O3 Powders Research Articles

Design, synthesis and characterization of advanced tritium breeder: Li4Si1-xTixO4 ceramics

Lithium orthosilicate (Li4SiO4) is an important tritium breeder for the fusion blanket concept. It was selected as the first candidate in China's test blanket model. In this study, in order to improve the thermal conductivity and mechanical properties of Li4SiO4, titanium was chosen to replace the silicon in it. This is because Ti has large atomic radius and the same charge as that of silicon. The fabrication and characterization of Li4Si1-xTixO4 solid solution was carried out. The Li4(Si,Ti)O4 powders were synthesised via a solid-state reaction, and the pebbles were fabricated using the freeze-drying method. The structure, morphology, thermal conductivity, and mechanical properties of the Li4(Si,Ti)O4 samples were analysed using X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, a laser thermal conductivity meter, and a universal testing machine. Moreover, the thermal conductivity of Li4SiO4 improved significantly after Ti doping, and the mechanical properties of the Li4(Si,Ti)O4 pebbles sintered at 1000 °C were significantly better than those of Li4SiO4.

Structural and dielectric properties of sol–gel processed Ce-doped BaTi0.97Y0.03O3 ceramics

Structural and dielectric properties of Ce-doped [Formula: see text][Formula: see text]O3 powders, with the chemical formulation (Ba[Formula: see text][Formula: see text](Ti([Formula: see text]- [Formula: see text]O3 such as [Formula: see text] = 0%, 1%, 3%, 5%, 7% and 9%, produced by the sol–gel method, have been investigated. X-ray diffraction analysis showed that Ce[Formula: see text] ions incorporated Ba sites until [Formula: see text]= 7% indicating that this concentration represents a solubility limit of Ce[Formula: see text] ions in [Formula: see text][Formula: see text]O3 matrix. Scanning electron microscopy (SEM) analysis showed a decrease in grain size down to the same concentration of 7%. Raman spectroscopy analysis showed the appearance of [Formula: see text] mode, which we attributed to the effect of incorporation of Ce[Formula: see text] and Y[Formula: see text] in BaTiO3 matrix. Dielectric measurements revealed that doping with cerium lowers the temperature of permittivity maximum at the ferroelectric-to-paraelectric transition (FPT) of the [Formula: see text][Formula: see text]O3 sample, and reaches a value that should be below [Formula: see text]C for [Formula: see text]= 9%. Moreover, the phenomenon of dielectric resonance was observed on all Ce-doped samples, which was not the case with other dopants as reported in the literature.

Synthesis of highly sinterable Tm,Ho:(Lu1-xScx)2O3 powders by spray co-precipitation for transparent ceramics: Influence of the variable x

Highly sinterable Tm,Ho:(Lu1-xScx)2O3 nanopowders were synthesized by a spray co-precipitation method. The influences of the calcination temperatures and x values on the morphology and composition of the powders were studied. The results indicated that the precursor gradually formed needlelike structures with increasing x values, and the powders calcined at 1100 °C for 2 h exhibited the highest uniformity and sintering activity. Using the powders calcined at 1100 °C, the Tm,Ho:(Lu1-xScx)2O3 ceramics with the highest in-line transmittance of 79.80% at 2090 nm were fabricated by vacuum sintering at 1550 °C for 10 h and further hot isostatic pressing under 190 MPa at 1700 °C. Owing to the disordered crystal structure of the (Lu1-xScx)2O3, the grain size of the ceramics decreased from 1.72 ìm to 1.16 ìm, and the emission spectra showed some variation with increasing x values. This work demonstrates promise in facilitating the production of Tm,Ho:(Lu1-xScx)2O3 transparent ceramics for their use in 2 ìm ultrashort laser pulse and other applications.

Vacuum-Drying of the LiNi1/3Co1/3Mn1/3O2 Cathode Material

Moisture greatly affects the performance of Li-ion batteries, so LiNi1/3Co1/3Mn1/3O2 (NCM111) powder is usually dried in vacuum before the slurry preparation. In this paper, vacuum-drying experimen...

