Pub Date : 2025-11-02DOI: 10.1016/j.oceram.2025.100875
Simon Keller, Bettina Osswald, Frank Kern
Due to their high strength, hardness and abrasion resistance alumina zirconia composites (ZTA) are well established materials for mechanical engineering and biomedical applications. While the basic material concept is simple, the effects of changes in raw materials are insufficiently investigated. In this study five different submicron alumina powders are combined with 10 vol% of an unstabilized zirconia powder. Samples are consolidated by hot pressing at 1475–1600°C and investigated with respect to microstructure, mechanical properties and phase composition. Adaptation of sintering parameter allows to manufacture ZTA of acceptable quality from all starting powders. Alumina powders of higher purity help to retain a well dispersed and stable microstructure at higher sintering temperatures while in ZTA from alumina powders of lower purity segregation and grain growth is observed at high sintering temperature.
{"title":"Properties of alumina 10 vol% zirconia composites — The role of alumina starting powders","authors":"Simon Keller, Bettina Osswald, Frank Kern","doi":"10.1016/j.oceram.2025.100875","DOIUrl":"10.1016/j.oceram.2025.100875","url":null,"abstract":"<div><div>Due to their high strength, hardness and abrasion resistance alumina zirconia composites (ZTA) are well established materials for mechanical engineering and biomedical applications. While the basic material concept is simple, the effects of changes in raw materials are insufficiently investigated. In this study five different submicron alumina powders are combined with 10 vol% of an unstabilized zirconia powder. Samples are consolidated by hot pressing at 1475–1600°C and investigated with respect to microstructure, mechanical properties and phase composition. Adaptation of sintering parameter allows to manufacture ZTA of acceptable quality from all starting powders. Alumina powders of higher purity help to retain a well dispersed and stable microstructure at higher sintering temperatures while in ZTA from alumina powders of lower purity segregation and grain growth is observed at high sintering temperature.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100875"},"PeriodicalIF":2.8,"publicationDate":"2025-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-11-01DOI: 10.1016/j.oceram.2025.100876
Yassine El Khessaimi , Maria Zapata , Youssef El Hafiane , Koichiro Fukuda , Agnès Smith
This study focuses on ye'elimite, a versatile mineral compound of low carbon sulfo-aluminate cements. While stoichiometric ye'elimite typically exhibits orthorhombic symmetry, the introduction of foreign ions, especially iron, stabilizes a pseudocubic symmetry. This research advances the field by synthesizing highly pure cubic ye'elimite doped with iron and sodium, a unique combination not extensively explored. The study integrates Bayesian optimization to systematically enhance the purity of doped ye'elimite. The results demonstrate an impressive 83 wt.% phase purity achieved with optimal fractions of Ca3.6Na0.4Al5.65Fe0.35SO16 after only 16 experimental iterations, highlighting the effectiveness of Bayesian optimization in streamlining the synthesis process of highly pure materials with reduced experiments.
{"title":"Bayesian experimental design for the synthesis of doped-ye'elimite","authors":"Yassine El Khessaimi , Maria Zapata , Youssef El Hafiane , Koichiro Fukuda , Agnès Smith","doi":"10.1016/j.oceram.2025.100876","DOIUrl":"10.1016/j.oceram.2025.100876","url":null,"abstract":"<div><div>This study focuses on ye'elimite, a versatile mineral compound of low carbon sulfo-aluminate cements. While stoichiometric ye'elimite typically exhibits orthorhombic symmetry, the introduction of foreign ions, especially iron, stabilizes a pseudocubic symmetry. This research advances the field by synthesizing highly pure cubic ye'elimite doped with iron and sodium, a unique combination not extensively explored. The study integrates Bayesian optimization to systematically enhance the purity of doped ye'elimite. The results demonstrate an impressive 83 wt.% phase purity achieved with optimal fractions of Ca<sub>3.6</sub>Na<sub>0.4</sub>Al<sub>5.65</sub>Fe<sub>0.35</sub>SO<sub>16</sub> after only 16 experimental iterations, highlighting the effectiveness of Bayesian optimization in streamlining the synthesis process of highly pure materials with reduced experiments.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100876"},"PeriodicalIF":2.8,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519780","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
CoFe2O4 was synthesized at 150 °C, 180 °C, and 210 °C temperatures using hydrothermal method to find the effect on its structural, magnetic, electric, and optical properties. The saturation magnetization, coercivity and magnetic anisotropy was found using Vibrating Sample Magnetometer (VSM), ranging from 50.36 to 53.66 emu/g. XRD (X-ray Diffraction Analysis) and SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) was used for structural analysis verifying the spinel ferrite structure with a single phase. The crystalline size and lattice strain was found using Size-Strain Plot (SSP) and Debye-Scherrer (D-S) method which proved that as the synthesis temperature increased, the crystallite size also increased. The crystalline size ranges from 39.40 to 82.24 nm as observed by XRD. SEM analysis found the crystal size range to be from 9 to 12 nm. It was found that the optimum temperature to synthesize cobalt ferrite nanoparticles are at 180 °C for sample H2 with a crystal size of 82.24 nm and band gap energy of 2.60 eV. The Ms value was determined to be 50.36 emu/g for H2 sample with Rs value of 0.31.
