Monoclinic Research Articles

The unanti-cipated oxidation of a tertiary amine in a tetra-cyclic glyoxal-cyclam condensate yielding zinc(II) coordinated to a sterically hindered amine oxide.

The complex, tri-chlorido-(1,4,11-tri-aza-8-azonia-tetra-cyclo-[6.6.2.04,16.011,15]hexa-decane 1-oxide-κO)zinc(II) monohydrate, [ZnCl3(C12H23N4O)]·H2O, (I), has monoclinic symmetry (space group P21/n) at 120 K. The zinc(II) center adopts a slightly distorted tetra-hedral coordination geometry and is coordinated by three chlorine atoms and the oxygen atom of the oxidized tertiary amine of the tetra-cycle. The amine nitro-gen atom, inside the ligand cleft, is protonated and forms a hydrogen bond to the oxygen of the amine oxide. Additional hydrogen-bonding inter-actions involve the protonated amine, the water solvate oxygen atom, and one of the chloro ligands.

Cis,cis,cis-Di-chlorido-bis-(N4,N4-di-methyl-pyridin-4-amine-κN1)bis-(dimethyl sulfoxide-κS)ruthenium(II).

The structure of the title compound, [RuCl2(C7H10N2)2(C2H6OS)2], has monoclinic (P21/n) symmetry. The Ru-N distances of the coordination compound are influenced by the trans chloride or di-methyl-sulfoxide-κS ligands. The mol-ecular structure exhibits disorder for two of the terminal methyl groups of a dimethyl sulfoxide ligand.

Investigation of structural and electronic properties of double perovskites A2LnRuO6 (A = Ba, Ca; Ln = Eu, Dy)

Using density functional theory, we investigated the structural, vibrational, and electronic properties of A2LnRuO6 (A = Ba, Ca; Ln = Eu, Dy) double perovskite oxides using GGA and GGA+U exchange-correlation approximations. Ba2LnRuO6 double perovskites exhibit a structure with cubic ( Fm3¯m ) symmetry, whereas Ca2LnRuO6 compounds have monoclinic (P21/n) symmetry. Raman spectroscopy analysis shows stability and the presence of A1g , E g and 2F2g modes for Ba2LnRuO6, while for Ca2LnRuO6, the observed Raman active modes are A g and B g . A2LnRuO6 shows semiconducting nature with an electronic band gap in the range of 1.3 eV-3.27 eV with GGA+U calculations. The spin-polarized calculations indicate the presence of strong magnetic behaviour with magnetic moment equal to 3 μ B /unit cell for Ba2LnRuO6 and 6 μ B /unit cell for Ca2LnRuO6. The spin-up and spin-down states show different band gap values so these compounds can be useful for applications in spintronics and magnetic memory devices.

Investigation of surfactant assisted Fe2(MoO4)3/rGO nanocomposite for supercapacitor application

Utilizing a hydrothermal method with PEG-6000 as a surfactant material, this study presents the synthesis of Fe2(MoO4)3 nanoparticles and their nanocomposites with carbonaceous material in the form of rGO. Comprehensive fundamental characterization studies, including XRD, Raman, and FTIR, confirm the monoclinic crystal structure of Fe2(MoO4)3 and its nanocomposites. Nanorod-structured Fe2(MoO4)3/PEG/rGO exhibits a surface area of 78.571 m2/g with pore volume of 0.202 cc/g. Electrochemical analyses, employing techniques such as Cyclic Voltammetry (CV), Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS), underscore the remarkable performance of the synthesized electrodes. Notably, the Fe2(MoO4)3/PEG/rGO electrode exhibits a specific capacitance of 575.13F/g at a scan rate of 10 mV/s and demonstrates significant cyclic retention over 20,000 cycles at a current density of 20 A/g in GCD analysis. This work highlights the promising electrochemical attributes of Fe2(MoO4)3/PEG/rGO electrodes, showcasing their potential for high-performance supercapacitor applications.