Analysis of BET specific surface area in several recycled oxide powders

The surface area data of feed oxide powders is of fundamental interest to optimize the process of nuclear fuel fabrication. The single-point Brunauer–Emmet–Teller (BET) specific surface area of several recycled powders (synthesized from rejected scrap fuel pellets) was determined and compared with as-received and standard specified powders. Recycled UO2, ThO2, (U,Pu)O2 powders from bulk microwave dissolution-denitration process showed acceptable specific surface area for fuel pellet fabrication. The dry oxidation–reduction process recycled UO2 and (U,Pu)O2 powders demonstrated lower surface area than the standard specified due to larger particle size (D50). The surface area of ThO2 from bulk microwave dissolution-denitration (3.5–4.5 m2/g) was comparable to the standard and further enhanced in polyvinyl alcohol (PVA) aided denitration.

Improved cycling stability of Ni-rich LiNi0.8Co0.1Mn0.1O2 cathode materials by optimizing Ti doping

Nickel-rich LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2 (NCM811) oxide is a prospective cathode material of Li-ion batteries owing to its high energy density and affordable price, however, it suffers from the poor cycling performance. The doping for metal cations is considered as an effective way to enhance its cycling stability. In this work, titanium was chosen to partially substitute transition-metal ions, i.e. Ni, Co and Mn, and the Ti content was optimized to improve the electrochemical performance of NCM811. The Ti-doped Li(Ni[Formula: see text]Co[Formula: see text]Mn[Formula: see text]Ti[Formula: see text]O2 powder was prepared using high temperature solid-state synthesis. The layered [Formula: see text]-NaFeO2-type structure of NCM811 survives in the doped samples, and the lattice parameters [Formula: see text] and [Formula: see text] increase linearly with the Ti content. XPS spectra indicate that the Ni ions show a mixing state of +2 and +3, and the portion of Ni[Formula: see text] increases by the Ti doping. The cycling stability is improved evidently by a small amount of Ti doping, i.e. capacity retention of 88.3–96.9% for [Formula: see text] = 0.01–0.03 versus 64.1% for [Formula: see text] = 0 after 100 cycles at 0.1 C. Thus, the sample with [Formula: see text] = 0.01 delivers the high discharge capacity of 180.6 mAh g[Formula: see text] after 100 cycles, much greater than 116.5 mAh g[Formula: see text] of [Formula: see text] = 0. Nevertheless, more Ti doping with [Formula: see text] = 0.04–0.05 deteriorates the electrochemical performance. It illustrates the presence of optimal Ti-doping range in NCM811, which was rationalized as the synergetic effects of bond strength, Li[Formula: see text] diffusion, chemical composition and valence state of cations.

X-RAY DIFFRACTION AND MÖSSBAUER SPECTROSCOPY INVESTIGATIONS OF THE (Al, Ni, Co)-DOPED AgFeO2 SYNTHESIZED BY HYDROTHERMAL METHOD

Delafossite AgFeO2, AgFe0.9Al0.1O2, AgFe0.9Ni0.1O2, and AgFe0.9Co0.1O2 powders were synthesized by hydrothermal method. The structural analysis and hyperfine interactions investigations were performed by X-ray diffraction and the Mössbauer spectroscopy. It was found that the (Al, Ni, Co)-doped delafossite phases with traces of metallic silver can be obtained during hydrothermal synthesis. Investigations revealed that the type of the incorporated element has an impact on the structural properties of the obtained delafossites. However, doping of cobalt, nickel, and alumina ions to the AgFeO2 delafossite structure does not cause significant changes in the values of the hyperfine interactions parameters. The of the Mössbauer spectra confirm the paramagnetic character of the obtained compounds at room temperature.

