Journal of the American Ceramic Society最新文献

{"title":"Microstructural Factors Governing Fracture Toughness in Lithium Silicate Dental Glass-Ceramics Using Machine Learning","authors":"Hongyeun Kim,&nbsp;Maziar Montazerian,&nbsp;Nicholas Clark,&nbsp;Donggeun Lee,&nbsp;Alexander Schöch,&nbsp;Theresa Senti,&nbsp;Alen Frey,&nbsp;Markus Rampf,&nbsp;John C. Mauro","doi":"10.1111/jace.71278","DOIUrl":"https://doi.org/10.1111/jace.71278","url":null,"abstract":"<p>The microstructure of lithium silicate-based dental glass-ceramics (LS-DGCs) is highly complex, consisting of multiple crystalline phases with diverse morphologies embedded within a residual glass matrix. This microstructure, which evolves through compositional changes and thermal treatment, strongly influences fracture resistance. Due to this complexity, identifying consistent microstructural factors within this commercial dataset that govern toughening becomes challenging. We established an experimentally grounded microstructure–property database for ten commercial LS-DGCs and utilized an Extremely Randomized Trees (ExtraTrees) regression model to capture the nonlinear relationships among numerous extracted microstructural descriptors. Indentation fracture toughness (<i>K</i>_c) was investigated alongside crack length (<i>c</i>) as a mathematically related consistency-check target. To reduce specimen-level data leakage, a fivefold GroupKFold validation strategy was used, with all images from the same physical specimen assigned to the same fold. Based on pooled out-of-fold predictions, the model achieved an <i>R</i>² of 0.671 for <i>K</i>_c. Fold-level performance varied across held-out specimen sets, indicating predictive utility within the present commercial dataset rather than uniform generalizability to every unseen specimen combination. Product-to-product and within-product correlation decomposition were used to examine whether descriptor associations extended beyond simple product identity. These analyses identified the LD aspect ratio and area fraction as candidate descriptors associated with <i>K</i>_c within the represented product families. Given the deterministic relationship between <i>K</i>_c and <i>c</i>, agreement in their SHAP rankings was interpreted as an internal consistency check rather than as independent mechanistic validation. This physics-guided framework helps distinguish the relative contributions of morphology-related descriptors and product-level compositional differences, providing complementary perspective on how microstructural evolution can lead to tougher LS-DGCs.</p>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jace.71278","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic Multi-Clay Porous Matrix for Form-Stable Capric Acid–Based Phase Change Composites","authors":"Imran Sk,&nbsp;Swastik Mondal","doi":"10.1111/jace.71281","DOIUrl":"https://doi.org/10.1111/jace.71281","url":null,"abstract":"<div>\u0000 \u0000 <p>The development of leakage-free and thermally reliable phase change materials (PCMs) is crucial for efficient thermal energy storage applications. In this study, a form-stable PCM composite was engineered using a hybrid porous matrix composed of montmorillonite-rich bentonite, kaolin, and perlite in an optimized 1:1:2 ratio, combined with a small amount (2 wt%) of expanded graphite to enhance thermal conductivity. Capric acid (CA) was incorporated via melt infiltration, and PCM loadings from 20 to 50 wt% were investigated. Although the 50 wt% composite exhibited a high latent heat of approximately 77 J g⁻¹, quantitative leakage testing revealed measurable PCM migration at this loading. In contrast, the optimized 35 wt% composite showed no detectable leakage under the applied test conditions, together with a latent heat of approximately 53 J g⁻¹ and superior mechanical integrity. Structural and physicochemical analyses confirm physical confinement of CA within the hierarchical pore network without chemical interaction. These results demonstrate that synergistic integration of multi-clay porous matrices with a minimal conductive additive provides a simple and potentially scalable approach for developing form-stable PCM composites for thermal energy storage applications.