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The Raman and infrared phonons in the tetragonal structure of double-perovskite Ba2MgTeO6 with space group I4/m have been studied using a short-range force constant model. This study used six stretching and two bending force constants to calculate zone centre phonons theoretically using the normal coordinate analysis. Some optical vibrational modes have been reported for the first time for Ba2MgTeO6 compounds in the I4/m phase using Wilson’s GF-Matrix method. The rest of the phonon modes calculated in this work have been compared with the available experimentally observed frequencies in the literature. The significance of interatomic force constant in the calculated Raman and infrared phonons has also been investigated in the potential energy distributions for the double-perovskite compound Ba2MgTeO6. [ABSTRACT FROM AUTHOR]

In this study, halide double perovskite (FA)2BiCuI6 is used as a light-harvesting layer for device structure FTO/WO3/(FA)2BiCuI6/Zn2P3/Pd. The device unveils best photovoltaic performance having fill factor (FF) of 78.54% and power conversion efficiency (PCE) of 19.89%. The double perovskite solar cell configuration FTO/WO3/(FA)2BiCuI6/Zn2P3/Pd is modeled further for optimum input specification of absorber layer. The most favorable absorber layer's thickness and defect density of (FA)2BiCuI6 layer are 0.7 µm and 1.0 × 1013 cm−3, respectively. The variation in temperature is made in the range of 300 to 480 K, and it has been observed that at 300 K temperature solar cell performance is enhanced. For maximum performance, device framework works on series resistance of 3 Ω cm and shunt resistance of 8000 Ω cm2. The estimation of optimum parameters of device input is done by the SCAPS-1D tool. Optimization of the device framework is done, and palladium (Pd) is used instead of popular back contact metal gold (Au). The results obtained for the proposed double perovskites solar cell (DPSC) show improved performance from the earlier reported work. [ABSTRACT FROM AUTHOR]

Formaldehyde, as a hazardous indoor contaminant following house decoration, is essential to its efficient removal at room temperature. This paper reports an eco-friendly approach for extracting cellulose acetate (CA) from waste cigarette filters to construct a nanofibrous composite membrane for formaldehyde degradation at ambient temperature. A composite nanofibrous membrane was fabricated by salable electrospinning of cellulose acetate and La2CoMnO6/CeO2 (LC), followed by hydrolysis and potassium doping with KOH. The membrane demonstrates excellent catalytic activity (97.56% of conversion), super stability (95.35% of conversion after 50 h) and long service life (93.96% of conversion after 3 catalysis cycles), which is ascribed to the synergistic catalytic effect of double perovskite and rapid hygroscopic properties of cellulose. In addition, the obtained membrane has a higher moisture regain (7.82%) than that of the LC/CA nanofibrous membrane (2.21%), and higher than that of the commercial air filter membrane using polypropylene (PP) fiber (near zero), accelerating formaldehyde adsorption and fastening the water removal, thereby allowing for the long-term positive progress of formaldehyde catalytic oxidation reaction. This work provides encouraging guidance for further exploration into formaldehyde degradation, which is promising for application in air cleaning. [ABSTRACT FROM AUTHOR]

Perovskites are of significant interest in the field of photocatalysis. To date, many perovskite nanostructures have been developed, and their applications in photocatalysis have been studied. There has been considerable improvement in the research on metal doping in the perovskite structure to improve their optical and structural properties. This mini-review examines the recent progress in the synthesis of lead-free double perovskite nanoparticles and their application in visible-light photocatalysis. Lead-free perovskites are emerging as an eco-friendly solution in energy, electrochemistry, and sensing. Double perovskites are known for their flexible structural, optical, and morphological properties due to their lattice framework having a general form AAʹBBʹO6. They are more useful for hydrogen evolution due to their higher conduction band potential than simple perovskites. Here, we summarize the current progress and provide insights for the future development of double perovskites toward efficient photodegradation. [ABSTRACT FROM AUTHOR]

Vacancy-ordered Cs 2 SnI 6 perovskite as an efficient light harvester sandwiched between the n -ZnO electron transport layer (ETL) and different p-type metal oxides, namely CuBi 2 O 4 , Cu 2 O, CuAlO 2 , and NiO, hole transport layers (HTL) with device architecture of FTO/ZnO/Cs 2 SnI 6 /HTL/Au, a lead-free all inorganic double perovskite solar cells. [Display omitted] • Eco-friendly all inorganic double perovskite solar cells (DPSCs). • Cs 2 SnI 6 double perovskite light harvester and metal oxide charge transport layer. • Ambient stable and highly efficient device with efficiency ∼ 30 %. • Theoretical modelling using SCAPS-1D for high efficiency DPSCs. Non-toxic and air-stable Cesium tin (IV) halide (Cs 2 SnI 6) is a promising alternative to lead halide perovskite for photovoltaic applications. This study reports the extensive analysis of vacancy-ordered Cs 2 SnI 6 perovskite as an efficient light harvester sandwiched between the n -ZnO electron transport layer (ETL) and different p-type metal oxides, namely CuBi 2 O 4 , Cu 2 O, CuAlO 2 , and NiO, hole transport layers (HTL), using SCAPS-1D software. Various physical parameters, viz. thickness, defect density (bulk and interfacial), and charge carrier concentration of different layers for the device architecture of FTO/ZnO/Cs 2 SnI 6 /HTL/Au, are systematically investigated along with the effect of parasitic resistance, work function, and operating temperature in the quest for best device performance in terms of photoconversion efficiency (PCE). The effect of DC biasing voltage is analyzed using C-V characteristics to understand the spatial charge distribution, absorber doping profile, and junction built-in potential. The frequency-dependent admittance was studied using simulated C-f characteristics to give an insight into the defect and the conductance. The Cesium tin (IV) halide (Cs 2 SnI 6) based device optimized with CuBi 2 O 4 , Cu 2 O, CuAlO 2 , and NiO HTLs has shown PCE of 28.18 %, 29.72 %, 29.43 %, and 29.33 %, respectively. [ABSTRACT FROM AUTHOR]

Double perovskites have recently received extensive attention due to their attractive photoluminescent properties. Herein, we report how the charge compensating agent influences the structural and spectroscopic properties of investigated ceramic powder. Ba 2 MgWO 6 :Eu3+ samples were co-doped with K+ and Li+ ions and obtained by the mechanochemical route. SEM images of the representative sample showed big objects with visible grain boundaries, sticking together. The charge compensator does not affect the character of Eu3+ ions emission which is, in both cases, the emission is composed of magnetic dipole emission from the 5D 0 excited level to the 7F 1 ground state. However, the experimental results showed that in the sample co-doped with K+ ions a higher number of irregular WO 6 groups were created and that they influence the shape and position of the host emission. The mechanism of emission generation from regular and irregular WO 6 groups and the interaction between them are discussed in detail. The experimental data are supported by the DFT calculation of the density of states of the samples with Na/K+ co-dopant. [ABSTRACT FROM AUTHOR]

