Solid-state Synthesis Method Research Articles

Study of RBO3-ScBO3 phase diagrams and RSc3(BO3)4 orthoborates (R = La, Pr and Nd)

RBO3 – ScBO3 diagrams (R = La, Pr and Nd) were investigated by the solid state synthesis and DSC methods. In these systems the solid solutions based on RSc3(BO3)4, RBO3 and ScBO3 were identified. The single crystals of RSc3(BO3)4 were grown by spontaneous crystallization method from LiBO2-LiF flux. The borates containing Pr and Nd have typical luminescence in the red/IR range which correlated to Pr3+: 3P0 → 3H6, 1D2 → 3H4 (~ 620 nm), and 3P0 → 2F2, 1D2 → 3H5 (~ 655 nm) and Nd3+ electron transitions 4F3/2 → 4I9/2 (875 nm) and 4F3/2 → 4I11/2 (1055 nm). The luminescence intensity strongly depends on the concentration of the fluorophores. In addition the SHG efficiency (for radiation of Nd:YAG laser, 1064 nm) for grown PrSc3(BO3)4 crystals was found to be 1.85 times higher (deff) than for KDP revealing its high potential for various NLO applications.

Improving the photostriction of BiFeO3-based ceramics by bandgap and domain size engineering

The photostrictive properties of (1−x)BiFe0.96Mn0.04O3-xBaTiO3 (0.23 ≤ x ≤ 0.38) ceramics were investigated using the solid-state synthesis method. Appropriate addition of manganese significantly reduces the bandgap, while the introduction of BaTiO3 changes the phase structure from rhombohedral to pseudo-cubic and significantly optimizes the ferroelectric domain size. The photostriction was observed in the visible light wavelength range with a response time of around 45 s. Specifically, both enhanced photo-induced deformation around 1.27×10−3 and high photostrictive efficiency of 8.40×10−12 m3 W−1 were obtained for the 0.67BiFe0.96Mn0.04O3-0.33BaTiO3 ceramics. The significantly narrow bandgap (∼1.89 eV) and the increased domain wall density due to reduction in ferroelectric domain size enhance the separation and motion of photo-generated carriers, and consequently improve the photostrictive performance. Besides, the prominent Raman peak redshift with the increasing of Raman power reveals the enhanced FeO6 octahedral distortion and stretching vibration of Fe–O bond, which indicates the lattice expansion caused by the photoexcited charge carriers.

Pilot scale fabrication of lanthanum tungstate supports for H2 separation membranes

This paper reports the fabrication of asymmetric tubular geometry lanthanum tungstate-based membranes for high temperature H2 separation applications. As starting materials, powders with the compositions La28-yW4+yO54+δ (y = 0.848), La28-yW4+yO54+δ (y = 1) and La28-y(W1-xMox)4+yO54+δ (x = 0.3, y = 1) were synthesized by solid state reaction method. Porous, thick-wall tubes made of lanthanum tungstate-based powders with high gas permeability (7–8 x10-15 m2 at 2 bar overpressure) and homogeneous porous microstructure were made by combining a cost-effective solid-state synthesis and thermoplastic extrusion method. Deposition of lanthanum tungstate-based dense thin film (∼20 μm) was achieved on top of porous supports through dip coating technique. The influence of conformation routes, thermal debindering and sintering processes were investigated in detail to achieve defect free H2 transport membranes. Asymmetric geometry membranes with ∼20 μm dense layer thickness supported on porous tubular (∼ 7.5 mm diameter and ∼0.8 mm thick) supports.As a result, a procedure for proton conducting ceramics manufacture was established which can be deployed to fabricate high temperature catalytic membrane reactors for synthetic fuel from gas-to-liquid (GTL) processes.

