Michelle Weichelt, Larissa Wahl, Nahum Travitzky
et al.
Porous ceramics have a wide range of applications regarding their exceptional structural and specific mechanical properties, such as adjustable permeability, high surface area, and high specific strength. To enhance the compressive strength of porous alumina further, core-shell structures with a dense core and porous shell were produced by combining co-extrusion and robocasting. Different amounts of spherical cellulose particles were added to the paste and subsequently burned out from the printed green bodies to obtain porous alumina. This leads to a porosity ranging from 18 % to 55 % in the samples, whereas the dense alumina shows a porosity of ∼2 %. Two different core-shell ratios were realized to investigate the influence of the dense core on the properties. The core-shell samples were characterized in terms of their porosity using the rule of mixture. The compressive strength of the fabricated structures was investigated and compared to the theoretical strength of porous samples without a dense core. The theoretical strength of porous reference samples was calculated using an empirical exponential expression. A novel approach to structurally reinforce highly porous ceramics was demonstrated by incorporating the dense core. With a porosity of 20 %, the core-shell structures have an average compressive strength of ∼850 MPa. The macrostructure and microstructure of the core-shell samples were investigated using SEM and µCT imaging. This leads to a lower failure of the structure under mechanical load and thus extends the range of possible applications.
Keisuke Makino, Naoto Tanibata, Hayami Takeda
et al.
Na-ion batteries are anticipated for large-scale energy-storage applications due to their resource advantages over Li-ion batteries. Chloride-based cathode materials exhibiting high voltage, offers the possibility to achieve high energy density. While chloride electrodes suffer from leaching into liquid electrolytes, employing all-solid-state batteries with solid electrolytes can mitigate this issue. A sodium chloride cathode material NaFeCl₄ has been reported to operate at a high voltage derived from chloride (3.45 V vs. Na/Na+) and demonstrates a high energy density of 281 Wh (kg-cathode)−1. However, the ionic conductivity of NaFeCl4 is relatively low (5.9 × 10−6S cm−1 at 30 ºC). In this study, we conducted anion substitution to improve the ionic conductivity of NaFeCl4 and found that substituting the chloride ion Cl− with the nitrite ion NO₂−, which has the same valence and a similar ionic radius, increased the ionic conductivity by approximately fourfold (2.7 × 10−5S cm−1 at 30 ºC). Raman spectroscopy and XRD measurements confirmed the incorporation of nitrite ion (NO₂−) units into the lattice, leading to lattice expansion. These findings demonstrate that the substitution of polyatomic anions is a promising approach for expanding the compositional space of chloride-based solid solutions and enhancing their ionic conductivity.
Balaton Borders translates ecological data from Lake Balaton into ceramic tableware that represents human impact on the landscape, from reedbed reduction to shoreline modification and land erosion. Designed for performative dining, the pieces turn shared meals into multisensory encounters where food and data ceramics spark collective reflection on ecological disruption.
Dislocations in ceramics have enjoyed a long yet underappreciated research history. This brief historical overview and reflection on the current challenges provides new insights into using this line defect as a rediscovered tool for engineering functional ceramics.
The growing number of ceramics exhibiting bulk plasticity at room temperature has renewed interest in revisiting plastic deformation and dislocation-mediated mechanical and functional properties in these materials. In this work, a data-driven approach is employed to identify the key parameters governing room-temperature bulk plasticity in ceramics. The model integrates an existing dataset of 55 ceramic materials, 38 plastically deformable and 17 brittle, and achieves accurate classification of bulk plasticity. The analysis reveals several key parameters essential for predicting bulk plasticity: i) Poisson's ratio and Pugh's ratio as macroscopic indicators reflecting the balance between shear and volumetric deformation resistance, and ii) Burgers vector, crystal structure and melting temperature as crystallographic descriptors associated with lattice geometry, slip resistance and thermal stability, and iii) Bader charge as a microscopic measure of bonding character. Together, these parameters define a multiscale descriptor space linking intrinsic materials properties to bulk room-temperature plasticity in ceramics, bridging the gap between empirical ductility criteria and atomistic mechanisms of dislocation-mediated plasticity. While preliminary, this study provides the first systematic, data-driven mapping of the governing factors of ceramic plasticity. The resulting framework establishes a foundation for unifying experimental and computational studies through shared datasets and descriptors, fostering collective progress toward understanding and designing intrinsically ductile ceramics.