Stable and efficient broadband near-infrared (NIR) emitting phosphors are vital for the next-generation NIR sources. However, it still remains challenging to construct such phosphors, particularly those with a NIR-II window. In this work, using the Cr3+-Yb3+ energy transfer (ET) strategy, the as-synthesized Ca 2 ScTaO 6 :Cr3+, Yb3+ phosphor retains 86.2% of the initial luminescence intensity of Yb3+ at 373 K with characteristic emissions of both activators ranging from 700 nm to 1200 nm. The occupation of Cr3+ into both Ta5+ and Sc3+ sites is confirmed by X-ray diffraction, time-resolved emission spectrum, and crystal structure. The efficient ET from Cr3+ to Yb3+ is revealed by the diffuse reflection spectrum, steady-state and transient fluorescence. As a result, it contributes to the excellent performance of the phosphor. Based on the optimized phosphor, a NIR light-emitting diode is fabricated and demonstrated its advantage in imaging and potential application in information encryption. The result highlights ET as a robust strategy to construct efficient NIR phosphor. [ABSTRACT FROM AUTHOR]

The polycrystalline sample of LaBaFe1.2Mn0.8O6 was synthesized by sol–gel method. Preliminary analysis of room-temperature X-ray data pattern of the sample confirms the formation of a single-phase compound in rhombohedral crystal system with the space group R 3 ¯ C. Detailed studies of dielectric and impedance spectroscopy complex with frequency at various temperatures confirmed the existence of relaxation phenomenon in the material. Studies of electrical properties show a strong correlation with the microstructure and resistive properties of the material. The electrical transport shows the existence of a non-exponential conductivity relaxation in the material. For different temperatures, the variation of the real part of the permittivity as a function of frequency suggests that the material is a relaxor. Furthermore, the temperature evolution of direct current conductivity indicates that the compound has a semiconductor property. CBH is the most appropriate conduction model. This sample has significant electrical and dielectric qualities; it has a high permittivity and low dielectric loss, making it suitable for technical applications such as capacitors in the electrical area. [ABSTRACT FROM AUTHOR]

Mn4+ activated oxide phosphor as plant growth LEDs is becoming a research hotspot owing to the high coincidence of spin-forbidden transition emission peaks in 2E g -4A 2g with the photosensitive pigment P fr required for plant growth. Moreover, the emission peaks of Mn4+ can be adjusted at 610–750 nm depending on the matrix. However, Mn4+ doped phosphors suffer from sharply decreased emission intensity at high temperature. In order to exploit phosphors with good thermal stability and high emission intensity, the charge compensation of the double perovskite structured phosphor Sr 2 ScSbO 6 :Mn4+ using Li+ dopant is conducted in this study, wherein the Li+ doping inhibits the adverse energy transfer between Mn4+, therefore increasing the luminescence intensity by 2.27 times and upgrading the thermal stability from 80.2% to 86.76% at 423 K with respect to its value at 303 K in comparison with that of pristine Sr 2 ScSbO 6 :Mn4+. Accordingly, an innovative PDMS-LED device is fabricated using the modified phosphor. The typical 2E g -4A 2g emission peak of Mn4+ at 697 nm under 365 nm UV chip excitation coincided well with the far-red light photosensitive pigment P fr required for plant growth. Meanwhile, the thermal imaging tests demonstrate the outstanding working stability of the constructed PDMS-LED device at different temperatures. The above results indicate that the Sr 2 ScSbO 6 :Mn4+/Li+ phosphor-based PDMS-LED device possesses high potential in promoting plant growth. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermo-electric (TE) material applications reduce reliance on traditional energy resources by converting heat to electric energy. We have studied, for the first time, the thermo-electric properties of Rb2SeX6 (X=Br,Cl). Using norm-conserving pseudo potentials in a plane wave basis set of Quantum Espresso code, the optoelectronic, elastic and thermo-electric properties of Rb2SeX6 (X=Br,Cl) have been investigated using density functional theory. Generalized Gradient Approximation of Perdew Burke Ernzerhof (GGA-PBE) and Generalized Gradient Approximation of Perdew Burke Ernzerhof adapted for Solid (GGA-PBESol) exchange correlation functionals were employed in all calculations. The band structure plots suggest that the studied double perovskites have indirect band gaps. Rb2SeBr6 band gap values of 1.7574/ 1.569 eV (using GGA-PBE/PBEsol) are remarkably similar to that of two effective inorganic/organic perovskites FAPbI3 and MAPbI3 . Maximum peaks generated from refractive index results indicate possible solar cell uses of the materials because they are in the visible and ultraviolet ranges. The results of other optical properties such as absorption coefficients, electron energy loss, conductivity, and reflectivity concludes that Rb2SeX6 (X=Br,Cl) have good values for electron generation, high potential for applications in the optoelectronic industry and are semiconductor in nature. The calculated shear anisotropy values of Rb2SeBr6/Cl6 are 3.09/1.71, suggesting that they are isotropic materials. With calculated Poisson’s ratio of 0.32 and 0.26, the materials are predicted to be ductile in nature. The two materials are appropriate for thermo-electric applications since their thermal to electrical conductivity ratio are small (the order of 10-5). The calculated minimum values of Seebeck coefficient values of 0.198×10³ / 0.166 ×10³ (mV/K) at 750 K, for Rb2SeBr6/Cl6 are positive, indicating that they have p-type conduction. Figure of merit values at all temperature range considered are greater than one (ZT > 1) for both Rb2SeBr6 and Rb2SeCl6, suggesting that they are good thermo-electric materials. The results of the calculations provide the basis for the industrial application of Rb2SeBr6/Cl6 as solar cells. [ABSTRACT FROM AUTHOR]

A semiconductor double perovskite oxide Y2CuTiO6 with a wide band gap was synthesized by solid-state reaction. The compound was characterized by x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, thermogravimetric analysis, UV–visible diffuse reflectance spectroscopy, photoluminescence excitation and emission spectroscopy. Rietveld refinement of x-ray diffraction pattern using the General Structure Analysis System-II indicated a hexagonal structure with space group P63cm (#185) with lattice parameters a = b = 6.199(2) Å and c = 11.516(4) Å. Trigonal bi-pyramidal Ti(IV)/Cu(II)O5 is arranged randomly in the B sites of Y2CuTiO6. Microscopic measurements confirmed a dense microstructure with Y:Cu:Ti = 2:1:1. Thermogravimetric analysis showed high thermal stability of this compound, which is desired for optical applications. UV–VIS DRS spectra displayed wide band absorption in the visible region with a band gap of 2.98 eV as commonly seen in wide-band-gap semiconductors. From the photoluminescence excitation spectra, maximum excitation was observed around 365 nm, so the compound was excited by a 355 nm laser to study the emission properties. A broad emission spectrum is observed in the visible range from the photoluminescence emission study. The lead-free double perovskite with high material stability against temperature showing huge absorption and emission in the visible region without any intrinsic doping is unique and interesting for a wide range of applications. [ABSTRACT FROM AUTHOR]

This work discusses the synthesis, characterization, and electrical properties of Gd 2 NiTiO 6 (GNTO) double perovskite synthesized using the sol-gel citrate auto-ignition method. The structure, microstructure, and compositional distribution of the sample were analyzed by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), and Energy Dispersive X-ray (EDX) analysis. Rietveld's refinement of the XRD pattern corroborated the single-phase monoclinic structure with space group P2 1 /n. The impedance spectra demonstrated grain and grain boundary contributions to the total conductivity and the non-Debye type relaxation. The electrical study also established the semiconductive character of the material. The investigation showed that the conduction mechanism was thermally activated. The frequency-dependent complex dielectric spectra have been investigated using the Havriliak-Nigami (HN) formalism. The temperature variation of leakage-current density was found from J-E characteristics curves. • Single phase Gd 2 NiTiO 6 was prepared through sol-gel citrate auto-ignition method. • Grain and grain boundary contribute to total conductivity. • Scaling shows conduction and relaxation processes as temperature-independent. • Relaxor-type dielectric behaviour of the sample Gd 2 NiTiO 6 was observed. • The leakage-current density follows the ohmic conduction process. [ABSTRACT FROM AUTHOR]

