Ba Substitution Research Articles

Enhanced Performance and Durability of Ruddlesden-Popper Oxide Anodes Decorated with Fe Nanoparticles for Direct Ammonia-Fed Solid Oxide Fuel Cells

Direct ammonia-fed solid oxide fuel cells (DA-SOFCs) efficiently convert ammonia into electricity, aligning with the necessary temperatures for thermal decomposition of ammonia. However, challenges such as nitridation of anode metal catalysts and decreased cell durability hinder further development. To address these issues, this study explores the partial substitution of Sr with Ba at the A-site of the Ruddlesden-Popper (RP) structure, enhancing the structure's mixed ionic and electronic conductivity (MIEC). This modification aims to improve ammonia's thermal decomposition and the overall electrochemical performance of SOFCs. Incorporating Ba modifies the RP crystal lattice to facilitate metal nanoparticle exsolution and increase basicity, crucial for enhancing nitrogen recombination and desorption during ammonia decomposition. This adaptation helps maintain active catalyst sites and improves durability against nitridation. The study focuses on in-situ exsolution of Fe nanoparticles (NPs) and partial Ba substitution, both of which enhance not only catalytic and electrochemical performance but also durability under operating conditions.Advanced characterization methods, including X-ray diffraction complemented by Rietveld refinement and high-resolution electron microscopy, elucidate the lattice changes and phase transitions induced by Ba. These modifications promote the exsolution of Fe NPs, pivotal for enhancing electrochemical performance. Electrochemical assessments show that the new Fe NPs exsolved La1.2Sr0.4Ba0.4Mn0.4Fe0.6O4- δ (R-LSBMF) anode material achieves nearly 100% ammonia decomposition conversion at 650oC and sustains this activity over time, demonstrating its durability. The in-situ reduced LSBMF mixed with GDC (Ce0.9Gd0.1O2) as a DA-SOFC anode shows a maximum power density (MPD) of 1.019 W cm-2 and significantly low ohmic resistance (0.154 Ω cm²) at 800 oC.This research advances the understanding of elemental substitution in anode materials and underscores the potential of Ruddlesden-Popper phase perovskites for high-efficiency, durable DA-SOFCs. It also enhances the prospects for ammonia as a viable fuel for SOFCs, driving the technology toward sustainable, eco-friendly energy solutions. Therefore, the outstanding catalytic and durability features of the R-LSBMF anode material open paths for commercializing DA-SOFCs, which is essential for addressing environmental challenges. Figure 1

High temperature thermoelectric properties of BaxSr2−xFeCoO6 double perovskites

Abstract In this study, environmentally benign BaxSr2-xFeCoO6 (BSFC) double perovskites are synthesized via solid-state reaction route for high-temperature thermoelectric applications. The crystal structure and morphology of the ceramic samples are analyzed using XRD and SEM, respectively. Rietveld refinement of XRD data confirms a cubic structure with Pm3̅m space-group. High-temperature thermoelectric measurements exhibits that substituting Ba for Sr in Sr2FeCoO6 increases the Seebeck coefficient (S) but at the expense of the electrical conductivity (σ). The highest Seebeck coefficient of 117 μV/K has been observed in Ba0.5Sr1.5FeCoO6 at 910 K. Temperature-dependent electrical conductivity measurements indicates a semiconductor-to-metal like transition in all samples, with BSFC (x = 0.1) achieving the highest conductivity of 4 × 104 S m−1 at ∼623 K. The thermoelectric power factor has been enhanced by over 50% with Ba substitution in Sr2FeCoO6. Electron transport in these double perovskites is found to follow the small polaron hopping conduction mechanism.

