Oxide Ceramics Research Articles

Nickel Age of High‐Temperature Superconductivity

AbstractUnconventional high‐temperature superconductivity has long been a captivating puzzle in condensed matter physics. The 1987 Nobel Prize in Physics celebrated the discovery of high‐temperature superconductivity in copper oxide ceramics. Nearly four decades later, a broad class of high‐temperature superconducting oxides has yet to be demonstrated, and the fundamental understanding of the pairing mechanism remains inconclusive. Recently, nickel oxides have emerged as a new class of high‐temperature superconductors, beyond copper, where correlated phases can be controlled by doping, pressure, strain, and dimensionality. In this article, we provide our perspective on the recent developments and prospects of the nickel age of high‐temperature superconductivity.

Covalently Anchoring an Ultrathin Conformal SiOx Coating on Polyolefin Separator for Enhanced Lithium Metal Battery Performance

AbstractSurface modification of separators with inorganic oxide ceramics such as SiOx, Al2O3, and TiO2 has emerged as a promising strategy to suppress lithium dendrite growth in lithium metal batteries, thereby enhancing safety and extending battery life. However, the binder‐dependent nature of these modifications often leads to increased separator thickness and a heightened risk of detachment during lithium plating, ultimately compromising both battery performance and energy density. In this study, a conformal, ultrathin (≈20 nm) SiOx coating with strong covalent bonding is grown on a porous separator through a liquid polymer‐derived method. Compared to the pristine polyethylene (PE) separators, this SiOx‐co‐PE separator exhibits significantly improved electrolyte wettability, mechanical strength, and thermal stability without any increase in thickness, leading to vastly enhanced cycling stability and dendrite resistance in cells with Li metal anodes. In a practical demonstration, a 402.9 Wh·kg−1 Li‐S pouch cell, with a high sulfur loading of 9 mg cm−2 and a low E/S ratio of 3.3 µL mg−1, is assembled with the SiOx‐co‐PE separator, achieving stable cycling over 70 cycles at 25 °C.

Oxidation of Cr (III) to Cr (VI) in the Synthesis of Bismuth-Chromium Oxide Ceramics

Oxidation of Cr (III) to Cr (VI) in the Synthesis of Bismuth-Chromium Oxide Ceramics

Review of Electrical Parameters Influence on Characteristics of Plasma Electrolytic Oxide Coating on Zircaloy

<p>Zircaloy-4 (Zr-4) is used as a fuel cladding material in Pressurized Water Reactor (PWR). Zr-4 as a cladding material works in extreme conditions in pressurized water up to 150 atm at 325 ˚C. In addition, the refuelling process in the reactor requires surface protection of the clay material to minimize corrosion and wear. One of the raising methods to enhance the corrosion resistance of the Zr-4 is by plasma electrolytic oxidation (PEO). Characteristics of the ceramic oxide layer produced by PEO are influenced by current density, type and composition of the electrolyte, and voltage mode. One of the challenges in the PEO development on the Zr-4 substrate is a high porosity with a range of 5%-20% and the low number (below 6%) of t-ZrO<sub>2</sub> phases in the inner and outer layers. Optimizing the electrical parameters is necessary to overcome this problem. The results of the literature study show that the cathodic current at the AC voltage plays an important role in determining the resulting plasma characteristics. Low duty cycle (cathodic current> 50%) produce plasma with high density, resulting in a low porosity layer. Oppositely, high duty cycle (cathodic current <50%) produced high content of t-ZrO<sub>2</sub> increase the mechanical resistance. Two-step PEO is beneficial in combining the low and high duty cycle to obtain the benefit of each step. </p>

Structural defect regulation in corundum-type medium-entropy oxides for enhanced infrared emissivity performance at high temperature