The structure, microstructure, charge transport properties, dielectric properties, and leakage current density of Dy 2 FeMnO 6 synthesized by the auto combustion method are investigated in this study. The monoclinic crystal structure of the sample with space group P2 1 /n was observed. The CoO 6 and MnO 6 octahedra were found distorted and tilted. The calculation of the bond valence sum confirmed the +3 and + 3/+4 oxidation states of Fe and Mn, respectively. The average crystallite, particle, and grain sizes were 43.01, 94, and 187.68 nm, respectively. The anticipated stoichiometry of the constituent elements was confirmed by energy–dispersive X–ray spectra. The frequency–dependent conductivity obeyed Jonscher's power law, and the frequency exponent associated with this law increased with temperature, indicating the non–overlapping small polaron tunnelling (NSPT) mechanism for charge conduction. The enhancement of the dielectric loss tangent with temperature was consistent with the dc conductivity. The frequency dependence of dielectric properties was explained using Havriliak–Negami formalism. The sample followed Vogel–Fulcher law, which is similar to the relaxor ferroelectrics, and the ferroelectricity increased with frequency. Conduction, migration, and dielectric relaxation all have similar activation energies. The sample exhibited low leakage current density, which followed Schottky emission with a barrier height of 0.02(4) eV. The obtained results were compared with other rare–earth–based double perovskites. [ABSTRACT FROM AUTHOR]

Modern day electronic devices are fascinated by various indispensable activities for various schemes. Transient devices are one of those systems useful for disposable electronics. However, choice of materials is an integral part, because the material should be compatible with the required device application and can show transient nature at the same time. Most importantly, the material for the aforesaid application should not possess any environmental hazard. In this work, we have for the first time integrated non-toxic double perovskite material in transient memristive application. The Cs 2 AgBiBr 6 integrated in between Au and indium doped tin oxide (ITO) electrode serves as the functional material and the proposed device exhibited dual-functional switching characteristics. The device could retain the reproducible and stable resistive memory feature along with high-density storage capacity. The threshold switching behavior is useful to realize selector device in cross-bar resistive memory architecture. Thus, the same device can be utilized simultaneously for both the application. In addition, the device could also demonstrate some basic synaptic functions. Finally, the modulation of device resistance could be ascribed to the establishment/dissolution of conductive path related to Br− vacancy and Ag filaments. Interestingly, the device could also display transient behavior as the Cs 2 AgBiBr 6 film and the device undergo rapid decomposition within 60 s in H 2 O. [ABSTRACT FROM AUTHOR]

In this study, we used the FP-LAPW technique based on density functional theory applied in WIEN2k code to examine the structural, electronic, elastic, and thermoelectric properties of cubic double perovskite Rb2InBiX6 (X = Cl, Br) compounds. The structural stability was confirmed from the tolerance factor, formation energy, and phonon dispersion. The exchange-correlation potentials LDA, GGA, mBJ, and HSE were used to estimate the electronic properties. According to the band structure computed band gap using mBJ, the HSE are 1.61 eV, 1.81 eV for Rb2InBiCl6 and 1.22 eV, 1.32 eV for Rb2InBiBr6 compounds, respectively. The mechanical stability of the materials under examination were reflected by the calculated elastic constants. The estimated bulk modulus-to-shear modulus ratios for Rb2InBiX6 (X = Cl, Br) are 2.13 and 3.65, respectively. This indicates that the examined compounds were ductile in nature. The optical properties in terms of real and imaginary dielectric functions, refractive index, and absorption coefficient were computed, indicating that they might be employed in optoelectronic and photovoltaic applications. In the temperature range 200–800 K, the electrical conductivity, Seebeck coefficient, thermal conductivity, and power factor (PF) were analysed. Relatively high PFs of about 2.7 × 1010 W/K2 ms and 3.1 × 1010 W/K2 ms were obtained for Rb2InBiX6 (X = Cl, Br) suggesting that these compounds are viable for usage in thermoelectric devices. Both the compounds showed strong absorption patterns and excellent PF signifying that these are suitable materials for photovoltaic and thermoelectric applications.

A polycrystalline sample of Sr9La2(WO6)4, nonastrontium dilanthanum tetrakis[orthotungstate(VI)], was prepared by heating a compacted powder mixture of SrCO3, WO3, and La2O3 with an Sr:La:W molar ratio of 9:2:4 at 1473 K. X-ray crystal structure analysis was performed for a Sr9La2(WO6)4 single-crystal grain grown by reheating the sample at 1673 K. Sr9La2(WO6)4 crystallizes with four formula units in the tetragonal space group I41/a and is isotypic with Sr11(ReO6)4. Two W sites with site symmetries of \overline{1} are located at the center of isolated [WO6] octahedra, and four mixed (Sr/La) sites are surrounded by eight to twelve O atoms of the [WO6] octahedra. The structure of Sr9La2(WO6)4 can be described on the basis of the double-perovskite structure with [WO6] and [(Sr/La)Ox] polyhedra alternately placed, and a vacancy (□).

Abstract Traditional lithium‐ion batteries cannot meet the ever‐increasing energy demands due to the unsatisfied graphite anode with sluggish electrochemical kinetics. Recently, the perovskite material family as anode attracts growing attention due to their advantages on specific capacity, rate capability, lifetime, and safety. Herein, a double perovskite La2MnNiO6 synthesized by solid‐state reaction method as a high‐performance anode material for LIBs is reported. La2MnNiO6 with an average operating potential of

Lead‐free double perovskites have attracted much attention as possible alternatives to lead halide based perovskites in photovoltaic applications. However, to date only few double perovskites have been successfully employed in optoelectronic device prototypes. Therefore, the search for stable and lead‐free materials is ongoing. Here, we present the successful growth of high‐quality Cs2NaFeCl6 single crystals and their temperature‐dependent structural and optical properties. By combining electron paramagnetic resonance (EPR), crystal structure analysis and density functional theory (DFT) we could determine a cubic crystal structure with a spin of 5/2 for this material, showing strongly spin polarized character. Furthermore, combining photoluminescence (PL) and optical absorption measurements we find a bandgap of approximately 2.1 eV at room temperature as well as the presence of excitonic states. Using Elliot's formula, we are able to extract the temperature‐dependent behavior of the bandgap as well as an estimated exciton binding energy of only 20 meV at 80 K.

