Comparison of Friction Produced at Backet-Wire Interface in Monocrystalline Ceramic Brackets of 8 Different Brands: An In Vitro Study.

Introduction: The esthetic during the various orthodontic treatments has led to the invention of the brackets. When different ceramic brackets and archwires are used, the different frictional forces may result in the different outputs. Hence, in the present study, we evaluated and compared the frictional resistance between eight standard monocrystalline ceramic bracket models and each of the archwires of four different alloys. Materials and Methods: Frictional force was tested using Instron testing machine, in vitro, for eight types of monocrystalline ceramic bracket, and four types of archwires beta-titanium, NiTi, copper-nickel-titanium, and stainless steel statistical analysis were done using various tools, and significance value of <0.05 was considered. Results: Ormco and AO (Radiance) monocrystalline ceramic brackets created lesser frictional resistance than other monocrystalline ceramic brackets. Stainless steel archwire generates lesser static friction. Beta-titanium archwire created higher static friction. A 0.017 × 0.025 inch stainless steel archwire generates lesser static friction to 0.019 × 0.025 inch TMA. Conclusion: It can be concluded that Ormco and AO (Radiance) monocrystalline ceramic brackets, with stainless steel archwires and of size 0.017 × 0.025 inch, can generate better forces when used for the orthodontic tooth movements.

Clinical performance and risk factors of all-ceramic screw-retained implant crowns in the posterior region based on a retrospective investigation.

OBJECTIVES: Clinical data on all-ceramic screw-retained implant crowns (SICs) luted on titanium base abutments (TBAs) over more than 3 years are sparse. This study aimed to evaluate the clinical performance and potential risk factors for these restorations. MATERIALS AND METHODS: Analysis took place based on the medical patient-records of three dental offices. Implant survival and prosthetic complications over time were evaluated. The study included SICs in premolar and molar regions made from monolithic lithium disilicate ceramic (M_LiDi) or veneered zirconia (V_ZiO) luted on a TBA documented over an observation time of at least 3 years. Survival and complication rates were calculated and compared by a log-rank test. Cox-Regressions were used to check potential predictors for the survival (p < .05). RESULTS: Six hundred and one crowns out of 371 patients met the inclusion criteria and follow-up period was between 3.0 and 12.9 (mean: 6.4 (SD: 2.1)) years. Over time, six implants had to be removed and 16 restorations had to be refabricated. The estimated survival rates over 10 years were 93.5% for M_LiDi and 95.9% for V_ZiO and did not differ significantly among each other (p = .80). However, V_ZiO showed significantly higher complication rates (p = .003). Material selection, sex, age, and implant diameter did not affect the survival of investigated SICs but crown height influences significantly the survival rate (hazard ratio, HR = 1.26 (95%CI: 1.08, 1.49); p = .043). CONCLUSIONS: Screw-retained SICs luted on TBAs that were fabricated from monolithic lithium disilicate ceramic or veneered zirconia showed reliable and similar survival rates. Increasing crown heights reduced survival over the years.

Long-Term Bonding Efficacy of CAD/CAM Hybrid Restorative Materials and Universal Adhesives.

OBJECTIVES: In-office and lab milled prostheses are the staple for indirect restorations. It is therefore critical to determine their long-term bonding durability. METHODS: CAD/ CAM blocks of two classes of restorative materials: 1) a nano-ceramic reinforced polymer matrix (NCPM) and, 2) a polymer-infiltrated ceramic network (PICN) were bonded using four different universal adhesives (UA) and silane systems. A lithium disilicate glassceramic (LDS) was used as a reference. The blocks were bisected and bonded with different UA/resin-cement pairs. Bonded blocks were then cut into 1.0x1.0x12.0 mm bar specimens for microtensile bond testing. Half the bars were subjected to bond strength testing immediately and the other half after aging by 50,000 thermal cycles between 5°C and 55°C. ANOVA and post-hoc tests were used to compare mean bond strength among groups. RESULTS: NCPM presented consistently high bond strength regardless of bonding techniques, while the bond strength of PICN and LDS were lower when bonded with UA relative to traditional silanes. The more hydrophilic UA produced higher bond strengths. DISCUSSION: Glass-ceramics exhibited lower bond strength with UA than the conventional etch-rinse-silane techniques. However, UAs preserved bonding interface in the long-term. SIGNIFICANCE: NCPM displayed superior bond strength relative to PICN and LDS regardless of the type of adhesives and bonding techniques.