Synthesis and luminescence studies of Dy3+ doped Li3Sc(BO3)2 polycrystalline powder for warm white light

Li3Sc(BO3)2, an orthoborate polycrystalline compound, was synthesised using the solid-state synthesis method as a pure and Dy2O3-doped material. Dy3+ ions were used in various concentrations (from 1 to 6 mol. %). The experimental powder X-ray diffraction data and calculated Rietveld refined data are found to be in good agreement, verifying the effectiveness of the synthesis procedure. The luminescence studies were performed under the excitations of X-ray, proton beam, and UV light. The success of radioluminescence studies verifies the prospects of the Dy3+-doped compound for its application as a radiation scintillator in imaging. The experimental study of cross-relaxation processes confirms the lack of potential evidence of the quenching of the emission peak at 765 nm through the absorption via 6H15/2 → 6F3/2 electronic transition cross-relaxation channel −1. The CIE 1931 colour coordinates and correlated colour temperatures were determined for all doped samples under X-ray, proton beam, and photoluminescence excitations. The obtained combined emission colour appeared in the warm white region, unlike many other Dy3+-doped phosphors that suffer suppression of luminescence through the cross-relaxation process.

Effect of LiSbO3 on dielectric and piezoelectric properties of KNN ceramics

K2CO3, Na2CO3, Li2CO3, Sb2O3 and Nb2O5 were used as the starting materials, the (K0.5Na0.5)NbO3-x mol% LiSbO3 (x=0.00, 0.01, 0.02, 0.03, 0.04 and 0.05) ceramics are prepared using solid state synthesis method, and the effects of LiSbO3 content on dielectric and piezoelectric properties of (K0.5Na0.5)NbO3 ceramics are investigated. The results show that the crystal structure for (Na0.5K0.5)NbO3 ceramics with different LiSbO3 content is all perovskite structure, and the new phase structure of KNN ceramics can’t be obtained when the LiSbO3 content is 0.00≤ x ≤0.05. The appropriate amount of LiSbO3 doped KNN ceramics can refine the grain size and increase the density of the ceramics. When x = 0.04, the relative dielectric constant reaches 980, the dielectric loss is 0.055, and the combined effect of Li+ and Sb 5+ makes the KNN ceramics have better dielectric properties. Due to the more easily the domain wall rotates at the grain boundary, the (K0.5Na0.5)NbO3 ceramics doped with 4 mol% LiSbO3 shows excellent piezoelectric properties in the system of study, and the piezoelectric constant d33 increases sharply to the maximum value of 126 pC/N.

A Comprehensive Review on Green Synthetic Approaches and Applications of 3d-Series Metal Oxide Nanoparticles

Transition metal oxides have been studied by many workers of fields who want to find new ways to use them in medical devices and other fields. Researchers have done a lot of research on solid-state synthesis methods, which require high temperatures and make molecules that are thermodynamically stable. Transition metal oxides have been used for a wide range of things, from nanoparticles that deliver drugs to systems that store information in more than one state. In materials science and technology research and development, a new era of “green synthesis” methods is getting a great attention. Basically, green synthesis of materials and nanomaterials, which is done through a process of regulation, control, cleaning and remediation, will directly help make them more friendly to the environment. In this review, various green approaches for 3d-series metal oxide nanoparticles and their applications are discussed.

Synthesis and spectroscopic identification of nickel and cobalt layered hydroxides and hydroxynitrates.

The formation of different nickel and cobalt layered hydroxide phases by a variety of solution and solid-state synthesis methods has been investigated. Initially, preparative methods were refined to generate single-phase products from metal(II) nitrate hexahydrate starting materials which were then characterised by powder X-ray diffraction, vibrational spectroscopy and thermogravimetric analysis. As well as the brucite type β-M(OH)2 and the hydrotalcite-like [M(OH)2-x(H2O)x]x+ alpha-phases (where M = Ni, Co), two different hydroxynitrate phases were isolated with the generic formula M(OH)2-x(NO3)x with x = 0.67 and 1.0 (where M = Ni, Co). The reduction of symmetry of the nitrate anion from D3h to C2v allows the alpha-phases to be distinguished from the two different layered hydroxynitrate phases by both infrared and Raman spectroscopy through the loss of symmetry and concomitant splitting of the degenerate bands. The symmetric N-O stretch enables the two hydroxynitrate phases to be distinguished from one another through the sharp absorption bands at ca. 1000 cm-1 (x = 0.67) and ca. 1050 cm-1 (x = 1.0). The thermogravimetric analysis data of the phases showed key differences between the layered hydroxides, with anhydrous phases having singular weight losses over short temperature ranges and hydrated phases having multiple losses over more extended temperature ranges.

