Solid-state Synthesis Research Articles

Fostering Li-ion conduction in Zr-Sn-Al-based mid-entropy NASICON electrolyte

NASICON (Na Super Ionic CONductor) type materials are an important class of solid-state electrolytes due to their high ionic conductivity along with decent chemical and electrochemical stability. In this study, a medium-entropy Li1.5Zr1.0Sn0.5Al0.5(PO4)3 (LZSAP) ceramic electrolyte was prepared via a solid-state synthesis method. Rietveld refinement confirmed the rhombohedral structure of the conventionally sintered sample (LZSAP-CS) at 1000 °C. The spark plasma sintering (SPS) technique was used for the densification of the pellet and resulted in ∼2.64 times higher room temperature conductivity (∼4.42 × 10−5 S cm−1) than that of the LZSAP-CS. The activation energy, calculated in the 30–100 °C range, decreased from 0.37 ± 0.01 eV for LZSAP-CS to 0.31 ± 0.01 eV for spark plasma sintered LZSAP pellet. The transference number of Li+ was ∼0.98, indicating that Li+ is the predominant charge carrier in this electrolyte. Further investigation of the lithium metal-electrolyte interface was conducted using a symmetric Li|LZSAP-SPS|Li cell configuration, demonstrating stability for over 500 h at 5 μA cm−2. LZSAP extends the list of suitable solid-state electrolytes for all-solid-state lithium batteries.

Synthesis of HTSP Y1<sub>1-x</sub>Fe<sub>x</sub>Ba<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub> by Sol-Gel and Solid-Phase Methods

A modified version of using of the sol-gel process at the initial stage of the synthesis of a high-temperature superconductor (HTSC) Y1-xFexBa2Cu3Oy with low Fe doping is proposed. The properties of samples obtained by sol-gel and solid-state synthesis have been compared. It has been shown that a more uniform distribution of the dopant throughout the volume of the sol-gel samples makes it possible to obtain materials with improved microstructural and performance characteristics.

Mechanochemically synthesized flower-like bismuth oxyhalides: An electrochemical platform for diclofenac detection

The emerging drug diclofenac (DICF) has been found to penetrates aquatic systems at alarming concentrations and poses serious and irreversible ecotoxicological threats around the world. In this work, we present the solid-state mechanochemical synthesis of 3D flower-like bismuth oxyhalides (BiOX, where X = Cl, Br, and I) as electrode materials for electrochemical detection of DICF. The characteristics of the flower-like BiOX are systematically investigated using spectroscopic and microscopic techniques. The BiOI-modified glassy carbon electrode (GCE) exhibits superior electrochemical performance for DICF detection compared to the pristine GCE, BiOCl/GCE, and BiOBr/GCE. The 3D flower-like architecture of BiOI facilitates favorable electrocatalytic activities due to its abundant electroactive sites, good conductivity, large surface area, and fast ion diffusion. Notably, the BiOI/GCE displays wide linear ranges (0.5–11.3 & 11.3−76), a low limit of detection (0.11 μM), high sensitivity (1.33 μA μM–1 cm–2), excellent repeatability (2.91 %), good reproducibility (2.88 %), and anti-interfering ability (<±5 %). To validate the practicality of the fabricated BiOI/GCE, the quantitative detection of DICF in human urine and river water is demonstrated and achieves acceptable recovery values. This study introduces an innovative approach to design and produce electrode materials with distinct properties, enabling enhanced electrocatalysis for various electrochemical sensing applications.

Highly saturated red-emitting novel europium doped yttrium calcium borate (Eu3+: Y2CaB10O19) phosphor materials for eco-friendly solid-state lighting applications

Optical parameters like low correlated color temperature (CCT), color rendering index (CRI), color purity, thermal stability and etc. are crucial parameters for the practical applications of white light emitting diode applications. High color purity around 100 % red emitting novel europium doped yttrium calcium borate (Eu3+: Y2CaB10O19) phosphors were harvested by conventional solid-state synthesis technique. The novel host material possesses monoclinic crystal structure with no observable shift in the diffraction lines with varying dopant concentrations. FTIR studies revealed the presence of BO3 and BO4 networks in the host lattice responsible for structural rigidity and good thermal stability. The phosphor materials synthesized xEu3+: Y2CaB10O19 (x = 0.01, 0.03, 0.05, 0.07 and 0.09), are sensitive to both 250 nm (UV) and 393 nm (Near UV/blue LED) for excitation that can produce deep orange (594 nm) emission along with red emission (612 nm). The optimum Eu3+ ion concentration was fixed at 5 mol% of dopant ions to prevent the concentration quenching. As prepared optimal phosphor material possesses high color purity around 100 %, CCT of 1214 K defines its applicability in WLED applications. The synthesized phosphor materials pertain excellent switching response, thermal stability and the fabricated P-i-G possesses desired photometric parameters for its practical applications.