{"title":"Crystallographic, morphological, magnetic and optical properties of nano cobalt ferrite synthesized by hydrothermal method over different synthesis temperature","authors":"Afia Yasmin , Bristy Biswas , Md. Lutfor Rahman , Juliya Khanam , Rabeya jahan Rakhi , Mahmuda Hakim , Md. Sahadat Hossain , Firoz Ahmed , Israt Jahan Lithi , Nahid Sharmin , Md. Farid Ahmed","doi":"10.1016/j.oceram.2025.100873","DOIUrl":"10.1016/j.oceram.2025.100873","url":null,"abstract":"<div><div>CoFe<sub>2</sub>O<sub>4</sub> was synthesized at 150 °C, 180 °C, and 210 °C temperatures using hydrothermal method to find the effect on its structural, magnetic, electric, and optical properties. The saturation magnetization, coercivity and magnetic anisotropy was found using Vibrating Sample Magnetometer (VSM), ranging from 50.36 to 53.66 emu/g. XRD (X-ray Diffraction Analysis) and SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) was used for structural analysis verifying the spinel ferrite structure with a single phase. The crystalline size and lattice strain was found using Size-Strain Plot (SSP) and Debye-Scherrer (D-S) method which proved that as the synthesis temperature increased, the crystallite size also increased. The crystalline size ranges from 39.40 to 82.24 nm as observed by XRD. SEM analysis found the crystal size range to be from 9 to 12 nm. It was found that the optimum temperature to synthesize cobalt ferrite nanoparticles are at 180 °C for sample H2 with a crystal size of 82.24 nm and band gap energy of 2.60 eV. The M<sub>s</sub> value was determined to be 50.36 emu/g for H2 sample with R<sub>s</sub> value of 0.31.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100873"},"PeriodicalIF":2.8,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The main objective of this study is to determine the prospects for using multilayer CrN/MoN ceramic coatings as protective sacrificial coatings providing increased resistance of steels to the complex destructive effects of hydrogen and aggressive environments due to the synergistic effect of alternating nitride layers and the formation of a dense, defect-resistant structure with highly effective diffusion barriers that restrain the diffusion of atomic hydrogen deep into the materials. The influence of hydrogenation processes on the wear and corrosion of the coating surface was determined using the scanning electron microscopy method, which was used to visualize surface defects formed as a result of external influences. Based on the data obtained, an analysis of the resistance of the coatings to degradation was conducted, and the role of the coatings in restraining destruction to wear and corrosion processes was determined. Moreover, it was found that increasing the number of layers from 4 to 20 inhibits degradation of strength properties by more than 2.2 times. Such changes in coating hardness and wear resistance are due to the barrier effect associated with the increased number of layers in the coating, which inhibits hydrogen diffusion into the coating. Tests of the resistance of samples after hydrogenation to an aggressive environment showed that the decrease in resistance to aggressive environments for coatings subjected to hydrogenation is most pronounced for samples subjected to hydrogenation for 100 h. In this case, the reduction in wear resistance (friction coefficient) is more than 1.5 to 2 times for coating samples subjected to hydrogenation compared to the original samples. According to an assessment of changes in the adhesive strength of coating samples after exposure to an aggressive environment, it was found that in the case of the original samples (not subjected to hydrogenation), an increase in the number of layers from 4 to 20 leads to a decrease in surface delamination from 1.51% to 0.95%. Moreover, for samples subjected to hydrogenation for 100 h, in the case of 4-layer coatings, the change in adhesion strength is more than 11.4%, and in the case of 20-layer coatings, the decrease in adhesion strength is approximately 6.9%, which is more than 1.5 times lower. The novelty of the study lies in determining the role of variation in the number of layers on resistance to degradation processes caused by hydrogenation and subsequent exposure to an aggressive environment, as well as determining the mechanisms of restraint due to variation in the number of layers and the barrier effects they create, which slow down the degradation processes of mechanical and strength properties.