Recently, increased efforts have been made to explore the possibility of using glass panes as structural components, such as shear stiffeners. However, there are obstacles to the widespread use of these panes, even though they have proven their load-bearing capacity in structural systems (Haese 2013). The sudden failure of individual glass panes is a major concern because it can affect the overall structural safety. To better understand the causes of this unpredictable behaviour of glass façades, a numerical and physical sensor concept in the form of a hybrid digital twin will be developed. This involves both measurements of real load-bearing systems and simulations using numerical sensors. The two concepts will initially be developed independently, whereby the virtual model is approximated in a continuous process using measurements of the real structure. For this idea of the hybrid digital twin, a numerical sensor model is first presented in this article, which is also used for the evaluation of real sensors and thus serves as a basis for further investigation. The research project on the safety of glass façades in load-bearing structures is an important step towards improving the reliability and durability of such structures. The introduction of a hybrid digital twin will contribute to the development of an improved safety concept and the further establishment of these applications.
The fabrication of piezoelectric multilayer actuators (MLA) with lead-free piezoceramic materials and excellent performance represents a great challenge in the process of replacing the current family of lead-based actuators. Sintering under low pO2 allows co-firing with base metal electrodes, which is an important step towards competitive multilayer actuator fabrication technologies. We prepared sodium potassium niobate (KNNLT) piezoelectric multilayer actuators with Ni electrodes by sintering at low pO2 of 10−11 atm at 950 °C, followed by reoxidation at 850 °C in 10−6 atm. We demonstrate the impact of the sintering protocol, i.e., sintering temperature Ts and pO2, on the phase composition and continuity of Ni electrodes, and on the actuator performance. We discuss the subtle interplay between sintering conditions, microstructure, reoxidation kinetics and piezoelectric performance. The Ni-MLA exhibits a unipolar strain of 0.74 ‰ at 3 kV/mm, a normalized strain coefficient d33* = 247 p.m./V and a loss of tanδ = 0.041.
This study focuses on fabrication of a Mo30Si60B10 coating with elevated silicon content, which enhances working properties of Mo-alloy based on the Т2 phase (t-Mo5SiB2). The Mo30Si60B10 coating has a columnar structure. The alloy is characterized by hardness of 17 GPa; Young's modulus of 304 GPa, and elastic recovery of 29 %. Deposition of the coating increased hardness by 40 %; the Young's modulus, by 18 %; and elastic recovery, by 25 %. Oxidation tests at 1200 °C demonstrated that the specific mass loss of the alloy with Mo30Si60B10 coating was 1.5-fold lower than that of the uncoated alloy. An 18 μm thick oxide layer based on a-SiВO and containing MoO2 particles was formed on the alloy surface. The coating contributes to a ∼14-fold reduction of oxide layer thick. The increase in oxidation resistance of alloy after coating deposition is related to sealing of substrate defects and formation of an a-SiВO layer with elevated silicon content.
Additive manufacturing holds more potential to enable the development of ceramic-based components. Ceramics offer high resistance to heat, high fracture toughness, and are extremely corrosion resistant. Thus, ceramics are widely used in sectors such as the aerospace industry, automotive, microelectronics, and biomedicine. Using various additive manufacturing platforms, ceramics with complex and uniquely designed geometry can be developed to suit specific applications. This project aims at innovating high-temperature thermocouples by embedding conductive metal pastes into a ceramic structure. The paste used includes tungsten, molybdenum, and antimony. The metal pastes are precisely extruded into a T-shaped trench inside the ceramic matrix. Following specific temperature ranges, the ceramic matrix is sintered to improve the properties of the material. The sensors produced can function at extremely high temperatures and are thereby suitable for high-temperature environments. Comparative testing of the 3D sintered sensors with conventional temperature sensors shows high correlation between the two classes of sensors. The resulting R-squared value of 0.9885 is satisfactory which implies the reliability and accuracy of 3D sintering sensors are satisfactory in temperature sensing applications.