Impact of Alkali Ions Codoping on Magnetic Properties of La0.9A0.1Mn0.9Co0.1O3 (A: Li, K, Na) Powders and Ceramics

The aim of the work was to check how the introduction of alkali and cobalt ions into a manganese structure can affect the structural disorder and, in consequence, lead to the changes (improvements) of magnetic properties. The high-pressure sintering technique was applied to check if the external factor can modify the magnetization of manganites. Nanocrystalline La0.9A0.1Mn0.9Co0.1O3 (where A is Li, K, Na) powders were synthesized by the combustion technique. The respective powders were used for nanoceramics preparation by the high-pressure sintering technique. The structure and morphology of the compounds were studied by X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Magnetization studies for all compounds were performed in order to check the changes induced by either codoping or the sintering pressure. It was found that the type of the dopant ion and sintering pressure produced significant changes to the magnetic properties of the studied compounds. Alkali ions lead to the stabilization of Co ions in the +2 oxidation state and the formation of positive exchange interactions Mn3+–Mn4+ and Co2+–Mn4+ and the subsequent increase in remanent magnetization. High sintering pressure leads to a decrease in grain size and reduction of long-range ferromagnetic order and lower magnetization.

Quenching Method and Performance of High Voltage Layered Lithium Rich Nickel Manganese Oxides

Due to their promise of high specific capacity layered lithium rich nickel manganese oxide materials have a large body of literature dedicated to their structure, and electrochemical behaviors[1–5]. Yet these materials have often been marred by significant capacity losses, rate capability limitations, and structural instability over the course of cycling. Several techniques involving surface and structural modifications have been used to mitigate these capacity losses[6–8]. In this work we used a hybrid acetate/nitrate precursors and sol-gel/combustion synthesis to conduct an unprecedented combined survey of the composition of Li(NixLi(1/3-2x/3)Mn(2/3-x/3))O2, and synthetic quench rates to elucidate the effects of these variables on electrochemical cycling behavior, bulk morphology, and surface morphology of the layered lithium rich manganese oxides. We find that the electrochemical behavior of these materials is dependent on both the nickel content as well as the quenching method, with a lower limit on the nickel content beyond which the effects of quenching are minimal. Despite XRD revealing loss of super lattice peaks indicating a loss of transition metal ordering, often associated with capacity loss, galvanostatic cycling of samples saw improved capacities over the course of cycling. SEM found bulk morphology of cathodes differs across nickel contents, yet it did not experience large changes over the course of cycling. The use of TEM found that the surfaces of Li(NixLi(1/3-2x/3)Mn(2/3-x/3))O2 powders is highly sensitive to quenching method, and comparison of surfaces over the course of cycling provided incites into the effects of quenching and nickel content on electrochemical cycling behaviors of the cathode materials. This investigation reveals that careful considerations in synthesis are required for the realization of high-performance layered lithium rich nickel manganese oxides.[1] Y. J. Park, Y.-S. Hong, X. Wu, K. S. Ryu, S. H. Chang, J. Power Sources 2004, 129, 288.[2] Z. Lu, L. Y. Beaulieu, R. A. Donaberger, C. L. Thomas, J. R. Dahn, J. Electrochem. Soc. 2002, 149, A778.[3] Z. Lu, J. R. Dahn, J. Electrochem. Soc. 2002, 149, A1454.[4] M. Jiang, B. Key, Y. S. Meng, C. P. Grey, Chem. Mater. 2009, 21, 2733.[5] J. Bréger, N. Dupré, P. J. Chupas, P. L. Lee, T. Proffen, J. B. Parise, C. P. Grey, J. Am. Chem. Soc. 2005, 127, 7529.[6] D. Eum, B. Kim, S. J. Kim, H. Park, J. Wu, S. P. Cho, G. Yoon, M. H. Lee, S. K. Jung, W. Yang, W. M. Seong, K. Ku, O. Tamwattana, S. K. Park, I. Hwang, K. Kang, Nat. Mater. 2020, 19, 419.[7] H. Z. Zhang, Q. Q. Qiao, G. R. Li, S. H. Ye, X. P. Gao, J. Mater. Chem. 2012, 22, 13104.[8] Y. Wu, A. Manthiram, Solid State Ionics 2009, 180, 50.