Cobalt single-atom catalyst tailored ceramic membrane for selective removal of emerging organic contaminants.

Water reuse is an effective way to solve the issues of current wastewater increments and water resource scarcity. Ultrafiltration, a promising method for water reuse, has the characteristics of low energy consumption, easy operation, and high adaptability to coupling with other water treatment processes. However, emerging organic contaminants (EOCs) in municipal wastewater cannot be effectively intercepted by ultrafiltration, which poses significant challenges to the effluent quality and sustainability of ultrafiltration process. Here, we develop a cobalt single-atom catalyst-tailored ceramic membrane (Co1-NCNT-CM) in conjunction with an activated peroxymonosulfate (PMS) system, achieving excellent EOCs degradation and anti-fouling performance. An interfacial reaction mechanism effectively mitigates membrane fouling through a repulsive interaction with natural organic matter. The generation of singlet oxygen at the Co-N3-C active sites through a catalytic pathway (PMS→PMS∗→OH∗→O∗→OO∗→1O2) exhibits selective oxidation of phenols and sulfonamides, achieving >90% removal rates. Our findings elucidate a multi-layered functional architecture within the Co1-NCNT-CM/PMS system, responsible for its superior performance in organic decontamination and membrane maintenance during secondary effluent treatment. It highlights the power of integrating Co1-NCNT-CM/PMS systems in advanced wastewater treatment frameworks, specifically for targeted EOCs removal, heralding a new direction for sustainable water management.

Fabrication of Layered SiC/C/Si/MeSi2/Me Ceramic-Metal Composites via Liquid Silicon Infiltration of Metal-Carbon Matrices.

The growing demand for composite materials capable of enduring prolonged loads in high-temperature and aggressive environments presents pressing challenges for materials scientists. Ceramic materials composed of silicon carbide largely possess high mechanical strength at a relatively low density, even at elevated temperatures. However, they are inherently brittle in nature, leading to concerns about their ability to fracture. The primary objective of this study was to develop a novel technique for fabricating layered composite materials by incorporating SiC-based ceramics, refractory metals, and their silicides as integral constituents. These layered composites were produced through the liquid-phase siliconization method applied to metal-carbon blanks. Analysis of the microstructure of the resultant materials revealed that when a metal element interacts with molten silicon, it leads to the formation of a layer of metal silicide on the metal's surface. Furthermore, three-point bending tests exhibited an enhancement in the bending strength of the layered composite in comparison to the base silicon carbide ceramics. Additionally, the samples demonstrated a quasi-plastic nature during the process of destruction.

A Review of Research Progress on Ti(C,N)-Based Cermet Binder by Intermetallic Compounds and High-Entropy Alloys.

Ti(C,N)-based cermet is a kind of composite material composed of a metal binder phase and a Ti(C,N)-hard phase, which is widely used in the fields of cutting machining and wear-resistant parts due to its high hardness, good toughness, wear resistance, and chemical stability. In recent years, the research on the replacement of traditional Ni, Co, and Fe binder phases by novel binder phases such as intermetallic compounds and high-entropy alloys has made remarkable progress, which significantly improves the mechanical properties, wear resistance, corrosion resistance, and high-temperature oxidation resistance of Ti(C,N)-based cermets. This paper reviews the latest research results, summarizes the mechanism of the new binder to improve the performance of metal-ceramics, and looks forward to the future research directions.

