Dariia Chernomorets, Vojtěch Nečina, Pietro Galizia
et al.
The synergistic effect of spark plasma sintering (SPS) and 0–15 mol. % of ZrO₂ doping on the microstructure, mechanical and optical properties of Y2O3 transparent ceramics was investigated. ZrO2-doped Y2O3 were obtained by SPS at 1300–1600 °C. Sintering at 1500 °C leads to defect-free, fully dense material with submicron grain size. The grain size of ceramics decreases from 5.2 to 0.11 µm for Y0Z and Y15Z, respectively, since ZrO2 acts as a grain growth inhibitor. The optimal concentration of ZrO2 to achieve the highest transparency of yttria is 3 mol. % (82.5 % for λ=5 μm). Increasing concentration of Zr4+ ions increases the number of interstitials Oi″, leading to a less efficient elimination of porosity. Vickers microhardness increased from 7.06 to 11.17 GPa with an increase in ZrO2 concentration, while opposite behavior was observed for fracture toughness. The influence of grain size and ZrO2 concentration on elastic modulus, shear modulus and Poisson’s ratio was not revealed.
C. Montero‐Tavera, M. D. Durruthy‐Rodríguez, K. M. Moya‐Canul
et al.
ABSTRACT Physical properties of the K0.5Na0.5NbO3 (KNN) system doped with less than 1.3 mol% of Li+, La3+, and Ti4+ ions were studied. These samples were prepared by a mixture of oxides and carbonates using high‐energy milling and solid‐state reactions. The sample KNNLa0.75 showed an orthorhombic phase, and the rest showed a mixture of monoclinic and orthorhombic phases. Ion doping induced an increase in the grain size, and improved the ferroelectric and pyroelectric properties, decreasing leakage currents. The thermal diffusivity decreases with doping and differential scanning calorimetry measurements allowed the identification of crystalline transition temperatures from orthorhombic‒tetragonal, monoclinic‒tetragonal, and tetragonal‒cubic phases.
Layered, hexagonal crystal structures, like zeta and eta phases, play an important role in ultra-high temperature ceramics, often significantly increasing toughness of carbide composites. Despite their importance open questions remain about their structure, stability, and compositional pervasiveness. We use high-throughput density functional theory to characterize the thermodynamic stability and elastic constants of layered carbides and nitrides M$_{n+1}$X$_{n}$ with $n$ = 1, 2, and 3, $M$ = Ta, Ti, Hf, Zr, Nb, Mo, V, W, Sc, Cr, Mn and $X$ = C, N. The stacking sequences explored are inspired by the possible use of MXenes as precursors to enable relatively low temperature processing of high-temperature ceramics. We identified 67 new hexagonal, layered materials with thermal stability comparable or better than previously observed zeta phases. To assess their potential for high temperature applications, we used machine learning and physics-based models with DFT inputs to predict their melting temperatures and discovered several candidates on par with the current state of the art zeta-like phases and five with predicted melting temperatures above 2500 K. The findings expand the range of chemistries and structures for high-temperature applications.
This paper presents an analytic solution of the incompressible Navier-Stokes equations as recurrence relations for the solution's derivatives, addressing the Clay Mathematics Institute's Millennium Prize problem on Navier-Stokes existence and smoothness.
Jian Zhang, Francesco Aiello, Mauro Salazar
et al.
To overcome the brittleness limitation of ceramics, various toughening mechanisms have been proposed. Some of the most remarkable, especially for oxides, include the tetragonal-to-monoclinic phase transformation leading to crack shielding in zirconia, and bioinspired brick-and-mortar microstructures fostering crack deflection. It has, however, proven challenging to incorporate both these mechanisms into a single all-ceramic material. In this work, we propose a computational methodology for the design of a material that combines these two toughening strategies, using a multiscale modeling approach that captures both their individual contributions and the overall fracture performance. This is achieved by developing an all-ceramic composite with a brick-and-mortar microstructure, in which the nanocrystalline mortar is transformation-toughened. Key factors influencing phase transformation, such as grain boundary properties, grain orientations, and kinetic coefficients, are analyzed, and the resulting transformation stress-strain behavior is incorporated into the microscale mortar constitutive model. We demonstrate that the synergistic effect of the two toughening mechanisms is achievable, and that it is an extremely effective strategy to boost fracture performance. The influence of brick size, mortar thickness, and properties of the constituent materials is then systematically investigated. Finally, a gradient-free optimization algorithm is employed to identify optimal geometric and material parameters, revealing that longer, thinner bricks with minimal mortar thickness provide the best fracture resistance. Optimal combinations of material properties are identified for given brick sizes and mortar thicknesses.