Optoelectronic and Dielectric Properties of Tenorite CuO Thin Films Sprayed at Various Molar Concentrations

The work in hand presents the elaboration of CuO thin films using a home-made spray pyrolysis technique at room atmosphere. The films were synthesized on preheated glass substrate at 450 °C. The source solution molarity was varied from 0.025 to 0.1 mol/L. The films were characterized by employing X-Ray Diffraction technique, UV-Vis-NIR spectrophotometry, Scanning Electron Microscope imagery, Energy Dispersive Spectroscopy, and four-points probe techniques. The X-ray diffraction analysis confirmed that all films are polycrystalline with a preferred orientation along the plane (−111) of the monoclinic crystal structure phase of tenorite (CuO). The SEM images showed a homogeneous and smooth surface. Crystallinity and grain size were improved. The rise of solution concentration induced a reduction of transmittance and reflectance in the visible region. The energy gap, the absorption coefficient, the extinction coefficient, refractive index, dielectric constant (ԑr and ԑi) and loss energy were estimated from transmittance and reflectance data. The gap energy decreases from 2.72 to 2.56 eV. The film deposited for 0.025 mol/L exhibits the highest real part of the dielectric constant (ԑr ~ 17). The film resistivity which is in order of 102 Ω cm decreases with the increase of molar concentration. The estimated dielectric constant indicated that the resulting CuO thin films could be used as dielectric layers for optoelectronic devices working in Vis-NIR region of radiation. Furthermore, the relatively high band gap, high absorption coefficient and high conductivity of the film obtained at 0.075 mol/L, make them good candidates as absorption layers in solar cells applications.

Synthesis, structure and electrochemical properties of Co-MOF containing pyridine polycarboxylic acid

Metal-organic frameworks (MOFs) have been widely used in filed of electrochemistry. Compared with traditional inorganic porous materials, the polyvalent pyridinecarboxylic acid ligands have many advantages which contains more active sites, flexible coordination mode, adjustable structure. Therefore, it becomes good choice for constructing MOFs materials with excellent performance. In this paper, a novel MOF was synthesized by pyridine polycarboxylic acid ligand and CoCl2·6H2O using solvothermal method. The physicochemical properties were characterized by FT-IR, powder diffraction and thermogravimetry. Single crystal X-ray diffraction reveal that MOF-1 crystallizes in monoclinic system with P21/C space group. The central Co2+ ions have a dual core structure with 5 and 6 coordination, respectively. The carboxyl groups show two kinds of coordination modes μ2: η1: η1 and μ2: η1: η2, and the pyridine N atoms also coordinate to form a three-dimensional network structure. Electrochemical experiments show that MOF-1 has a lower overpotential (339.4 mV) and Tafel slope (65.3 mV·dec−1) with higher ECSA and better OER kinetics. A large number of exposed active sites indicate that the MOF has higher potential as catalyst for oxygen evolution reaction.

Slow evaporation synthesis, crystal structure, DFT calculations, molecular docking, and pharmacokinetic studies of hexaaquazinc(II) dihydrogen benzene-1,2,4,5-tetracarboxylate

A new complex formed from the reaction of benzene-1,2,4,5-tetracarboxylic dianhydride with zinc(II) acetate dihydrate was synthesized and characterized by single-crystal X-ray diffraction, thermal analysis (TGA), and density functional theory (DFT). [C10H4O8][Zn(H2O)6] (1), crystallized in a monoclinic system with space group P2/m. Theoretical modeling was performed at the DFT/B3LYP computational level with 6–311 G(d,p) and LanL2DZ basis sets. The Zn(II) is six-coordinate, forming an ideal octahedral geometry. A Hirshfeld surface analysis of the complex indicated that H···O/O···H contacts contribute to 47.8% of the crystal packing. The stability of 1 was investigated by determining the global chemical reactivity descriptors (GCRD). The nonlinear optical (NLO) behavior was investigated by analyzing the dipole moment, polarizability, and first-order hyperpolarizability (μ, α and β) via a theoretical approach, indicating that 1 has important nonlinear optical properties. A molecular docking study shows binding of 1 on the active site of receptors from human cyclooxygenase-2 enzyme (PDB code: 5IKT) and Escherichia coli MenB (PDB code: 3T88).