Energy-Harvesting Device Based on Lead-Free Perovskite

This research investigates the solid-state synthesis of lead-free (K, Na)0.5NbO3 ceramics to improve the performance of triboelectric nanogenerators (TENGs) for energy-harvesting applications. The TENGs have developed as potential devices for converting mechanical energy into electrical energy. However, traditional TENG materials frequently include lead, which raises environmental and health problems. To overcome this issue, lead-free ceramics were examined as alternative materials with superior properties. In this work, a TENG was fabricated using potassium sodium niobate (KNN) ceramics as one triboelectric layer, Kapton as the other triboelectric layer, and a flexible substrate. The aim was to create TENGs with improved performance and environmental sustainability. The output performance of the TENG was estimated to be 70 V and 1100 nA. The TENG was further used to charge capacitors, light up an LED, and harvest energy from various body motions.

Larger grains in high-Tc superconductors synthesized by the solid-state reaction route

Solid-state synthesis is widely used in exploratory research to study various structural modifications that affect the properties (critical temperature, critical current density, irreversibility field, etc.) of superconductors. The popularity of this method is due to its relative simplicity and availability of the necessary equipment. Combining solid-state synthesis and top-seeded melt growth allows us to increase the grain size in a Tm- and Nd-based 1-2-3 superconductor. Samples with a grain size up to 0.1 mm have been obtained. X-ray diffraction, scanning electron microscopy and magnetization measurements have been used for investigating this superconducting material. The magnetization width ΔM has increased significantly in the synthesized samples. However the temperature dependence of the intragrain critical current density and the pinning force scaling give evidences that the pinning mechanism in the obtained superconductor is essentially the same as in polycrystalline superconductors synthesized by standard solid-state technology. The increase in grain size in the synthesized samples is the main reason for the high values of ΔM.

On the synthesis and formability of high-entropy oxides

This paper reports on a straightforward and general solution-based synthesis method for high-entropy oxides (HEOs) of different types and compositions. The flexibility and simplicity of this method are hoped to drive development of new HEOs and study of their properties and applications. Thirteen HEOs with rock salt, fluorite, spinel, and perovskite structures were synthesized using a Pechini-type synthesis at temperatures significantly lower than those necessary in solid-state synthesis (400–900 °C). Metal nitrates, nitrites, chlorides, and even water-sensitive alkoxides were used as the metal precursors with the present method. The HEOs were characterized using powder X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Relaxation of cation size and charge rules and formability of HEOs are also discussed. The present results indicate that the classical criteria for material stability do not readily translate to high-entropy systems. For example, the well-known criteria for Goldschmidt and octahedral tolerance factors established for ordinary perovskites do not seem to describe formability of perovskite HEOs well. The discussed relaxation of cation size and charge rules will contribute to the understanding of HEO systems and development of new HEO phases.

Inhibition of the growth rate of ZnS anode crystal plane: boosting photocatalytic hydrogen production performance

The catalyst's particle size plays a crucial role in enhancing photocatalytic performance. However, it is still unclear to analyse the mechanism by which surfactants affect the particle size of photocatalysts from the perspective of crystal growth. Herein, ZnS nanomaterials with different particle sizes were synthesized using a simple solid-state chemical synthesis method, and the intrinsic influence mechanism between surfactant and catalyst particle size was analyzed from the perspective of crystal growth. It was discovered that the particle size of ZnS kept getting smaller due to changes in polyethylene glycol, cetyltrimethylammonium bromide, and sodium dodecyl sulfate. Analyzing the reasons revealed that the catalyst's particle size was related to the type of surfactant: anionic surfactants could reduce the catalyst size. Correspondingly, the catalyst with a smaller particle size has the optimal performance for photocatalytic hydrogen production. Photocatalysts Z-SDS exhibited outstanding photocatalytic performance, yielding 11.47 mmol/g of hydrogen after a five-hour illumination. Furthermore, the intrinsic influence mechanism between anionic and cationic surfactants, photocatalyst particle size, and catalytic performance was investigated. This investigation provides a new idea for synthesizing small-size and high-performance photocatalysts.

