{"title":"Q factor enhancement in Nd2Zr3(MoO4)9 microwave ceramics via B-site (Bi0.5Ta0.5)4 + substitution and low-temperature sintering","authors":"Yuan-Bin Chen, Ling Tang, Xiuyuan Su","doi":"10.1016/j.jeurceramsoc.2025.117771","DOIUrl":"10.1016/j.jeurceramsoc.2025.117771","url":null,"abstract":"<div><div>Low-temperature sintered microwave dielectric ceramics are gaining increasing attention for next-generation wireless communication systems, particularly within the 6 G frequency range. However, materials that simultaneously exhibit ultra-low dielectric loss and low sintering temperatures remain scarce. In this study, Nd<sub>2</sub>[Zr<sub>1-X</sub>(Bi<sub>0.5</sub>Ta<sub>0.5</sub>)<sub>X</sub>]<sub>3</sub>(MoO<sub>4</sub>)<sub>9</sub> ceramics were prepared via a conventional solid-state reaction method and exhibited a single-phase structure with a trigonal symmetry (space group R<span><math><mover><mn>3</mn><mo>¯</mo></mover></math></span>C, No. 167). The optimal sample at x = 0.11 sintered at 750 ℃ showed excellent performance: ε<sub>r</sub> = 11.4, Q×f = 186,300 ± 8900 GHz, and τ<sub>f</sub> = –42.9 ppm/℃. The elevated Q×f value is chiefly ascribed to increased lattice energy, with its variation more plausibly arising from intrinsic effects within the material. The dielectric constant (εᵣ), analyzed using the Clausius–Mosotti equation, was predominantly influenced by ionic polarizability. According to P–V–L theory, the effective bond strength f<sub>iNd–O</sub> played a major role in determining εᵣ, while τ<sub>f</sub> was governed by the bond energy and thermal expansion behavior of Mo–O bonds. Raman spectroscopy further confirmed the structure–property relationships. These results suggest that B-site substitution with (Bi<sub>0.5</sub>Ta<sub>0.5</sub>)<sup>4+</sup> not only promotes densification and increases lattice energy, but also maintains thermal stability, thereby enhancing Q×f without compromising τ<sub>f</sub>. This system offers strong potential for integration into future microwave dielectric components.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 2","pages":"Article 117771"},"PeriodicalIF":6.2,"publicationDate":"2025-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144997242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jiao Li , Piotr Klimczyk , Yuliia Rumiantseva , Yiquan Wu
{"title":"Phase transformation and densification of cBN-Y2O3 nanocomposites by high pressure and high temperature","authors":"Jiao Li , Piotr Klimczyk , Yuliia Rumiantseva , Yiquan Wu","doi":"10.1016/j.jeurceramsoc.2025.117770","DOIUrl":"10.1016/j.jeurceramsoc.2025.117770","url":null,"abstract":"<div><div>Composite cBN- Y<sub>2</sub>O<sub>3</sub> ceramics with a 30 vol% cBN content were successfully fabricated at sintering temperature ranging from 800 to 1600 °C under a high pressure of 7.2 GPa. The high sintering pressure was observed to prevent phase transformation of cubic BN phase, while simultaneously inducing the transformation from cubic Y<sub>2</sub>O<sub>3</sub> to monoclinic Y<sub>2</sub>O<sub>3</sub> phase. No significant change in the grain size of cBN within the composites was observed, attributed to the low sintering temperatures and short holding time. In contrast, the grain size of Y<sub>2</sub>O<sub>3</sub> within the cBN- Y<sub>2</sub>O<sub>3</sub> composite was reduced to less than 100 nm after sintering at 800 and 1000 °C. This observation indicates that the high pressure-induced phase transformation of Y<sub>2</sub>O<sub>3</sub>contributed to its grain refinement. As a result of the retained cubic BN phase and refined Y<sub>2</sub>O<sub>3</sub> grains, the cBN- Y<sub>2</sub>O<sub>3</sub> composite ceramics sintered for 60 s achieved a relative density of 94 % and a hardness of approximately 11 GPa. These results demonstrated that the high pressure and high temperature (HPHT) technique is a promising route in achieving fully dense cBN-Y<sub>2</sub>O<sub>3</sub> composite ceramics with enhanced performance.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 2","pages":"Article 117770"},"PeriodicalIF":6.2,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144933596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Korbinian Aicher, Thomas Berger, Ulrich Aschauer, Oliver Diwald