With the increasing demand in industry and hypersonic vehicles, advanced materials with high-performance infrared radiation need to be developed. Herein, two corundum-type medium-entropy oxide ceramics M3 (Al1/3Cr1/3Fe1/3)2O3 and M4 (Al0.25Cr0.25Fe0.25Ga0.25)2O3 were prepared by solid-state reaction method at different temperatures. Their chemical structure and infrared emissivity performance were analyzed through systematic experiments and theoretical analysis. Compared to the M3, M4 prepared at 1773 K possessed more preeminent emissivity performance, exhibiting emissivity values of 0.917, 0.912 and 0.90 in the wavelength of 0.2–0.78 μm, 0.78–2.50 μm and 2.5–14 μm, respectively. Meanwhile, the infrared emissivity of M4 still could exceed 0.85 at 800 °C in the wavelength of 1.5–25 μm, displaying excellent emissivity and stability under high temperature. As a consequence of lower bandgap and defects formation energy, more oxygen vacancy defects were generated in M4, resulting in better infrared emissivity performance. The results demonstrates that M4 as coating has great potential to be applied in energy-related and thermal protection of hypersonic vehicles.

Ultrahigh‐Pressure Structural Modification in BiCuSeO Ceramics: Dense Dislocations and Exceptional Thermoelectric Performance

AbstractDislocations as line defects in crystalline solids play a crucial role in controlling the mechanical and functional properties of materials. Yet, for functional ceramic oxides, it is very difficult to introduce dense dislocations because of the strong chemical bonds. In this work, the introduction of high‐density dislocations is demonstrated by ultrahigh‐pressure sintering into a typical ceramic oxide, BiCuSeO, for thermoelectric applications. The ultrahigh‐pressure induces shear stresses that surpass the critical strength for dislocation nucleation, followed by dislocation glide and profuse multiplication, leading to a high dislocation density of ≈9.1 × 1016 m−2 in Bi0.96Pb0.04CuSeO ceramic. These dislocations greatly suppress the phonon transport to reduce the lattice thermal conductivity, reaching 0.13 Wm−1 K−1 at 767 K and resulting in a record‐high zT of 1.69 in this oxide thermoelectric ceramic. This study demonstrates the feasibility of generating dense dislocations in ceramic oxides via ultrahigh‐pressure sintering for tuning functional properties.

Investigation on melt growth (Mg, Co, Ni, Cu, Zn)O oxide ceramics prepared by laser directed energy deposition

High-entropy oxides (HEOs) have attracted extensive research interest due to their unique structural features, customizable elemental compositions, and tunable functional properties. Nevertheless, the complexity, low efficiency, and high cost of the existing HEO synthesis methods place limitations on them. In this study, Laser directed energy deposition (LDED) was employed to synthesize (Mg, Co, Ni, Cu, Zn)O oxides. Additionally, the novelty of applying the LDED process to multicationic systems was emphasized. The comparison between specimens fabricated from mixed powder via LDED(MP) and those fabricated from pre-sintered powder via LDED(SP) encompasses macroscopic morphology, microstructure, and performance. The results showed that SP significantly enhanced the density from 86.44% to 96.70% compared to MP. The macro-segregation of Cu and Cu2O in the phase composition was observed in MP and SP. High-temperature pre-sintering promoted the solid solution formation of Co and Ni during LDED, leading to more severe micro-segregation of Co and Ni. When employed as anodes in lithium-ion batteries, MP and SP have outstanding long-term cycle stability, according to electrochemical performance studies. At a current density of 100 mAg-1, these specimens maintained a capacity retention rate of 100% even after 200 cycles. The initial discharge capacities of MP and SP were respectively 477.73 mAh g-1 and 373.86 mAh g-1. This study is expected to present a novel approach for the rapid synthesis of (Mg, Co, Ni, Cu, Zn)O oxide ceramics.

Impact of Substrate Material, Esthetic Material Thickness, and Cement on Color Reproduction in Implant-Supported Fixed Restorations.

