Ion Substitution Research Articles

First-principles investigations on the structural and optoelectronic properties of lead-free perovskite Mn:CsSnX3

Nontoxic metal halide perovskites have become a research hotspot in the field of solar cells and other optoelectronic devices. However, low power conversion efficiency owing to their instability limits their wide practical applications. Herein, the structural stability and optoelectronic properties of 12.5% Mn-doped CsSnX3 (X = I, Br, and Cl) perovskite systems were investigated via first-principles computations. The investigations of the formation energy and mechanical parameters indicated that Mn-doping improved the structural stability. As for electronic properties, the band structures of CsSnX3 changed from direct to indirect bandgap after Mn-doping because of the modulation of the crystal field between ions caused by the substitution of Sn ions with Mn ions. The optical properties of the CsSn0.875Mn0.125X3 perovskite were studied, including absorption coefficient, extinction coefficient, reflectivity, and refractive coefficient. The results of this work provide theoretical support for the design of next-generation lead-free and low-toxicity optoelectronic and photovoltaic materials and devices.

A Porphyrin-Based MOF Thin Film with Oriented Nanosheet Arrays for Optimizing a Nonlinear Optical Response.

Developing two-dimensional (2D) hybrid nanosheet arrays integrating inorganic and organic components is highly significant for third-order nonlinear optical (NLO) applications. Herein, an oriented 2D porphyrin-based MOF (ZnTPyP(Co)) thin film composed of vertically stacked ultrathin nanosheets was fabricated via the liquid-phase epitaxial (LPE) layer-by-layer (LBL) method. The prepared ZnTPyP(Co) thin film exhibits an outstanding third-order NLO response with a high third-order nonlinear susceptibility of ∼2.63 × 10-7 esu, which is ascribed to the hybrid nanosheet array structure. Additionally, experimental Z-scan measurement and theoretical calculations also demonstrate that the substitution of Co metal ions in the porphyrinic core can increase the level of delocalization of the porphyrinic group and contribute to the material's enhanced NLO properties. These findings not only provide new film candidates for NLO application but also highlight the potential of 2D MOF nanosheets in advanced optical devices.

Structural, Electronic, and Magnetic Properties of Gd-Substituted Bi2Fe4O9 Multiferroic: A Combined Experimental and DFT Approach

Abstract We present the structural, electronic, and magnetic properties of Gd3+ substituted Bi2Fe4O9 (BFO) via experimental analysis as well as density functional theory (DFT). Rietveld refined X-ray diffraction data shows phase purity of the samples having orthorhombic phase with space group: ‘Pbam’. Gd3+ ions substitution at Bi3+-site is confirmed by the shift in peaks ((002) and (220)) at higher 2θ angles as well as the reduction in lattice parameters. The PBE+U calculations predict a band gap of 1.76 eV (BFO) and 1.6 eV (Gd substituted BFO) which is in close agreement with the experimental values. This reduction in band gap due to Gd3+ substitution enhances conduction in substituted samples. The calculated density of states illustrates considerable hybridization between Fe-3d and O-2p states with substantial overlap among the Bi-6p and O-2p states. Incorporating Gd3+ ions further introduces additional exchange interactions between Gd-Fet and Gd-Feo, thus leading to enhanced magnetization as well as an increase in antiferromagnetic transition temperature (TN). This characteristic feature is supported by temperature-dependent magnetic susceptibility (χ) and dχ/dT plots. Hence, our experimental and theoretical findings suggest that BFO and its substituted samples are potential multiferroic materials for various device applications.