{"title":"Determination of the efficiency of using multilayer CrN/MoN ceramic coatings for protection against hydrogen absorption and exposure to aggressive environments","authors":"Ye.A. Kenzhin , D.I. Shlimas , A.M. Zikirina , A.L. Kozlovskiy","doi":"10.1016/j.oceram.2025.100872","DOIUrl":"10.1016/j.oceram.2025.100872","url":null,"abstract":"<div><div>The main objective of this study is to determine the prospects for using multilayer CrN/MoN ceramic coatings as protective sacrificial coatings providing increased resistance of steels to the complex destructive effects of hydrogen and aggressive environments due to the synergistic effect of alternating nitride layers and the formation of a dense, defect-resistant structure with highly effective diffusion barriers that restrain the diffusion of atomic hydrogen deep into the materials. The influence of hydrogenation processes on the wear and corrosion of the coating surface was determined using the scanning electron microscopy method, which was used to visualize surface defects formed as a result of external influences. Based on the data obtained, an analysis of the resistance of the coatings to degradation was conducted, and the role of the coatings in restraining destruction to wear and corrosion processes was determined. Moreover, it was found that increasing the number of layers from 4 to 20 inhibits degradation of strength properties by more than 2.2 times. Such changes in coating hardness and wear resistance are due to the barrier effect associated with the increased number of layers in the coating, which inhibits hydrogen diffusion into the coating. Tests of the resistance of samples after hydrogenation to an aggressive environment showed that the decrease in resistance to aggressive environments for coatings subjected to hydrogenation is most pronounced for samples subjected to hydrogenation for 100 h. In this case, the reduction in wear resistance (friction coefficient) is more than 1.5 to 2 times for coating samples subjected to hydrogenation compared to the original samples. According to an assessment of changes in the adhesive strength of coating samples after exposure to an aggressive environment, it was found that in the case of the original samples (not subjected to hydrogenation), an increase in the number of layers from 4 to 20 leads to a decrease in surface delamination from 1.51% to 0.95%. Moreover, for samples subjected to hydrogenation for 100 h, in the case of 4-layer coatings, the change in adhesion strength is more than 11.4%, and in the case of 20-layer coatings, the decrease in adhesion strength is approximately 6.9%, which is more than 1.5 times lower. The novelty of the study lies in determining the role of variation in the number of layers on resistance to degradation processes caused by hydrogenation and subsequent exposure to an aggressive environment, as well as determining the mechanisms of restraint due to variation in the number of layers and the barrier effects they create, which slow down the degradation processes of mechanical and strength properties.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100872"},"PeriodicalIF":2.8,"publicationDate":"2025-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-28DOI: 10.1016/j.oceram.2025.100871
K.T. Streckel , L. Koch , M. Müller , M. Schmitkamp , D. Sebold , S. Baumann , A. Nijmeijer , W.A. Meulenberg , N. Knoblauch
The stability of ceria‑based redox oxides under high‑temperature solar‑thermal operation is crucial for fuel‑producing reactors. This study demonstrates that the gas pressure governs CeO2 sublimation from Gd0.1Ce0.9O1.95 (GDC-10) under solar thermochemical conditions. Annealing GDC-10 at 1400 °C in vacuum (≈10-4 bar) produces a porous, sponge like surface layer enriched in Gd, confirming selective CeO2 sublimation; identical treatments in argon at the same temperature and duration do not generate comparable porosity. Time resolved electron microscopy reveal a diffusion controlled, linear growth of the cerium depleted zone, while dilatometry records irreversible chemical expansion, indicating structural damage. Co-doping with 5 mol % Zr (Ce0.9Gd0.05Zr0.05O1.975) reduces CeO2 loss and yields a saturated surface. Knudsen effusion mass spectrometry shows reduced CeO2 volatility for the co-doped material after aging, linking thermodynamic stability to improved microstructural integrity. These results establish Zr co-doping as a potential strategy to stabilize GDC type redox oxides for durable solar thermochemical fuel production.