Evolution of α-V2O5 into electrochemically transformed NaV3O8 structure: Structural changes and supercapacitor application

Nowadays, cost-effective and environmentally friendly supercapacitors (SCs) with high energy and power densities are gaining significant research attention since they could broaden the application of capacitors. The present study demonstrates a low-cost green synthesis technique to prepare the α-V2O5 phase using Aloe Vera leaf extract. X-ray diffraction technique confirmed the formation of the orthorhombic α-V2O5 phase. The prepared α-V2O5 was employed as an electrode material for SC application. During an electrochemical cyclic voltammetry test in Na2SO4 electrolyte, Na+ ions intercalation and de-intercalation processes resulted in a phase transformation of α-V2O5 to NaV3O8. Structural transformation (i.e., orthorhombic to monoclinic crystal structure) and morphological changes were also observed during the electrochemical phase conversion process. This electrochemical phase transformation process improved the overall supercapacitive performance of the α-V2O5 material. Such electrochemically converted NaV3O8 displayed a maximum specific capacitance of 640.1 F g−1 at 0.5 A g−1 with a long cyclic stability. Furthermore, the AC // NaV3O8 asymmetric SC coin cell device delivered a maximum energy density of 62.6 Wh kg−1 and a power density of 7.3 kW kg−1 along with an excellent cycling stability of ∼81 % over 5000 GCD cycles.

Preparation, structure and properties of a novel one-dimensional erbium (III) complex

A novel one-dimensional erbium complex [ErL2(NO3)(H2O)2]n (HL = 2-picolinic acid) was synthesized by hydrothermal methods, and its crystal structure was determined by single crystal x-ray diffraction. The complex crystallize in monoclinic system, space group C2/c with a = 15.7525(5) Å, b = 11.4958(4) Å, c = 9.7977(3) Å, β = 102.862(3) º, V = 1729.72(10) Å3, C12H10ErN3O9, Mr = 507.49, Z = 4, Dc = 1.949 g•cm-3, F(000) = 972,  = 4.901 mm-1, S= 1.119, λ(MoKα) = 0.071073 nm, R = 0.0239 and wR = 0.0668. The 2-picolinic acid ligand adopts bidentate bridging coordination mode to connect adjacent erbium ions to form a one-dimensional chain structure. A series of properties of the complex were measured by solid-state photoluminescence, solid-state diffuse reflection and differential scanning calorimetry.

Synthesis, Structural Characterization, Hirschfeld Surface Analysis, Density Functional Theory, and Photocatalytic CO2 Reduction Activity of a New Ca(II) Complex with a Bis-Schiff Base Ligand.

A new bis-Schiff base (L) Ca(II) complex, CaL, was synthesized by the reaction of calcium perchlorate tetrahydrate, 1,3-diamino-2-hydroxypropane, and 2-formyl phenoxyacetic acid in an ethanol-water (v:v = 2:1) solution and characterized by IR, UV-vis, TG-DTA, and X-ray single crystal diffraction analysis. The structural analysis indicates that the Ca(II) complex crystallizes in the monoclinic system, space group P121/n1, and the Ca(II) ions are six-coordinated with four O atoms (O8, O9, O11, O12, or O1, O2, O4, O6) and two N atoms (N1, N2, or N3, N4) of one bis-Schiff base ligand. The Ca(II) complex forms a tetramer by intermolecular O-H…O hydrogen bonds. The tetramer units further form a three-dimensional network structure by π-π stacking interactions of benzene rings. The Hirschfeld surface of the Ca(II) complex shows that the H…H contacts represent the largest contribution (41.6%) to the Hirschfeld surface, followed by O…H/H…O and C…H/H…C contacts with contributions of 35.1% and 18.1%, respectively. To understand the electronic structure of the Ca(II) complex, the DFT calculations were carried out. The photocatalytic CO2 reduction test of the Ca(II) complex exhibited a yield of 47.9 μmol/g (CO) and a CO selectivity of 99.3% after six hours.