Tunable Optical Properties and Relaxor Behavior in Ni/Ba Co-Doped NaNbO3 Ceramics: Pathways Toward Multifunctional Applications

In this study, Ni/Ba co-doped NaNbO3 ceramics (NBNNOx) were synthesized using a solid-state method to explore the effects of Ni2+ and Ba2+ ion substitution on the structural, optical, and dielectric properties of NaNbO3. X-ray diffraction (XRD) confirmed that the ceramics retained an orthorhombic structure, with crystallinity improving as the doping content (x) increased. Significant lattice distortions induced by the Ni/Ba co-doping were observed, which were essential for preserving the perovskite structure. Raman spectroscopy revealed local structural distortions, influencing optical properties and promoting relaxor behavior. Diffuse reflectance measurements revealed a significant decrease in band gap energy from 3.34 eV for undoped NaNbO3 to 1.08 eV at x = 0.15, highlighting the impact of co-doping on band gap tunability. Dielectric measurements indicated relaxor-like behavior at room temperature for x = 0.15, characterized by frequency-dependent anomalies in permittivity and dielectric loss, likely due to ionic disorder and structural distortions. These findings demonstrate the potential of Ni/Ba co-doped NaNbO3 ceramics for lead-free perovskite solar cells and other functional devices, where tunable optical and dielectric properties are highly desirable.

Effect of Rare Earth doping on Structural, Morphological, Optical, and Magnetic Properties of the Y1-x(Gd, Dy)xBaCuFeO5+δ (x = 0.2, 0.4, 0.6, and 0.8) Ceramics

The effect of the rare earth (RE) ion substitution on the structural, morphological, optical and magnetic properties of the Y1-xRExBaCuFeO5 (RE = Gd, Dy; x = 0.2, 0.4, 0.6, and 0.8) multiferroic compounds grown by the solid-state reaction is evaluated using X-ray diffraction (XRD), scanning electron microscopy (SEM), dispersive X-ray spectroscopy (EDX), reflectance spectroscopy techniques diffuse (UV-vis-NIR) and vibrating sample magnetometry (VSM). The results indicate that the RE substitution led to growth of single-phase materials, with a tetragonal structure and P4mm symmetry. The morphological analysis shows the formation of polycrystalline materials composed of grains of various shapes and sizes. Furthermore, the compositional analysis reveals that the materials do not present elements other than those used in the synthesis. The band gap (Eg) is tuned from 0.88 to 0.90 eV upon RE substitution. The magnetization curves obtained in the Zero-Field-Cooled/Field-Cooled (ZFC-FC) modes between 50 and 390 K, reveal a paramagnetic behavior, which could be attributed to the dominance exerted by the magnetic moments of the Gd/Dy ions.

Modulating the chemical environment of Ni2+ for the oxidative dehydrogenation of ethane: The formation of LAS(Al3+/Ga3+)-Ni-OH site

The oxidative dehydrogenation of ethane to ethylene (ODHE) usually suffers from the issues of ethane conversion-ethylene selectivity seesaw. Herein, a series of alumina-supported Ni and Ga catalysts with different molar ratios of Ni to Ga were synthesized by facile impregnation method constructing the Lewis acid site (LAS) strategy to obtain great ethylene selectivity (97 %). The variation of Ni:Ga ratio adjusted the ionic substitution ability, redox ability and acidity, thus regulate the chemical environment of Ni2+ to the formation of LAS(Al3+/Ga3+)-Ni-OH structure, which was proposed to be the active site for selective oxidation of ethane to ethylene, as proved by H2-TPR, ToF-SIMS, quasi in-situ XPS and in-situ FTIR. Moreover, the probable mechanism of ODHE reaction was proposed that C2H6 molecules were mainly adsorbed on LAS sites and activated on Ni-OH site of the catalyst. The pulse test further suggested that O- was mainly associated with the generation of CO2 and Ni(2-n)+ was connected with the production of CH4. It is highlighted that adjusting the Ni-related species and oxygen species on the catalyst surface are crucial to further improve the ethylene selectivity.