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sr and Ag Co-Doped Bioactive Glasses: Modeling and Monte Carlo Simulation of pH, Ion Release, and Osteoblast Response","authors":"Mohammed H. Al-Bayati,&nbsp;Siok Yee Chan,&nbsp;Zaid Nazar Ibrahim,&nbsp;Fariborz Sharifianjazi,&nbsp;Masoumeh Khamehchi,&nbsp;Ketevan Tavamaishvili","doi":"10.1111/jace.71275","DOIUrl":"https://doi.org/10.1111/jace.71275","url":null,"abstract":"<div>\u0000 \u0000 <p>Multifunctional bioactive glasses co-doped with silver (Ag⁺) and strontium (Sr²⁺) represent a compelling approach for engineering biomaterials capable of concurrently supporting bone regeneration and suppressing microbial infection. Leveraging experimental data from our prior work on sol–gel-derived SiO₂–P₂O₅–CaO–SrO–Ag₂O glasses (Ag₂O: 1–10 mol%), a novel multiscale computational framework is presented that predicts the coupled evolution of physicochemical and biological responses during in vitro degradation. The framework unifies three physically informed sub-models: (i) a modified Jones-type kinetics model for time- and composition-dependent pH dynamics in simulated body fluid (SBF); (ii) a pH-coupled diffusion–reaction formalism capturing the release profiles of five ionic species (Ag⁺, Ca²⁺, Sr²⁺, P⁵⁺, Si⁴⁺); and (iii) dual hormesis-based equations describing the biphasic effects of Ag⁺ on osteoblast viability (MTT) and differentiation (ALP). All model coefficients were calibrated using experimental datasets and rigorously validated against a held-out test subset of the experimental dataset, yielding exceptionally low coefficients of variation: 0.30% (pH), 0.92% (Ag⁺), 0.60% (Ca²⁺), 11% (P⁵⁺), 0.72% (Sr²⁺), 1.84% (Si⁴⁺), and 1.85% (both MTT and ALP). Monte Carlo simulations were applied to quantify the probability of satisfying key design criteria, pH &gt; 8.3, controlled release of Ag⁺, Ca²⁺, Sr²⁺, P⁵⁺, and Si⁴⁺, and enhanced osteoblast proliferation and differentiation, across 0–10 mol% Ag₂O and 1–21 days of immersion. The analysis identifies 5 mol% Ag₂O (BG-5A) as the optimal formulation, striking an ideal balance between robust antibacterial efficacy and maximal osteogenic stimulation without inducing cytotoxicity.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase Evolution and Vapor-Environment Stability of Electrospun Mullite–Zirconia Nanofibrous Ceramic Membranes","authors":"Mohamedazeem M. Mohideen,&nbsp;Han Guo,&nbsp;Netsanet Ayele Getachew,&nbsp;Jinqiu Ye,&nbsp;Ping Hu,&nbsp;Ce Wang,&nbsp;Yong Liu","doi":"10.1111/jace.71283","DOIUrl":"https://doi.org/10.1111/jace.71283","url":null,"abstract":"<div>\u0000 \u0000 <p>Flexible oxide ceramic nanofibers that maintain structural integrity under extreme thermal and corrosive environments remain fundamentally limited by grain coarsening and interfacial instability at elevated temperatures. Here, we report a mullite–zirconia nanofibrous ceramic membrane synthesized via dual-template electrospinning followed by controlled thermal treatment (900°C–1300°C). Unlike our previously reported pure mullite fibers, in which Al₂O₃ nanograins crystallize within a single amorphous SiO₂ matrix, zirconia introduces an independent, earlier nucleation pathway that delays mullite formation and produces a distinct amorphous–crystalline interphase. This interphase suppresses grain coarsening and stabilizes fiber morphology up to 1300°C, and drives strong phonon boundary scattering that yields an ultralow thermal conductivity of 0.032 W m⁻¹ K⁻¹ while retaining fibrous bendability. The membrane also withstands acidic, alkaline, and humid vapor corrosion at 150°C, with corrosion resistance tracking crystallinity across the MZNF-1100 to 1300 series, a property not evaluated in single-phase mullite systems. These results identify zirconia-mediated phase competition, rather than compositional addition alone, as the mechanism governing thermal and chemical durability in electrospun oxide nanofiber membranes. In addition, this study provides a future direction for understanding how interfacial structural engineering can simultaneously enhance thermal stability, mechanical compliance, and environmental resistance.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Insights Into the Structural and Thermodynamic Behavior of Gold-Based MAX Phases M2AuC (M = Cr, V)","authors":"Muhammad Yaqoob Khan,&nbsp;Ali H. Reshak,&nbsp;Ahmed Azzouz-Rached,&nbsp;Nasir Rahman,&nbsp;Dania Ali,&nbsp;Eman M. Alshehri,&nbsp;Hind Albalawi,&nbsp;Vineet Tirth,&nbsp;Ali Algahtani,&nbsp;Essam A. Al-Ammar,&nbsp;Mubashir Hussain","doi":"10.1111/jace.71282","DOIUrl":"https://doi.org/10.1111/jace.71282","url":null,"abstract":"<div>\u0000 \u0000 <p>A comprehensive first-principles investigation of the structural, mechanical, electronic, and thermodynamic properties of M₂AuC (M = Cr, V) MAX phases using the FP-LAPW method within the WIEN2k framework is performed. Both compounds that crystallize in a hexagonal Cr₂AlC-type structure (space group P6₃/mmc) exhibit negative formation energies with respect to their constituent elemental reference states, indicating favorable formation from the elements; however, stability against decomposition into competing binary or ternary phases requires further phase-stability analysis. Phonon dispersion analyses show the absence of imaginary frequencies, validating their dynamical stability. The computed elastic constants satisfy the Born–Huang criteria, indicating mechanical stability up to 30 GPa. Both compounds exhibit elastic anisotropy and show a tendency toward ductile mechanical behavior, while their elastic indicators suggest predominantly nondirectional bonding with an appreciable ionic contribution. Electronic band structures and density of states reveal metallic behavior primarily governed by M-d and Au-d orbitals. Thermodynamic analyses based on the quasi-harmonic Debye model show that heat capacity approaches the Dulong–Petit limit at high temperatures, while Debye temperature and thermal expansion exhibit typical temperature- and pressure-dependent trends. These findings establish M₂AuC (M = Cr, V) as mechanically robust, dynamically stable metallic materials with promising high-temperature applications.