Thermo-electric (TE) material applications reduce reliance on traditional energy resources by converting heat to electric energy. We have studied, for the first time, the thermo-electric properties of Rb2SeX6 (X=Br,Cl). Using norm-conserving pseudo potentials in a plane wave basis set of Quantum Espresso code, the optoelectronic, elastic and thermo-electric properties of Rb2SeX6 (X=Br,Cl) have been investigated using density functional theory. Generalized Gradient Approximation of Perdew Burke Ernzerhof (GGA-PBE) and Generalized Gradient Approximation of Perdew Burke Ernzerhof adapted for Solid (GGA-PBESol) exchange correlation functionals were employed in all calculations. The band structure plots suggest that the studied double perovskites have indirect band gaps. Rb2SeBr6 band gap values of 1.7574/ 1.569 eV (using GGA-PBE/PBEsol) are remarkably similar to that of two effective inorganic/organic perovskites FAPbI3 and MAPbI3 . Maximum peaks generated from refractive index results indicate possible solar cell uses of the materials because they are in the visible and ultraviolet ranges. The results of other optical properties such as absorption coefficients, electron energy loss, conductivity, and reflectivity concludes that Rb2SeX6 (X=Br,Cl) have good values for electron generation, high potential for applications in the optoelectronic industry and are semiconductor in nature. The calculated shear anisotropy values of Rb2SeBr6/Cl6 are 3.09/1.71, suggesting that they are isotropic materials. With calculated Poisson’s ratio of 0.32 and 0.26, the materials are predicted to be ductile in nature. The two materials are appropriate for thermo-electric applications since their thermal to electrical conductivity ratio are small (the order of 10-5). The calculated minimum values of Seebeck coefficient values of 0.198×103 / 0.166 ×103 (mV/K) at 750 K, for Rb2SeBr6/Cl6 are positive, indicating that they have p-type conduction. Figure of merit values at all temperature range considered are greater than one (ZT > 1) for both Rb2SeBr6 and Rb2SeCl6, suggesting that they are good thermo-electric materials. The results of the calculations provide the basis for the industrial application of Rb2SeBr6/Cl6 as solar cells.

Doping can improve the structural stability and photoelectric properties of perovskite materials. In this study, indium element was added into Tl-Co double based perovskite material to stabilize its structure and improve its photoelectric performance. The results show that the doped material Cs2In0.5Tl0.5CoX6(X = I, Br, Cl) has better ductility and stability than the original Cs2TlCoI6 by elastic constants and phonon spectra. Moreover, indium doping can improve the band structure of Tl-Co double-base perovskite materials, such as changing the band value to the optimal band gap value of solar energy absorber and transforming from indirect band structure to quasi-direct band structure. In terms of optical properties, indium doping can expand the wavelength range of the material's light absorption, making its absorption spectrum more matching with the simulated AM1.5 spectrum. Cs2In0.5Tl0.5CoCl6 is proposed to be a promising candidate for optoelectronic applications based on its structural stability, bandgap value and optical absorption spectrum.

Herein, structural, morphological, and energy‐storage properties of Y2MnCoO6 double perovskite synthesized by hydrothermal process are reported. The electrochemical investigation of Y2MnCoO6 is a novel aspect of the work, and this composition is being synthesized for the first time employing the hydrothermal technique. The powder X‐ray diffraction analysis shows formation of cubic crystal phase with Ia3¯(206) symmetry and lattice parameters as a = b = c = 10.60 Å. It is indicated in the microstructure study that the morphology of the sample material is almost homogenous in the form of microspheres. The microsphere shape allows superior charge movement at the nanoscale, enabling more area available for electrochemical reactions to take place. The high‐resolution transmission electron microscopy (HRTEM) reveals the grain size in the range of 50–100 nm. The X‐ray photoelectron spectroscopy reveals the occurrence of Y3+, Mn3+, and Co2+/3+, ions on the surface of Y2MnCoO6. The energy‐storage behavior of nanostructured Y2MnCoO6 electrodes studied via cyclic voltammetry and chronopotentiometry displays the redox nature of the Y2MnCoO6. The calculated value of specific capacitance is found to be ≈148.0 Fg−1 at current density of 0.5 Ag−1; with ≈85% specific capacitance retention, after 10 000 cycles. [ABSTRACT FROM AUTHOR]

Various properties of S r 2 M W O 6 (M = V , R h , R u) are investigated based on the DFT theory using the full-potential linearized augmented plane wave (FP-LAPW) method. Their magnetic properties show a half metallic bahavior for M = V and Rh with high magnetic moments. However, for S r 2 R u W O 6 , the bands for up and down spins are symmetric and thus this material is non-magnetic with an energy band gap of 1.4 e V . The presence of Ru and Rh in S r 2 M W O 6 structure increases the absorption of this material, especially in the visible light range. The elastic constants C α β for all studied compounds were obtained using Elastic1.1 and satisfy the Born stability criterion. This indicates that all the compounds are mechanically stable. Finally, electrical properties were determined using BoltzTraP package leading to interesting aspects. The obtained results are comparable with other perovskite phases. Therefore, these coupled features of the title compounds make them promising material for different applications. [ABSTRACT FROM AUTHOR]

In this study, the stabilities and conversion efficiencies of perovskite solar cells including cesium (Cs) or formamidinium (FA) at the CH₃NH₃ site were investigated. The additive effects on the photovoltaic properties and crystalline structures were investigated via current–voltage measurements, X-ray diffraction, and scanning electron microscopy. The simultaneous co-addition of Cs and FA to the CH3NH3PbI3 perovskite crystal improved the photovoltaic properties, which may be due to the suppression of the decomposition of the perovskite crystals and the promotion of crystal growth. [ABSTRACT FROM AUTHOR]

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Magnetic refrigeration by utilizing the magnetocaloric effect of magnetic solid materials has been expected to be a green energy technology. In this work, double perovskite oxides Gd 2 NiMn 1- x Ti x O 6 (0 ≤ x ≤ 1) were successfully synthesized via the traditional solid-state reaction method. Structural, magnetic and cryogenic magnetocaloric properties of the prepared samples were experimentally investigated. The magnetic measurements indicate that the ferromagnetic phase is progressively suppressed by Ti substitution in Gd 2 NiMn 1- x Ti x O 6 owing to the dilution effect of nonmagnetic Ti4+ with 3 d 0 configuration. In addition, the two vital parameters of magnetic entropy change and refrigeration capacity for magnetocaloric properties have been calculated and analyzed. The values of the maximum magnetic entropy change and refrigeration capacity show a similar change regularity, which decrease firstly from 23.33 J kg−1 K−1 (334.68 J kg−1) at x = 0 to 13.70 J kg−1 K−1 (226.07 J kg−1) at x = 0.4, and then increase significantly to 27.57 J kg−1 K−1 (360.02 J kg−1) at x = 1 under Δ H = 6 T. A possible mechanism for the effect of Ti substitution on the magnetic and magnetocaloric properties of Gd 2 NiMn 1- x Ti x O 6 has been proposed. The present work indicates that Gd 2 NiMn 1- x Ti x O 6 could be important candidates for magnetic refrigeration application. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is deliberated as an assuring track to use renewable energy for the production of hydrogen; yet, its industrial application is limited by the anodic oxygen evolution reaction (OER). Perovskite oxide‐based materials have been comprehensively explored as assuring catalysts for OER in alkaline media, with (electro)chemically persuaded alteration of their initially crystalline surface into an amorphous state. This perspective highlights the features of double perovskite electrocatalyst for the oxygen evolution reaction in particular, oxygen‐deficient double‐perovskite with multiple cationic redox sites. The rational reordering of A‐ and B‐sites, along with oxygen vacancy, lead to the generation of an array of novel double perovskite catalysts. A new signifier in stability level is also projected to highlight the relationship between performance and surface stability of OER with perovskite catalyst. This descriptor will offer potential strategies to optimize OER catalytic performance by tuning the surface structure of double‐perovskites. [ABSTRACT FROM AUTHOR]