{"title":"Activation and cold sintering of commercial ZnO powders: Compaction-induced oxide reduction","authors":"Korbinian Aicher, Thomas Berger, Ulrich Aschauer, Oliver Diwald","doi":"10.1016/j.jeurceramsoc.2025.117769","DOIUrl":"10.1016/j.jeurceramsoc.2025.117769","url":null,"abstract":"<div><div>Defect formation and changes in electronic reducibility occur during cold sintering of ZnO powder compacts. For this reason, materials design must consider the material history and processing-related changes in the electronic structure. We performed spectroscopic investigations (UV-Vis-NIR diffuse reflectance, photoluminescence, Raman, electron paramagnetic resonance) on commercially available ZnO powders that were cold-sintered in H<sub>2</sub>O or in aqueous acetic acid as a transient phase and find significant lattice oxygen depletion in the latter case. As a result, shallow donor states emerge in UV-Vis-NIR diffuse reflectance and electron paramagnetic resonance via an isotropic resonance signal at g = 1.96. The use of NH<sub>4</sub>Cl, instead of aqueous and/or acidic liquids as an activator to promote cold sintering, leads to identical spectroscopic fingerprints that are indicative of stoichiometry changes in ZnO. The spectroscopic results underline that cold sintering-induced protonation of the metal oxide lattice favors the formation of defects and electronic donor states.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 2","pages":"Article 117769"},"PeriodicalIF":6.2,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144916589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yanlin Ma , Jie Li , Kui Liu , Yida Lei , Yang Xiao , Yingli Liu , Zhiyong Zhong
{"title":"Single‑step cold sintering: Low‑temperature densification of Co2Z–Li2MoO4 composites with enhanced magnetodielectric properties","authors":"Yanlin Ma , Jie Li , Kui Liu , Yida Lei , Yang Xiao , Yingli Liu , Zhiyong Zhong","doi":"10.1016/j.jeurceramsoc.2025.117766","DOIUrl":"10.1016/j.jeurceramsoc.2025.117766","url":null,"abstract":"<div><div>A single-step cold sintering process (CSP) was developed to achieve low-temperature densification of Co<sub>2</sub>Z–Li<sub>2</sub>MoO<sub>4</sub> (LMO) composite ceramics for radio frequency applications. Both phases retained their crystal structures during CSP, LMO precipitated into the interplatelet gaps, promoting particle rearrangement and filling original porosity. Consequently, relative density increased from 76 % for pure Co<sub>2</sub>Z to over 94 % in the composites. Although LMO is nonmagnetic, the substantial increase in densification leads to pronounced improvements in magnetodielectric properties. Low LMO loadings improved permeability, while higher loadings increased permittivity and reduced dielectric loss by an order of magnitude. This work demonstrates that cold sintering with a second phase enables low‑temperature densification of Co<sub>2</sub>Z‑based ceramics with available magnetodielectric properties for antenna substrates.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 1","pages":"Article 117766"},"PeriodicalIF":6.2,"publicationDate":"2025-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144885510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haoran Zou , Wen Zhang , Chao Zhang , Jinyong Zhang , Lin Ren , Weimin Wang , Fan Zhang , Zhengyi Fu
{"title":"Oxidation behavior of high-entropy M4AlC3/15vol%Al2O3 (M=Ti, V, Mo, Nb, Ta) composite in air in the temperature range of 800℃–1500℃ via silicon pack cementation","authors":"Haoran Zou , Wen Zhang , Chao Zhang , Jinyong Zhang , Lin Ren , Weimin Wang , Fan Zhang , Zhengyi Fu","doi":"10.1016/j.jeurceramsoc.2025.117764","DOIUrl":"10.1016/j.jeurceramsoc.2025.117764","url":null,"abstract":"<div><div>A novel high-entropy M<sub>4</sub>AlC<sub>3</sub>/15 vol%Al<sub>2</sub>O<sub>3</sub> (M = Ti, V, Mo, Nb, Ta) composite exhibits excellent mechanical properties, showing great potential as a structural material. However, its moderate oxidation resistance has limited its applications. a one-step silicon pack cementation process was employed to fabricate a 133 μm silicide coating on the composite surface, significantly enhancing oxidation resistance while retaining mechanical performance. After oxidation at 1500 ℃ for 20 h, the cemented sample showed a mass gain of only 774 g/m², far lower than the uncemented sample oxidized at 800 ℃ (1065 g/m²). This improvement is attributed to the dense coating's ability to inhibit oxygen diffusion and its self-healing behavior at elevated temperatures. Additionally, outward diffusion of aluminum contributes to the formation of a protective Al<sub>2</sub>O<sub>3</sub> layer. This study demonstrates that one-step silicon cementation can endow MAX phase ceramics with superior environmental resistance, offering valuable guidance for designing next-generation high-temperature structural ceramics.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 1","pages":"Article 117764"},"PeriodicalIF":6.2,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144904605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xin Wang , Dandan Qin , Chun Shang , Cunlei Zou , Huijun Kang , Yunzhuo Lu , Jiehe Sui