Pimpilai Wannasut, Orawan Khamman, Pharatree Jaita
et al.
In this work, the complex lead-free piezoelectric ceramics with formula (1 − x)[0.995 Bi0.5(Na0.80K0.20)0.5TiO3–0.005LiNbO3]–xFe2O3, where x = 0, 0.010, 0.015 and 0.020 mol fraction, have been prepared via a conventional solid-state method. The effects of Fe2O3 doping on the physical, microstructural electrical, energy harvesting and magnetic properties have been systematically investigated. All ceramics were sintered at 1150°C for 2 hours with obtained relative density of ~ 96-97%. The XRD and Raman data revealed the coexisting rhombohedral and tetragonal phases for all samples. SEM image presented angular grain packing with the average grain size range of 0.43–1.03 μm. The addition of Fe2O3 content improved in electrical properties of undoped sample particularly at a composition of x = 0.015. The maximum values of εm = 6250, Smax = 0.29, d*33 = 578 pm/V, d33 = 211 pC/N and FOM = 3.54. All ceramics indicated ferromagnetic behavior with slim hysteresis shape. The results suggest a potential for its applications as an eco-friendly compound for further use in sensor, spintronic and microelectronic devices applications.
Marco Zaccaria, Miriam Schuster, Jagoda Cupać
et al.
Remanucycling is the process of disassembling a product at its end-of-life into its constituent parts and materials with the purpose of maximizing their reclamation potential. The components which are still in good working conditions can be used as constituent for remanufacturing new products, those that cannot be used for remanufacturing can then be recycled and eventually downcycled, whilst the landfill path is to be banned. For remanucycling to occur products must be disassemblable and the resulting components fit for the purpose. This applies to the most widespread architectural glass product: the insulating glass unit, whereby the glass panes could be reused or recycled. Recently, an industrial machine capable of disassembling insulating glass units was developed. This innovation represents a crucial step for implementing circularity of transparent façades, but it is not the only step required for remanucycling to occur. Selective deconstruction must replace demolition, the material flow is to be diverted from landfill towards disassembly plants, from where additional new logistic routes are to be established. The glass transport will have to shift from a predominantly stock-size model to a cut-size model. Selective deconstruction and cut-size transport are more work-intensive than demolition and stock-size transport, respectively. This hints that one of the challenges for remanucycling to occur is to develop extremely effective practices that can keep the costs of operation below a break-even threshold. In order to reuse glass components, specific quality protocols are to be proposed, established, validated and eventually standardized. These protocol are to be specific by glass type. The environmental footprint of remanucycling is yet to be assessed, but its benefit mainly comes from scaling-up. This study introduces the concept of remanucycling and applies it specifically to the architectural flat glass industry. The transformation needed, along with the challenges and opportunities arising from this transformation are described. The purpose is to provide a holistic view of how the glass industry might shift towards a circular economy so that the changes needed can be identified and coordinated at industry and scientific level.