Donnan Dialysis-based Approach for Reclamation of Waste Acid with a Low Concentration

This study provides a proof-of-concept investigation into the direct utilization of low-concentration recovered acid as a proton source for the efficient recovery of organic acids via Donnan dialysis, a scenario of particular significance in industrial parks. A primary objective is to examine the implications of waste acid concentration on the coupling process. To evaluate the technological feasibility, process simulations are performed utilizing a mathematical model grounded in the Nernst-Planck equation and associated equilibrium relationships. Furthermore, a variety of experimental conditions, encompassing different types of organic acids and varying concentrations of waste acid, are explored to analyze the ion substitution behaviors involved. The findings from both simulations and experiments indicate that weaker organic acids demonstrate superior performance, particularly regarding recovery rates and process efficiency. Additionally, it is revealed that merely increasing the concentration of the draw solution does not constitute an effective approach for improving the DD-based organic acid recovery process, thereby suggesting the potential for the direct application of low-concentration recovered acid. Given its significant advantages, the proposed DD-based coupling technology shows considerable promise for future applications.

The Influence of Fe-Doping on the Structural, Electrical and Magnetic Behavior of Mechanically Activated SrTiO3 Ceramics

This research focused on the structural, dielectric and magnetic properties of Fe-doped strontium-titanate (SrTiO3) ceramics prepared from mechanically activated powders. A solid-state method was used for powder preparation with mechanical activation times of 10, 30 and 120min. The SrTiO3 ceramics were doped with various iron(III) oxide (Fe2O3) contents of 1.5wt%, 3wt% and 6wt%. X-ray diffraction analysis showed the presence of structure distortion due to ion substitution which caused changes in lattice parameter. For samples activated for 30 and 120min Fe ions were predominantly incorporated onto Sr sites for 3wt% Fe2O3, while for 6wt% Fe2O3 Fe ions were predominantly incorporated onto Ti sites. Microstructural analysis showed that the 120min activated sample (6wt% Fe2O3) had the highest homogeneity and bulk density (4.75gcm-3). Also, this sample exhibited multiferroic behavior as a consequence of the incorporation of Fe ions onto Ti sites in the structure, where magnetic properties are induced by doping without significantly impairing the dielectric properties. Based on these results, the optimal electrical and magnetic properties of SrTiO3 ceramics can be achieved by the appropriate choice of mechanical activation time and dopant concentration.

Microwave Absorption and Magnetic Properties of M-Type Hexagonal Ferrite Ba0.95Ca0.05Fe12-xCoxO19 (0 ≤ X ≤ 0.4) at 1-18 GHz.

In order to improve the microwave-absorption performance of barium ferrite and broaden its microwave-absorption band, BaFe12O19, Ba0.95Ca0.05Fe12O19, and Ba0.95Ca0.05Fe12-xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites were synthesized by the solid-state reaction method, and the influence of Co ion substitution on the phase composition, microstructure, magnetic properties, and microwave-absorption ability of the ferrites in this system was studied. Introducing minor Co ions (x < 0.2) facilitated sintering and grain growth. At x ≥ 0.2, XRD revealed the emergence of the Co2X phase alongside the BaM phase. Increasing Co ion concentration and the secondary X-phase led to slight reductions in saturation magnetization (69 to 63.5 emu/g) and substantial decline in coercivity (2107.02 to 111.21 Oe), attributed to grain size growth and Co2X's soft magnetic nature. Notably, Co2X incorporation significantly enhanced the microwave absorption and provided a tunable absorption band from the Ku to the C band. For a sample with a thickness of 2.0 mm and a doping level of x = 0.2, a minimum reflection loss of -59.5 dB was achieved at 8.92 GHz, with an effective absorption bandwidth of 3.31 GHz (7.07-10.38 GHz). The simple preparation method and good performance make Ba0.95Ca0.05Fe12-xCoxO19 (x = 0.1, 0.2, 0.3 and 0.4, respectively) hexaferrites promising microwave-absorbing materials.