The spatial resolution of transmission electron microscopes (TEMs) and scanning transmission electron microscopes (STEMs) has been drastically improved by introducing aberration correction. However, observable range in electron sensitive zeolites are still limited due to electron irradiation damages. Nevertheless, atomic resolution imaging of some zeolites is currently being realized by various developments in electron microscopic hardware, such as high sensitivity cameras. On the other hand, surveying the status of TEM and STEM imaging is very important for further progress in the structural analysis of zeolites. Here, we demonstrate and compare the high-resolution imaging of zeolites with several kinds of imaging modes.
Single Ti3C2Tx MXene (MTO) materials are not suitable for electromagnetic (EM) wave absorption due to their high conductivity and impedance mismatch. To address this issue, we ingeniously took advantage of easily oxidized characteristics of Ti3C2Tx MXene to establish structural defects and multiphase engineering in accordion-like TixO2x−1 derived from Ti3C2Tx MXene by a high-temperature hydrogen reduction process for the first time. Phase evolution sequences are revealed to be Ti3C2Tx MXene/anatase TiO2 → Ti3C2Tx MXene/rutile TiO2 → TixO2x−1 (1 ≤ x ≤ 4) during a hydrogen reduction reaction. Benefiting from conductance loss caused by hole motion under the action of an external electric field and heterointerfaces caused by interfacial polarization, the impedance match and EM attenuation capability of accordion-like TixO2x−1 absorbers derived from Ti3C2Tx MXene are superior to that of pristine Ti3C2Tx MXene/TiO2 materials. Additionally, simulated whole radar cross section (RCS) plots in different incident angular of the Ti3C2Tx MXene/rutile TiO2 product are lower than −20 dBm2, and the minimum RCS value can reach −43 dBm2, implying a great potential for practical applications in the EM wave absorption. Moreover, the relationship among charges, defects, interfaces, and EM performances in the accordion-like TixO2x−1 materials is systematically clarified by the energy band theory, which is suitable for the research of other MXene-derived semiconductor absorbing composites.
Brahim Lemkalli, Saad Bensallam, Muamer Kadic
et al.
Acoustic metamaterials have gained popularity as promising materials for enhancing noise reduction. Here, we explore the use of metamaterials, based on Helmholtz resonators (HRs), to enhance the performance of standard clay hollow brick. By incorporating HRs in the upper and lower hollows, we transform the standard brick into metaBrick, which is essentially designed based on metamaterial principles. We evaluate the acoustic and thermal performance of walls constructed with clay metaBricks, focusing on sound transmission loss and heat resistance. Both the finite element method and experimental analysis were employed to highlight the performance of metaBricks compared to standard clay bricks. Results show that metaBricks significantly enhance acoustic and thermal insulation, achieving an attenuation of $20$ \si{dB} across a broad frequency range from $500$ to $2500$ \si{Hz} and an $8$\% increase in thermal resistance. However, compressive strength is reduced by $33$\%, though it remains above the standard requirements for building materials. These findings indicate that metaBrick is a promising building material, offering improved sound and thermal insulation.
Alekseeva L. S., Nokhrin A. V., Yunin P. A.
et al.
Oxide Y2.5Nd0.5Al5O12 (YAG:Nd) with garnet structure was synthesized in the powder and ceramics forms. Fine-grained YAG:Nd ceramics with a relative density of ~99% were obtained by the Spark Plasma Sintering method (SPS). The radiation resistance of ceramics was studied under irradiation with swift Xe-ions (E = 146 MeV). A gradient defect structure is formed in irradiated ceramics, varying from layer to layer. The strained YAG phase formed as a result of Xe ions irradiation is localized in a near-surface layer with a thickness of ~5 μm. Full amorphization of the samples was observed under irradiation with a fluence of 1x10^13 cm-2. The calculated critical fluence was 6.5x10^12 cm-2, which corresponded to 0.03 dpa. The microhardness of the surface layers of irradiated ceramics is less than the central layers, and, in general, decreases with increasing ion fluence.