Interfacial engineering of tungstic disulfide-carbide heterojunction for high-current-density hydrogen evolution.

Developing low-cost and high-efficiency electrocatalysts to electrolyze water is an effective method for large-scale hydrogen production. For large-scale commercial applications, it is crucial to call for more efficient electrocatalysts with high-current density (≥1000 mA cm−2). However, it is challenging to simultaneously promote the large-scale production and hydrogen evolution reaction (HER) activity of these hydrogen catalysts. Herein, we report the large area tungstic disulfide–carbide (W/WS2–WC) heterojunction electrode vertically grown on an industrial-grade tungsten substrate by the solid-state synthesis method. The W/WS2–WC heterojunction electrode achieves a low overpotential of 473 mV at 1000 mA cm−2 in alkaline electrolytes.

SOLID-STATE SYNTHESIS, SPECTRAL AND BIOLOGICAL STUDIES OF Fe (II) COMPLEX DERIVED FROM PARACETAMOL

New solid-state metal complex of Fe (II) with paracetamol (ligand), that is, [Fe(para)2Cl2] were synthesized mechanically in 1:2 ratio. The complex has been characterized using physicochemical properties and spectral studies. From the IR and electronic spectral studies, the spectra of the complex were different from that of ligand suggesting the formation of coordination compound. Paracetamol was found to be bidentate ligand in which Fe (II) ion coordinated through the oxygen atom of carbonyl of ketone and nitrogen atom of amide in which the complex is assumed to have octahedral geometry. The complex has shown good antimicrobial activities. The solid-state synthetic method is quick and gives a higher yield, without the need of solvent or heating. Its present higher efficiency in terms of materials, time and energy compared to solution-based synthesis. It is therefore, recommended among others that, solid-state synthesis method should be used in the synthesizing drugs with metals.

Determination of spectroscopic parameters and thermoluminescence studies of Dy3+-activated Ba2ZnSi2O7 phosphor

The presented study deals with white light emission from Dy3+-activated Ba2ZnSi2O7 phosphors with a variable concentration of the dopant (0.1–2.5 mol.%). Ba2ZnSi2O7:Dy3+ phosphors are prepared using the modified solid-state synthesis method. The structural analysis of phosphors was conducted using the powder X-ray diffraction analysis (XRD), and refined parameters were calculated using the match software. Morphology and particle size were analysed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Intense white light emission with the Commission Internationale de I'Eclairage (CIE) chromaticity coordinates (0.30, 0.33) was achieved for an optimal doping concentration of 1.5 mol.%. Highest emission intensity was obtained for the 487, 544 and 594-nm emission, indicating its potential applicability in the fields of lighting and displays. Thermoluminescence (TL) glow curves are composite in nature and a broad band, found at 300°C, was deconvoluted by the computerized glow curve deconvolution program to calculate its kinetic parameters. The glow curve intensity increases upon increasing the UV exposure time. This study is useful in detecting trap parameters and TL dosimeters.

Tailoring the properties of Ni-Mn based NTC thermistors by Cu and Li addition

The influence of Cu and Li doping in the structural and R-T characteristics of Ni-Mn-based spinel oxide negative temperature coefficient (NTC) thermistors prepared using the conventional solid-state synthesis method was investigated in this study. The doping of Cu and Li in nickel manganite plays an important role in tailoring the thermistor parameters. The structural characterization of the prepared samples using XRD revealed that the basic structure of the samples is not altered by the addition of the dopants Cu and Li. The particle size of the samples was obtained at less than 50 nm. R-T characteristics showed a decrease in resistance with temperature. It was observed that the addition of dopant Cu in a minimal amount helps to tune the resistance of the thermistor in the required range and Li addition, as a dopant, stabilized the thermistor parameters B and alpha.