A luminescent double perovskite phosphor Sr2YNbO6 doped with Eu3+ crystallized to the monoclinic phase and was synthesized successfully via a conventional high‐temperature combustion method. The formation of the crystal structure, phase purity, and surface morphology were studied using X‐ray diffraction patterns and scanning electron microscopy. The characteristic vibrations between the atoms of the functional groups present in phosphor were studied using Fourier transform infrared spectra analysis. The luminescence properties of the prepared phosphors were investigated in terms of photoluminescence (PL) and thermoluminescence (TL). PL excitation spectra exhibited charge transfer bands and the characteristic 4f6 transitions of Eu3+. A prominent PL emission was obtained for the phosphor doped with 4 mol% Eu3+ under the 396 nm excitation wavelength. PL emission quenching was observed for the higher doping concentrations due to a multipole–multipole interaction. A highly intense PL emission arose due to the hypersensitive 5D0–7F2 electric dipole transition of Eu3+ that dominated the emission spectra. The thermal stability of the phosphor was examined through temperature‐dependent PL. The TL properties of the Sr2YNbO6 double perovskites irradiated with a 90Sr beta source at different doses were measured. The double perovskite phosphors under study showed a linear dose–response with increasing beta dose, ranging from 1 Gy to 10 Gy. Trapping parameters of the TL glow curves were determined using Chen's peak shape method and computerized glow curve deconvolution (CGCD). CGCD fitting of the TL glow curves revealed that it was consisted of three major peaks and followed second‐order kinetics. The estimated activation energies were determined using different methods and were comparable and significant. [ABSTRACT FROM AUTHOR]

The advancement of lead-free double perovskite materials has drawn great interest thanks to their reduced toxicity, and superior stability. In this regard, Cs2AgBiBr6 perovskites have appeared as prospective materials for photovoltaic (PV) applications. In this work, we present design and numerical simulations, using SCAPS-1D device simulator, of Cs2AgBiBr6-based double perovskite solar cell (PSC). The initial calibrated cell is based on an experimental study in which the Cs2AgBiBr6 layer has the lowest bandgap (Eg = 1.64 eV) using hydrogenation treatment reported to date. The initial cell (whose structure is ITO/SnO2/Cs2AgBiBr6/Spiro-OMeTAD/Au) achieved a record efficiency of 6.58%. The various parameters that significantly affect cell performance are determined and thoroughly analyzed. It was found that the conduction band offset between the electron transport layer (ETL) and the Cs2AgBiBr6 layer is the most critical factor that affects the power conversion efficiency (PCE), in addition to the thickness of the absorber film. Upon engineering these important technological parameters, by proposing a double ETL SnO2/ZnO1-xSx structure with tuned absorber thickness, the PCE can be boosted to 14.23%. [ABSTRACT FROM AUTHOR]

BaTiO3 properties can be enhanced to improve capacitor energy storage density through electric-field (E) dipole engineering at the nanoscale (E-DENS). E-DENS allows engineers to modify the internal E through dipole interactions. E-DENS of Ba[(Y3+,Ta5+)xTi1-2x]O3 with 0.0000 ≤ x ≤ 0.0500 are investigated by substituting Y3+-Ta5+ dipole pairs for Ti4+-Ti4+ non-dipolar pairs within the BaTiO3 structure. The Y3+ and Ta5+ ions are more polarizable than Ti4+ and are expected to increase the temperature at which the material becomes cubic and paraelectric. Room temperature XRD, UV-Vis-NIR, LCR, and resistivity analysis have been used to characterize Ba[(Y3+,Ta5+)xTi1-2x]O3 with 0.0000 ≤ x ≤ 0.0500. [ABSTRACT FROM AUTHOR]

The double perovskite halides A2BIBIIIX6 provide flexibility for various formulation adjustments and are of less toxicity in comparison with well-discussed complex lead halide derivatives. Such type of structure can be formed by replacing two Pb2+ ions in the cubic lattice with a pair of non-toxic heterovalent (monovalent and trivalent) metal cations, such as silver and indium. The aim of this work is to briefly characterize the phase equilibria in the ternary system CsBr-AgBr-InBr3 and investigate the thermodynamic availability of synthesis of Cs2AgInBr6 double perovskite phase by solid-state sintering or melt crystallization. The results demonstrate the unfeasibility of the Cs2AgInBr6 phase but high stability of the corresponding binary bromides perspective for optoelectronics. [ABSTRACT FROM AUTHOR]

In this research, we are interested to study the physical properties of the double perovskite oxide Ba2GdNbO6 under the effect of octahedral tilting, where this material crystallises in the tetragonal structure (I4/m (no. 87), Z = 2). The structural, electronic and magnetic properties are investigated using the spin-polarised density functional theory within the framework of the GGA + U approximation. The structural stability for Ba2GdNbO6 compound has been verified; this shows that I4/m structure is reported as stable ground state of Ba2GdNbO6 compound. The phenomenon of octahedral tilting contributes to the stability of this material and to the apparition of the quantum aspect. The X-spectra study show that the structural transition can occur between the I4/m symmetry system (the stable ground state) and the Fm 3 ¯ m symmetry system (the excited state), the absorbed radiation of this structural transition corresponds to the Middle-Wave-Infrared (MWIR). The electronic structure of Ba2GdNbO6 compound has been investigated in the stable ground state; the results show that the octahedral Ba2GdNbO6 compound has semiconductor behaviour with an indirect band gap. The results of total and partial spin-magnetic moments of Ba2GdNbO6 compound show that the main contribution to the total magnetic moment comes from the Gd ion, it is obvious to note that the half-filled in Gd (4f7) orbital is responsible for the semiconductor behaviour. Moreover, the GGA + U approximation supported by QTL programme shows that the multiplicity in the occupied 4f-Gd states is corresponding to the lower energy level of (8 S ( 7 2 ) ↑ ). [ABSTRACT FROM AUTHOR]

In this present work, the double perovskite Y2NiMnO6 nanostructures had been successfully synthesized through the hydrothermal route. Using various characterization techniques, the structural, morphological, impedance, dielectric, electrochemical, and magnetic properties were analyzed. The monoclinic (P21/n) structure of the prepared Y2NiMnO6 was confirmed using powder X-ray diffraction. Results from the scanning electron microscope showed the formation of Y2NiMnO6 nanostructures. TEM image of Y2NiMnO6 nanoparticles revealed d-spacing of 0.56 nm and selected area electron diffraction pattern showed (311) plane for Y2NiMnO6. Fast Fourier transform (FFT) analysis was performed on the lattice fringes and the diffraction spots indexed to the cubic spinel. The dielectric, impedance, modulus, and AC conductivity of the synthesized double perovskite Y2NiMnO6 were studied in the frequency range of 100 Hz–5 MHz at room temperature. The effect of grain and grain boundary was analyzed by the Nyquist plot. The presence of non-Debye type of relaxation was confirmed from the dielectric, impedance, and modulus studies. The elaborated studies of complex impedance spectra provided the basis to understand the electrical properties, which had strong relations with the microstructure and resistive nature of the prepared material. The electrochemical behavior of the prepared Y2NiMnO6 with three-electrode system was found to have pseudocapacitive nature with the specific capacitance value 8.633 F/g for 0.5 M KOH, 75.476 F/g for 1 M KOH, and 78.201 F/g for 2 M KOH at the scan rate of 10 mV/s. The specific capacitance values were improved by increasing the concentration of electrolyte. The vibration sample magnetometer of the synthesized Y2NiMnO6 shows the paramagnetic behavior at room temperature. [ABSTRACT FROM AUTHOR]