Effect of different amounts of barium substitution for calcium on the hydraulic activity of the high belite binary C2S-C4A3$ system

The substitution of Ba2+ for Ca2+ in both dicalcium silicate (C2S) and ye'elimite (C4A3$) has the potential to stimulate the development of early hydration activity of high belite sulfoaluminate cement (HBSAC). To relieve the emission pressure of CO2 in the cement industry and promote the early compressive strength development of HBSAC, the C2S-C4A3$ binary system with different amounts of Ba2+ substitution for Ca2+ was synthesized and investigated in this study. The SEM-EDS and XRD test methods confirmed the stoichiometric composition of Ba-bearing C2S-C4A3$ binary systems. The results showed that Ba2+ tends to preferentially replace Ca2+ in C4A3$ compared to replacing Ca2+ in C2S, resulting in more substitution amount of Ba2+ in C4A3$ mineral, as the designed substitution amount of barium increased from 25 wt.% to 55 wt.%, the stoichiometric formula of Ba-bearing C2S was transformed from Ca1.66Ba0.34SiO4 to Ca1.45Ba0.55SiO4, and the stoichiometric formula of Ba-bearing C4A3$ was transformed from Ca2.29Ba1.71Al6SO16 to Ca0.86Ba3.14Al6SO16. While excessive amount of barium (more than 45 wt.%) resulted in the increased content of by-products, such as BaSO4 and BaAl2O4, as well as the formation of C3S. The hydration properties of each group of synthetic clinker were investigated, including compressive strength, qualitative and quantitative analyses of the hydration products, leaching solution environment, and micromorphological analysis. The hydration products including C-(A)-S-H and AH3, as well as hydroxide (Ca(OH)2 and Ba(OH)2·8H2O), which can be carbonated to form carbonates (BaCO3 and CaCO3) by CO2 in the air. As the substitution amount of Ba2+ increased from 25 wt. % to 35 wt. %, the hydration degree of Ba-bearing α′L-C2S was promoted in the early stage, and the presence of C3S may affected the increase of early hydration activity of Ba-bearing α′L-C2S, however, the hydration degree of α′L-C2S with the most amount doping of barium in A055 samples exhibited the highest hydration degree of 88.0 % after hydration for 90 days. The compressive strength of high belite C2S-C4A3$ binary system of 3-day displayed a rapid increase from 8.6 MPa to 16.1 MPa, with the amount of barium increased from 25 wt. % to 55 wt. %. The compressive strength of A025 and A035 after hydration for 90 days increased steadily, reaching 35.0 MPa and 34.0 MPa respectively. However, the compressive strength of hydrated A045 and A055 samples for 90 days deteriorated and even cracked seriously for the hydrated A055 sample, which was attributed to the formation of a large amount of Ba(OH)2·8H2O and BaCO3 by excessive barium amount, and leading to the expansion and broken of the matrix. Thus, the designed amount of barium substitution for calcium in the C2S-C4A3$ binary system should be controlled, for a higher content of barium more than 35 wt. % could be damage to the development of the long-term hydration strength of the clinker. These results provided a theoretical basis to make it possible for the large-scale application of activated HBSAC, devoted to the sustainable development of infrastructure.

Ti- and Ba-rich phlogopitic micas in alkaline basic and upper mantle igneous rocks; stoichiometry, stability, and Fe valence estimation reassessed and rationalised

