Journal of the American Ceramic Society最新文献

Based on the previous optimal concentration of Er³⁺/Yb³⁺/Mo⁴⁺ co-doped BiTa₇O₁₉ (BTO) samples, Sc³⁺ or Sb is planned to be doped into BTO:Er³⁺/Yb³⁺/Mo⁴⁺ for further improving the upconversion luminescence (UCL) intensity under 980-nm laser excitation. A series of BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sc³⁺ and BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sb samples are prepared by high-temperature solid-phase sintering method. The microstructure and UCL properties are investigated by X-ray diffraction, Raman, X-ray photoelectron spectroscopy (XPS), diffuse reflection, and luminescence spectrum. The green UCL intensity of BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sb is little better than that of BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sc³⁺, which reaches 2.40 times than that of β-NaYF₄:Er³⁺/Yb³⁺. XPS results show that Sc is 3+, Mo is 4+, and Sb is 3+ and 5+. Raman spectra show that BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sb has lower phonon energy and more disorder than BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sc³⁺. The maximum relative temperature sensitivity is got as 0.01012 K⁻¹ at 303 K based on luminescence intensity ratio technology. BTO:Er³⁺/Yb³⁺/Mo⁴⁺/Sb has outstanding pure green UCL intensity, which can be applied to luminescence display and temperature sensing.

https://doi.org/10.1111/jace.19517

The article corrects “Tailored engineering of zinc carbide triggered by N-enriched carbon nanotubes for prospective water splitting” with https://doi.org/10.1111/jace.19517, authored by Ibrahim A. Shabaan, Karam Jabbour, Mehar Un Nisa, Abdul Ghafoor Abid, Nasreen Bibi, Mohammad Numair Ansari, Abdul Rasheed Rasid, Sumaira Manzoor, Muhammad Abdullah, and Muhammad Naeem Ashiq.

The affiliation of Muhammad Naeem Ashiq was mistakenly written number 4 which is actually number 3. We really apologize for it.

We have observed that in the submission process, the XRD, FTIR, and XPS (survey spectrum) analysis provided in the manuscript was processed via baseline correction and data smoothed to remediate the noised spectrum, carried out on OriginPro software. The baseline correction and smoothening of data has caused slight deviation from the raw data, which may lead the reader of the prestigious journal to be confused. Thus, we have provided unprocessed (not baseline and smoothed) plots for these figures. This would cause no change on the scientific discussion and text.  

We apologize for the inconvenience and would be much more careful in future submissions.

This study investigates the structural, electrical, leakage current, and magnetic characteristics of the double perovskite material Nd₂NiTiO₆ synthesized through the sol–gel citrate auto-ignition method. The Rietveld refinement of the X-ray diffraction patterns confirmed a monoclinic symmetry (space group P2₁/n) with an ordered arrangement of alternate NiO₆ and TiO₆ octahedra. Impedance spectroscopic analysis exhibited the material's non–Debye-type relaxation mechanism and semi-conductive nature. AC conduction analysis revealed that the conduction of charge carriers occurs via the nonoverlapping small polaron hopping mechanism, consistent with Mott's variable range hopping model. Temperature- and frequency-dependent dielectric measurements were interpreted using the Maxwell–Wagner interfacial polarization model. The analysis of thermal- and field-dependent leakage currents established that conduction is ohmic, which the Schottky barrier model explains. Studies on magnetization ruled out the presence of magnetic ordering connected to indirect interaction between Ni²⁺ ions via Ti⁴⁺ ions and the rare-earth cation (Nd³⁺) moment.

High-activity TiB₂ submicron powders were synthesized via microwave-assisted carbothermal reduction, and their oxidation behavior at 550°C–1000°C for 0.5–1.5 h in air atmosphere was carried out by the isothermal oxidation test. The phase composition and microstructure evolution of the oxidation products were performed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). It was established that TiB₂ submicron powders had been significantly oxidized at 550°C, and the oxidation products were TiO₂ and B₂O₃. Hexagonal plate-like TiB₂ grains had been completely disappeared, and fragmented into uniform nano-scale spherical TiO₂ particles after being oxidized at 1000°C for 1 h, accompanied by the violent evaporation of B₂O₃ products at temperatures above 1000°C. In addition, the corresponding oxidation kinetics was investigated by using a non-isothermal thermogravimetric (TG)–differential scanning calorimetry (DSC) technique. The results showed that the Mample power law (n = 1) was the most probable mechanism function, and the oxidation activation energy E of TiB₂ submicron powders was 640.58 kJ/mol.