Wastewater treatment using moving bed biofilm reactor technology: a case study of ceramic industry.

Biological approaches and coagulation are frequently used to reduce the chemical oxygen demand (COD) for treatment of ceramic effluent water. The technology known as the moving bed biofilm reactor (MBBR) can accomplish this goal. Further, the process of emulsification-aided innovative MBBR using biosurfactants can be proposed for ceramic effluent treatment. In a step-by-step upgrading scheme, biosurfactants and a consortia of halophilic and halotolerant microbial culture was utilized for the treatment of the effluent water. Over the course of 21 days, a progressive decrease in COD of up to 95.79% was achieved. Over the next 48 h period, the biochemical oxygen demand (BOD) was reduced by 98.3%, while total suspended solids (TSS) decreased by 79.41%. With the use of this innovative MBBR technology, biofilm formation accelerated, lowering the COD, BOD, and TSS levels. This allows treated water to be used for further research on recycling it back into the ceramics sector and repurposing it for agricultural purposes. PRACTITIONER POINTS: Implementation of modified MBBR technology for the treatment of effluent water. Biosurfactants could reduce in the organic and inorganic loads. Increase in MLSS values with COD removal observed. The plant operations without the use of chemical coagulants was effective with biosurfactants. Biofilm formation on carriers was scraped and the presence of surfactin and rhamnolipid was confirmed.

Failure and complication rates of different materials, designs, and bonding techniques of ceramic cantilever resin-bonded fixed dental prostheses for restoring missing anterior teeth: A systematic review and meta-analysis.

OBJECTIVES: The objective of this review was to assess clinical trials that have examined the materials, design, and bonding of ceramic cantilevered resin-bonded fixed dental prostheses (RBFDPs) as a potential option for replacing missing anterior teeth. The evaluation primarily focuses on the rate of restoration failure and clinical complications. MATERIALS AND METHODS: A thorough search of databases including PubMed/MEDLINE, Scopus, and the Cochrane Library, was conducted. The most recent search was performed in October 2023. Clinical studies that compared ceramic cantilevered RBFDPs with double retainers or cantilevered RBFDPs using different ceramic materials or bonding systems were included. The outcome measures considered were restoration failure and complication rates. RESULTS: Twelve studies met the eligibility criteria. The pooled data showed a statistically significant decrease in complication events when using cantilever designs compared with double retainer designs (p < 0.05); however, there were no differences found between the two designs in terms of restoration failure. The complication and failure rate of cantilever RBFDPs did not show a statistically significant difference with or without ceramic primer application before luting with phosphate monomer-containing luting resin (p > 0.05). CONCLUSIONS: Ceramic cantilevered RBFDPs have lower complication rates compared with those with double retainers. The use of a ceramic primer prior to luting composite resin for ceramic cantilevered RBFDPs decreases the occurrence of complications and failures, although this effect was not statistically significant. Additional research is required to confirm these findings. Glass ceramic cantilever RBFDPs showed a decrease in success after 6 years, requiring ongoing monitoring, but both zirconia and glass-infiltrated alumina cantilever RBFDPs have demonstrated durability with excellent long-term success and survival rates for up to 10 and 15 years. CLINICAL SIGNIFICANCE: Cantilever ceramic RBFDPs in the anterior region are a less invasive and valuable treatment option, providing good esthetic results.

Can a Self-etching Primer be Effective in Bonding Aligner Attachments to Different Types of Ceramics?