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Developing a secure anti-counterfeiting technology with more dimensional encryptions is urgently demanded. The lead-free double perovskite (DP) family represented by A2BIBIIIX6 hold great potential for applications in advanced fluorescence anti-counterfeiting owing to of large-bandgap engineering via BI/BIII site transmutation or exotic dopants. Herein, Ln3+ (Ln3+ = Eu3+, Ho3+, and Yb3+)-doped Cs2Ag0.3Na0.7InCl6 DP microcrystals (MCs) were firstly successfully synthesized by a hydrothermal method. By selective excitation of different luminescence centrals through precise control of excitation wavelength, we demonstrate dynamic color tuning in the Ln3+-doped Cs2Ag0.3Na0.7InCl6 DPMCs. Specifically, under various excitations of UV 300, 394, and NIR 980 nm, the as-synthesized DPMCs display triple emissions of warm yellow, red, and green, respectively. The warm yellow light stems from the self-trapped exciton (STE) downconversion (DC) luminescence of the DP matrix, while the red and green lights can be attributed to the strong Eu3+ 5D0→7FJ (J = 1, 2, 3, 4) DC luminescence and Ho3+ (5F4→5I8) upconversion (UC) luminescence sensitized by Yb3+. Thus, the as-synthesized Ln3+-doped Cs2Ag0.3Na0.7InCl6 DPMCs, which possess tunable combined DC/UC luminescence, show great potential to be an anti-counterfeiting material with a high security level. [ABSTRACT FROM AUTHOR]

The structural, electronic and optical properties of monoclinic Sr2NiTeO6 double perovskite have been studied using corrected density functional theory–local density approximation with applying of Hubbard U corrected energy (DFT–LDA + U) method in plane-wave pseudopotential basis. The influence of on-site Coulomb interaction on structural, electronic and optical properties of Sr2NiTeO6 double perovskite compound, which consists of strongly localized Ni 3d electrons, were investigated. The highly Coulomb repulsion between electrons was corrected using Hubbard U parameter, varying from 0 to 8 eV for Ni 3d orbitals. The calculated results demonstrated that Sr2NiTeO6 double perovskite was sensitive to the change in U values. The optimized structural properties give a good agreement with experiment and other calculation data with lattice parameters a = 5.673 Å, b = 5.565 Å, c = 7.847 Å, α = 89.999°, β = 90.257° and γ = 90.000°. The DFT–LDA + U predicted the calculated electronic band structure of Sr2NiTeO6 was showed metallic behaviour (0 and 2 eV) and insulator behaviour (4, 6 and 8 eV). The density of state (DOS) shows that there was a significant effect on hybridization of Ni 3d and O 2p states at the conduction and valence band, respectively. Moreover, the results of optical studies such as dielectric function, absorption and reflectivity were found significant to the variation of U values applied indicates that the U values give a better description on the electronic localization of Ni 3d states.

Double perovskite Ba 2 CoNbO 6 , obtained by pyrolysis of nitrate-organic mixtures, was studied by XRD, XRF, DFT, AC/DC-magnetization, specific-heat, thermoelectric, and ESR methods. The sample has cubic symmetry space group Pm 3 m with a = b = c = 4.0074(11) Å. Deficiency in oxygen ions shows the presence of Co ions in both 3+ and 2+ valency. According to AC-magnetization and specific-heat data, Ba 2 CoNbO 6 demonstrates spin-glass ordering at T SG = 30 K at external field value of 0.1 kOe. This temperature of spin glass transition drops with field power increase down to complete suppression at 10 kOe. The effective magnetic moment determined using the Curie-Weiss approximation is 4.29 μ B , which is consistent with the theoretical estimation for Co ions in the intermediate-spin state. The peak at T = 90 K, observed in the temperature dependence of the specific heat and accompanied by a peak in the ESR linewidth, is possibly due to the structural transition at this temperature. The Seebeck coefficient of the compound is S = 4–6.5 μ V/K and the band gap obtained within the small-polaron-jump conductivity model is Δ E = 0.284 eV in the temperature range of 350–550 K connected with DFT calculation. An intensity ESR line, related to Co2+ ions, was observed in ESR spectra. • Double perovskite Ba 2 CoNbO 6 shows presence of two sublattices. • Co3+ ions present in the compound in intermediate- and low-spin states (S = 1 and S = 0, respectively). • Measurements show transitions in canonical spin-glass state at 30K for Ba 2 CoNbO 6. • The effective magnetic moment per unit cell is μ eff = 4.29 μ B. • Band gap is ΔE = 0.284eV. [ABSTRACT FROM AUTHOR]

Figure 1 The unit cell of Ba 2 MnReO 6 , Ba 2 NiReO 6 , and Sr 2 MnReO 6 Double Perovskite compounds. Figure 2 Charge carrier concentration dependence of Power factor (PF , in W.cm−1.s−1.K−2) and figure of merit (ZT , dimensionless) at selected temperatures T: 300, 600 and 900K, Ba 2 MnReO 6 , and Sr 2 MnReO 6 compounds. [Display omitted] • The mechanical stability of Ba 2 MnReO 6 , Ba 2 NiReO 6 , and Sr 2 MnReO 6 was confirmed, and their elastic properties were analyzed. • These materials observed low thermal conductivity and a moderate thermal expansion coefficient. • Good thermoelectric performance, with ZT exceeding 0.6 at high temperatures, was indicated for Ba 2 MnReO 6 and Sr 2 MnReO 6. The present work involves a computational investigation of the elastic, thermal, and thermoelectric characteristics of Ba 2 MnReO 6 , Ba 2 NiReO 6 , and Sr 2 MnReO 6 from the Double Perovskite family. The study verified the mechanical stability of the three compounds and investigated Young's modulus, Poisson, bulk, and shear modulus in various stress orientations. We were also able to compute longitudinal, transverse, and average sound velocities (Vl, Vt, and Vm, in m/s), and the findings revealed that Sr 2 MnReO 6 had a greater longitudinal velocity than the other two compounds. Thermodynamic characteristics revealed that Ba 2 MnReO 6 , Ba 2 NiReO 6 , and Sr 2 MnReO 6 exhibit low lattice thermal conductivity (K l) at medium temperatures, strong heat absorption, and a moderate coefficient of thermal expansion.The analysis of the electron and hole charge carriers' transport characteristics revealed that, when doped with an electron concentration close to 1020 cm−3, the two materials, Ba 2 MnReO 6 and Sr 2 MnReO 6 , may have an excellent figure of merit surpassing 0.6 at temperatures over 600 K. [ABSTRACT FROM AUTHOR]

Polycrystalline Gd 2 NiIrO 6 double perovskite compound was synthesized by the solid-state route. Rietveld refinement of the X-ray diffraction pattern revealed that the compound was crystallized in a monoclinic structure with P 2 1 / n space group (IUCr. No. 14). The scanning electron micrograph showed that the grains were spherical and well distributed with an average grain size of around 1 μm. The temperature-dependent magnetic measurements showed magnetic transitions at 165 K and 149 K in the low-temperature region. Below the transition temperatures, weak ferromagnetism was evidenced by field-dependent magnetization measurements. Exchange bias effects were observed which were driven by Dzyaloshinsky–Moriya interactions in the compound. The UV–visible measurement evidenced that the compound had an optical band gap of 1.8 eV. The electronic structure calculations using the DFT + U method revealed that Gd 2 NiIrO 6 compound exhibited a bandgap only when on-site correlations for the d -states were included, and the calculation showed that the AF1 configuration was energetically favourable. [ABSTRACT FROM AUTHOR]