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146898","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Understanding Surface Interfacial Phenomena During Tricalcium Silicate Dissolution From TEM and XRR","authors":"Aidyn Tugelbayev,&nbsp;Hongyu Wang,&nbsp;David Jarret Wright,&nbsp;Jing Zhao,&nbsp;F. Marc Michel,&nbsp;Alexander S. Brand","doi":"10.1111/jace.71267","DOIUrl":"https://doi.org/10.1111/jace.71267","url":null,"abstract":"<p>Understanding the dissolution mechanism of tricalcium silicate (C₃S) is essential for interpreting its reactivity in cementitious systems. While the dissolution mechanism of C₃S has been considered to follow the classical leached-layer model, the mechanism has also been proposed to occur through the coupled interfacial dissolution–reprecipitation (CIDR) pathway, which has been demonstrated for other silicate minerals. In this work, dissolved surfaces of C₃S were examined using transmission electron microscopy (TEM) and X-ray reflectivity (XRR) to distinguish between these competing dissolution mechanisms. XRR measurements of polycrystalline C₃S indicated changes in near-surface density following dissolution; however, the polycrystalline nature of the specimens prevented definitive attribution to either mechanism. In contrast, TEM imaging identified a sharp, well-defined boundary between the crystalline C₃S and an amorphous reaction layer, which can be indicative of CIDR. The precipitated amorphous silica-rich surface layers were passivating and non-passivating depending on the crystallographic orientation of the grains, which could influence the dissolution rates of C₃S. These results collectively suggest that C₃S dissolution is more consistent with the CIDR mechanism, although further experiments are required to confirm the atomistic exchange associated with this phenomenon.</p>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jace.71267","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Chromium-Free Fe-Added MgO–SiC–C Refractory With Superior Dynamic Matte Slag Corrosion Resistance","authors":"Xu Zhao,&nbsp;Tianbin Zhu,&nbsp;Weijie Guo,&nbsp;Qilong Chen,&nbsp;Yuhang Zhang,&nbsp;Yawei Li,&nbsp;Yajie Dai,&nbsp;Wengang Yang,&nbsp;Honggang Sun","doi":"10.1111/jace.71272","DOIUrl":"https://doi.org/10.1111/jace.71272","url":null,"abstract":"<div>\u0000 \u0000 <p>To develop a chromium-free alternative to MgO–Cr₂O₃ refractories for matte smelting furnaces, this study investigated three novel MgO–SiC–C refractories (with Fe, Si₃N₄, or Si₃N₄–Fe additions) via induction furnace tests simulating actual smelting. Results showed MgO–Cr₂O₃ sample had poor slag penetration resistance due to a porous layer filled with low-melting (Mg₁₋_x, Fe_x)₂SiO₄, impairing stability and allowing partial Cu₂S penetration. The Fe-containing MgO–SiC–C sample exhibited superior dynamic corrosion resistance (comparable to MgO–Cr₂O₃, better in penetration resistance), attributed to low porosity, protective Mg(Fe, Al)₂O₄ and MgAl₂O₄ phases, Fe–Si alloy void filling, and graphite-inhibited Cu₂S penetration. Si₃N₄-containing samples degraded dynamically (despite good static slag resistance) as Si₃N₄ formed low-melting (Mg₁₋_x, Fe_x)₂SiO₄, weakening stability. Overall, the Fe-containing MgO–SiC–C refractory is a promising chromium-free alternative for matte smelting furnaces.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146706","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of Cf/SiC Composites in Linear Scanning Ablation by Femtosecond Laser","authors":"Zhigang Dong,&nbsp;Rongzhe Jiao,&nbsp;Feng Yang,&nbsp;Guangyi Ma,&nbsp;Zhaoji Li,&nbsp;Renke Kang,&nbsp;Yan Bao","doi":"10.1111/jace.71273","DOIUrl":"https://doi.org/10.1111/jace.71273","url":null,"abstract":"<div>\u0000 \u0000 <p>C_f/SiC is a preferred material for high-temperature-resistant components in aerospace, but it is characterized by anisotropy, non-homogeneity, and brittleness. Femtosecond laser processing technology, characterized by high precision and small heat-affected zone, has great potential in processing C_f/SiC. In response to the problem of unclear linear scanning ablation mechanism between laser and materials, this paper conducted femtosecond laser linear ablation and simulation experiments on C_f/SiC composites, obtaining the development laws of electron as well as crystalline host lattice both in temperatures and physical morphology over time and space. The ablation mechanisms involving sublimation and ionization under femtosecond laser irradiation were revealed. It was found that laser power has a greater influence on ablation width, in comparison to scribing speed. Conversely, when compared to laser power, scribing speed has a more significant impact on ablation depth and micromorphology. Periodic structures emerged on the surface of the ablation groove in which laser power was below 2 W and the scribing speed was above 100 mm/s. The ablation parameters were optimized, providing theoretical support and data basis for high-efficiency, high-quality femtosecond laser processing of C_f/SiC composites.