Purpose This study aimed to evaluate the impact of substrate material, esthetic material type and thickness, and cement shade on the final color reproduction of implant-supported fixed restorations. The goal was to identify optimal combinations for achieving clinically acceptable esthetic outcomes. Material and methods An in vitro study was conducted using four substrate materials, hybrid polyetherketoneketone (PEEK)-based ceramic-reinforced polymer (BioHPP), chromium-cobalt alloy (CrCo), grade 5 titanium (Ti), and white zirconium oxide ceramic (WZirCAD), and three esthetic materials, lithium disilicate ceramic (e.max CAD), polymethyl methacrylate (PMMA), and zirconia oxide ceramic (e.max ZirCAD), at five different thicknesses (0.5, 1, 1.5, 2, and 2.5 mm). Color differences (ΔE*) were measured using a spectrophotometer, both with and without cement application. Statistical analysis was performed using the Kruskal-Wallis test and Bonferroni correction to assess the effects of material combinations on color reproduction. Results The study found that a 1 mm thickness of e.max CAD on BioHPP and CrCo substrates provided the best color matching, with ΔE* values closest to clinical acceptability. PMMA showed higher ΔE* values, indicating lower color stability compared to e.max CAD and e.max ZirCAD. Cement shade had a near-significant influence on final color perception, particularly with e.max ZirCAD on CrCo substrates. Conclusions The study suggests that using e.max CAD at 1 mm thickness on BioHPP or CrCo substrates provides superior esthetic results, underscoring the need for careful material selection in clinical practice. Further in vivo research is recommended to validate these findings and explore long-term outcomes.

Synthesis of Complex Oxide Ceramics in a Fast Electron Beam

Synthesis of Complex Oxide Ceramics in a Fast Electron Beam

A multifunctional Mg2Si5Al4O18/Y2Si2O7 glass-ceramic coating for porous Si3N4 ceramic

In order to enhance the oxidation and moisture resistance of porous Si3N4 ceramics, here we design a novel Y2O3-MgO-Al2O3-SiO2 glass-ceramic coating through a straightforward scraping process followed by sintering method. The crystalline phase, water absorption, dielectric properties and high temperature resistance of the coating are evaluated systematically. The result shows that the coating obtained by sintering at 1200 °C for 30 min exhibits high density, with an approximate thickness of 88 ± 5 μm. The crystalline phases present in the coating are composed of Mg2Si5Al4O18 and Y2Si2O7. The water absorption rate of the coating is only 0.59 %, and its dielectric constant ranges from 3.3 to 3.4 in the frequency range of 2–20 GHz, with a low dielectric loss tangent below 4 × 10−3. After exposure to high-temperature (1000 °C for 30 min), no significant changes are observed in the microstructure or water absorption rate of the coating. Therefore, this study has successfully developed a multifunctional glass-ceramic coating that is moisture-proof, high-temperature resistant, and exhibits low dielectric loss.

Changes in the levels of cytokines IL-1β, IL-4, IL-8, and IL-10 in dental orthopedic fixed prosthetics

Despite significant advances in materials science, introduction of new methods and principles of prosthetic treatment into the practice of dentists, complications after prosthetics with fixed structures are encountered. The result of dental prosthetics of patients with defects of hard tissues of teeth depends not only on the chosen construction and materials from which they are made, but is closely connected with the functional activity of the immune system. Cytokines are an important factor of mucosal immunity. The cytokine system represents one of the key components of mucosal immunity. It regulates normal physiological functions, restoration of haemostasis in the interaction of physical, chemical and biological factors on the body and participates in the pathogenesis of allergic, autoimmune, and autoinflammatory processes. The aim of the study is to compare the content of IL-1â, IL-8, IL-10, and IL-4 in unstimulated saliva and gingival fluid in patients during adaptation to metal-ceramic and oxide ceramic tooth-supported constructions. In the period from 2021-2024, we examined 3 groups of patients aged 46±2 years: group 1 – comparison group, patients without dental constructions in the oral cavity (25 people); group 2 – patients treated with tooth-supported metal-ceramic (MC) crowns (25 people); and group 3 – patients treated with tooth-supported zirconium dioxide (ZrO2) crowns (25 people). On the basis of IL-1â, IL-8, IL-10, and IL-4 we concluded that the mucosal immunity of oral mucous membranes is less affected by the structures made of oxide ceramics compared to the crowns made of metal-ceramics. Similar patterns of changes in the levels of IL-1â, IL-8, and IL-4 in saliva and gingival fluid in patients who underwent dental rehabilitation were found, which allows us to use only saliva in order to eliminate the complexity and specificity of gingival fluid sampling. Also, changes in cytokine indices in saliva and gingival fluid at different stages of prosthodontics reflect the level of reaction of oral mucosal immunity, which can serve as a criterion of the quality of the performed dental treatment.