Microwave (MW) transmission, absorption, and reflection loss spectra of the ferrimagnetic U-type hexaferrite Sr$_4$CoZnFe$_{36}$O$_{60}$ ceramics were studied from 100 MHz to 35 GHz at temperatures between 10 and 390 K. 9 MW magnetic excitations with anomalous behavior near the ferrimagnetic phase transitions were revealed. They also change under the application of weak bias magnetic field (0 - 700 Oe) at room temperature. 6 pure magnetic modes are assigned to dynamics of the magnetic domain walls and inhomogeneous magnetic structure of the ceramics, to the natural ferromagnetic resonance (FMR) and to the higher-frequency magnons. Three modes are considered as the magnetodielectric ones with dominating influence of the magnetic properties on their temperature and field dependences. Presence of the natural FMR in all ferrimagnetic phases proves existence of the non-zero internal magnetization and magnetocrystalline anisotropy. Splitting of the FMR into the two components without magnetic bias was observed in the collinear phase and is attributed to a change of the magnetocrystalline anisotropy during the phase transition. The high-frequency FMR component critically slows down to the phase transition. At room temperature, the FMR splitting and essential suppression of the higher-frequency modes was revealed under the weak bias field (300 - 700 Oe). The highly nonlinear MW response and the FMR splitting are caused by the gradual evolution of the polydomain magnetic structure to a monodomain one. The high number of magnetic excitations observed in the MW region confirms the suitability of using hexaferrite Sr$_4$CoZnFe$_{36}$O$_{60}$ ceramics as MW absorbers, shielding materials and highly tunable filters.
T. H. T. Rosa, M. A. Oliveira, Y. Mendez-Gonzalez
et al.
Perovskite structure materials based on the Ba1-xGdxTiO3 system, where x = 0.001, 0.002, 0.003, 0.004 and 0.005, were prepared via the Pechini chemical synthesis route. The dielectric properties have been analyzed over a wide temperature and frequency range, revealing a significant contribution of the conduction mechanisms in the dielectric response of the studied ceramics. In fact, by using the Davidson-Cole formalism, the observed electrical behavior was found to be associated with relaxation processes related to intrinsic defects mobility promoted by a thermally-activated polaronic mechanism. The obtained values of the activation energy for the relaxation processes, estimated from the Arrhenius law for the mean relaxation time, revealed a decrease from 0.29 up to 0.21 eV as the Gd-doping concentration increases, which suggests the conduction process to be associated with the polaronic effects due to the coexistence of Ti4+ and Ti3+ ions in the structure. Analysis from the conductivity formalism, by using the Jonscher universal power-law, confirmed the polaron-type conduction mechanism for the dielectric dispersion, as suggested by the dielectric analysis, being the nature of the hopping mechanism governed by small polaron hopping (SPH) charge transport in the studied Ba1-xGdxTiO3 ceramics.
In recent years, with the development of batteries, ceramics, glass and other industries, the demand for lithium has increased rapidly. Due to the rich lithium resources in seawater and salt-lake brine, the question of how to selectively adsorb and separate lithium ions from such brine has attracted the attention and research of many scholars. The Li-ion sieve stands out from other methods thanks to its excellent special adsorption and separation performance. In this paper, mesoporous titanium dioxide and lithium hydroxide were prepared by hydrothermal reaction using bacterial cellulose as a biological template. After calcination at 600 °C, spinel lithium titanium oxide Li2TiO3 was formed. The precursor was eluted with HCl eluent to obtain H2TiO3. The lithium titanate were characterized by IR, SEM and X-ray diffraction. The adsorption properties of H2TiO3 were studied by adsorption pH, adsorption kinetics, adsorption isotherm and competitive adsorption. The results show that H2TiO3 has a single-layer chemical adsorption process, and has a good adsorption effect on lithium ions at pH 11.0, with a maximum adsorption capacity of 35.45 mg g−1. The lithium-ion sieve can selectively adsorb Li+, and its partition coefficient is 2242.548 mL g−1. It can be predicted that the lithium-ion sieve prepared by biological template will have broad application prospects.
Lithography based additive manufacturing (L-AMT) is a widely used additive manufacturing technique for the fabrication of ceramics like Al2O3. Al2O3 shows many favorable properties e.g. high temperature resistance, high hardness, and good corrosion and erosion resistance As a drawback, ceramics are generally brittle, limiting the achievable strength and toughness of the material. One approach to increase fracture toughness is by short fiber reinforcements. The scope of this work focuses on the processing of short aluminosilicate fiber reinforced alumina by lithography based ceramic manufacturing (LCM). As fibers tend to agglomerate when incorporating them into a ceramic slurry, different dispersing additives and amounts were investigated. Using 5 wt% Disperbyk 2155, a slurry containing 1 wt% of aluminosilicate fibers could be processed, showing a viscosity of 11 Pa s at 10 s−1 and agglomerates of maximal (45 ± 17) μm. This viscosity makes the material processable in L-AMT.