Objective: This in vitro study aimed to evaluate the effectiveness of pretreatment with a self-etching primer for bonding aligner attachments to lithium disilicate (LD) and monolithic zirconia (MZ) ceramics. Methods: Forty ceramics, including LD (n=20) and MZ (n=20), were divided into four study groups according to the surface pretreatments: LD specimens pretreated with universal primer (Monobond Plus, MP) after hydrofluoric acid etching (Group 1); MZ ceramics pretreated with MP after sandblasting (Group 2); LD ceramics pretreated with self-etching ceramic primer (Monobond etch & prime, MEP) (Group 3); and MZ ceramics pretreated with MEP after sandblasting (Group 4). The aligner composite (GC Aligner Connect) and universal adhesive (GPremio Bond) were used to prepare the resin attachments. The bond strength was evaluated by micro-shear bond strength (SBS) testing (0.1 mm/min) after thermocycling, and the remnant adhesive was scored according to the resin attachment remnant index (RARI). The SBS data were analyzed using ANOVA and Tukey tests, and the RARI scores were analyzed using the chi-square test. Results: Group 1 had the lowest SBS, and group 2 had the highest SBS. There were significant differences between the groups in terms of bond strength (p<0.05). The RARI scores showed no significant differences, regardless of the pretreatment and ceramic type. Conclusion: The use of a self-etching primer increased the bond strength of resin attachments on LD ceramics. For zirconia ceramics, both ceramic primers are recommended for aligner attachment bonding.

Nanodiamond-based berberine aquasomes for enhancing penetration across epidermis to treat psoriasis.

The use of berberine hydrochloride (BCS class III) has limited application in psoriasis, when given as topical drug delivery systems, due to low permeability in the skin layer. Hence, berberine hydrochloride-loaded aquasome nanocarriers were developed for skin targeting, particularly epidermis (primary site of psoriasis pathophysiology) and enhance the skin permeability of berberine hydrochloride. Aquasomes were formulated using the adsorption method and characterized by structural morphology TEM, % drug adsorption, drug release profile (in-vitro and ex-vivo), in-vivo efficacy study and stability study. The reduced particle size and higher surface charge of SKF3 formulation (263.57 ± 27.78 nm and -21.0 ± 0.43 mV) showed improved stability of aquasomes because of the development of higher surface resistance to formation of aggregates. The adsorption of hydrophilic berberine and the non-lipidic nature of aquasomes resulted in % adsorption efficiency (%AE) of 94.46 ± 0.39 %. The controlled first-order release behavior of aquasomes was reported to be 52.647 ± 14.63 and 32.08 ± 12.78 % in in-vitro and ex-vivo studies, respectively. In-vivo studies demonstrated that topical application of berberine hydrochloride loaded aquasomes significantly alleviated psoriasis symptoms like hyperkeratosis, scaling and inflammation, due to the reduction in the inflammatory cytokines (IL-17 and IL-23). Therefore, aquasome formulation exhibits an innovative approach for targeted application of berberine hydrochloride in the management of psoriasis.

Reverse Atom Capture on Perovskite Surface Enabling Robust and Efficient Cathode for Protonic Ceramic Fuel Cells.

Protonic ceramic fuel cells (PCFCs) hold potential for sustainable energy conversion, yet their widespread application is hindered by the sluggish kinetics and inferior stability of cathode materials. Here, a facile and efficient reverse atom capture technique is developed to manipulate the surface chemistry of PrBa0.5Sr0.5Co1.5Fe0.5O5+δ (PBSCF) cathode for PCFCs. This method successfully captures segregated Ba and Sr cations on the PBSCF surface using W species, creating a (Ba/Sr)(Co/Fe/W)O3-δ (BSCFW)@PBSCF heterostructure. Benefiting from enhanced kinetics of proton-involved oxygen reduction reaction and strengthened chemical stability, the single cell using the optimized 2W-PBSCF cathode demonstrates an exceptional peak power density of 1.32 W cm-2 at 650 °C and maintains durable performance for 240 h. Theoretical calculations unveil that the BSCFW perovskite delivers lower oxygen vacancy formation energy, hydration energy, and proton transfer energy compared to the PBSCF perovskite. This protocol offers new insights into advanced atom capture techniques for sustainable energy infrastructures. This article is protected by copyright. All rights reserved.

One case of complicated crown root fracture of upper anterior teeth managed by multidisciplinary joint approaches.