Structure and electrical properties of BCZT ceramics derived from microwave-assisted sol\u2013gel-hydrothermal synthesized powders

A novel microwave-assisted sol–gel-hydrothermal method was employed to rapidly synthesize Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) powders. The effects of reaction time on the structure, crystallinity, purity and morphology of the products were investigated. The results of XRD, FTIR, SEM and TEM indicated that BCZT powders could be obtained in even 60 min at a low synthesis temperature of 180 °C, which were well-crystallized with stoichiometric composition and uniform grain size (~ 85 nm). BCZT ceramic derived from the rapidly-synthesized powders had a dense microstructure and good electrical properties (εm = 9579, d33 = 496 pC/N, 2Pr = 25.22 µC/cm2, 2Ec = 7.52 kV/cm). The significant electrical properties were closely related to the high activity of the BCZT powders, resulting from the rapid microwave-assisted sol–gel-hydrothermal process.

Influence of Nanoscale Intimacy and Zeolite Micropore Size on the Performance of Bifunctional Catalysts for n-Heptane Hydroisomerization.

In this study, Pt nanoparticles on zeolite/γ-Al2O3 composites (50/50 wt) were located either in the zeolite or on the γ-Al2O3 binder, hereby varying the average distance (intimacy) between zeolite acid sites and metal sites from “closest” to “nanoscale”. The catalytic performance of these catalysts was compared to physical mixtures of zeolite and Pt/γ-Al2O3 powders, which provide a “microscale” distance between sites. Several beneficial effects on catalytic activity and selectivity for n-heptane hydroisomerization were observed when Pt nanoparticles are located on the γ-Al2O3 binder in nanoscale proximity with zeolite acid sites, as opposed to Pt nanoparticles located inside zeolite crystals. On ZSM-5-based catalysts, mostly monobranched isomers were produced, and the isomer selectivity of these catalysts was almost unaffected with an intimacy ranging from closest to microscale, which can be attributed to the high diffusional barriers of branched isomers within ZSM-5 micropores. For composite catalysts based on large-pore zeolites (zeolite Beta and zeolite Y), the activity and selectivity benefitted from the nanoscale intimacy with Pt, compared to both the closest and microscale intimacies. Intracrystalline gradients of heptenes as reaction intermediates are likely contributors to differences in activity and selectivity. This paper aims to provide insights into the influence of the metal–acid intimacy in bifunctional catalysts based on zeolites with different framework topologies.

Micro-structured lepidocrocite-type H1.07Ti1.73O4 as anode for lithium-ion batteries with an ultrahigh rate and long-term cycling performance

The lepidocrocite-type H1.07Ti1.73O4 microsized structures with a tap density of 0.88 g·cm−3 were prepared through the ion exchange method with K0.8Li0.27Ti1.73O4 powder as the precursor, and they exhibited good rate performance and outstanding cycle stability as an anode material for lithium ion batteries (LIB). The ion exchange method provides favorable conditions for H1.07Ti1.73O4 as an anode electrode material for LIBs. X-ray photoelectron spectroscopy (XPS) result demonstrates the existence of defects in the nonstoichiometric H1.07Ti1.73O4, which have a beneficial effect on the LIB performance. The electrochemical performance test proves that the half-cell with microsized H1.07Ti1.73O4 as the anode electrode can maintain a specific capacity of 129.5 mAh·g−1 after 1100 cycles and 101 mAh·g−1 after 3000 long cycles at high current densities of 2.0 and 5.0 A·g−1, respectively. In addition, the small volume change rate of 3.6% in H1.07Ti1.73O4 during Li ion insertion was confirmed by real-time in situ transmission electron microscopy (TEM). The LiFePO4||H1.07Ti1.73O4 full battery exhibits a long-term cycling stability with a specific capacity of 73.8 mAh·g−1 at a current density of 500 mA·g−1 after 200 cycles.