{"title":"Thermodynamic stability of doped ceria for solar reactors: Sublimation and surface segregation","authors":"K.T. Streckel , L. Koch , M. Müller , M. Schmitkamp , D. Sebold , S. Baumann , A. Nijmeijer , W.A. Meulenberg , N. Knoblauch","doi":"10.1016/j.oceram.2025.100871","DOIUrl":"10.1016/j.oceram.2025.100871","url":null,"abstract":"<div><div>The stability of ceria‑based redox oxides under high‑temperature solar‑thermal operation is crucial for fuel‑producing reactors. This study demonstrates that the gas pressure governs CeO<sub>2</sub> sublimation from Gd<sub>0.1</sub>Ce<sub>0.9</sub>O<sub>1.95</sub> (GDC-10) under solar thermochemical conditions. Annealing GDC-10 at 1400 °C in vacuum (≈10<sup>-4</sup> bar) produces a porous, sponge like surface layer enriched in Gd, confirming selective CeO<sub>2</sub> sublimation; identical treatments in argon at the same temperature and duration do not generate comparable porosity. Time resolved electron microscopy reveal a diffusion controlled, linear growth of the cerium depleted zone, while dilatometry records irreversible chemical expansion, indicating structural damage. Co-doping with 5 mol % Zr (Ce<sub>0.9</sub>Gd<sub>0.05</sub>Zr<sub>0.05</sub>O<sub>1.975</sub>) reduces CeO<sub>2</sub> loss and yields a saturated surface. Knudsen effusion mass spectrometry shows reduced CeO<sub>2</sub> volatility for the co-doped material after aging, linking thermodynamic stability to improved microstructural integrity. These results establish Zr co-doping as a potential strategy to stabilize GDC type redox oxides for durable solar thermochemical fuel production.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100871"},"PeriodicalIF":2.8,"publicationDate":"2025-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145519781","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-24DOI: 10.1016/j.oceram.2025.100870
Anass Hatim , Driss Khaddoudi , Fatima Abida , Hicham Ait Ali Ouydir , Sanaa Kouzbour , Mahfoud Agunaou , Youssef El Hafiane , Abdelkrim Abourriche , Abdelaziz Benhammou , Zineb Hatim , Younes Abouliatim
Hydroxyapatite is a versatile material with strong potential for environmental remediation, yet its large-scale use is limited by the cost and purity requirements of conventional precursors. This study introduces a low-cost and sustainable synthesis route for hydroxyapatite using technical-grade phosphoric acid, highlighting the beneficial role of industrial impurities in tuning its structural, optical, and adsorption properties, thus promoting its broader use in environmental applications. Hydroxyapatite powders were synthesized from calcium hydroxide and technical-grade phosphoric acid (Ca/P = 1.67) at 25 °C in aqueous medium, then dried and calcined (500–1100 °C). Structural, chemical, and optical analyses revealed single-phase nano-hydroxyapatite (12.6–57.3 nm) with high surface area (176.95 m²·g-1) and strong wettability. The optical band gap decreased from 4.5 ± 0.4 eV to 3.2 ± 0.4 eV after calcination, indicating defect-induced electronic modification. The poorly crystallized hydroxyapatite exhibited excellent Cd²⁺ and Pb²⁺ adsorption (99 % and 97 % removal in 100 min) but limited bisphenol A elimination (2.73 % in 180 min).