[Display omitted] • Double perovskite Ca 2 MgWO 6 : x % Eu3+ (x = 1–11 mol) luminescent systems were synthesized via gel-combustion route. • Photoluminescence emission spectra show a prominent red emission peak at 616 nm. • The photometric studies of the phosphors portray their red emission with excellent color purity. • The innovative and reliable anti-counterfeiting patterns were developed using a prepared system. The rapid escalation of counterfeiting activities in recent years has posed significant challenges across diverse fields, such as pharmaceuticals, currency, luxury goods, and electronics. In response, inorganic phosphors have emerged as promising tools to combat counterfeiting due to their inherent durability and stability. The present work focuses on the synthesis of Ca 2 MgWO 6 : x % Eu3+ (x = 1–11 mol) luminescent systems via a gel-combustion route. The structural analysis of the synthesized luminescent systems confirmed a monoclinic crystal phase with a P2 1 /n space group. The morphological study of the luminescent system revealed a network-like structure comprising interconnected particles. Photoluminescence emission spectra show a prominent red emission peak at 616 nm, corresponding to the 5D 0 → 7F 2 4f–4f electronic transition of Eu3+ ions in the host matrix. The emitted red light demonstrates a color purity and quantum efficiency of 93.1 % and 77.41 %, respectively. The anti-counterfeiting security patterns were developed using the Ca 2 MgWO 6 : x % Eu3+ (x = 9 mol) luminescent system, which showcases virtually invisible under normal light. However, developed patterns exhibit vivid red luminescence when exposed to multiple stimuli i.e., ultraviolet light at 365 and 395 nm wavelength, which envisages the versatility of the systems for enhancing product authentication and protecting against fraudulent activities across multiple industries. The aforementioned results demonstrated the efficacy of Ca 2 MgWO 6 : Eu3+ luminescent systems for integration into advanced security measures. [ABSTRACT FROM AUTHOR]

[Display omitted] • The physical properties of Li 2 AgAsZ 6 (Z = F, Cl, Br, I) are calculated via First-principle method. • Structural and thermodynamic stability of these materials are demonstrated by theoretical calculations. • Li 2 AgAsZ 6 (Z = F, Cl, Br, I) exhibits indirect band gaps. • Materials have potential to use in optoelectronic devices. • The higher ZT values suggest the suitability to use in thermoelectric devices. Using density functional theory, the current investigation investigates the physical attributes of the halide double perovskites Li 2 AgAsZ 6 (Z = F, Cl, Br, I). The cubic layout and values of the octahedral and tolerance factors have been evaluated to confirm phase stability. The formation energy of each perovskite has been calculated to ensure thermodynamic stability. The electronic properties have been elaborated, which indicates the semiconductor behavior of Li 2 AgAsZ 6. The calculations exhibited that the energy band gaps of Li 2 AgAsF 6 , Li 2 AgAsCl 6 , Li 2 AgAsBr 6 , and Li 2 AgAsI 6 are 2.35 eV, 2.08 eV, 1.57 eV, and 1.05 eV, respectively. We also computed and comprehensively studied the optical characteristics of these materials in the energy range of 0–8 eV. These materials demonstrate absorption bandwidth in the visible range and are viable contenders for optoelectronic applications. To determine the transport and thermodynamic aspects, we used the BoltzTraP and Gibbs2 codes, respectively. The figures of merit values are observed as 0.79, 0.77, 0.76, and 0.71, respectively. Thermodynamic properties confirm the high-temperature stability of studied materials. Finally, these perovskites can benefit photovoltaic and thermoelectric devices, further requiring experimental validation. [ABSTRACT FROM AUTHOR]

Efficient oxygen reduction kinetics as well as excellent stability are the main goals of current electrode materials for solid oxide fuel cells (SOFCs). Here, we present the latest findings regarding the augmentation of performance in SOFC through utilization of a novel heterogeneous cathode, consisting of an excess cation-deficient double perovskite Nd 0.9 BaCo 2 O 5+ δ (NBC90) backbone and in situ exsolved BaCo 1- y Bi y O 3- x nanoparticles modified by bismuth (NBC90+B). The anisotropic growth of such self-assembled nanoparticles and the formation of multiple heterointerfaces exhibit an extremely strong activation effect. The in situ formed BaCo 1- y Bi y O 3- x nanoparticles and cation-deficient NBC90 parental perovskite significantly enhance the catalytic activity and durability of the cathode toward oxygen reduction. The structural stability and CO 2 tolerance of the cathode are greatly enhanced, which is attributed to the penetration of the high acidic Bi ions in the separated phase and the synergistic effect of the two-phase interface. The results unequivocally demonstrate the exceptional stability and efficiency of the NBC90+B composite as a promising cathode candidate for SOFCs. [Display omitted] • Bismuth ion modified NBC90+B self-assembled heterostructure cathode was prepared. • The formation of heterointerfaces exhibit an extremely strong activation effect. • The in-situ growth of nanoparticles can significantly enhance the catalytic activity • NBC90+B heterostructures exhibit excellent ORR activity remarkable CO2 tolerance. [ABSTRACT FROM AUTHOR]

• Ferromagnetic phase of Ba 2 InOsO 6 is most stable, with magnetism from osmium (Os). • Ba 2 InOsO 6 shows half-metallicity, with a 3.62 eV band gap (TB-mBJ+U), reduced by SOC. • Material displays n-type conductivity and high thermopower for thermoelectric use. • DFT with Hubbard U correction and SOC models electronic and magnetic properties. • Electronic and magnetic traits suggest potential in spintronic applications. In this study, we comprehensively investigate the structural, electronic, magnetic, elastic, and thermal properties of the double perovskite Ba 2 InOsO 6 using density functional theory (DFT). Our results show that the ferromagnetic phase is the most stable, with the net magnetic moment primarily arising from the Os atom. The half-metallic behavior exhibited by Ba 2 InOsO 6, characterized by a band gap of 3.62 eV in the TB-mBJ + U approximation, decreases upon the inclusion of spin–orbit coupling (SOC). This half-metallic property, coupled with the stability of the ferromagnetic phase, makes Ba 2 InOsO 6 particularly suitable for spintronic applications, as it can facilitate efficient spin injection and transport. Elasticity analysis indicates moderate brittleness, while thermoelectric properties, calculated using the Boltzmann transport model, reveal n-type conductivity and notable thermopower, suggesting potential for thermoelectric applications. This work provides a solid foundation for future experimental studies and potential applications in advanced technologies. [ABSTRACT FROM AUTHOR]