Ti- and Ba-rich tri-octahedral micas occur in fractionated basic igneous rocks, metasomatized mantle peridotites, metamorphosed pelites/carbonates, and hydrothermally altered mineral deposits. Electron microprobe analyses (EMP), with all iron reported as FeO, were widely used in the 1970/80s to interpret Ti and Ba substitution mechanisms, based on 22 O2– unit cell calculations, implying that cation vacancies occur in octahedral and/or intersheet sites. In 1996 EMP with chemical and physical analyses for ferric and total Fe, H2O, (OH), and element-specific Fe X-ray Absorption Spectroscopy (both K and L-edges) established valence states for Fe and Ti and cation site occupancies, that ∼50 % O replaces (OH) molecules, and that 24 anion cell formulae show the absence of cation vacancies. Cell formula calculation protocol for phlogopitic micas is refined here and results tested against the stoichiometric formula for vacancy-free phlogopite, XIIK2VIMg6IV[Si6Al2]O20(OH)4. Hypothetical sheet silicate compositions, calculated with fixed contents of vacancies linked to particular mixed-valence element substitutions, confirm that reliable unit cell formulae for natural mica solids require that each stoichiometric vacancy must be accounted for. If reliable estimates for ‘excess O’ (denoted WO2−) are assigned to EMP analyses, the proportion of the oxy-mica component in a mica solid solution can be defined. This approach is tested using published analyses for Ti- and Ba-rich biotites from fractionated basic and ultramafic volcanic igneous rocks (oxymica range 2.5–45 %; TiO2 up to 14 %; BaO up to 23 %), upper mantle peridotites (equivalent values 7–18 %; 6 %; 0.7 %), and metasomatised upper mantle (2–37 %; 9 %; 23 %). Enrichments of Ti and Ba in micas are clearly linked to the extra oxygen charge required to neutralise the more highly charged Ba2+ and Ti4+ replacing K+ and Mg2+.Substitution mechanisms involving Ba, Ti, and Fe3+ in ideal phlogopite involve coupled inter-site/inter-valence interactions so both site-ordering and valence-balance between the different cation sites must be accounted for. The cation exchange 2XIIK+ + 4VI(Mg2+ + Fe2+) + 4IVSi4+ ↔ XIIBa2+ + 3VITi4+ + 4(Altotal + Fe3+ + Crtotal)3+ is used here so that valence and site order can be considered together. Compositional variations show well-defined trends towards high-oxymica content and vacancy-free Ti and Ba mica end-members, rather than to oxy-free end-members with essential vacancies. Average compositions for different source rock micas are used to assess compositional trends; molecular WO2− values are refined by relating initial estimates directly to the wt.% TiO2 contents; and refined WO2− and stoichiometrically calculated Fe3+/Fetotal ratios ranging ∼0.1–0.5) are correlated with possible primary magmatic values.

Effect of Ba substitution on dielectric and magnetic properties in La2MnNiO6 double perovskite

This paper reports the synthesis of single-phase La2-xBaxMnNiO6 (x = 0.0 and 0.5) double-perovskite using sol-gel auto-combustion route. ADXRD studies confirm the pure phase formation of the compound with the space group R3‾c and that no other structural transformation was observed even after Ba substitution. FESEM analysis show the formation of uniformly distributed ball-shaped nanoparticles and EDX spectra endorses the stoichiometric composition of the as prepared samples. The existence of mixed oxidation states of Ni and Mn ions is validated by XPS. The dielectric properties studied in the temperature range 100 K–320 K show the enhancement in the dielectric constant and the relaxor nature of the compound upon Ba substitution. The fitting of power law and Arrott's plot validates the presence of short-range ordering i.e. Griffith-like phase. The dielectric and magnetic properties are strongly linked and correlated based on enhanced antisite disorder (∼10 %). The ESR spectroscopy was used to calculate spin relaxation time and verify the existence of double exchange interaction in the compound.

Synthesis and properties of Sr2La2NiW2O12, a new S= 1 triangular lattice magnet.

Magnetic materials featuring triangular arrangements of spins are frequently investigated as platforms hosting magnetic frustration. Hexagonal perovskites with ordered vacancies serve as excellent candidates for two-dimensional triangular magnetism due to the considerable separation of the magnetic planes. In this work, the effects of chemical pressure on the ferromagnetic ground state of Ba2La2NiW2O12 by substitution of Ba2+ with Sr2+ to produce Sr2La2NiW2O12 are investigated. The two materials are characterized using synchrotron-based XRD, XANES and EXAFS in addition to magnetometry in order to correlate their crystal structures and magnetic properties. Both materials form in space group R3, yet as a result of the enhanced bending of key bond angles due to the effects of chemical pressure, the TC value of the magnetic Ni2+ sublattice is reduced from ∼6 K in Ba2La2NiW2O12 to 4 K in Sr2La2NiW2O12.