Exploiting Deep‐Ultraviolet Nonlinear Optical Material Rb2ScB3O6F2 Originated from Congruously Oriented [B3O6] Groups

AbstractThe exploration and research for deep‐ultraviolet (UV) nonlinear optical (NLO) crystals are of great significance for all‐solid‐state lasers. This work is based on the excellent structural [B3O6] units which manipulate the excellent performances of famous commercial NLO crystal β‐BaB2O4 (β‐BBO) to explore new alternatives of deep‐UV NLO materials. A deep‐UV rare‐earth metal borate fluoride Rb2ScB3O6F2 (RSBF) is successfully designed by combining the heterovalent ions substitution strategy, and fluorination strategy. Expectedly, RSBF exhibits an extremely short cutoff edge below 175 nm (189 nm for β‐BBO), and a moderate birefringence of 0.088 at 1064 nm. The shortest phase‐matching (PM) wavelength of RSBF (λPM=182 nm) is shortened by 23 nm compared with β‐BBO (λPM=205 nm) due to the improvements in the chromatic dispersion and cutoff edge, and an experimental frequency‐doubling effect 1.4×KH2PO4 (KDP) further suggests that RSBF can output a deep‐UV harmonic laser. This work provides new sights from the original influencing factors for the rational and purposeful design of deep‐UV NLO materials.

Exploiting Deep-Ultraviolet Nonlinear OpticalMaterial Rb2ScB3O6F2 Originated from Congruously Oriented [B3O6] Groups.

The exploration and research for deep-ultraviolet (UV) nonlinear optical (NLO) crystals are of great significance for all-solid-state lasers. This work is based on the excellent structural [B3O6] units which manipulate the excellent performances of famous commercial NLO crystal β-BaB2O4 (β-BBO) to explore new alternatives of deep-UV NLO materials. A deep-UV rare-earth metal borate fluoride Rb2ScB3O6F2 (RSBF) is successfully designed by combining the heterovalent ions substitution strategy, and fluorination strategy. Expectedly, RSBF exhibits an extremely short cutoff edge below 175 nm (189 nm for β-BBO), and a moderate birefringence of 0.088 at 1064 nm. The shortest phase-matching (PM) wavelength of RSBF (λPM=182 nm) is shortened by 23 nm compared with β-BBO (λPM=205 nm) due to the improvements in the chromatic dispersion and cutoff edge, and an experimental frequency-doubling effect 1.4×KH2PO4 (KDP) further suggests that RSBF can output a deep-UV harmonic laser. This work provides new sights from the original influencing factors for the rational and purposeful design of deep-UV NLO materials.

Temperature stable (1-x)BaAl2Si2O8-xBa3V2O8 (0.2 ≤ x ≤ 0.5) microwave dielectric composite ceramics for LTCC applications

BaAl2Si2O8 microwave dielectric ceramics possess dielectric properties of low permittivity (εr) and low loss, coupled with low synthesis cost, making them promising for commercialization. However, the hexagonal structure undergoes high-temperature phase transitions that deteriorate thermal shock resistance and durability, hindering its practical use. In this work, we report temperature-stable BaAl2Si2O8-Ba3V2O8 low temperature co-fired ceramics (LTCC). The combination of Ba3V2O8 and G9 glass achieved a near-zero τf and a thermal expansion coefficient of ∼ 8.5 ppm/℃, significantly enhancing the temperature stability of BaAl2Si2O8 ceramics. By employing ion substitution and enhancing lattice disorder, the components of G9 glass were strategically designed to successfully induce hexagonal-to-monoclinic transformation of BaAl2Si2O8 phase. The dielectric properties of 0.5BaAl2Si2O8-0.5Ba3V2O8-9 wt% G9 sintered at 900 ℃ were εr ∼9, Q×f ∼22,000 GHz and τf ∼ +1.9 ppm/℃. Good chemical compatibility with silver powders was confirmed by further investigation of the co-firing behavior. This work provides attractive candidate for BaAl2Si2O8-based LTCCs and an available approach for modifying BaAl2Si2O8 ceramics.

Preparation and Luminescence Property Study of Red-Emitting Na3.6Y1.8(PO4)3:Eu3+,Li+/K+ Phosphors with Excellent Thermal Stability for Light-Conversion Application.