• Vanadium was successfully doped by citric acid-glycine combustion method. • The existence of V reduced the alkalinity and enhanced its stability. • V doping significantly improved the long-term stability of SSOCs. Using solid oxide cells to produce and utilize hydrogen is an effective method for addressing energy demands. In this study, vanadium (V) was doped into the B site of the La 0.3 Sr 1.7 Fe 1.3 Ni 0.2 Mo 0.5 O 6-δ double perovskite, which served as the electrode material for symmetrical solid oxide cells. Doping with high-valence V4+/V5+ reduced both the average Fe valence state and the concentration of oxygen vacancies, while simultaneously decreasing the reducing activity of the material and enhancing its stability. After operating at 750 °C and ± 400 mA cm−2 for 150 h, the degradation rates for Cell-LSFNM were 4.56 % and 8.32 %, respectively, while those for Cell-LSFVNM were only 0 % and 3.32 %, respectively. Although V doping slightly diminished the electrochemical performance of the single cell, it significantly improved long-term operational stability in solid oxide fuel/electrolysis cell (SOFC/SOEC) modes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dy3+ doped Ca 2 SrWO 6 down-conversion phosphor was prepared via the combustion synthesis. • The phosphor under study exhibited excellent white PL emission upon 278 and 388 nm excitations. • The LED parameters, thermal stability and PL quantum efficiency are determined. • The photometric analysis includes determination of CIE color coordinates, color purity, and CCT. Luminescent Ca 2 SrWO 6 :Dy3+ double perovskites are synthesized via the combustion route of material synthesis, wherein urea is taken as fuel. The as-prepared phosphor series comprehensively characterized for their structural and photoluminescence (PL) properties. The Rietveld refinement of XRD data revealed monoclinic crystallized microcrystals with mixed particles of the size of less than 1 µm, studied via SEM. Ca 2 SrWO 6 :Dy3+ displayed standard Dy3+ transitions 4F 9/2 –6H 15/2 (blue emission) and 4F 9/2 –6H 13/2 (yellow emission) collectively resulted in white light emission, confirmed via CIE study. Under 278 and 388 excitations, 2 mol% doping of Dy3+ found to be optimum concentration, beyond which concentration quenching is observed due to dipole–dipole interaction. The Y/B ratio ∼1 shows potential to produce white light and make phosphor suitable for WLED applications. The Ca 2 SrWO 6 :Dy3+ phosphor displayed notably high thermal stability with PL intensity persisted 77.6 % at LED burning temperature (150 °C) when compared to PL intensity attained at room-temperature, which is basically due to the rigid perovskite structure. In addition, the PL decay lifetime of 4F 9/2 state was calculated by utilizing decay curves. Subsequently, the PL quantum efficiency and non-radiative relaxation rate are determined. The theoretical model of Auzel's fit function is used to calculate to quantum efficiency and was found to be 93.27 % for Ca 2 SrWO 6 :2 % Dy3+ phosphor. Moreover, the photometric results reveals that the CIE points are lies in white region of CIE diagram with comparable CCT. The collective results indicated the utility of the phosphor for potential WLED applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Landau theory has been exploited to generate isothermal M (H, T) curves near PM-FM phase transition. • An iterative method based on modified Arrott plot was used to determine critical exponents. • The β, γ and δ critical exponents are verified with various techniques. • The critical exponents identified (β, γ, and δ) do not belong to any universally recognized classes. • The obtained critical exponents fulfill Widom scaling relation. In this paper we investigate the critical aspects of our La 2−x Ce x/2 Er x/2 NiMnO 6 samples with (x = 0.00, 0.025 and 0.035) during the paramagnetic (PM) – ferromagnetic (FM) phase transition by observing the relationship between magnetization (M) and magnetic field (µ o H). This approach relies on an iterative strategy that employs modified Arrott plots. Firstly the Landau theory was used to generate isothermal M (H, T) curves near the PM – FM phase transition. Afterwards, alternative methods were used to evaluate the critical exponents acquired for manganite materials, including the Kouvel-Fisher (KF) approach and the critical isotherm (CI) around T C. Furthermore, Widom's scaling law (δ = 1 + γ/β) was employed to validate the precision of the critical exponent parameters. Additionally, the scaling formula identified by M H , ε = ε β f ± H ε β + γ with ε = (T − T C)/T C was utilized to further validate the appropriateness of the obtained exponents. According to the scaling formula, two separate branches of the M-µ o H-T curves were observed; one above and another below T C. Moreover, the exponents determined in this study did not belong to any universally recognized classes. These results suggest that the critical phenomenon in our samples, which was an inhomogeneous ferromagnet around T C , influenced by magnetic disorder due to oxygen vacancies, cannot be described within the framework of existing universality classes and probably belong to a separate class. [ABSTRACT FROM AUTHOR]

The study aimed at simulating a model of bilayer La 2 NiMnO 6 /MASnI 3 hybrid perovskite solar cell having a potential benefit of better stability at higher operating temperature with higher band gap of LNMO. This numerical analysis of La 2 NiMnO 6 /MASnI 3 based hybrid solar cell performance parameters has been carried out as a function of temperature and optical band gap (E g) of La 2 NiMnO 6 (LNMO). The analysis reveals that the fill factor of solar cells operated at room temperature has not been affected too much on varying E g of LNMO and decreases non-linearly with increasing operating temperature. The open circuit voltage of solar cells operated at room temperature increases with increasing E g of LNMO and drops linearly with increasing operating temperature. The short-circuit current density (J SC) increases non-linearly at different rates with increasing the operating temperature. The value of dη/dT increases up to a critical temperature (T c) and then decreases in the solar cells comprised with higher E g of LNMO (E g ∼ 1.50 eV–1.60 eV). The T c value was shifted towards higher operating temperature in the higher E g of LNMO (E g ≥ 1.50 eV), enabling more stable solar cell at higher operating temperature. • SCAPS-1D simulation of La 2 NiMnO 6 /MASnI 3 based solar cell devices. • Band gap of oxide double perovskite La 2 NiMnO 6 and temperature affect the performance of solar cells. • The bilayer solar cell structure provides wide range of absorption spectrum with enhanced efficiency. • Higher band gap of La 2 NiMnO 6 provides high range operating temperature of the solar cell. [ABSTRACT FROM AUTHOR]

The generation of high-quality syngas combined with high-purity hydrogen is an essential challenge in the chemical looping steam methane reforming (CL-SMR) process, in which the design of oxygen carriers (OCs) is crucial. In this study, La 2 FeBO 6 (B Cr, Ni，Co) and La 2 Fe 2-x Co x O 6 (x = 0.2, 0.4, 0.6, 0.8, 1.0) double perovskites have been investigated as OCs in the CL-SMR process. Various analytical techniques (BET, XPS, XRD, H 2 -TPR, Raman.) have been deployed to characterize the OCs' specific surface area, crystal structure, and surface oxygen species. The fixed-bed experiments revealed that the Cr-modified perovskite had the lowest reactivity, which was attributed to the creation of LaCrO 3 limiting the oxygen release rate of the OC. Meanwhile, Ni doping exhibited the maximum methane conversion (99.15 %), but it resulted in more carbon deposition due to methane cracking, and its carbon deposition was four times than that of Co doping. Whereas, the Co doped double perovskite OCs showed excellent overall performance, in which La 2 Fe 1.8 Co 0.2 O 6 (L 2 F 1.8 Co 0.2) exhibited the optimum CO selectivity (90.72 %), H 2 selectivity (96.91 %), and H 2 purity (96.84 %), as well as the lowest carbon deposition. Moreover, the L 2 F 1.8 Co 0.2 also exhibited outstanding stability in 10 cycles, and it could be a prospective material for CL-SMR, enabling the simultaneous generation of high-quality syngas and high-purity hydrogen. [Display omitted] • The effect of transition metal （Cr、Ni、Co） doping on the perovskite was elucidated. • The formation of La 2 NiO 4 in La 2 FeNiO 6 was detrimental to its activity. • Less Co doping in oxygen carriers could help reduce carbon deposition. • La 2 Fe 1.8 Co 0.2 O 6 exhibited an optimal CO selectivity of 90.72 %. • La 2 Fe 1.8 Co 0.2 O 6 showed an excellent reaction stability. [ABSTRACT FROM AUTHOR]