Effect of Ca, Ba, Be, Mg, and Sr Substitution on Electronic and Optical Properties of XNb2Bi2O9 for Energy Conversion Application Using Generalized Gradient Approximation–Perdew–Burke–Ernzerhof

Bismuth layered structure ferroelectrics (BLSFs), also known as Aurivillius phase materials, are ideal for energy-efficient applications, particularly for solar cells. This work reports the first comprehensive detailed theoretical study on the fascinating structural, electronic, and optical properties of XNb2Bi2O9 (X = Ca, Ba, Be, Mg, Sr). The Perdew–Burke–Ernzerhof approach and generalized gradient approximation (GGA) are implemented to thoroughly investigate the structural, bandgap, optical, and electronic properties of the compounds. The optical conductivity, band topologies, dielectric function, bandgap values, absorption coefficient, reflectivity, extinction coefficient, refractive index, and partial and total densities of states are thoroughly investigated from a photovoltaics standpoint. The material exhibits distinct behaviors, including significant optical anisotropy and an elevated absorption coefficient > 105 cm−1 in the region of visible; ultraviolet energy is observed, the elevated transparency lies in the visible and infrared regions for the imaginary portion of the dielectric function, and peaks in the optical spectra caused by inter-band transitions are detected. According to the data reported, it becomes obvious that XNb2Bi2O9 (X = Ca, Ba, Be, Mg, and Sr) is a suitable candidate for implementation in solar energy conversion applications.

Study on the possibility of band gap widening of thermoelectric semiconductor α-SrSi2 by isoelectronic elements incorporation

The material α-SrSi2 has considerable application potential as a near room temperature thermoelectric material. However, it has a very narrow band gap which can vanish due to impurities, defects, and grain boundaries. To obtain guidelines for controlling the band gap and improving the thermoelectric properties, we have studied the substitution of isoelectronic impurities (Mg, Ca, and Ba for Sr, and C, Ge, and Sn for Si) through first-principles calculations using the Gaussian-Perdew-Burke-Ernzerhof hybrid functional. From these calculations, it was found that:(1) The band gap change due to Ca, Ba, Ge, and Sn substitutions is almost the same as that predicted from the change in the lattice constant of pure α-SrSi2.(2) Substitution with C was energetically unfavorable and therefore high levels of substitution would be difficult to achieve. However, it was expected to increase the band gap, contrary to the prediction from the decrease in the lattice constant.(3) An increase in the Mg substitution of the Sr site from 0 at. % to 8 at. % caused a decrease in the lattice constant from 0 % to −1.189 %

Improved sintering behavior and microwave dielectric properties on BaZnP2O7-based ceramics

The effects of Ca2+ substitution for Ba2+ in BaZnP2O7 ceramics on the phase composition, sintering behavior, and microwave dielectric mechanism were systematically investigated. When x ≤ 0.02, the ceramics crystallized into a single-phase solid solution of BaZnP2O7, whereas samples with x ≥ 0.04 showed mixed phases of BaZnP2O7 and CaZnP2O7. The sintering behavior was ameliorated by Ca2+ substitution, and the sintering temperature of Ba1-xCaxZnP2O7 (0 ≤ x ≤ 0.1) was reduced from 920 to 840 °C effectively. The Raman spectra and P–V-L theory confirmed that the compressed P–O bond caused by Ca2+ substitution is beneficial to reducing the lattice anharmonic vibration and enhancing the lattice energy (U), which is conducive to the improvement of the Q × f value of the Ba1-xCaxZnP2O7 ceramic when x = 0.02. Excellent microwave dielectric properties were obtained for the Ba0.98Ca0.02ZnP2O7 ceramic after sintered at 880 °C for 4 h, i.e., εr = 8.29, Q × f = 84,116 GHz, τf = −23.84 ppm/°C.