Synthesize, characterization and topological properties of new hydrazone derivatives

New hydrazone derivatives, [2-(Naphthalen-2-yloxy)-1-phenyl-ethylidene]-hydrazine (compound 1) and N-(2,4-Dinitro-phenyl)-N′-[2-(Naphthalen-2-yloxy)-1-phenyl-ethylidene]-hydrazine (compound 2) have been synthesized by solid-state synthesis method. These compounds have been characterized by spectroscopic (FTIR, 1HNMR, 13CNMR) techniques. Quantum chemical calculations have been carried out on these molecular structures. The results of the electrostatic potential (ESP) surface indicate that compound 1 has stronger nucleophilic site while compound 2 has stronger nucleophilic sites. Also, there is a flow of electrons from almost all the parts of the molecule towards the NO2 group attached at the para position in compound 2. The second order perturbation energy E(2) values show that the delocalization interactions involving the lone pair of electrons are much stronger than the other interactions but, the molecular geometries have been stabilized predominantly by the π→π* interaction forces. The Laplacian of electron density ∇2ρBCP profile suggest that co-valent character of the C−H bonds of naphthyl and phenyl rings of compound 2 have been enhanced by the substitution of 2,4-Dinitro Phenyl hydrazine. The ∇2ρBCP values qualitatively have good correlation with the decrement/increment of electron density around some of the carbon nuclei as signalled by the NMR chemical shift positions.

Preparation of spinel LiMn2O4 cathode material from used zinc-carbon and lithium-ion batteries

Due to the progressive shortage of primary resources and growing environmental concerns over industrial and household residues, proper management of electronic wastes is of great importance in addressing sustainability issues. Spent batteries are considered as important secondary sources of their constituting components. In this study, the co-recycling of used zinc-carbon and lithium-ion batteries was performed aiming at the recovery of their manganese and lithium contents as compounds which can be used as precursors for the synthesis of spinel LiMn2O4. Manganese was recovered in the form of amorphous, submicron, spherical nodules of MnO2 after acid leaching of zinc-carbon battery pastes. Lithium was obtained from nickel-manganese-cobalt (NMC) batteries as its monohydrate oxalate (C2HLiO4.H2O) through selective leaching in oxalic acid followed by crystallization. Lithium carbonate was also prepared by subsequent calcination of the oxalate. The synthesis of LiMn2O4 spinel cathode was investigated using the reclaimed Li- and Mn-containing compounds via solid-state synthesis method. The effect of such parameters as type of precursors (C2HLiO4.H2O/Li2CO3 with Mn2O3/MnO2), temperature (750, 800, and 850 °C), and time (8 and 10 h) on the synthesis of LiMn2O4 was investigated. The products were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The crystallographic parameters from XRD analysis were used to predict the electrochemical behavior of the synthesized cathode materials. Based on these, the spinel powder synthesized at 850°C−10h from Li2CO3−Mn2O3 starting mixture was determined as the cathode material with the best electrochemical properties among the synthesized samples. The galvanostatic charge/discharge evaluation within the voltage range of 2.5–4.3 V showed the specific capacity of the 850°C-10 h sample to be 127.87 mAhg−1.

Promoted Ni–Co–Al2O3 nanostructured catalysts for CO2 methanation

15 wt.%Ni-12.5 wt.%Co–Al2O3 catalysts promoted with Fe, Mn, Cu, Zr, La, Ce, and Ba were prepared by a novel solid-state synthesis method and employed in CO2 methanation reaction. BET, XRD, EDS, SEM, TPR, TGA, and FTIR analyses were conducted to identify the chemicophysical characteristics of the prepared samples. The addition of Fe, Mn, La, Ce, and Ba was effective to improve the catalytic performance of the 15 wt%Ni-12.5 wt%Co–Al2O3 due to the higher CO2 adsorption capacity of the promoted catalysts. Among the studied promoters, the Fe-promoted catalyst possessed the highest catalytic activity (XCO2 = 61.2% and SCH4 = 98.87% at 300 °C). Also, the effect of calcination temperature, feed composition, and GHSV on the performance of the 15 wt%Ni-12.5 wt%Co-5wt%Fe–Al2O3 catalyst in CO2 methanation reaction was assessed. The outcomes confirmed that the 15 wt%Ni-12.5 wt%Co-5wt%Fe–Al2O3 catalyst with the BET area of 122.4 m2/g and the highest pore volume and largest pore diameter had the highest catalytic activity. Also, the catalytic performance in the methanation of carbon monoxide was studied, and 100% conversion of carbon monoxide was observed at 250 °C.