{"title":"Low-cost and sustainable hydroxyapatite synthesis using technical-grade phosphoric acid for environmental applications: Structural and morphological insights","authors":"Anass Hatim , Driss Khaddoudi , Fatima Abida , Hicham Ait Ali Ouydir , Sanaa Kouzbour , Mahfoud Agunaou , Youssef El Hafiane , Abdelkrim Abourriche , Abdelaziz Benhammou , Zineb Hatim , Younes Abouliatim","doi":"10.1016/j.oceram.2025.100870","DOIUrl":"10.1016/j.oceram.2025.100870","url":null,"abstract":"<div><div>Hydroxyapatite is a versatile material with strong potential for environmental remediation, yet its large-scale use is limited by the cost and purity requirements of conventional precursors. This study introduces a low-cost and sustainable synthesis route for hydroxyapatite using technical-grade phosphoric acid, highlighting the beneficial role of industrial impurities in tuning its structural, optical, and adsorption properties, thus promoting its broader use in environmental applications. Hydroxyapatite powders were synthesized from calcium hydroxide and technical-grade phosphoric acid (Ca/P = 1.67) at 25 °C in aqueous medium, then dried and calcined (500–1100 °C). Structural, chemical, and optical analyses revealed single-phase nano-hydroxyapatite (12.6–57.3 nm) with high surface area (176.95 m²·g<sup>-1</sup>) and strong wettability. The optical band gap decreased from 4.5 ± 0.4 eV to 3.2 ± 0.4 eV after calcination, indicating defect-induced electronic modification. The poorly crystallized hydroxyapatite exhibited excellent Cd²⁺ and Pb²⁺ adsorption (99 % and 97 % removal in 100 min) but limited bisphenol A elimination (2.73 % in 180 min).</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100870"},"PeriodicalIF":2.8,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145466698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-21DOI: 10.1016/j.oceram.2025.100869
E. Tiffo , C.J.N. Sabouang , M. Mouafon , C.C.L. Tchamo , A. Pountouenchi , H.K. Tchakouté , D. Njoya , A. Elimbi
Thermal stability is an essential parameter to consider before using a binder at elevated temperature. This study investigates the effects of boehmite (B) on thermal behaviour and fired characteristics of sodium-based geopolymers respectively obtained from kaolin (K) and metakaolin (MK). To that end, B was used to partially replace the aluminosilicates (0 and 30 % by mass), the resulting mixtures were alkali-activated to produce geopolymers (GK, GKB30, GMK, GMKB30), which were cured, heated (900–1100–1150 °C) and characterised. Thermal behaviour revealed that B improves the thermal stability in the products of GKB30 and GMKB30. Additionally, the compressive strengths were improved respectively of about 66.7 and 82.0 % in GKB30 (1100 °C) and GMKB30 (1150 °C), attributed to densification coupled with the presence of mullite, corundum and quartz. These products endowed with improved fired characteristics and enhanced thermal stability can be used as binders for refractory applications as well as precursors for the production of ceramics.
{"title":"Thermal behaviour of blends kaolin-boehmite and metakaolin-boehmite based-geopolymers: physical and mechanical properties","authors":"E. Tiffo , C.J.N. Sabouang , M. Mouafon , C.C.L. Tchamo , A. Pountouenchi , H.K. Tchakouté , D. Njoya , A. Elimbi","doi":"10.1016/j.oceram.2025.100869","DOIUrl":"10.1016/j.oceram.2025.100869","url":null,"abstract":"<div><div>Thermal stability is an essential parameter to consider before using a binder at elevated temperature. This study investigates the effects of boehmite (B) on thermal behaviour and fired characteristics of sodium-based geopolymers respectively obtained from kaolin (K) and metakaolin (MK). To that end, B was used to partially replace the aluminosilicates (0 and 30 % by mass), the resulting mixtures were alkali-activated to produce geopolymers (GK, GK<sub>B</sub><sup>30</sup>, GMK, GMK<sub>B</sub><sup>30</sup>), which were cured, heated (900–1100–1150 °C) and characterised. Thermal behaviour revealed that B improves the thermal stability in the products of GK<sub>B</sub><sup>30</sup> and GMK<sub>B</sub><sup>30</sup>. Additionally, the compressive strengths were improved respectively of about 66.7 and 82.0 % in GK<sub>B</sub><sup>30</sup> (1100 °C) and GMK<sub>B</sub><sup>30</sup> (1150 °C), attributed to densification coupled with the presence of mullite, corundum and quartz. These products endowed with improved fired characteristics and enhanced thermal stability can be used as binders for refractory applications as well as precursors for the production of ceramics.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100869"},"PeriodicalIF":2.8,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The phase relations in the Sm2O3–Fe2O3 system at 1300 and 1400 °C were studied in the whole concentration range by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The samples were prepared with a concentration step of 1–5 mol %. The isothermal cross-sections of the Sm2O3–Fe2O3 phase diagram at 1300 and 1400 °C are characterized by the presence of four single-phase (B–Sm2O3, SmFeO3(R), Sm3Fe5O12, Fe2O3), three two-phase (B–Sm2O3+SmFeO3, SmFeO3+ Sm3Fe5O12, Sm3Fe5O12+Fe2O3) regions. The refined lattice parameter of the unit cell and the boundaries of the homogeneity fields for solid solutions were determined. The range of homogeneity of solid solutions based on the R-phase extends from 49 to 52 mol % Sm2O3 at 1300 and 1400 °C. Nanocomposites based on the perovskite phase (SmFeO3) were obtained by the Pechini method and heterogeneous precipitation from nitrate solutions. The influence of the production method on the microstructure, morphology, and magnetic properties of nanopowders (SmFeO3) was studied. According to XRD, infrared spectroscopy, SEM, the synthesized perovskite SmFeO3 is single-phase with a particle size of 50–60 nm. The morphology of powder particles primarily depends on the method of material synthesis. The powders display superparamagnetic-like loops at 300 K, typical of nanoparticle ensembles.