Microwave-assisted combustion synthesis and characterization studies of novel dysprosium doped yttrium calcium borate (Dy3+: Y2CaB10O19) phosphor materials for efficient white light applications

Micro-wave assisted combustion synthesis technique was adopted to synthesize the dysprosium-doped yttrium calcium borate xDy3+: Y(2-x) CaB10O19 (Dy:YCB) polycrystalline phosphor materials with varying concentrations (x = 1, 3, 5, 7 and 9 mol %) for the first time. The formation of phase, crystal structure was analyzed by x-ray diffraction study and was affirmed to be formed pertaining to the monoclinic crystal structure (a = 11.475 Å, b = 6.345 Å, c = 9.223 Å and α = γ = 90°, β = 91.83°) with C2 space group. The absorption capability of the prepared samples was investigated by UV-DRS spectroscopy and the optical band gap was found to be 5.28 eV. FTIR study validated the presence of functional groups and their molecular vibrations. The excitation wavelength of the synthesized samples was found to be 350 nm from photoluminescence excitation (PLE) spectra. The PL emission spectra were recorded to authenticate the emission wavelengths and found to possess two emission peaks at 480 nm (blue) and 577 nm (yellow) contributed by the Dy3+ ions. The optimized dopant concentration of dysprosium ion was fixed at x = 0.07 to avoid the concentration quenching effect. The chromaticity co-ordinate of optimized sample was determined to be x = 0.3188, y = 0.3233 which are closer to ideal white light co-ordinate. The color temperature was determined to be 6209 K, which occurs in the cool white light region. Luminous efficacy of radiation (LER) was determined to be 269.31 l m/Wopt for the optimal phosphor. The luminous efficiency for the optimal phosphor was determined to be 40%. Color rendering index (CRI) of the optimal sample was evaluated to be 77. Internal quantum yield (IQE) of the optimal sample was determined to be 50.58 %. The phosphor materials have excellent thermal stability as validated from the temperature dependent PL measurements.

Crystal Structure and Optical Properties Characterization in Quasi-0D Lead-Free Bromide Crystals (C6H14N)3Bi2Br9·H2O and (C6H14N)3Sb3Br12.

Low dimensional organic inorganic metal halide materials have shown broadband emission and large Stokes shift, making them widely used in various fields and a promising candidate material. Here, the zero-dimensional lead-free bromide single crystals (C6H14N)3Bi2Br9·H2O (1) and (C6H14N)3Sb3Br12 (2) were synthesized. They crystallized in the monoclinic crystal system with the space group of P21 and P21/n, respectively. Through ultraviolet-visible-near-infrared (UV-vis-NIR) absorption analysis, the band gaps of (C6H14N)3Bi2Br9·H2O and (C6H14N)3Sb3Br12 are found to be 2.75 and 2.83 eV, respectively. Upon photoexcitation, (C6H14N)3Bi2Br9·H2O exhibit broad-band red emission peaking at 640 nm with a large Stokes shift of 180 nm and a lifetime of 2.94 ns, and the emission spectrum of (C6H14N)3Sb3Br12 are similar to those of (C6H14N)3Bi2Br9·H2O. This exclusive red emission is ascribed to the self-trapping exciton transition caused by lattice distortion, which is confirmed through both experiments and first-principles calculations. In addition, due to the polar space group structure and the large spin-orbit coupling (SOC) associated with the heavy elements of Bi and Br of crystal 1, an obvious Rashba effect was observed. The discovery of organic inorganic metal bromide material provides a critical foundation for uncovering the connection between 0D metal halide materials' structures and properties.