Structural development and luminescent enhancement of CaAlSiN3:Eu2+ phosphor via replacing Al3+ by Ga3+

The preparation of high intensity red emitting Eu2+ doped CaAl1−xGaxSiN3 solid solution phosphor was successfully achieved by using a low-temperature, low-pressure, solid-state synthesis method with the efficient substitution of GaN. For the experiment, GaN is more active than AlN, so it is much simpler to engage in reactions at lower temperatures. DFT calculations were used to check the structure stability and influence of Ga3+ substitution in CaAlSiN3 host lattice. The findings of the experiments revealed that the excitation spectra had a broad spectrum from near-UV to visible light. The electronic transition between the valence and conduction band of CaAlSiN3 host lattice causes the dominant peak at 240 nm. The peaks at 320 and 460 nm are attributed to the 4–4 f65d transition of the Eu2+ activators. Broadband emission, ranging from 500 nm to 800 nm was observed in all the analyzed phosphors samples. Due to high crystallinity, a high-quality final product of CaAl1−xGaxSiN3:0.016Eu2+ phosphors powder was formed with (x = 0.00–0.20) GaN which caused an increase the emission intensity.

Pollen-like self-supported FeIr alloy for improved hydrogen evolution reaction in acid electrolyte

Ir is recognized as efficient catalyst for hydrogen evolution reaction (HER). The high price, however, has hindered its application in the production of hydrogen. In this work, we prepared the self-supported FeIr alloy nanoparticles, taking advantage of solid-state synthesis method. The as-prepared FeIr alloy possesses a novel morphology of pollen, which is consist of smaller FeIr nanoparticles. DFT calculations reveal that the change of the free Gibbs for Ir is negative after the adsorption of active H, while it is positive for the case of Fe. Thus, the alloying of Fe and Ir not only effectively reduces the cost, but also can achieve more adequate adsorption of active H species. Benefitting from this, the as-prepared FeIr alloy nanoparticle exhibits superior HER performance with an overpotential of 19 mV at a current density of 10 mV/cm2 and a Tafel slope of 32 mV/dec, when tested in 0.5 M H2SO4, better than pure Ir and Pt/C. This work paves the way to the exploration of efficient alloy electrocatalysts for HER.

Exploration of (1−x)BaTiO3 + xZnFe2O4 magneto-electric ceramic composite on charge density: Structure and its characterization

Magneto-electric ceramic composite of (1−x)BaTiO3 + xZnFe2O4 (x = 0.2, 0.4, 0.6, 0.8) was prepared by solid state synthesis method. Powder XRD confirms the presence of two distinct phases (BaTiO3 and ZnFe2O4) as tetragonal and cubic. Charge density distribution in the unit cells of BaTiO3 and ZnFe2O4 were analyzed and correlated with the observed results of the characterization. The PE characterization of the electrical studies reveals that the prepared composite changes from lossy capacitance and to resistive capacitance with the increase in the ferrite composition. For x = 0.8 (20% BaTiO3; 80% ZnFe2O4), the dielectric constant is the maximum. The dielectric loss increases with the increase in the ferrite content. From the charge density studies, it can be inferred that the TiO bond assumes a major role in elucidating the electrical characterization of the prepared composite. The magnetic characterization confirms the presence of small ferromagnetic property in the composite. Saturation magnetization varies from 0.583 emu/g to 1.359 emu/g at room temperature with an increase in the ferrite content. In addition to the ferrite content in the composite, the charge density between the atoms is also responsible for the magnetization of the composite.