Investigation of structural, dielectric, impedance, and conductivity properties of layered perovskite type compound; NaYSnO4

In this paper, the structural study of NaYSnO4 (NYSO), a layered perovskite ceramic oxide, was done using an X-ray diffractometer (XRD) to identify the phase and determine the composition of NYSO. The microscopic structure of the sample seen by Scanning Electron Microscopy (SEM) was found to be polycrystalline and a mixture of large and small grains, which indicate the anisotropic nature of the sample. A FTIR spectroscopic behaviour of the material was used to identify the formation of different bonds in the material, and the XPS study gives an idea of the binding energy of each element in NYSO. A thorough analysis of the impedance, dielectric constant, dielectric loss, modulus and AC conductivity properties concerning temperature and frequency displays the electronic device characteristics. The complex impedance spectra were studied at temperatures range between 25 and 500˚C and frequency of 100 Hz to 1 MHz range. Nyquist plots reveal the charge conduction mechanism of the grain and well-defined grain boundaries that correspond to the resistive and capacitive phenomena of the material. Furthermore, the activation energy has been estimated to investigate the charge transportation mechanism. This article concludes by discussing future possibilities and scientific challenges in NTCR thermistors using NYSO.

Synthesis and NEXAFS and XPS Characterization of Pyrochlore-Type Bi1.865Co1/2Fe1/2Ta2O9+Δ

A cubic pyrochlore with the composition Bi1.865Co1/2Fe1/2Ta2O9+Δ (space group Fd-3m, a = 10.5013(8) Å) was synthesized from oxide precursors using solid-phase reactions. These ceramics are characterized by a porous microstructure formed by randomly oriented grains of an elongated shape with a longitudinal size of 0.5–1 µm. The electronic state of cobalt and iron ions in oxide ceramics was studied by NEXAFS and XPS spectroscopy. The parameters of the XPS spectra of Bi4f, Bi5d, Ta4f, Co2p, and Fe2p ionization thresholds for a complex pyrochlore were compared with the parameters of the corresponding oxides of the transition elements. The energy position of the XPS-Ta4f and -Ta5p spectra is shifted towards lower energies compared to the binding energy in tantalum(V) oxide by 0.75 eV. According to XPS spectroscopy, bismuth and tantalum cations have the corresponding effective charge of +3 and +(5-δ). The NEXAFS-Fe2p spectrum of ceramics coincides with the spectrum of Fe2O3 in its main spectrum characteristics and indicates the content of iron ions in the oxide ceramics in the form of octahedral Fe(III) ions, and according to the character of the Co2p spectrum, cobalt ions are predominantly in the Co(II) state.

Full-scale insight into high-entropy ceramics from basic concepts, synthesis technologies, structural characteristics, and properties to application prospects

High-entropy ceramics (HECs) are an emerging material system that has gained significant attention and become a focal point of research due to their unique structure and outstanding performance. This paper provides a comprehensive examination of the basic concepts, synthesis methods, structural characteristics, unique properties, and application prospects of HECs. It begins with an overview of the basic concepts and historical context, followed by a detailed comparison of synthesis techniques, including both traditional and innovative approaches. The paper then analyzes the structural characteristics and phase compositions of HECs, particularly focusing on oxide, carbide, boride, and other non-oxide ceramics. In addition, it delves into the mechanical, thermal, electrical, and magnetic properties of HECs. The article also reviews the applications of HECs in high-temperature structural materials, functional materials, high-performance coatings, and biomedical implants. Finally, it discusses the future challenges and development pathways for HECs. By highlighting new applications and transformative possibilities, this study not only sheds light on cutting-edge research but also emphasizes the significant impact of HECs on sustainable material development. The integration of machine learning and artificial intelligence can further unlock the unique structural capabilities of HECs, offering substantial potential for advancements in emerging fields like new energy and biomedicine.

