluted magnetic semiconductors with concentrations (x = 0.0625, 0.125, and 0.25) are studied using first-principle calculations of density functional theory in order to seek out the possibility to use these materials for the spin injection in the field of spintronic applications. The electronic structures of Al 1−x Mn x P at all concentrations exhibit a half-metallic ferromagnetic behavior with 100 % magnetic spin polarization and half-metallic gap. While, the analysis of partial densities of states reveals that strong hybridization between 3p (P) and 3d (Mn) partially filled states dominates the gap, which stabilizes the ferromagnetic state configuration associated with double-exchange mechanism. Also, the magnetic proprieties prove an integer total magnetization of 4 u B that confirms the half-metallic ferromagnetic feature of Al 1−x Mn x P compounds.

The structural, electronic and magnetic properties of beryllium chalcogenides such as BeS, BeSe and BeTe doped with magnetic vanadium (V) impurity as ternary Bei(1-x)V(x)Z (Z = S, Se and Te) compounds in zinc blende phase have been performed at concentration x = 0.25, by employing first-principles calculations of full-potential linearized augmented plane-wave method within the framework of density functional theory. The electronic structures of Be(0.75)V(0.25)Z (Z = S, Se and Te) compounds revealed a half-metallic ferromagnetic character with 100% spin polarized that emerges this behavior results from the band gap of minority spin and metallic nature of majority spin due to a strong hybridization between 3d (V) and p (S, Se and Te) states dominating at Fermi level. According to the results of magnetic properties calculations, the total magnetic moments of Be(0.75)V(0.25)Z (Z = S, Se and Te) are integers Bohr magneton of 3 mu B that confirms the half-metallic behavior of these compounds. Therefore, the Be(0.75)V(0.25)Z (Z = S, Se and Te) compounds seem to be potential candidates to explore half-metallic ferromagnetism property for near future applications in spintronics. (C) 2015 Elsevier Ltd. All rights reserved.

Ferroelectric domain properties of a (BiFeO3)2(SrTiO3)4 superlattice were studied by means of piezoresponse force microscopy and density functional theory calculations. A combination of out-of-plane and in-plane piezoresponse force imaging confirms that the ferroelectric domains are oriented along the out-of-plane [001] direction of the film. Density functional theory calculations evidence that this orientation is due to the tetragonal-like structure adopted by the BiFeO3 units inside the superlattice in response to the interfacial strains. In addition, antiferrodistortive rotations of the BO2 planes within both types of ABO3 blocks (i.e., SrTiO3 as well as BiFeO3 units) are highlighted. Besides, a much lower coercive voltage is measured on superlattices compared to BiFeO3 single layers, suggesting a more reliable switching capability. The results are expected to enable the design of promising multifunctional oxide superlattices.

The crystal structure of Pd5As was refined simultaneously from laboratory X-ray, synchrotron and neutron powder diffraction data (space group C2/m, a = 551.82(2) pm, b = 774.50(3) pm, c = 842.13(4), beta = 99.037(2)degrees, Z = 4). This is in contrast to earlier work, which describes the structure in the non-centrosymmetric space group C2. Eight palladium atoms form a bicapped trigonal prism around arsenic. Two such polyhedra are connected by a common edge to double prisms (average distance As-Pd 252 pm). Palladium has got coordination numbers of 11 (average distance 276 pm) or 12 (average distance of 278 pm). The crystal structure of Pd5As represents a strongly distorted cubic closest packing as proven by crystallographic group-subgroup relationships. Pd5As does not take up hydrogen up to 5.0 MPa hydrogen pressure and temperatures up to 723 K. Quantum-mechanical calculations using DFT methods using an ab initio evolutionary algorithm confirm the crystal structure of Pd5As and reveal the stability of a hypothetical hydride Pd5AsH. The lack of reactivity might be due to kinetic hindrance because of an endothermic rearrangement of the metal matrix necessary for hydrogen incorporation. Above 5.8 GPa, however, this phase transition becomes thermodynamically favourable, making hydrogenation of Pd5As likely to occur. (c) 2015 Elsevier B.V. All rights reserved.

First principles density functional calculations, using a full potential linearized augmented plane wave (FP-LAPW) method in local spin density approximation(LSDA), have been performed in order to investigate the structural, electronic and magnetic properties of In1−xTMxN(TM=Cr,Fe,Mn,V) in zinc-blende phase. Dependence of structural parameter values on the composition x have been analyzed in the x=0.25, x=0.50, and x=0.75, we found the existence of deviation from Vegard׳s law. Calculated electronic structure and the density of states of these alloys are discussed in terms of the contribution of TM 3d, N 2p, and In 3d states. The magnetic moment of In1−xTMxN has been studied by increasing the concentration of TM atom. The contribution of TM atom is the most important source of the total magnetic moment in these alloys, while it is minor in In and N.