Inhibitory Effect of Alternanthera Sessilis, Cucurbita Maxima and Aerva Lanata on Whewellite Urinary Crystals

Phosphate stones, such as struvite (magnesium ammonium phosphate hexahydrate), brushite (calcium hydrogen phosphate dihydrate), and oxalates like whewellite (calcium oxalate monohydrate) are different kinds of urinary stones. Such kidney stones can be treated with herbs for natural healing and side effects-free results. These urinary crystals are traditionally created in the lab using the gel growth process and a silica gel medium at a specified pH. The inhibitory effects can be analysed by using the extracts of herbal plants. In the present study, ethanol extracts of leaves of Alternanthera sessilis, seeds of Cucurbita maxima and flowers of Aerva lanata are investigated for their inhibitory activity against the whewellite urinary crystals. They are characterized using Fourier transform infrared spectrum and their crystalline nature is examined through powder X-ray diffraction. Asymmetric and symmetric stretching unit of C=O in oxalate appears at 1620 cm-1 and 1400, 1310 cm-1 respectively. The monoclinic crystal system with a space group of P21/n is confirmed from the powder X-ray diffraction studies. The results indicated that among the three ethanol extracts, leaves of Alternanthera sessilis, seeds of Cucurbita maxima and flowers of Aerva lanata- the flowers of Aerva lanata exhibited inhibition towards whewellite crystals. KEYWORDS Extract, flowers, herbs, oxalates, pH, seeds

Investigation of glucose biosensors by non-enzymatic photoluminescent detection using oleic acid treated Ag2S nanoparticles

The immobilization of carboxylic acid moieties on the surface of nanoparticles to promote the development of non-enzymatic detection of target molecules (sensors) with better feasibility and selectivity has been investigated. This work is focused on treating Ag2S nanoparticles with Oleic acid, a potential carboxylic acid moiety with good stereochemical compatibility, photochemical responses, photoluminescence (PL) quantum yield, and biocompatibility. The hydrothermally synthesized Ag2S was crystalline in nature with a monoclinic crystal system, as inferred from X-ray diffractograms. The surface morphology of Ag2S studied using the SEM micrographs showed nearly spherical and fused particles. ATR-FTIR was recorded by the compensation method in the wavenumber range 600–4000 cm−1 and the changes in the chemical composition of pristine Ag2S and Oleic acid-treated Ag2S (with or without glucose molecules) were investigated. UV–Vis analysis was carried out to establish the absorption region of the respective nanoparticles, and the corresponding inferred excitation wavelength (396 nm) was fixed for the PL analysis. Photoluminescence spectra (PL) of Ag2S with oleic acid and glucose at various concentrations showed a reduction in PL intensity as glucose concentration increased. This PL reduction arises due to various oxidation processes that take place on the large surface of Oleic acid-treated Ag2S. Chronoamperometric studies were used to analyze the electrocatalytic glucose oxidation that occurs in Ag2S nanoparticles with Oleic acid with a low-cost procedure. The concentration of glucose was varied from 0.25 to 30 mM, and the significant sensing abilities of the oleic acid-treated Ag2S were demonstrated.

Electron Localization Induced by Disordered Anions in an Organic Conductor.

We report on a new organic conductor κ″-(ET)2Cu[N(CN)2]Br (κ″-Br), which is the first polymorph of an organic superconductor κ-(ET)2Cu[N(CN)2]Br (κ-Br), where ET denotes bis(ethylenedithio)tetrathiafulvalene. κ″-Br has a similar κ-type arrangement of ET molecules to κ-Br, but, in contrast to the orthorhombic κ-Br, which has ordered polyanion chains, presents a monoclinic crystal structure with disordered polymeric anion chains. To elucidate the electronic state of κ″-Br, we performed band calculations as well as transport, magnetic, and optical measurements. The calculated band dispersion, magnitude of electron correlation, and room-temperature optical conductivity spectra of κ″-Br were comparable to those of κ-Br. Despite these similarities, the κ″-Br salt exhibited a semiconducting behavior. The electron spin resonance and Raman spectroscopies indicated that there is neither magnetic nor charge order in κ″-Br, suggesting the occurrence of Anderson localization due to disordered anion layers.