{"title":"Phase relations in the Sm2O3-Fe2O3 system: Structure and magnetic properties of perovskite SmFeO3 ceramics","authors":"O.V. Chudinovych , T.V. Tomila , V.G. Kolesnichenko , A.V. Samelyuk , D.V. Vedel , A. Lynnyk","doi":"10.1016/j.oceram.2025.100866","DOIUrl":"10.1016/j.oceram.2025.100866","url":null,"abstract":"<div><div>The phase relations in the Sm<sub>2</sub>O<sub>3</sub>–Fe<sub>2</sub>O<sub>3</sub> system at 1300 and 1400 °C were studied in the whole concentration range by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The samples were prepared with a concentration step of 1–5 mol %. The isothermal cross-sections of the Sm<sub>2</sub>O<sub>3</sub>–Fe<sub>2</sub>O<sub>3</sub> phase diagram at 1300 and 1400 °C are characterized by the presence of four single-phase (B–Sm<sub>2</sub>O<sub>3</sub>, SmFeO<sub>3</sub>(R), Sm<sub>3</sub>Fe<sub>5</sub>O<sub>12</sub>, Fe<sub>2</sub>O<sub>3</sub>), three two-phase (B–Sm<sub>2</sub>O<sub>3</sub>+SmFeO<sub>3</sub>, SmFeO<sub>3</sub>+ Sm<sub>3</sub>Fe<sub>5</sub>O<sub>12</sub>, Sm<sub>3</sub>Fe<sub>5</sub>O<sub>12</sub>+Fe<sub>2</sub>O<sub>3</sub>) regions. The refined lattice parameter of the unit cell and the boundaries of the homogeneity fields for solid solutions were determined. The range of homogeneity of solid solutions based on the R-phase extends from 49 to 52 mol % Sm<sub>2</sub>O<sub>3</sub> at 1300 and 1400 °C. Nanocomposites based on the perovskite phase (SmFeO<sub>3</sub>) were obtained by the Pechini method and heterogeneous precipitation from nitrate solutions. The influence of the production method on the microstructure, morphology, and magnetic properties of nanopowders (SmFeO<sub>3</sub>) was studied. According to XRD, infrared spectroscopy, SEM, the synthesized perovskite SmFeO<sub>3</sub> is single-phase with a particle size of 50–60 nm. The morphology of powder particles primarily depends on the method of material synthesis. The powders display superparamagnetic-like loops at 300 K, typical of nanoparticle ensembles.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100866"},"PeriodicalIF":2.8,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145416607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerous studies have highlighted the beneficial effects of flash-calcined sediment (SF) substitution on the mechanical performance of materials. However, very few studies have investigated its impacts on durability, especially the leaching. This study aims to assess its potential effects on the mechanical-microstructural development as well as durability against chloride ingress and leaching. The results indicate that the high specific surface area of SF accelerates cement hydration at early ages, while its pozzolanic reactivity contributes to an enhancement of compressive strength and microstructure in SF-based mortar (MSF) in the long term compared to the reference mortar (Mref). In addition, the formation of addition C-S-H gels from the pozzolanic reaction and the reduction in the critical diameter of pores explain the improved resistance of MSF mortar to chloride penetration. The leaching reveals a significant enhancement in the durability of SF-based cement paste, demonstrated by lower quantities of leached elements and reduced degradation depth compared to the reference. These benefits are attributed to lower Ca(OH)₂ content, a reduced Ca/Si ratio in C–S–H, and a refined microstructure in the MSF paste, which strongly hinder ion diffusion. The dissolution of hydrates during leaching also leads to a decrease in the Young’s modulus of hydration products, and degradation of the microstructure. However, the SF incorporation significantly mitigates this effect compared to the reference.