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146950","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Designing Porous Boroaluminate Catalysts via Non-Hydrolytic Ether Elimination","authors":"Michal Mlynek,&nbsp;Ales Styskalik,&nbsp;Iaroslav Doroshenko,&nbsp;Jan Varada,&nbsp;Jiri Pinkas,&nbsp;Johan G. Alauzun,&nbsp;Zdenek Moravec","doi":"10.1111/jace.71263","DOIUrl":"https://doi.org/10.1111/jace.71263","url":null,"abstract":"<p>Boroaluminates are mixed oxides of boria and alumina that show promise for various catalytic applications due to their mild acidity. In this work, boroaluminate xerogels were successfully synthesized via alternative non-hydrolytic sol-gel (NHSG) ether elimination pathways, offering a controlled, template-free strategy for their design. We investigated the synthesis using four distinct alkoxide precursor combinations, utilizing aluminum isopropoxide and <i>sec</i>-butoxide as aluminum sources, alongside boron methoxide and isopropoxide as boron sources. This ether elimination approach provides an excellent alternative to traditional alkyl halide elimination routes, allowing the final porosity, coordination states, and surface acidity to be targeted more easily solely through precursor selection and precursor-to-solvent ratios. The synthesized boroaluminates exhibit a highly homogeneous bulk dispersion of aluminum and boron throughout the xerogel networks (as confirmed by XPS, ICP-OES, and EDS mapping), though calcination at 600°C appears to have led to a surface depletion of boron species. Three of the four synthetic pathways yielded high-surface-area materials (590–772 m² g⁻¹) without the use of structure-directing agents. Analysis by ¹¹B and ²⁷Al MAS NMR, combined with NH₃-TPD, revealed that precursor choice directly affects the local atomic coordination, yielding unique catalytic centers—specifically 5-coordinated aluminum alongside 3- and 4-coordinated boron—and a heterogeneous distribution of weak and medium acid sites. Additionally, these materials were evaluated as heterogeneous catalysts in the dehydration of ethanol. The boroaluminates exhibited highly temperature-dependent selectivity, favoring diethyl ether at lower temperatures and shifting predominantly to ethylene at higher temperatures. Four of the five prepared samples showed promising catalytic activity, consistently achieving ethanol conversions between 79% and 93% at 275°C.</p>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1111/jace.71263","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149146705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthesis and Atmosphere-Driven Phase Evolution of Ultrafine Mn3O4-Based Ceramics","authors":"Dmytro Demirskyi,&nbsp;Minoru Takeda","doi":"10.1111/jace.71264","DOIUrl":"https://doi.org/10.1111/jace.71264","url":null,"abstract":"<div>\u0000 \u0000 <p>We report a surfactant‑controlled synthesis of ultrafine Mn₃O₄ and a systematic study of phase formation and microstructure evolution as a function of surfactant content and annealing conditions. We consider Mn₃O₄ to be a promising catalyst for accelerating ortho–para hydrogen conversion. Our approach involves synthesizing Mn(OH)₂ precursors that convert to Mn₃O₄ under normal atmospheric conditions. This change has been verified through in situ x-ray diffraction experiments. To control particle size and phase purity, we use sandalwood oil as a surfactant. An optimal ratio of 1:3 yields single-phase Mn₃O₄ but produces the coarsest particles (20–60 nm). Calcination at 260°C is conducted in argon or hydrogen. Argon annealing promotes the time-dependent growth of MnO and the development of fine oxide crystallites in the surface layer, with sizes ranging from 5–12 nm at 260°C to 3–6 nm at 160°C. Processing in an inert atmosphere or in hydrogen can significantly alter the composition of the catalyst and its surface conditions prior to ortho–para hydrogen conversion testing at the catalyst activation stage via formation of MnO. This should directly impact the catalytic characteristics and is relevant to other oxide/hydroxide catalysts.</p>\u0000 </div>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":"109 10","pages":""},"PeriodicalIF":4.2,"publicationDate":"2026-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149048221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}