Prospective light-harvesting material of L-phenylalaninium selenate monohydrate: Synthesis, thermal behavior, vibrational and optical properties

The present work focuses on the study of a new organo-selenate hybrid material, namely [C9H12NO2]2SeO4.H2O, abbreviated as (LPA)2.SeO4.H2O, which was successfully obtained at room temperature by slow evaporation. The structure was studied by the X-ray single-crystal diffraction process. This compound crystallizes in the monoclinic system, with a non-centrosymmetric P21 space group and the following lattice parameters: a = 12.817(3) Å; b = 6.272(15) Å; c = 13.629(3) Å, β=103.847(7)°, Z = 2 and V = 1063.7(4) Å3. The atomic arrangement in the structure is described as an alternation of organic and inorganic entities along the a-axis. The IR and Raman spectra were recorded in the 500–4000 cm-1 and 10–4000 cm-1 frequency region, respectively, confirming the existence of vibrational modes that correlate with organic and inorganic groups. The crystal arrangement is determined by hydrogen bonds of the type NH…O, OH…O and OW-H…O. The intermolecular interactions in the crystal structure were quantified and analyzed using Hirshfeld surface analysis. TGA-DTG and DSC analyses have shown that compound dehydration at around 90°C produces an anhydrous compound that is thermically stable until 122°C. Experimental UV–Visible absorption of the compound demonstrated its semiconducting properties, revealing a direct optical band gap at 5.53 eV. Finally, photoluminescence measurements indicate that the synthesized material exhibits solid-state luminescence properties. Optimized geometry and HOMO-LUMO were calculated using the B3LYP/6–311+ G(dd,p) basis set. The theoretical calculations performed by density functional theory are in agreement with the experimental results obtained.

Structural, morphological, dielectric, and electrical characteristics of a brownmillerite material for electronic devices: KBiMn2O5

The main objective this communication is to study the structural, morphological, dielectric, and electrical properties of a novel brownmillerite material, KBiMn2O5. Preliminary analysis of the X-ray diffraction (XRD) pattern with N-TREOR09 (trial and error method) with Le-Bail method shows monoclinic symmetry (a = 10.919 Å, b = 5.114 Å, c = 10.453 Å, β = 104.428˚). The examination of scanning electron microscopic spectrum provides the nature of the morphological surface of the sample having an average grain size of 19.89 μm. We have examined Maxwell-Wagner dielectric dispersion, relaxation, and transport mechanisms by analyzing the dielectric, impedance, and conductivity spectra across a wide range of experimental frequencies (1 kHz to 1 MHz) and temperatures (25°C to 500°C). The value of relative permittivity (εr) rapidly increases 200 (room temperature) to 85000 (500°C) with an increase in temperature from room temperature. The high value of εr shows colossal dielectric response (CDR) of the material. The low value of tangent loss (≥ 4.5) can also be applicable to electronic devices. On increasing frequency (1 kHz to 1 MHz), the activation energy of the charged ions from 0.391 eV to 0.328 eV shows a thermally activated relaxation mechanism in the material. The thermistor constant (β), determined as 6317.16, and the temperature coefficient of resistance (TCR) -0.00331 are suitable for high-temperature NTC thermistors, temperature sensors, and other electronic device applications. The study of room temperature non-Ohmic charge conduction and current-voltage charecteristics confirms the suitability of the material for devices.

A 1D Sb-containing hybrid organic-inorganic material: Synthesis, structural characterization, hirshfeld surface, thermal behavior, vibrational and optical properties