Rietveld Refinement, Structural Morphology and Magnetic Properties of La0.57Sm0.1Sr0.33−xBaxMnO3 Manganite Nanoparticles

Lanthanide-based manganite perovskites due to their possible integration both in conventional Si-based electronics, and in innovative full-oxide electronics, have led to a massive resurgence of interest. The properties and applicability of these perovskites can be tailored with the interplay of foreign ion substation, and thus lot of efforts have been made by the researchers by using various types of compound combinations. In this work, a systematic study of Ba-substituted lanthanide of a chemical formula La[Formula: see text]Sm[Formula: see text]Sr[Formula: see text]Ba[Formula: see text]MnO3 (where, [Formula: see text], 0.05, 0.1, 0.20 and 0.33) was done and the manganites were synthesized by sol–gel auto-combustion method. The structural and magnetic properties were investigated by thermogravimetric/differential thermal analysis, which was also carried out to investigate the thermal stability of the prepared samples. X-ray diffraction (XRD) patterns, transmission electron microscopy (TEM), scanning electron microscopy (SEM) etc. were employed to investigate the crystallographic structure. XRD patterns and selected area electron diffraction patterns revealed the formation of single-phase La[Formula: see text]Sm[Formula: see text]Sr[Formula: see text]Ba[Formula: see text]MnO3 perovskite materials without any signature of secondary phases. Elemental composition of the synthesized samples was investigated by the energy dispersive analysis of X-ray analysis, which confirmed the expected stoichiometry of the prepared samples. TEM and SEM observations revealed the nano-crystalline nature of the prepared samples, where particle size obtained from TEM ranges from 40[Formula: see text]nm to 70[Formula: see text]nm. It has been found that structural and magnetic properties of the parent La[Formula: see text]Sm[Formula: see text]Sr[Formula: see text]MnO3 system were greatly affected by the Ba substitution.

Synergetic effect of CO2 curing and bottom ash with low Ca on the enhancement of carbonation behavior and mechanical performance

This study investigated ordinary Portland cement substituted with ground bottom ash (BAOPC) under various conditions of BA contents and CO2 curing. In samples without CO2 curing, the strength development along with degree of hydration were limited as expected. A higher BA content led to decreased compressive strength, indicating an inferior pozzolanic reaction of BA. Meanwhile, in the CO2-cured samples, a positive correlation between calcium carbonate (CC) content and compressive strength was confirmed, suggesting that CC is a key factor influencing strength development as a result of external CO2 supply. In particular, a higher amount of CC was present in the BAOPC composite with 20% BA substitution compared to the sample with 100% OPC, and substantial mechanical bonding between CC crystals was also confirmed. This study revealed that the combination of BA with limited Ca content and CO2 curing holds promise for developing eco-friendly formulations with enhanced mechanical properties and CO2 utilization.

Catalytic Transformation of Nitroarenes to Amines over Ba(1-x)SrxTiO3 (0 < x < 1) Perovskites in Water.

This work is focused on the application of lanthanide-free perovskite Ba1-xSrxTiO3 (0 < x < 1) in valorization of toxic pollutants as 4-nitrophenol (4-NPh). The series of perovskites were fabricated by facile, one-step solid-state preparation method and characterized via various techniques: elemental analysis (Inductively Coupled Plasma Optical Emission Spectrometry, ICP-OES), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and dielectric properties (impedance spectroscopy, IS). The methods confirmed the assumed composition, structure and high purity of the materials. The results showed that substitution of Ba2+ by Sr2+ in the perovskite crystal lattice influenced the dielectric properties of samples and the size of the grains. The absorption and catalytic properties of Ba(1-x)SrxTiO3 (0 < x < 1) series were evaluated in reduction of 4-NPh in water using NaBH4 as reducing agent. No adsorption of 4-NPh was found for all the materials during 180 min of contact (experiment without reducing agent), and the best catalytic performance was found for the Ba(1-x)SrxTiO3 (x = 0.3) sample. The catalytic transformation of 4-NPh to 4-APh follows a pseudo-first-order model, and the catalysts can be easily regenerated via mild annealing (300 °C).