A microwave‐based one‐pot process for homogeneous surface coating: improved electrochemical performance of Li(Ni1/3Mn1/3Co1/3)O2 with a nano‐scaled ZnO:Al layer

AbstractIn this article, a versatile process based on microwave‐assisted sol–gel synthesis is introduced in order to apply a surface coating on cathode material for lithium‐ion batteries. Here, a nano‐scaled ZnO:Al (AZO) layer is coated homogeneously onto Li(Ni1/3Mn1/3Co1/3)O2 (NMC111) powder at temperatures below 210°C within a few minutes. In contrast to other wet‐chemical coating techniques, the method described here is conducted in a one‐pot reaction and does not require a post‐annealing step at elevated temperatures. Investigations via high resolution transmission electron microscopy (HR‐TEM), scanning transmission electron microscopy (STEM) and inductively‐coupled plasma optical emission spectroscopy (ICP‐OES) promote a thorough understanding of coating microstructure and quality in dependence of reaction temperature, duration and precursor concentration. The AZO protective coating on NMC111 significantly reduces capacity fading during cycling in the voltage range of 3.0‐4.5 V. Furthermore, applying optimal quantities of the coating agent on NMC111 lead to enhanced specific capacities compared to the uncoated material.

Characterisation of Fe Doped Layered Cathode Material as Nano-Rechargeable Batteries

This research focuses on the layered doped lithium conductive metal oxides with the universal form Li MO2 (M = Co, Ni, Ag or Fe doped solutions) adjustment of cathode electrodes for lithium-ion cells (LIBs). Preparation in a low temperature combustion reaction promotes its electrochemical efficiency. The modification starts with the preparation of the LiCo0.5Ni0.45Fe0.5O2 (LCNFO) powder with citric acid, which is used as fuel, along with deionized water (DW). As binding materials, nitrate of ions (Li+) and ions (Fe+) were added to this mixture to create a uniformed mixture. The required amount of citric acid and de-ionised water was added to this unified mixture to create a powder. This powder was cautiously heated to 150 C0–200C0 initially, and finally annealed at a range from 600 C0 to 1000 C0 for six hours.The resulting product was submitted to a thermal analysis (TGA), which is a useful tool to explore a wide array of polymer properties. This research demonstrates the different applications of TA methods in the field of polymer-nanomaterial research and displays several examples of implementation of the differential scanning calorimeter (DSC). TGA was deployed to investigate the performance of thermal characteristics, which vary with the temperature, for the illustrations and structural characterisation, X-ray Diffraction (XRD) and analysis. A meticulous annealed temperature will output pure, single phase LCNFO / NP material with electrochemical behaviour. The powder was studied, and the dimensions of the cathode material were designed approximately for the XRD data using the Scherer’s equation. Furthermore, we used the Fourier transform for the IR (FT-IR) and surface morphology EDS and SEM analysis. The results focused on modifying the LiCoO2 of the cathode materials by adding materials that are similar to Ni and Fe because these materials are documented as being their own state and not contaminated with the hexagonal geometry arrangement and R three m (gap assembly). We noticed that doped Fe has material that will perform better according to the capacity, power, rate capability stability and low cost, with increased storage capacity due to the nano-size effects.

Synthesis and studies of structured support Ce0.75Zr0.25O2/θ-Al2O3/FeCrAl

The procedure for preparing a structured composite system Ce0.75Zr0.25O2/θ-Al2O3/FeCrAl, which is used as a support for complete oxidation catalysts and catalysts for the conversion of liquid and gaseous hydrocarbons into synthesis gas, has been improved. The method for the synthesis of Ce0.75Zr0.25O2 powder has been optimized to facilitate its depositing on a FeCrAl mesh pre-coated by protective θ-Al2O3 layer. It has been shown by X-ray diffraction that the model powder sample and the cerium-zirconium mixed oxide coating on the alumina-precoated FeCrAl mesh have the same phase compositions. The protective layer of θ-Al2O3 on FeCrAl mesh possesses excellent adhesion properties that ensures high mechanical strength of the Ce0.75Zr0.25O2 coating under repeated heating–cooling cycles. The use of metal substrate as a component of the composite support provides high thermal conductivity, and thus reduces the formation of local hot spots under conditions of highly exothermic catalytic processes.