A series of red-emitting phosphors, Na3.6Y1.8-x(PO4)3:xEu3+, have been synthesized by a high-temperature solid-phase method. The impact of the partial Li+/K+ ion substitution on the crystal structure and photoluminescence (PL) performance of Na3.6Y1.05(PO4)3:0.75Eu3+ phosphor have been investigated. Various techniques have been used for characterization of the as-obtained materials. X-ray diffraction (XRD) analysis was utilized to confirm the composites of these samples, and the morphology and element distribution were examined by scanning electron microscope (SEM) and transmission electron microscope (TEM). This study found that the developed Na3.6Y1.8-x(PO4)3:xEu3+ phosphors exhibited a prominent emission peak at ~620 nm when excited at 393 nm, which corresponded to 5D0 → 7F2 transitions of Eu3+ ions. Furthermore, the robust emission peak at ~705 nm (5D0 → 7F4) of these phosphors enables a better match with plant pigment absorption. Beyond that, the partial substitution of Li+/K+ ions probably changed the crystal structure, and reduces the symmetry around Eu3+, leading to significantly enhanced luminous intensities by 23.24% and 18.29%, with the highest quantum yields (QYs) reaching 99.85% and 96.29%, respectively. Additionally, the prepared phosphors show non-thermal quenching and superior thermal stability at elevated temperatures from 298 to 473 K. These findings and results suggest that Li⁺/K⁺-substituted Na3.6Y1.05(PO₄)₃:0.75Eu3⁺ phosphors can serve as promising red-emitting phosphors for plant lighting applications.

Assessment of the influence of glycol and alcohol on the morphology and protective properties of iron carbonate in carbon dioxide corrosion of gas pipelines

The potential effect of hydrate formation inhibitors (glycols, alcohols) — components of the liquid phase of gas pipeline operating media — on carbon dioxide corrosion during the transport of aggressive gas has not been sufficiently studied. The paper presents the results of a study of the corrosive effect of glycol (alcohol) present in the liquid phase on the composition and properties of corrosion products on steel when modeling the main aggressive factors under conditions of transport of CO2-containing gas. On a corrosion stand, the aggressive conditions of alternating wetting of gas pipeline walls with water were reproduced. The fluid circulation characteristic of a partially filled pipeline can have an effect on preventing the formation or destruction of films of corrosion products (iron carbonate, siderite) on the steel surface. In places of cracking and peeling of siderite formed in the presence of CO2, conditions will be created for the formation of general and local corrosion damage. During simulation tests, monoethylene glycol and isopropanol, as well as their aqueous solutions of different concentrations, were used. For the first time, data on the formation and composition of non-stoichiometric siderite in water-glycol and water-alcohol media at CO2 partial pressures and temperature were obtained. By processing diffraction patterns obtained by X-ray diffraction, the degree of substitution of iron ions in non-stoichiometric siderites by other cations was determined. The dependence of the degree of substitution on the concentration of alcohol (glycol) in their aqueous solutions was analyzed. It was revealed that with an increase in glycol concentration, a decrease in the rate of local corrosion is observed. With a high glycol content, internal corrosion is completely suppressed in the presence of CO2. It has been established that in aqueous-alcoholic media at elevated temperatures, local carbon dioxide corrosion does not occur. This is apparently due to the uneven distribution of water and alcohol in the mixture. The results obtained can be used in assessing internal carbon dioxide corrosion in the presence of glycol (alcohol), used at gas facilities as an inhibitor of hydrate formation.

Energy band gap tuning of Ba-Ca hexagonal ferrite by Dy3+ ion substitution (0 ≤ x ≤ 0.2) to improve spectral, structural, dielectric and photocatalytic properties