Effect of Ba and Mg Substitution on the Phase Formations of Combustion Synthesized BSCCO Superconductor

Effect of Ba and Mg Substitution on the Phase Formations of Combustion Synthesized BSCCO Superconductor

Effect of Ba substitution on structure, magnetic properties and microwave properties of NdFeO3

In this paper, Nd1-xBaxFeO3 (x = 0, 0.05, 0.10, 0.15) have been synthesized utilizing the sol-gel technique. No impurity phase was generated by XRD analysis, and all of them were solid-dissolved in the perovskite structure. Given the disparity in atomic radii between Ba2+ and Nd3+, the crystal lattice undergoes lattice distortion. The entry of Ba2+ makes NdFeO3 change from ferromagnetic to antiferromagnetic, leading to reductions in both saturation magnetization and coercivity. However, the doping of Ba2+ improves the electromagnetic properties of NdFeO3, which makes the microwave absorption properties move to low frequencies. Notably, Nd0.90Ba0.10FeO3 has better absorbing performance, the maximum reflection loss and bandwidth of it reached − 17.2 dB and 3.38 GHz, respectively. Different thicknesses can also be selected for deployment across various frequency ranges, expanding its range of potential applications.

Room temperature properties of microstructure and resistivity of alkaline earth – doped on lanthanide manganite

Microstructure of material has a strong relation with resistivity property. Here we report our interesting sample of La0.7(Sr1-xBax)0.3MnO3 (x = 0, 0.3, 0.6, and 0.9) material that has been synthesized by using sol-gel method successfully. All pattern of X-ray diffractometer (XRD) on the successful samples show that all samples are single phase confirmed without significant crystal disorder. The XRD pattern refinement yield that all samples formed R-3c space group with a rhombohedral structure. Although the substitution of Ba2+ to Sr2+ ions have significant difference in atomic radius; it does not change the crystal structure. However, the alkaline earth – doped on lanthanide manganite causes a change in lattice parameters which is followed by shifted of average crystal size, bond length, cell unit volume and bond angle at Mn-O-Mn. The microstructure results by means of scanning electron microscope (SEM) characterization shows that substitution of Ba2+ ions decrease the grain size and yield agglomeration. The relation on the microscopic result resistively confirmed by cryogenic magnetometer characterization in the concentration x = 0 has minimum resistivity of 1.28.10-3 Ωm and the maximum resistivity in the concentration x = 0.9 is 1.85.10-1 Ωm. The Ba2+ doped into Sr2+ in lanthanum manganite may cause a wider resistivity range.

Revealing performance limiting factors in Cu2BaSnS4 thin film solar cells

Cation disorder in Cu2ZnSnS4 (CZTS) thin films has been a critical issue in realizing high efficiency solar cells. Recently, Ba substitution in CZTS that yields Cu2BaSnS4 (CBTS) has been suggested to improve the cation ordering and hence, the device performance. Although CBTS solar cells have shown very promising results in a short span of time, their performance is still inferior to that of the CZTS devices. In this work, the performance limiting factors in the CBTS solar cells have been systematically investigated and a pathway to improve it beyond the reported maximum efficiency has been suggested. In particular, the decisive role of defect densities at back and top interfaces (i.e., MoS2/CBTS and CBTS/CdS) and in the bulk CBTS, coefficients of various recombinations, and thickness of layers has been established. The effect of bulk defect density was found to be more profound compared to that due to the defects at the interfaces. Considerable improvement in efficiency was achieved by optimizing coefficients of Auger and radiative recombinations, carrier density of CBTS and CdS layers and facilitating current transport by tailoring the band alignment at the CBTS/CdS junction. The proposed recipe yielded the highest efficiency of ∼11%, which is significantly higher than that of the current experimental champion cell (∼6.2%).