Tailoring charge transport in BaTiO3 crystals through dislocation engineering

AbstractDislocations in oxide ceramics significantly influence their physical properties by creating substantial local strain fields, new electronic states, and space‐charge layers. In this study, we investigated the effects of mechanically introduced dislocations on the electrical conductivity of BaTiO3 single crystals. High‐temperature plastic deformation was employed to introduce a high dislocation density with a {100}〈100〉 slip system. Impedance measurements revealed a significant anisotropy in the conductivity due to the presence of oriented dislocation structures. The crystals with dislocation lines aligned parallel to the measurement axis ([001] crystallographic direction) exhibited 16‐fold higher conductivity compared to those measured across the dislocations. Compared to the pristine crystals, this means an increase in conductivity when the measurements were carried out parallel to dislocation lines and a decrease in perpendicular measurements. Our study demonstrates that not only ferroelectric properties but also charge transport can be modified by dislocation introduction in BaTiO3.

Transparent rare earth‐doped gallium oxide ceramics with oriented microstructure

AbstractGallium oxide (Ga2O3) has attracted much attention due to its promising applications in optical and electronic devices, while it is difficult to fabricate high‐quality Ga2O3 transparent ceramics because of the non‐cubic crystal structure. In this work, fully densified undoped and rare earth (RE = Tb, Dy. Er)‐doped Ga2O3 transparent ceramics were successfully fabricated by using spark plasma sintering (SPS) and co‐precipitated ceramic powders. Both the powders and ceramics showed pure monoclinic β‐ Ga2O3 crystal structure and unique orientation. After sintering by SPS for 30 min, all the ceramics reached a relative density higher than 99.21%. The total transmittance of RE‐doped Ga2O3 transparent ceramics ranges from 60% to 69% originating from the oriented and dense microstructures. The photoluminescence spectra and fluorescence lifetime of RE‐doped Ga2O3 transparent ceramics confirm characteristics of energy transfers corresponding to Tb3+, Dy3+, or Er3+ ions in the visible and NIR spectral region. This study demonstrates that oriented RE‐doped Ga2O3 transparent ceramics have great potential to be used in various optical applications.

Boosting corrosion resistance of Mg-Li alloy: Implanting bioinspired superhydrophobic surfaces into MAO matrix for enhanced protection

The corrosion problem has significantly impeded the practical application of Mg-Li alloys. In this report, a method that combines micro-arc oxidation (MAO) with electrochemical deposition is developed to create a superhydrophobic matrix on Mg-Li substrate. The combination approach harnesses the superiority of both coverages, including MAO as the dense, firmly bonded ceramic oxide layer on the metal substrate and the superhydrophobic surface (SHS) implanted into MAO matrix. The MAO-SHS coating exhibits high mechanical stability, maintaining the superhydrophobicity due to the “implanting effect” even after a long distance of friction effect. For corrosion inhibition, compared to the bare Mg-Li with icorr of 9.26 × 10−5 A/cm2, the icorr for MAO and MAO-SHS is 7.83 × 10−6 A/cm2 and 7.50 × 10−9 A/cm2, respectively, representing the reduction of approximately one and four orders of magnitude. Focusing the atmospheric corrosion inhibition, MAO-SHS proves to manipulate the dynamic evolution of saline solution evaporation and salt particle deliquation. The salt particle crystalized from saline solution on MAO-SHS is found to have significantly smaller contact area than that of the bare Mg-Li and MAO. By employing atomic force microscopy, the adhesion force of salt particle is revealed as ca. 45 nN, 13 nN, and 2 nN for salt particle on Mg-Li, MAO, and MAO-SHS, respectively. This suggests that the salt can be more easily removed from the MAO-SHS surface, thereby reducing the susceptibility to corrosion. The in situ deliquation is conducted to understand the formation of the droplet on different surfaces. The air in the SHS layer hinders chloride ingress and the SHS layer seals the pores in MAO layer, proving the synergistic effect afforded by MAO-SHS to achieve superior corrosion resistance.