In the present study, Dy3+ substituted M-type Ba0.5Ca0.5DyxFe12-xO19 (0.00 ≤ x ≤ 0.20) hexagonal ferrites were synthesized using sol-gel auto-combustion method with lemon extract as a fuel. The single hexaferrite phase with space group P63/mmc is revealed by the X-ray powder diffraction (XRD) patterns. The Field emission scanning electron microscopy (FESEM) exhibits the agglomeration of nanoplates with vacancies at some places. Energy dispersive X-ray photoelectron spectroscopy (EDAX) mapping confirmed the presence of Ba, Ca, Fe, O, and Dy in the hexaferrite. Fourier Transform Infrared (FTIR) spectroscopy exhibits two characteristic bands at 579 and 429 cm−1 corresponding to tetrahedral and octahedral metal ions-oxygen stretching, revealing the occurrence of the ferrite phase. The optical energy band gap calculated using the Tauc plots was found to increase with the increase in dysprosium substitution to fall within the range of 2.8–3.5 eV. The Raman spectra confirmed the Raman vibration modes and M-type structures of hexagonal ferrites (HFs). The dielectric constant values drop rapidly with increasing frequency up to a few KHz and then gradually for the further higher frequencies. The occurrence of Ba and Ca with 2+, while Dy, and Fe with 3+ oxidation states is confirmed using X-ray photoelectron spectroscopy (XPS). The HFs exhibit remarkable efficiency by degrading the Reactive Brown dye to 99.3 % in just 15 min, equivalent to a high degradation reaction rate constant (k) value of up to 0.0396 min−1. Consequently, the catalyst shows promising potential for environmental remediation.

CuO and spinel CuCo2O4 supported on mesoporous nanocubes with dual redox-active centers for electrocatalytic H2O2 reduction and sensing

The copper hexacyanoferrate (CuHCF) nanocube and its cobalt-substituted analogue (CoCuHCF) possess numerous micropores; however, they demonstrate limited electrocatalytic performance for H2O2 reduction. Heat treatment of CuHCF in air (CuHCF-ht) results in the formation of CuO and Fe3O4 with noticeable aggregation. In contrast, the heat treatment of CoCuHCF in air (CoCuHCF-ht) preserves its nanocube structure while also forming a spinel CuCo2O4 phase. The partial substitution of cobalt ions for copper ions in CuHCF enhances both thermal and structural stability, leading to the transformation of micropores into mesopores during heat treatment. This transformation improves electrolyte accessibility and structural integrity. The CoCuHCF-ht electrode features dual redox-active centers (Cu+/Cu2+ couple) derived from the CuO and CuCo2O4 phases, serving as catalytic redox mediators for H2O2 reduction. This dual redox activity results in superior performance for H2O2 reduction compared to CuHCF-ht, which only exhibits a single pair of Cu+/Cu2+ couple from CuO as an active mediator. This enhanced performance is evidenced by a lower Tafel slope, a higher catalytic rate constant, and improved mass transfer of analytes. The CoCuHCF-ht catalyst, characterized by dual redox-active centers in mesoporous nanocubes, demonstrates a high sensitivity of 234.03 μA mM−1 cm−2 and a low limit of detection (0.26 μM), along with high selectivity, stability, repeatability, and reproducibility.

Triggering Asymmetric Layer Displacement Polarization and Redox Dual-Sites Activation by Inside-Out Anion Substitution for Efficient CO2 Photoreduction.

Sluggish bulk charge transfer and barren catalytic sites severely hinder the CO2 photoreduction process. Seeking strategies for accelerating charge dynamics and activating reduction and oxidation sites synchronously presents a huge challenge. Herein, an inside-out chlorine (Cl) ions substitution strategy on the layered polar Bi4O5Br2 is proposed for achieving layer structure-dependent polarization effect and redox dual-sites activation. Cl ions in the bulk phase shrink the halogen layer interspace by 8‰, triggering asymmetric [Bi4O5]2+ layer displacement polarization, prolonging the average photocharge lifetime to 201.8ps. Meanwhile, surface substituted Cl ions enhance the electron-donating capability of neighboring Bi atoms, activating the intrinsic Bi reduction sites, and increasing H2O molecule adsorption on nearby intrinsic O oxidation site (cal. by 0.105eV), also self-donating as an alien oxidation site. Besides, Cl upshifts the p-band center closer to the Fermi level, facilitating the reactant adsorption. Therefore, the energy barrier for CO2 activation and rate-limiting *COOH intermediate formation steps are significantly decreased. Without cocatalysts and sacrificial reagents, inside-out Cl-substituted Bi4O5Br2 delivers a remarkable CO2-to-CO photoreduction rate of 50.18µmol g-1 h-1, being one of the state-of-the-art catalysts. This finding offers insights into exploiting polarization at the molecular-level and enhances understanding of catalytic site activation.