This study investigates the synthesis and characterization of Al₂O₃ nanoparticles derived from multilayered packaging (MLP) waste, specifically postconsumer coffee capsules, and evaluates their efficacy in fluoride adsorption from aqueous solutions. The nanoparticles were synthesized using a facile thermal degradation technique followed by leaching and precipitation processes. Characterization techniques, including inductively coupled plasma-mass spectroscopy, XRF, Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscope, confirmed the formation of γ-Al₂O₃ nanoparticles with a cubic crystal structure. The adsorption process was found to be endothermic and spontaneous, with a maximum adsorption capacity of 9.60 mg/g. Kinetic studies revealed that the pseudo-second order model best described the adsorption process, indicating a complex multistep mechanism involving both physisorption in the initial rapid adsorption and chemisorption in the latter slower phase. The Freundlich–Langmuir isotherm provided the best fit for equilibrium data suggesting a complex adsorption mechanism involving both homogeneous and heterogeneous surface interactions. The presence of competing anions, particularly carbonate and phosphate, significantly affected the adsorption efficiency. This research demonstrates the potential of upcycling MLP waste into valuable adsorbents for wastewater treatment applications, offering both environmental and economic benefits.

The competition between surficial and volumetric diffusion during the sintering process for ceramic polymorphism at different sintering temperatures is worth deeply exploring. In the current work, various sintering cases of mixed TiO₂ nanoparticles with rutile and anatase types were investigated and the effects of crystalline phase, sintering temperature, and particle size on the sintering process were systematically investigated. The difference in thermodynamic stability and surficial activity of the crystalline phase could promote the decomposition and densification of the nanoparticles. Comparing the mixed-phase sintering process at different sintering temperatures, the results showed that the particle binding process at low temperature relied mainly on surficial diffusion, however, volumetric diffusion played a crucial role at high temperature. The internal occurrence of volumetric diffusion inhibited the surficial diffusion, resulting in a smaller diameter of the sintering neck and a different sintering rate. In the case of sintering three nanoparticles with rutile and anatase types, it could be found that the decomposition of nanoparticles is more uniform in mixed-phase sintering at high temperatures and the sintering rate is not significantly influenced by the sintering temperature. This work demonstrates the advantage of a mixed-phase sintering strategy for TiO₂ nanoparticles, which could provide insight into ceramic materials with polymorphism.

Surface ablation temperature and linear ablation rate are two crucial indicators for ceramic coatings under ultrahigh temperatures service, yet the results collection of such two indicators in the process is difficult due to the long-period material preparation and the high-cost test. In this work, four kinds of machine learning models are applied to predict the above two indicators. The Random Forest (RF) model exhibits a high accuracy of 87% in predicting surface ablation temperature, while a low accuracy of 60% in linear ablation rate. To optimize the model, the novel features are constructed based on the original features by the sum of the importance weights in the model. Thereafter, the importance of the newly constructed features increases significantly, and the accuracy of the optimized RF model is improved by 11%, exceeding 70% in accuracy. By validation with available data and experiments, the optimized model demonstrates precise predictions of the target variables.

We present a hybrid similarity kernel that exemplifies the integration of short- and long-range descriptors via the use of an average kernel approach. This technique allows for a direct measure of the similarity between amorphous configurations, and when combined with an active learning (AL) spectral clustering approach, it leads to a classification of the amorphous configurations into uncorrelated clusters. Subsequently, a minimum size database is built by considering a small fraction of configurations belonging to each cluster and a machine learning interatomic potential (MLIP), within the Gaussian approximation scheme, is fitted by relying on a Bayesian optimization of the potential hyperparameters. This step is embedded within an AL loop that allows to sequentially increase the size of the learning database whenever the MLIP fails to meet a predefined energy convergence threshold. As such, MLIP are fitted in an almost fully automatized fashion. This approach is tested on two diverse amorphous systems that were previously generated using first-principles molecular dynamics. Accurate potentials with less than 2 meV/atom root mean square energy error compared to the reference data are obtained. This accuracy is achieved with only 175 configurations sampling the studied systems at various temperatures. The robustness of these potentials is then confirmed by producing models with several thousands of atoms featuring a good agreement with reference ab initio and experimental data.

Helium (He) exerts significant influence on the physicochemical, structural, and electronic properties of pyrochlores. This paper reviews recent advancements in computer simulations aimed at stabilizing nuclear waste, focusing on disordered structures of pyrochlores, zirconate pyrochlores, and high-entropy pyrochlores. Using Pu-La₂Zr₂O₇ as a case study, we demonstrate how a first-principles approach facilitates the understanding of how He modifies the structural and electronic properties of this system. The incorporation of He interstitials in Pu-La₂Zr₂O₇ typically leads to an expansion in lattice constant and volume swelling. Analysis of the formation energies in this system reveals that octahedral interstitial sites or zirconium (Zr) vacancy sites are favored for He occupation, resulting in the formation of substitutional He atoms. The low concentration of He atoms in Pu-La₂Zr₂O₇ reduces the formation energy of cation antisite defects. Bader charge analysis indicates that the < Zr-O > bond exerts a greater influence on the irradiation resistance of the He-Pu-La₂Zr₂O₇ system compared to the < La-O > bond. Moreover, the capacity for He interstitials increases with higher Pu concentration in the octahedrons.

The presentation of Figures 1 and 2 in the published manuscript is smooth and baseline corrected, which may cause difficulty for readers of the journal. Therefore, we want to present the raw version of these figures without smoothing or baseline correction. Additionally, Figure 2 had a labeling issue which now has been corrected. We apologize for these mistakes which will not affect the scientific conclusions.