{"title":"Dual-approach enhancement of thermoelectric performance in Yb-filled skutterudites: In-situ pore architecture engineering and carrier concentration optimization","authors":"Xin Wang , Dandan Qin , Chun Shang , Cunlei Zou , Huijun Kang , Yunzhuo Lu , Jiehe Sui","doi":"10.1016/j.jeurceramsoc.2025.117763","DOIUrl":"10.1016/j.jeurceramsoc.2025.117763","url":null,"abstract":"<div><div>While Yb-filled skutterudites are promising candidates as mid-temperature thermoelectric materials, their practical application remains constrained by inadequate performance. In this study, we propose a dual optimization strategy to modulate the electro-thermal transport performance. The as-cast ingots underwent initial densification via hot-pressing, followed by pressureless annealing. By utilizing the solid solution of the YbSb<sub>2</sub> phase, we not only increase the Yb filling fraction but also achieve precise pore architecture engineering through volume changes induced by phase transformation. Notably, the integration of Yb filling and a prolonged 72-hour annealing treatment not only optimized carrier concentration but also dramatically inhibited phonon propagation, leading to a 57 % reduction in lattice thermal conductivity at 773 K. Thus, the optimized Yb<sub>0.3</sub>Co<sub>4</sub>Sb<sub>12</sub> sample demonstrated enhanced thermoelectric performance, attaining a peak <em>ZT</em> value of 1.44 at 873 K. This work provides fundamental insights into the synergistic improvement of thermoelectric properties in filled skutterudites.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 2","pages":"Article 117763"},"PeriodicalIF":6.2,"publicationDate":"2025-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144921376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Subcritical crack growth in cold sintered ZnO ceramics","authors":"Abdullah Jabr , Peter Supancic , Raul Bermejo","doi":"10.1016/j.jeurceramsoc.2025.117761","DOIUrl":"10.1016/j.jeurceramsoc.2025.117761","url":null,"abstract":"<div><div>The long-term mechanical reliability of ceramic components is often compromised by the subcritical growth of defects (SCCG), especially under high relative humidity environments. In this study, structural degradation associated with SCCG is investigated for the first time in cold sintered ZnO and compared to counterparts of same density sintered at 1000°C. Constant stress rate experiments ranging between 0.001 MPa/s and 1000 MPa/s are performed in air and water for both samples. While both cold sintered and conventionally sintered ZnO ceramics are susceptible to SCCG in the same manner, the former exhibit a distinct threshold behaviour up to relatively high stress intensity levels (ca. 0.7<span><math><mo>·</mo></math></span><em>K</em><sub>Ic</sub>). The effect of the nanoscale grain size and potential chemical effects associated with the cold sintering process on SCCG are discussed. The findings are supported by constant stress experiments and fractographic analyses, providing valuable insights for the mechanical design and lifetime assessment of cold sintered components.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 1","pages":"Article 117761"},"PeriodicalIF":6.2,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144893753","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Effects of alkaline-earth metal oxides and heat treatment on the structure and cyan-luminescence properties of Bi3+-doped SiO2-MO-Y2O3-ZnO-ZrO2-Ga2O3 (M = Ca, Sr, Ba) glass and Y2Zr2O7 transparent glass-ceramic","authors":"Jianshan Yang, Zhiwei Luo, Haozhang Liang, Nanshan Ma, Xiangtao Lin, Yu Li, Juxia Tong, Xianjun Feng, Tingxiao Wu","doi":"10.1016/j.jeurceramsoc.2025.117758","DOIUrl":"10.1016/j.jeurceramsoc.2025.117758","url":null,"abstract":"<div><div>Parent glasses with the composition of 55SiO<sub>2</sub>-22MO-6Y<sub>2</sub>O<sub>3</sub>-8ZnO-5.5ZrO<sub>2</sub>-3.5Ga<sub>2</sub>O<sub>3</sub>- 1Bi<sub>2</sub>O<sub>3</sub>(M = Ca, Sr, Ba, mol%) were prepared. After heat treatment, glass-ceramics containing Y<sub>2</sub>Zr<sub>2</sub>O<sub>7</sub> crystal were obtained. The increase in the atomic number of alkaline-earth metals favors the crystallization in the glass. Under the optimum excitation wavelength of 340 nm, the emission peak exhibits a redshift. The emission intensity reaches a maximum value when BaO is introduced. As the heat treatment temperature rises and time extends, the diffraction peak intensity of the glass-ceramics enhances, with significant grain agglomeration occurring. The optimal heat treatment regime is nucleation at 780 °C for 10 h, followed by crystallization at 830 ℃ for 4 h. Under this regime, the emission intensity is 2.75 times that of the parent glass. The glass-ceramics are promising candidates for WLEDs, with the emission spectra fully covering the 480–520 nm range at an ideal intensity and chromaticity coordinates falling within the cyan region.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 1","pages":"Article 117758"},"PeriodicalIF":6.2,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144885615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Shiji Shen , Jie Chen , Yanna Tian , Hongbo Chen , Xuan Yang , Hui Lin , Shengming Zhou , Jun Wang