With the capability of interconversion between electrical and mechanical energy, piezoelectric materials have been revolutionized by the implementation of perovskite-piezoelectric-ceramic-based studies over 70 years. In particular, the market of piezoelectric ceramics has been dominated by lead zirconate titanate for decades. Nowadays, the research on piezoelectric ceramics is largely driven by cutting-edge technological demand as well as the consideration of a sustainable society. Hence, environmental-friendly lead-free piezoelectric materials have emerged to replace lead-based Pb(Zr,Ti)O3 (PZT) compositions. Owing to the inherent high mechanical quality factor (Qm) and low energy loss, (Li,Na)NbO3 (LNN) materials have recently drawn increasing attention and brought advantages to high-power piezoelectric applications. Although the crystallographic structures of LNN materials were intensively investigated for decades, the technical strategies for electrical performance are still limited. As a result, the property enhancement appears to have approached a plateau. This review traces the progress in the development of LNN materials, starting from the polymorphism in terms of the crystal structures, phase transitions, and local structural distortions. Then, the key milestone works on the functional tunability of LNN are reviewed with emphasis on involved engineering approaches. The exceptional performance at a large vibration velocity makes LNN ceramics promising for high-power applications, such as ultrasonic welding (UW) and ultrasonic osteotomes (UOs). The remaining challenges and some strategic insights for synergistically engineering the functional performance of LNN piezoceramics are also suggested.
Piotr Malczyk, Tilo Zienert, Florian Kerber
et al.
The development and evaluation of novel stainless steel-based composites for direct contact with liquid aluminum alloys has been carried out. The Steel Ceramic Composite consisted of 60 vol% 316L stainless steel powder and 40 vol% of MgO or TiO2 ceramic powder. The sample were manufactured using uniaxial pressing and subsequent surface pre-oxidation at 850, 1000 °C for 24 h.The corrosion resistance of composite was investigated against molten AlSi7Mg0.3 alloy using crucible corrosion tests. The tests were carried out at 850 °C for 24 h and 168 h. The influence of pre-oxidation on the corrosion resistance of the samples was analyzed using XRD and SEM/EDS. The corrosion phases formed in the aluminum alloy were investigated using SEM/EDS/EBSD and PSEM/ASPEX/AFA and included the assessment of aluminum alloy contamination by evaluation of corrosion precipitation content, quantity and size. The sample Steel-MgO exhibited excellent corrosion resistance with negligible contamination of the aluminum alloy.
Understanding the atomistic mechanism of ion conduction in solid electrolytes is critical for the advancement of all-solid-state batteries. Glass-ceramics, which undergo crystallization from a glass state, frequently exhibit unique properties including enhanced ionic conductivities compared to both the original crystalline and glass forms. Despite these distinctive features, specific details regarding the behavior of ion conduction in glass-ceramics, particularly concerning conduction pathways, remain elusive. In this study, we demonstrate the crystallization process of glass-Li$_3$PS$_4$ through molecular dynamics simulations employing machine learning interatomic potentials constructed from first principles calculation data. Our analyses of Li conduction using the obtained partially crystallized structures reveal that the diffusion barriers of Li decrease as the crystallinity in Li$_3$PS$_4$ glass-ceramics increases. Furthermore, Li displacements predominantly occur in the precipitated crystalline portion, suggesting that percolation conduction plays a significant role in enhanced Li conduction. These findings provide valuable insights for the future utilization of glass-ceramic materials.
This paper presents a Python software package, Ph3pyWF, providing a more convenient platform to realize high-throughput analysis of lattice thermal conductivity for ceramic materials. The interface of Ph3pyWF is friendly for users with different needs and from different level. For novices of interests, the inputs can be quite simple, just with initial unit cell structure. Other parameters would be automatically filled. And for expert-level researchers with varied requirements, plenty of procedure parameters can be customized. The core concept of Ph3pyWF is to build a data exchange and task management system with high efficiency. The design details of the Ph3pyWF will be clarified in this paper and following with a few typical oxide ceramics examples to demonstrate the applicability of this software package.