Computational Screening of Chalcogen-Terminated Inherent Multilayer MXenes and M2AX Precursors.

Sulfur-terminated single sheet (ss-)MXene was recently achieved by delamination of multilayered van der Waals bonded (vdW)-MXenes Nb2CS2 and Ta2CS2 synthesized through solid-state synthesis, rather than via the traditional way of selectively etching A-layers from the corresponding MAX phase. Inspired by this, we perform a computational screening study of vdW-MXenes M2CCh2 isotypical to Nb2CS2 and Ta2CS2, with M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta, Mo, or W and Ch = S, Se, or Te. The thermodynamic stability of each vdW-MXene M2CCh2 is assessed, and the dynamical stability of both vdW- and ss-MXene is considered through phonon dispersions. We predict seven stable vdW-MXenes, out of which four have not been reported previously, and one, V2CSe2, incorporates a new transition metal element into this family of materials. Electronic properties are presented for the vdW- and ss-forms of the stable vdW-MXenes, suggesting that the materials are either metallic, semimetallic, or semiconducting. In previous experimental reports the vdW-MXene Nb2CS2 is synthesized by manipulation of the corresponding M2AX phase Nb2SC. Therefore, we also evaluate the thermodynamic stability of the corresponding M2AX phases, identifying 15 potentially stable phases. Six of these are experimentally reported, leaving nine new M2AX phases for future experimental investigation.

Solid-state reaction synthesis of LuPO4:Yb3+, Tb3+ phosphors and the ultraviolet/near-infrared responsive spectra performances

Yb3+/Tb3+ co-doped LuPO4 phosphors were prepared by solid-state reaction method. The effects of Yb3+/Tb3+ doping concentrations on the downshifting and upconversion spectral performances of the synthesized phosphors were investigated. Upon the ultraviolet light excitation, the phosphors show obvious visible light emission, which can be assigned to the 5D4→7FJ (J=6, 5, 4, and 3) transitions of Tb3+ ions respectively, the green light emission at 543 nm is dominant. Upon 980 nm excitation, the phosphors display intense green and blue light emission, and weak yellow and red light emission, which originates from the cooperative energy transfer process between Yb3+ and Tb3+ ions. The synthesized LuPO4:Yb3+, Tb3+ phosphors show good ultraviolet/near-infrared responsive spectra, color-tunable and thermal-stability performances and may have potential applications in the related fields.

Layered sodium manganese oxides for toxic nitrogen dioxide gas removal in ambient conditions

In this study, Na0.7MnO2 samples were successfully synthesized using a solid-state synthesis route with Na and Mn acetate precursors. The resulting Na0.7MnO2 crystallized in a hexagonal lattice with space group P63/mmc. These materials were investigated for their capacity to adsorb 100 ppm of NO2 gas at room temperature. Na0.7MnO2 exhibited an exceptional NO2 adsorption capacity of 163.3 mg/g, surpassing many previously reported porous and non-porous materials. Comprehensive experimental and spectroscopic analyses confirmed the formation of NO, NO2–, and NO3– species, following NO2 adsorption on the Na0.7MnO2 surface. Theoretical calculations further supported the chemisorption of NO2 gas molecules on the Na0.7MnO2 surface, with a maximum adsorption energy of –1.937 eV. Spectroscopic and Bader charge analyses confirmed that the NO2 gas molecule acted as a charge acceptor species on the oxide surface. This work represents the first detailed study validating Na0.7MnO2 as an effective room-temperature adsorbent for capturing and mineralizing NO2 gas. The exceptional NO2 adsorption capacity and the mechanistic insights into the adsorption process suggest the promising potential of Na0.7MnO2 and related oxides for applications in NO2 gas capture and conversion.