{"title":"Roles of non-stoichiometric Mg2+-Si4+ co-doping in the sintering process of TAG ceramics with higher optical quality","authors":"Shiji Shen , Jie Chen , Yanna Tian , Hongbo Chen , Xuan Yang , Hui Lin , Shengming Zhou , Jun Wang","doi":"10.1016/j.jeurceramsoc.2025.117760","DOIUrl":"10.1016/j.jeurceramsoc.2025.117760","url":null,"abstract":"<div><div>Non-stoichiometric Mg<sup>2+</sup>-Si<sup>4+</sup> co-doping in lattice site can effectively reduce the presence of residual phases at grain boundaries and enhance the optical quality of Tb<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>(TAG) garnet transparent ceramics, outperforming traditional weight ratio single-component sintering aids. However, further experimental validation and a deeper analysis of the underlying mechanisms are required to fully understand this phenomenon. In this study, a systematic investigation was carried out to explore the effects of non-stoichiometric Mg<sup>2+</sup>-Si<sup>4+</sup> co-doping on the sintering process of TAG ceramics. Through extensive experiments and analyses, the solid-solution behavior of Mg<sup>2+</sup>/Si<sup>4+</sup> at various sintering stages was revealed, and its correlation with densification, phase evolution, and microstructure of the grain boundary was disclosed. Through analysis of lattice parameter and oxygen vacancy concentration change, it was found that Si<sup>4+</sup> enters the lattice earlier than Mg<sup>2+</sup>, and as temperature increases, the presence of Si<sup>4+</sup> in turn enhances the solid solubility of Mg<sup>2+</sup>. By precisely controlling the Mg<sup>2+</sup>/Si<sup>4+</sup> atomic ratio, optimized control of the densification process was achieved. TEM analysis of the optimal sample's grain boundaries showed that under high addition amounts of MgO and TEOS, the non-stoichiometric design method significantly reduced grain boundary residual phases. This discovery highlights the importance of synergistic optimisation of aids species and content under non-stoichiometric doping for preparing higher optical quality garnet transparent ceramics.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 1","pages":"Article 117760"},"PeriodicalIF":6.2,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144902719","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
B.M. Moshtaghioun , R. Cano Crespo , F.L. Cumbrera , D. Gómez-García , M. García Fernández , M.A. Rodríguez , R. Moreno
{"title":"Mechanical performance of sub-stoichiometric titanium carbide ceramics synthesized by a hybrid SHS and SPS methodology","authors":"B.M. Moshtaghioun , R. Cano Crespo , F.L. Cumbrera , D. Gómez-García , M. García Fernández , M.A. Rodríguez , R. Moreno","doi":"10.1016/j.jeurceramsoc.2025.117748","DOIUrl":"10.1016/j.jeurceramsoc.2025.117748","url":null,"abstract":"<div><div>Sub-stoichiometric titanium carbide ceramics were synthesized via a hybrid route combining self-propagating high-temperature synthesis (SHS) and spark plasma sintering (SPS). TiC₁₋ₓ powders were produced through a single, rapid SHS step by the direct reaction of titanium and graphite, followed by attrition milling to achieve an average particle size of 3–5 μm. Particular attention was devoted to analyzing sub-stoichiometry variations associated with carbon vacancy formation during both SHS and SPS processes. SPS treatments at temperatures up to 1800 °C promoted sub-stoichiometric deviations reaching compositions as low as TiC<sub>0.74</sub>, which remained nearly stable even under more extreme SPS conditions. Additionally, a minor and unexpected precipitation of a disordered graphite phase was detected. The resulting sub-stoichiometric titanium carbide ceramics exhibited high Vickers hardness values, reaching up to 27 GPa. Microstructural analysis revealed plastic deformation, attributed to dislocation interactions with graphite precipitates. The dislocation dynamics were found to be governed by cationic diffusion mechanisms.</div></div>","PeriodicalId":17408,"journal":{"name":"Journal of The European Ceramic Society","volume":"46 1","pages":"Article 117748"},"PeriodicalIF":6.2,"publicationDate":"2025-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144902720","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}