{"title":"Effects of flash-calcined sediment on the mechanical – microstructural development and the durability of cementitious materials against to chloride attack and leaching","authors":"Mouhamadou Amar , Mahfoud Benzerzour , Duc Chinh Chu , Nor-Edine Abriak , Joelle Kleib","doi":"10.1016/j.oceram.2025.100868","DOIUrl":"10.1016/j.oceram.2025.100868","url":null,"abstract":"<div><div>Numerous studies have highlighted the beneficial effects of flash-calcined sediment (SF) substitution on the mechanical performance of materials. However, very few studies have investigated its impacts on durability, especially the leaching. This study aims to assess its potential effects on the mechanical-microstructural development as well as durability against chloride ingress and leaching. The results indicate that the high specific surface area of SF accelerates cement hydration at early ages, while its pozzolanic reactivity contributes to an enhancement of compressive strength and microstructure in SF-based mortar (MSF) in the long term compared to the reference mortar (Mref). In addition, the formation of addition C-S-H gels from the pozzolanic reaction and the reduction in the critical diameter of pores explain the improved resistance of MSF mortar to chloride penetration. The leaching reveals a significant enhancement in the durability of SF-based cement paste, demonstrated by lower quantities of leached elements and reduced degradation depth compared to the reference. These benefits are attributed to lower Ca(OH)₂ content, a reduced Ca/Si ratio in C–S–H, and a refined microstructure in the MSF paste, which strongly hinder ion diffusion. The dissolution of hydrates during leaching also leads to a decrease in the Young’s modulus of hydration products, and degradation of the microstructure. However, the SF incorporation significantly mitigates this effect compared to the reference.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100868"},"PeriodicalIF":2.8,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145362544","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-10-18DOI: 10.1016/j.oceram.2025.100867
Siddhartha Roy
As porous ceramics are attractive materials for different high-temperature applications, such as thermal insulators, high-temperature filters, porous burners, etc., a thorough understanding of their thermal properties is crucial. Among different thermal properties, while the melting points and coefficients of thermal expansion are independent of porosity, thermal conductivity, thermal shock resistance, and thermal fatigue resistance strongly depend upon the selection of the bulk ceramic, amount of porosity, and different pore characteristics such as pore shape and size, pore connectivity and anisotropy, etc. In this review paper, a thorough description of the different structural and physical characteristics controlling the thermal properties of porous ceramics has been provided, along with a critical analysis of the published experimental results. Finally, some potential directions for future research on the thermal properties of porous ceramics have been identified.
{"title":"Thermal properties of porous ceramics","authors":"Siddhartha Roy","doi":"10.1016/j.oceram.2025.100867","DOIUrl":"10.1016/j.oceram.2025.100867","url":null,"abstract":"<div><div>As porous ceramics are attractive materials for different high-temperature applications, such as thermal insulators, high-temperature filters, porous burners, etc., a thorough understanding of their thermal properties is crucial. Among different thermal properties, while the melting points and coefficients of thermal expansion are independent of porosity, thermal conductivity, thermal shock resistance, and thermal fatigue resistance strongly depend upon the selection of the bulk ceramic, amount of porosity, and different pore characteristics such as pore shape and size, pore connectivity and anisotropy, etc. In this review paper, a thorough description of the different structural and physical characteristics controlling the thermal properties of porous ceramics has been provided, along with a critical analysis of the published experimental results. Finally, some potential directions for future research on the thermal properties of porous ceramics have been identified.</div></div>","PeriodicalId":34140,"journal":{"name":"Open Ceramics","volume":"24 ","pages":"Article 100867"},"PeriodicalIF":2.8,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145363278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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