Complicated crown root fracture is a serious combined fracture of the enamel, dentin, and cementum in dental trauma. The treatment method is complicated. During the procedure, the condition of pulp, periodontal, and tooth body should be thoroughly evaluated, and a multidisciplinary approach combined with sequential treatment is recommended. This case reported the different treatment and repair processes of one case of two affected teeth after complicated crown root fracture of upper anterior teeth, including regrafting of broken crown after flap surgery at the first visit, direct resin repair to remove broken fragments, and pulp treatment and post-crown repair at the second visit. After 18 months of follow-up, the preservation treatment of the affected teeth with complicated crown root fracture was achieved. Therefore, fragment reattachment and post-crown restoration are feasible treatment options for children with complicated crown root fracture.

Enabling High-Performance Hybrid Solid-State Batteries by Improving the Microstructure of Free-Standing LATP/LFP Composite Cathodes.

The phosphate lithium-ion conductor Li1.5Al0.5Ti1.5(PO4)3 (LATP) is an economically attractive solid electrolyte for the fabrication of safe and robust solid-state batteries, but high sintering temperatures pose a material engineering challenge for the fabrication of cell components. In particular, the high surface roughness of composite cathodes resulting from enhanced crystal growth is detrimental to their integration into cells with practical energy density. In this work, we demonstrate that efficient free-standing ceramic cathodes of LATP and LiFePO4 (LFP) can be produced by using a scalable tape casting process. This is achieved by adding 5 wt % of Li2WO4 (LWO) to the casting slurry and optimizing the fabrication process. LWO lowers the sintering temperature without affecting the phase composition of the materials, resulting in mechanically stable, electronically conductive, and free-standing cathodes with a smooth, homogeneous surface. The optimized cathode microstructure enables the deposition of a thin polymer separator attached to the Li metal anode to produce a cell with good volumetric and gravimetric energy densities of 289 Wh dm-3 and 180 Wh kg-1, respectively, on the cell level and Coulombic efficiency above 99% after 30 cycles at 30 °C.

Spinel-Based ZnAl2O4: 0.5%Cr3+ Red Phosphor Ceramics for WLED.

To address the issue of the lack of red light in traditional Ce3+: YAG-encapsulated blue LED white light systems, we utilized spark plasma sintering (SPS) to prepare spinel-based Cr3+-doped red phosphor ceramics. Through phase and spectral analysis, the SPS-sintered ZnAl2O4: 0.5%Cr3+ phosphor ceramic exhibits good density, and Cr3+ is incorporated into [AlO6] octahedra as a red emitting center. We analyzed the reasons behind the narrow-band emission and millisecond-level lifetime of ZAO: 0.5%Cr3+, attributing it to the four-quadrupole interaction mechanism as determined through concentration quenching modeling. Additionally, we evaluated the thermal conductivity and thermal quenching performance of the ceramic. The weak electron-phonon coupling (EPC) effects and emission from antisite defects at 699 nm provide positive assistance in thermal quenching. At a high temperature of 150 °C, the thermal conductivity reaches up to 14 W·m-1·K-1, and the 687 nm PL intensity is maintained at around 70% of room temperature. Furthermore, the internal quantum efficiency (IQE) of ZAO: 0.5%Cr3+ phosphor ceramic can reach 78%. When encapsulated with Ce3+: YAG for a 450 nm blue LED, it compensates for the lack of red light, adjusts the color temperature, and improves the color rendering index (R9). This provides valuable insights for the study of white light emitting diodes (WLEDs).

Utilizing a High-Performance Piezoelectric Nanocomposite as a Self-Activating Component in Piezotronic Artificial Mechanoreceptors.