Magnetic and Terahertz–Infrared Properties of Nanodispersed Hexaferrite SrxBa(1−x)Fe12O19 Solid Solutions

Hexagonal ferrites with the formula SrxBa(1−x)Fe12O19 (x = 0; 0.3; 0.5; 0.7; and 1) were prepared using the citrate method. The main feature of this synthesis is a relatively low calcination temperature of 700 °C. An X-ray diffraction study revealed a single-phase material. According to SEM, the particles were 50−70 nm in diameter. The Curie temperature of the samples that were determined using the DSC method varied in a very narrow range of 455−459 °C. Analysis of the magnetic hysteresis loops obtained at 300 K and 50 K indicated all samples as magnetically hard materials in a single-domain state. The maximal magnetic characteristics encompass strontium hexaferrite. The terahertz spectra of complex dielectric permittivity and the spectra of infrared reflectivity were measured at room temperature in the range of 6–7000 cm−1. The obtained broad-band spectra of the real and imaginary parts of permittivity reveal significant changes associated with structural distortions of the (Sr,Ba)O12 anti-cuboctahedron caused by the substitution of Ba2+ with Sr2+ in the same crystallographic positions.

Improved room-temperature magnetoelectric coupling properties for multiferroic Z-type hexaferrites

Here we present the results of a systematic investigation of the effect of Ba substitution on the spiral magnetic structure and magnetoelectric effect in polycrystalline BaxSr3−xCo2Fe24O41 (x = 0.0, 0.1, 0.3, 0.5, and 0.7). The magnetoelectric coupling coefficient was improved from 455 ps/m (x = 0.0) to 624 ps/m (x = 0.3). Furthermore, the magnetic field range at which the magnetoelectric signal appears extended from 0-∼0.4 T (x = 0.0) to 0-∼0.9 T (x = 0.5), demonstrating that the transverse conical spin structure was significantly strengthened by Ba substitution. These improvements are attributed to the decrease of Fe-O-Fe bond angle near the L and S blocks boundary, the reduction of cone angle in the transverse conical spin structure, and the change in the distribution of magnetic Co ions caused by the substitution of large Ba ions for small Sr ions. In general, we achieved the improved magnetoelectric coupling strength in polycrystalline Z-type hexaferrite for the first time.

Favourable modification of magnetic and magnetocaloric properties of La0.5Sr0.5CoO3 upon Ba substitution

Favourable modification of magnetic and magnetocaloric properties of La0.5Sr0.5CoO3 upon Ba substitution

Elucidating the effect of Pb and Ba substitution in SrTcO3 for advanced radioactive semiconducting applications

In this work, lead (Pb) and barium (Ba) substitution in SrTcO3 (STO) has been studied in detail using density functional theory. The structural stability was tested using optimization, enthalpy of formation and tolerance factor. The structure of SrTc(1−x)ZxO3 for (Z = Ba and Pb; x = 0, 0.25, 0.50 and 0.75) is found to be thermodynamically stable and thus can be made and studied experimentally, in which 25% Ba is the most stable form with ΔH = − 25.43 eV. In electronic properties, the band analysis is performed using PBE-GGA functional and found to follow the Moss–Burstein shift for the studied compounds, while DOS and contour plots have shown mixed p–d hybridization among the constituent elements, which indicates a mixing of covalent and ionic bond between its content atoms. The magnetic properties revealed the existence of weak ferromagnetism which is found to decrease (6.45, 6.02, 6.00 μB) with the increase of Pb content in STO while it increases to (0.04, 5.24, 6.89 μB) for the Ba substitution. Ba substitution shows good electrical conductivity. The optical analysis has shown a high reflectivity value for visible light (especially for 50% Ba with R(0) = 91.3%) and high conductivity σ(ω) (especially for 50% Ba with 12.6 × 103/Ω cm) value in the UV region which suggests the ability of these materials to be used as optical reflectors to prevent radiations and as non-radioactive photocatalysis and optoelectronic sensors.