Metal-organic frameworks with a sulfur-rich heterocycle: synthesis, gas adsorption properties, and metal exchange.

Three new three-dimensional (3D) metal-organic frameworks [M2(ttdc)2(dabco)] (M = Zn(II), 1-Zn; Cu(II), 1-Cu; and Zn/Cu, 1-ZnCu) based on thieno[3,2-b]thiophene-2,5-dicarboxylate (ttdc2-) were synthesized and characterized by a combination of physicochemical methods (single crystal X-ray diffraction, powder X-ray diffraction, chemical and thermogravimetric analyses and IR spectroscopy). 1-Cu demonstrated permanent porosity (Vpore = 0.790 cm3 g-1 and SBET = 1725 m2 g-1) and significant CO2, CH4, C2H2, C2H4 and C2H6 gas uptakes under ambient conditions. The adsorption selectivities for gas mixtures, calculated by IAST, were 10.8 (10.7), 14.6 (9.4), 1.7 (1.6) and 1.5 (1.6) for the equimolar gas mixture compositions CO2/N2, C2H6/CH4, C2H6/C2H4 and C2H6/C2H2 at 1 bar and 273 K (298 K), respectively. The mixed-metal compound 1-ZnCu was prepared by a crystal-to-crystal ion exchange metathesis reaction from 1-Zn with a 52% degree of ion substitution, confirmed by energy-dispersive X-ray spectroscopy, optical microscopy and single crystal X-ray diffraction analysis.

Viability and antibacterial properties of Ba2-x AgxFeMoO6(x=0.0, 0.05) double perovskite oxides

Double perovskite Ba2FeMoO6 (BFMO) and doped with Ag ions were synthesized via the sol-gel method. The structural and antibacterial properties and viability of the samples were systematically investigated. The results of the Rietveld refinement indicated that both samples exhibited a single phase with cubic structure and space group Fm-3m. The substitution of Ag ions led to an increase in the unit cell and lattice parameters of BFMO, resulting in a change in the sample's morphology. The direct band gap (∼2eV) was measured for samples by Diffuse Reflectance Spectroscopy (DRS). Antibacterial activity of the Ba2FeMoO6 and Ba1.95Ag0.05FeMoO6 samples was assessed on the Gram-positive bacteria (Staphylococcus aureus) and the Gram-negative bacteria (Escherichia coli) using the spread plate method. The results showed that the samples were effective against Staphylococcus aureus but not against Escherichia coli. The sample doped with Ag ions showed a higher antibacterial effect than the pristine sample. An MTT assay of the normal fibroblast cell line treated with an Ag-doped sample showed a higher percentage of viability.

Dilution induced magnetic localization in Rb(Co[formula omitted]Ni[formula omitted])2Se2 single crystals

We report experimental studies on a series of Rb(Co1−xNix)2Se2 (0.02 ≤x≤ 0.9) powder and single crystal samples using x-ray diffraction, neutron diffraction, magnetic susceptibility, and electronic transport measurements. All compositions are metallic and adopt the body-centered tetragonal structure with I4/mmm space group. Anisotropic magnetic susceptibilities measured on single crystal samples suggest that Rb(Co1−xNix)2Se2 undergo an evolution from ferromagnetism to antiferromagnetism, and finally to paramagnetism with increasing Ni concentration. Neutron diffraction measurements on the samples with x = 0.1, 0.4, and 0.6 reveal an A-type antiferromagnetic order with moments lying in the ab plane. The moment size changes from 0.69 (x=0.1) to 2.80μB (x=0.6) per Co ions. Our results demonstrate that dilution of the magnetic Co ions by substitution of nonmagnetic Ni ions induces magnetic localization and evolution from itinerant to localized magnetism in Rb(Co1−xNix)2Se2.