Practical synthesis of manganese oxide MnO2·0.5H2O for an advanced and applicable lithium ion-sieve

Solid-phase reactions were used for the synthetization of the spinel Li1.6Mn1.6O4 powder and the lithium ion-sieve MnO2·0.5H2O was subsequently obtained by the leaching of the lithium. The physical characterization showed that the polycrystalline precursor and the MnO2·0.5H2O were nearly pure spinel, as well as that during the process of the adsorption-desorption, the structural stability was high. The Langmuir isotherm and pseudo second-order kinetics model showed consistency with the adsorption behavior, which indicated the presence of homogeneous adsorption sites for the lithium adsorption and that its process was chemisorption. Adsorbents were found to remain being characterized with a relatively high Li+ uptake (26.13 ​mg ​g−1) with low manganese extracted (1.71%) after the circulation experiment was performed up to 5 times, proving a significant repeatability and stability for the lithium ion-sieve. The concentration factors exhibited the highly selective adsorption capacity for absorbent from Qarhan raw brine with high concentrations of Na+, K+, Ca2+, Mg2+. The adsorbents could be efficiently used for Li+ recovery from Salt Lake brine as well as its excellent potential for further application.

High performance of ceramic current collector fabricated at 550 °C through in-situ joining of reduced Mn1.5Co1.5O4 for metal-supported solid oxide fuel cells

A well-connected and high-porosity current collector layer fabricated at a low temperature of 550 °C is designed for metal-supported solid oxide fuel cells (SOFCs). Reduced Mn1.5Co1.5O4 (MCO) powders are used as the binder through the reforming of MCO in the air atmosphere. A high conductivity phase La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) is added to keep the porous frame microstructure and decease the ohmic polarization of the current collector layer. Three current collector layers are prepared: MCO, MCO/LSCF, and LSCF. The working state of each current collector layer in planar SOFC stack is reproduced by special experimental design; the performance is tested in the range of 550–750 °C. The results show that the current collector layer for SOFC is achieved at low temperatures using the reduction-oxidation properties of MCO, and the performance is improved by adding high conductivity phase LSCF. The gas distribution at the cathode side is also simulated for designing a high performance SOFC.

Fischer-Tropsch synthesis over Co/g-Al<sub>2</sub>O<sub>3</sub> catalyst loaded on ceramic monolith-structured substrate

Cobalt-based catalyst supported on g-Al2O3­ was prepared by impregnation method and loaded on ceramic monolith-structured substrate by wash-coating slurry method. Physico-chemical properties of the catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) specific surface area and H2 temperatured-programmed reduction (H2-TPR). Activity of the catalysts for Fischer-Tropsch synthesis was investigated in a tubular reactor in a temperature range of 200-275 oC at 20 bar and GHSV = 3000 h-1. Co/g-Al2O3 catalyst loaded on ceramic monolith-structured substrate enhanced efficacy of Fischer-Tropsch synthesis by increasing and stabilizing CO conversion and C5+ selectivity, compared to Co/g-Al2O3 powder catalyst.

Structural investigation of barium zirconium titanate Ba(Zr0.5Ti0.5)O3 particles synthesized by high energy ball milling process

In this study, pure barium zirconium titanate Ba(Zr0.5Ti0.5)O3 (BZT) powders were successfully synthesized via the mechanochemical route using barium carbonate and titanium oxide as precursors. Structural properties of BZT are characterized by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscope, energy dispersive X-ray spectrometry, thermogravimetric analysis, and FT-IR spectroscopy. It was observed that the ball milling operation has a significant influence on sintering temperature. Single-phase BZT was obtained under sintering conditions at 1350 °C. XRD and Rietveld refinement studies revealed that BZT composition has a cubic structure with a space group of Pm-3m (#221). As estimated by the Scherrer formula, the average crystallite size was determined as 79.2 nm for sintering temperature at 1350 °C.

THICKNESS INFLUENCE ON THE PYROELECTRIC SIGNAL OF DOPPED PZT CERAMIC PELLETS

Pb0.98Bi0.02Zr0.5Fe0.1Nb0.09Ti0.31O3 (PBiZFNT) powder obtained by a solid state reaction technique was uniaxial pressed and sintered at 1200°C in order to fabricate dense thin disk ceramics with different thickness (200µ up to 600µm). The pyroelectric response was influenced by the thickness of the ceramics. The thin ceramic disks of 250 µm thickness show better pyroelectric signal (≈35 mV) which recommend them for potential use in laser energy meters.