A novel interesting hybrid organic-inorganic material of Bis (2-amino-3-nitropyridinuim) pentachloroantimoinates (III) with the formula [C5H6N3O2]2SbCl5 was elaborated by slow evaporation at room temperature. This compound was crystallized in the monoclinic system with the P 21/c space group, as shown using the X-ray diffraction results. The parameters are the following: a = 16.484(6) Å, b = 7.7170 (19) Å, c = 16.159 (7) Å, β= 109.26(5)°, Z = 4 and V = 1940,5(14) Å3. The asymmetric unit consists of one Sb (III) cation surrounded by five Cl− and two protonated cations 2-amino-3-nitropyridinuim. The crystal packing cohesion was maintained by NH…Cl and NH…O hydrogen bonds to form a three- dimensional network. The infrared IR and Raman studies which were recorded at room temperature in the 4000–400 cm−1 and 0–4000 cm−1 frequency regions, respectively, confirmed the existence of vibrational modes that correspond to the organic and inorganic groups. The Hirshfeld analysis results show that the predominate interactions were H…Cl and O…H contacts (39.9, 14.5 % respectively). The Thermogravimetric analysis TGA shows that this compound remains stable up to about 150 °C. The optical properties were characterized experimentally by UV–visible absorption studies and photoluminescence measurements. The Photoluminescence spectrum manifests a broad and strong band of luminescence around 454 nm (2.73 eV), which can be even observed with the naked eye at room temperature and is due to exciton emission.

Synthesis, crystal structure and photoluminescence properties of Mn4+ activated K2WO2F4·H2O

Oxyfluorides activated with Mn4+ have great potential in phosphors converted LED. Phosphors with intensive zero phonon line (ZPL) emission are expected to improve the performance of the light sources. Microcrystalline powders of oxyfluoride K2WO2F4·H2O activated with Mn4+ were synthesized by using a coprecipitation method. The structural parameters and atomic coordinations of K2WO2F4·H2O were determined by both refinement and calculation. K2WO2F4·H2O crystallizes in the monoclinic crystal system with C2/m group space. The unit cell could be considered as a stack of KWO2F4 slices with another K+ ion and H2O molecule in the interstitial. The morphology and photoluminescence properties of K2WO2F4·H2O: Mn4+ were studied as a function of Mn4+ concentration. It is revealed that the microcrystalline shows highly orientational preferred growth. Mn4+ shows bright red emission upon the excitation of blue light. The emission is due to the 2Eg→4A2g transition. Furthermore, the photoluminescence features intensive ZPL emission and short excitation state lifetime, which is ascribed to the highly distorted coordination environment. The effects of octahedron distortion and the second coordination sphere on the ZPL emission intensity are discussed.

Magnetostructural Transformation and Magnetocaloric Properties of (Ni37.5Co12.5Mn35Ti15)100−xBx (x = 0.0 and 0.4) Melt-Spun Ribbons

The effect of B-doping on the martensitic transformation (MT), microstructure, room temperature (RT) crystal structure, and magnetocaloric properties of a typical all-d-metal Ni37.5Co12.5Mn35Ti15 quaternary alloy was studied by synthesizing melt-spun ribbon samples of nominal composition (Ni37.5Co12.5Mn35Ti15)100−xBx with x = 0.0 and 0.4. For B-free samples, SEM images show a grain-oriented microstructure formed by the columnar in shape-elongated grains with their major axis oriented along the thermal gradient during solidification. By contrast, the B-doped samples show smaller grains whose orientation tends to be perpendicular to the contact surface with the copper wheel. For all samples, austenite (AST) and martensite (MST) phases exhibited a cubic B2-type and 5M monoclinic crystal structure, respectively. The martensitic transition temperature (TM) and the Curie temperature of the austenite phase (TCA) were reduced from 295 K to 253 K and 333 K to 276 K, respectively, with the addition of B. The effect of thermal annealing for different times (from 30 min to 4 h) at 1073 K was studied. Thermal annealing increases the martensitic transformation temperature, whereas TCA remains unchanged. The maximum magnetic field-induced entropy changes |ΔST|max for B-doped samples were around 4.5 J kg−1 K−1 and 4.7 J kg−1 K−1 for as-solidified and annealed samples (1073 K–4 h), respectively, compared to that found for the undoped samples (i.e., ΔST = 16 J kg−1 K−1). However, the entropy reduction is accompanied by an increase in the full width at half-maximum of the ΔST(T) curve.