Unraveling impacts of polycrystalline microstructures on ionic conductivity of ceramic electrolytes by computational homogenization and machine learning

The ionic conductivity at the grain boundaries (GBs) in oxide ceramics is typically several orders of magnitude lower than that within the grain interior. This detrimental GB effect is the main bottleneck for designing high-performance ceramic electrolytes intended for use in solid-state lithium-ion batteries, fuel cells, and electrolyzer cells. The macroscopic ionic conductivity in oxide ceramics is essentially governed by the underlying polycrystalline microstructures where GBs and grain morphology go hand in hand. This provides the possibility to enhance the ion conductivity by microstructure engineering. To this end, a thorough understanding of microstructure–property correlation is highly desirable. In this work, we investigate numerous polycrystalline microstructure samples with varying grain and grain boundary features. Their macroscopic ionic conductivities are numerically evaluated by the finite element homogenization method, whereby the GB resistance is explicitly regarded. The influence of different microstructural features on the effective ionic conductivity is systematically studied. The microstructure–property relationships are revealed. Additionally, a graph neural network-based machine learning model is constructed and trained. It can accurately predict the effective ionic conductivity for a given polycrystalline microstructure. This work provides crucial quantitative guidelines for optimizing the ionic conducting performance of oxide ceramics by tailoring microstructures.

Electromechanical coupling in alkaline-earth doped-ceria ceramics

Oxygen-deficient cerium oxide ceramics exhibit an anomalously high electromechanical response called giant electrostriction. This feature has been linked to the polarization and reorganization of ionic defects, i.e., VO··, under an electric field. However, the exact mechanism and how it is related to intrinsic/extrinsic characteristics of doped ceria remains unclear. The present work investigates how alkaline-earth dopants with different defect–dopant interactions affect the overall electrochemical properties and defect chemistry and, ultimately, how these features impact the final electromechanical properties. We found higher dopant–defect associations attenuate the low-frequency relaxation of the electrostrictive coefficient. The defect chemistry is shown to be the main factor controlling the final electromechanical properties rather than defect concentration. All compositions show a similar electrostrictive response at high frequencies, indicating a common underlying mechanism. All samples showed a high electrostrictive coefficient (up to 3·10−17 m2/V2) and pseudo-piezoelectric response (32 pm/V).

Interfacial performance evolution of ceramics-in-polymer composite electrolyte in solid-state lithium metal batteries

The incorporation of ceramics into polymers, forming solid composite electrolytes (SCEs) leads to enhanced electrical performance of all-solid-state lithium metal batteries. This is because the dispersed ceramics particles increase the ionic conductivity, while the polymer matrix leads to better contact performance between the electrolyte and the electrode. In this study, we present a model, based on Hybrid Elements Methods, for the time-dependent Li metal and SCE rough interface mechanics, taking into account for the oxide (ceramics) inclusions (using the Equivalent Inclusion method), and the viscoelasticity of the matrix. We study the effect of LLTO particle size, weight concentration, and spatial distribution on the interface mechanical and electrical response. Moreover, considering the viscoelastic spectrum of a real PEO matrix, under a given stack pressure, we investigate the evolution over time of the mechanical and electrical performance of the interface. The presented theoretical/numerical model might be pivotal in tailoring the development of advanced solid state batteries with superior performance; indeed, we found that conditions in the SCE mixture which optimize both the contact resistivity and the interface stability in time.