Large direct and inverse electrocaloric effects in lead-free Dy doped 0.975KNN-0.025NBT ceramics

Undoped and Dy3+ doped 0.975 K1/2Na1/2NbO3-0.025Na1/2Bi1/2TiO3 (0.975KNN-0.025NBT) ceramics were synthesized using the solid-state synthesis method. X-ray diffraction analysis revealed pure perovskite structure without any secondary phases. The dielectric investigations of both ceramics revealed low dielectric losses in the dysprosium doped ceramic, particularly for temperatures higher than 100 °C. The dielectric loss anomaly around room temperature corroborates the polymorphic phase boundary (PPB) between orthorhombic and tetragonal phases detected by XRD investigations. The electrocaloric effect (ECE) was investigated using the indirect method based on the Maxwell equation and thermal P–E hysteresis loops. The maximum ECE value was found equal to 0.63 K at 83 °C for KNNBT0.025. However, in Dy doped KNNBT0.025 ceramics, both direct and inverse ECE responses were found with values of 1.01 K at 118 °C and −1.79 K at 80 °C, respectively. Besides, yellow light emission was detected under an excitation wavelength of 350 nm. The simultaneous existence of high ECEs, good dielectric performance, and photoluminescence properties makes KNNBT-Dy a promising candidate for solid-state refrigeration and optoelectronic devices.

Patternable Mesoporous Thin Film Quantum Materials via Block Copolymer Self-Assembly: An Emergent Technology?

Recent developments in quantum materials hold promise for revolutionizing energy and information technologies. The use of soft matter self-assembly, for example, by employing block copolymers (BCPs) as structure directing or templating agents, offers facile pathways toward quantum metamaterials with highly tunable mesostructures via scalable solution processing. Here, we report the preparation of patternable mesoporous niobium carbonitride-type thin film superconductors through spin-coating of a hybrid solution containing an amphiphilic BCP swollen by niobia sol precursors and subsequent thermal processing in combination with photolithography. Spin-coated as-made BCP-niobia hybrid thin films on silicon substrates after optional photolithographic definition are heated in air to produce a porous oxide, and subsequently converted in a multistep process to carbonitrides via treatment with high temperatures in reactive gases including ammonia. Grazing incidence small-angle X-ray scattering suggests the presence of ordered mesostructures in as-made BCP-niobia films without further annealing, consistent with a distorted alternating gyroid morphology that is retained upon thermal treatments. Wide-angle X-ray scattering confirms the synthesis of phase-pure niobium carbonitride nanocrystals with rock-salt lattices within the mesoscale networks. Electrical transport measurements of unpatterned thin films show initial exponential rise in resistivity characteristic of thermal activation in granular systems down to 12.8 K, at which point resistivity drops to zero into a superconducting state. Magnetoresistance measurements determine the superconducting upper critical field to be over 16 T, demonstrating material quality on par with niobium carbonitrides obtained from traditional solid-state synthesis methods. We discuss how such cost-effective and scalable solution-based quantum materials fabrication approaches may be integrated into existing microelectronics processing, promising the emergence of a technology with tremendous academic and industrial potential by combining the capabilities of soft matter self-assembly with quantum materials.

Ultra-fast charge-discharge and high energy storage density realized in NaNbO3–La(Mn0.5Ni0.5)O3 ceramics

Lead-free antiferroelectric (AFE) NaNbO3 (NN) is one of promising materials for dielectric capacitors, but the recoverable energy-storage density and efficiency get restrained owing to huge remanent polarization and limited dielectric breakdown field strength. In this work, a variety of NN based lead-free bulk (1-x)NaNbO3-xLa(Mn0.5Ni0.5)O3 (abbreviated as (1-x)NN-xLMN, x = 0, 0.05, 0.10, 0.15, 0.20) ceramics were designed using a solid-state synthesis method. Remarkably, an ultra-fast charge-discharge speed 47 ns and an acceptable recoverable energy-storage density Wrec ~1.77 J/cm3 with a high efficiency η = 77% were obtained under the Eb of 200 kV/cm at x = 0.05. The superior energy storage performance is attributed to the regulation of domain size and voltage resistance by special ions substitution of A and B sites. This work not only proposes an efficient strategy to realize high recoverable energy-storage density and efficiency, but also provide an candidate material for application of advanced pulsed power capacitors.