Synthesis and luminescence properties of CaZr4(PO4)6 : RE (RE = Eu3+,Dy3+) orthophosphate phosphor for n-UV solid-state lighting prepared by solid state synthesis

Synthesis and luminescence properties of CaZr4(PO4)6 : RE (RE = Eu3+,Dy3+) orthophosphate phosphor for n-UV solid-state lighting prepared by solid state synthesis

Solid-state synthesis of novel anticancer drug eutectic mixture; anticancer, physical and thermal studies

Green, solvent-free synthesis is adopted for a new pharmaceutical drug-drug eutectic with the utmost 100% yield. The synthesized eutectic mixture is significant for anticancer activity. The mandate of clinical tests could be avoided as selected nicotinamide, salicylamide, p-aminoacetinilide and benzanilide are known drugs. The compositional behaviors and established phase diagrams infer the formation of eutectics. The thermal behaviors of eutectics are studied using DSC. Further studies of eutectics are targeted for their biological applications, particularly for cell viability and anticancer activity against SiHa cancer cells where eutectic of benzanilide-salicylamide system infers its potential applicability for anticancer activity.

Enhanced fluorescence in Cs2ZnI4 powders by Cu doping

Cu+-doped metal halide Cs2ZnI4 phosphor powders were synthesized by a facile solid-state synthesis method. The introduction of Cu+ makes the weakly luminous Cs2ZnI4 emit stronger blue light around 450 nm. When the doping concentration is 5 %, the photoluminescence quantum yield (PLQY) is up to 17.76 %. This work provides a feasible strategy for the preparation of metal halide phosphors applied to blue-light-excitable LED devices, and also gives an insight into understanding self-trapped excitons (STEs) emission in zero-dimensional metal halides.

Exploring novel anticorrosive applications: Solid-state synthesis and characterization of Li2CuP2O7 and Na2CuP2O7 pyrophosphates

This work shows the importance of inorganic materials Li2CuP2O7 and Na2CuP2O7, especially the effect of Li and Na atoms, in their use as inhibitors that preserve Mild steel in 1.0 M HCl solution. Lithium and Sodium copper (II) pyrophosphate crystals were synthesized through solid-state reaction and characterized using Infrared Spectroscopy technique (IR), as well as X-ray diffraction (XRD). The infrared spectrum of compounds Li2CuP2O7 and Na2CuP2O7 was captured and interpreted, revealing a bent POP bridging angle within these compounds. Furthermore, the inhibitory effect of these pyrophosphates on Mild steel corrosion in a 1.0 M HCl solution was studied. During this investigation, electrochemical techniques alongside surface examination through SEM and EDX. The experimental findings demonstrated that Li2CuP2O7 and Na2CuP2O7 act as effective inhibitors, with inhibition efficiency (ηPP%) rising as the inhibitor concentration increases. At a concentration of 10−3 M, Li2CuP2O7 exhibited a remarkable inhibition efficiency of 93 %, which appears to be mixed-type inhibitors.

Synthesis and thermoluminescence characterization of either Cu- or Ag-doped lithium triborate

Lithium Triborate (LiB3O5 or LTB), is characterized by chemical stability and good mechanical properties, and it has an effective atomic number (Zeff = 7.39) close to that of the human tissue (Zeff = 7.42), making it a potential dosimeter. The objective of this research is to examine the Thermoluminescence (TL) features and dosimetric characteristics of both Cu-doped and Ag-doped LTB. The material was synthesized using the solid-state synthesis method and four different dopant levels were used for each element (0.1%, 0.5%, 1%, 3%); various techniques such as X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy were used for structural and compositional characterization, for samples annealed at 500 °C for 1 h in all cases. Specific TL features were studied, such as TL glow curve shape, sensitization and sensitivity, fading behavior as well as kinetic characterization using two supplementary techniques, namely fractional glow technique and deconvolution analysis. The effect of each dopant element is different in the (same) lithium triborate matrix in terms of sensitivity. TL dosimetric peaks are yielded for both dopant elements; however, the optimum doping level is 3% for Ag but just 0.1% for Cu. Furthermore, the samples were irradiated at different doses, ranging from 0.5 to 2048 Gy, in order to study the corresponding dose response. A remarkable dose response linearity was observed for the main dosimetric peak of both materials, ranging up to ∼1 kGy.The fading results suggest that LTB doped with 0.1% Cu is the most promising material for dosimetric applications.