Revealing the hardening and strengthening mechanisms is crucial for facilitating the design of superhard and high-strength high-entropy ceramics (HECs). Here, we take high-entropy diborides (HEB$_2$) as the prototype to thoroughly investigate the hardening and strengthening mechanisms of HECs. Specifically, the equiatomic 4- to 9-cation single-phase HEB$_2$ ceramics (4-9HEB$_2$) are fabricated by an ultra-fast high-temperature sintering method. The as-fabricated 4-9HEB$_2$ samples possess similar grain sizes, comparable relative densities (up to ~98%), uniform compositions, and clean grain boundaries without any impurities. The experimental results show that the hardness and flexural strength of the as-fabricated 4-9HEB$_2$ samples have an increasing tendency with the increase of metal components. The first-principles calculations find that lattice distortion is essential to the hardness and strength of HEB$_2$. With the increase of metal components, an aggravation of lattice distortion accompanied by B-B bond strengthening is determined, resulting in the enhancement of the hardness and flexural strength. Moreover, the correlation between other potential indicators and the hardness/flexural strength of HEB$_2$ has been disproved, including valence electron concentration, electronegativity mismatch, and metallic states. Our results unravel the hardening and strengthening mechanisms of HECs by intensifying lattice distortion, which may provide guidance for developing superhard and high-strength HECs.
Luca Guidi, Giovanni Inghirami, Gerardo Masiello
et al.
Façades are one of the main elements that affect indoor environmental quality (IEQ) in buildings and building performance. Given the increasing development of sensor technology, the collection of building monitoring data is useful to understand whether the building and in particular the façade system performs as designed. The increasing use of Technical Building Management (TBM) as well as Building Automatic and Control System (BACs) has been demonstrated to be a promising method to decrease the energy consumption and increase the indoor comfort in new and existing buildings. This project aims to develop a tool showing and processing the monitoring data in a BIM environment using an IFC model. The application has been developed thinking about a BIM approach in the building management. Nowadays IFC models are the most used exchange file format in a BIM process. An IFC file can be loaded into a common data environment (CDE) reachable from stakeholders, sharing information and management strategies. The developed tool is a stand-alone application written in C# which is called MICA (Monitoring Internal Comfort Application). MICA can properly display the monitoring data of building sensors, sharing information between different building actors using the IFC format. It is a platform to visualize, manage and identify the IEQ aspects of building based on real monitored data.
Razyeh Behbahani, Hamidreza Yazdani Sarvestani, Erfan Fatehi
et al.
Laser machining is a highly flexible non-contact manufacturing technique that has been employed widely across academia and industry. Due to nonlinear interactions between light and matter, simulation methods are extremely crucial, as they help enhance the machining quality by offering comprehension of the inter-relationships between the laser processing parameters. On the other hand, experimental processing parameter optimization recommends a systematic, and consequently time-consuming, investigation over the available processing parameter space. An intelligent strategy is to employ machine learning (ML) techniques to capture the relationship between picosecond laser machining parameters for finding proper parameter combinations to create the desired cuts on industrial-grade alumina ceramic with deep, smooth and defect-free patterns. Laser parameters such as beam amplitude and frequency, scanner passing speed and the number of passes over the surface, as well as the vertical distance of the scanner from the sample surface, are used for predicting the depth, top width, and bottom width of the engraved channels using ML models. Owing to the complex correlation between laser parameters, it is shown that Neural Networks (NN) are the most efficient in predicting the outputs. Equipped with an ML model that captures the interconnection between laser parameters and the engraved channel dimensions, one can predict the required input parameters to achieve a target channel geometry. This strategy significantly reduces the cost and effort of experimental laser machining during the development phase, without compromising accuracy or performance. The developed techniques can be applied to a wide range of ceramic laser machining processes.