Revealing the impact of ball milling as an intermediate stage in solid-state reaction synthesis of SmFeO3 particles

In this work, the impact of milling time on the structural, morphological, and magnetic properties is investigated in SmFeO3 (SFO) powders obtained by solid state reaction. Specifically, the ball milling process is incorporated as an intermediate step during the synthesis and their magnetic properties vary when the samples are milled for 4 and 10 h. Based on X-ray diffraction, the resulting samples crystallized in Pbnm space group, with a slight decrease in crystallite size and cell volume with milling time. These results are also supported by confocal Raman microscopy with a slight shift towards lower wavenumbers. In this sense, magnetic characterization demonstrates a weak ferromagnetic contribution coexisting with the dominant antiferromagnetic order. Butterfly shaped hysteresis loops are observed in both samples for T > 200 K while a single shaped loop is achieved for T < 200 K. Zero field cooled, and field cooled magnetization curves shows a broad maximum centered at 140 K and bifurcation of the two curves because of the competing interaction between the Sm+3 and Fe3+ ions into the SFO crystal structure. Interestingly, exchange bias (EB) effect is found up to 200 K with a field cool of 20 kOe for both samples. The existence of Fe–Fe, Fe–Sm, and Sm–Sm interactions in a cluster glass state induced by ball milling processes might be the main cause of such EB effect.

Solid state synthesis of Ce-doped zircon from the mechanically activated CeO2–ZrO2–SiO2 mixture

Zircon is a promising candidate for use as a matrix in the immobilization of radioactive waste. However, high temperatures (1400–1600 °C) and calcination durations are generally required to produce it. In this letter, we report the synthesis of cerium-containing solid solution based on zircon Zr1-xCexSiO4 by means of a straightforward and environmentally sustainable milling-assisted solid-phase approach conducted at a reduced temperature. Our study demonstrated that the utilization of mechanical activation of the oxide mixture in a mill not only diminished the temperature (to 1200 °C) and the duration of calcination but also increased the Ce content in zircon up to 6.4 at.%. Additionally, we propose a novel method for determining the phase composition of calcined samples using Vegard's law and mass balance.

(Invited) Novel High Entropy Perovskite Oxides for High-Performance Protonic Ceramic Electrochemical Cells

Due to the intermediate operating temperatures (400-600oC), protonic ceramic electrochemical cells have attracted significant attention in the last 10 years because of the demonstration of potential applications of fuel-flexible fuel cells, water electrolysis to produce hydrogen, solid-state ammonia synthesis, electrochemical reduction of carbon dioxide to fuels, and fuel processing (e.g., natural gas to liquids). In addition to developing specific fuel electrodes for different electrocatalytic reactions, we need to discover new electrolyte and oxygen electrode materials generically for all the protonic ceramic electrochemical cells to further decrease the operating temperatures, increase performance, and prolong the long-term stability. The recently emerging materials of high entropy perovskite oxides have been reported to be able to serve as promising electrolyte and oxygen electrode materials. In this talk, we will summarize what Clemson University has done about developing, characterizing, understanding, and demonstrating high entropy perovskite oxides as high-performance and stable electrolyte and oxygen electrode materials for protonic ceramic electrochemical cells.

(Invited) Single Crystal Ni-Rich Cathode Materials: Synthesis, Scaleup and Validation

Synthesis of high-performance single crystal Ni-rich NMC, especially when Ni≥0.8, poses a challenge. A conflict exists because as Ni content increase in NMC811, a lower calcination temperature is preferred due to Ni reduction at elevated temperatures, while high temperatures favour single crystal growth.Therefore, molten salt is sometimes employed as the reaction media to promote growth of single crystal NMC811. In general, four approaches for synthesizing of Ni-rich NMC single crystals: molten salt, hydrothermal, direct solid-state synthesis and multi-step lithiation. Molten salt and hydrothermal approaches result in the formation of well-segregated large crystals, but they also increase manufacturing cost. Direct solid-state synthesis, which involves ball milling all precursors together followed by calcination, is a time-saving approach. However, it poses challenge for impurity control due to contamination from milling media, and it can damage the material structure. The calcination of TM(OH)2 precursor with LiOH at very high sintering temperatures forms micron-sized primary particles which, however, still exhibit significantly agglomerated. A post-synthesis milling process is required to break down those NMC811 crystal clusters.This talk will discuss an innovative nanoscale phase separation approach for synthesis of high-performance single crystal NMC811 that is readily adaptable for industry manufacturing. The reaction mechanism of single crystal growth is investigated to understand the synthesis-morphology-performance relationship in growing single crystal NMC811 in the absence of molten salts. The scaled single crystal NMC811 is then further validated in a 2Ah Li-ion pouch cells, demonstrating 1000 stable cycling, confirming the feasibility of this new synthesis approach. This work provides new insights that are broadly applicable for cost-efficient large-scale synthesis of single crystals for different advanced battery technologies to accelerate deep decarbonization process.