Challenges such as poor dispersion and insufficient polarization of BaTiO3 (BTO) nanoparticles (NPs) within poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) composites have hindered their piezoelectricity, limiting their uses in pressure sensors, nanogenerators, and artificial sensory synapses. Here, we introduce a high-performance piezoelectric nanocomposite material consisting of P(VDF-TrFE)/modified-BTO (mBTO) NPs for use as a self-activating component in a piezotronic artificial mechanoreceptor. To generate high-performance piezoelectric nanocomposite materials, the surface of BTO is hydroxylated, followed by the covalent attachment of (3-aminopropyl)triethoxysilane to improve the dispersibility of mBTO NPs within the P(VDF-TrFE) matrix. We also aim to enhance the crystallization degree of P(VDF-TrFE), the efficiency characteristics of mBTO, and the poling efficiency, even when incorporating small amounts of mBTO NPs. The piezoelectric potential mechanically induced from the P(VDF-TrFE)/mBTO NPs nanocomposite was three times greater than that from P(VDF-TrFE) and twice as high as that from the P(VDF-TrFE)/BTO NPs nanocomposite. The piezoelectric potential generated by mechanical stimuli on the piezoelectric nanocomposite was utilized to activate the synaptic ionogel-gated field-effect transistor for the development of self-powered piezotronics artificial mechanoreceptors on a polyimide substrate. The device successfully emulated fast-adapting (FA) functions found in biological FA mechanoreceptors. This approach has great potential for applications to future intelligent tactile perception technology.

Preparation of Ceramic Fiber Threads with Enhanced Abrasion Resistance Performance.

Ceramic fiber thread is one of the key components in flexible external thermal insulation blankets, and it has been applied in various fields as a flexible ceramic fibrous material with excellent deformability and high-temperature resistance. However, ceramic fiber threads are often subjected to reciprocating friction motion at specific bending angles, making them highly susceptible to abrade and fracture. Enhancing the abrasion resistance performance of ceramic fiber threads under bending conditions is the future trend and remains a significant challenge. Hence, we design and construct a novel polyurethane-modified coating on the ceramic fiber threads to improve their abrasion resistance performance. The effects of the types and concentrations of modifiers on the microstructure, abrasion resistance property, and tensile property of ceramic fiber threads are systematically investigated. The ceramic fiber threads, after modification with hexamethylene diisocyanate waterborne polyurethane (HDI-WPU) with a concentration of 3%, exhibit excellent abrasion resistance properties. The number of friction cycles at fracture of the modified ceramic fiber thread is more than three times, and the tensile strength is more than one and a half times, that of the original ceramic fiber thread, demonstrating the great potential of the HDI-WPU modifier for enhancing the abrasion resistance performance of ceramic fiber threads.

Heat-Localized and Salt-Resistant 3D Hierarchical Porous Ceramic Platform for Efficient Solar-Driven Interfacial Evaporation.

Solar-driven interfacial evaporation (SDIE) is a highly promising approach to achieve sustainable desalination and tackle the global freshwater crisis. Despite advancements in this field, achieving balanced thermal localization and salt resistance remains a challenge. Herein, the study presents a 3D hierarchical porous ceramic platform for SDIE applications. The utilized alumina foam ceramics (AFCs) exhibit remarkable corrosion resistance and chemical stability, ensuring a prolonged operational lifespan in seawater or brines. The millimeter-scale air-filled pores in AFCs prevent thermal losses through conduction with bulk water, resulting in heat-localized interfaces. The hydrophilic nature of macroporous AFC skeletons facilitates rapid water replenishment on the evaporating surface for effective salt-resistant desalination. Benefiting from its self-radiation adsorption and side-assisted evaporation capabilities, the AFC-based evaporators exhibit high indoor evaporation rates of 2.99 and 3.54 kg m-2 h-1 under one-sided and three-sided illumination under 1.0 sun, respectively. The AFC-based evaporator maintains a high evaporation rate of ≈2.77 kg m-2 h-1 throughout the 21-day long-term test. Furthermore, it achieves a daily water productivity of ≈10.44 kg m-2 in outdoor operations. This work demonstrates the potential of 3D hierarchical porous ceramics in addressing the trade-off between heat localization and salt resistance, and contributes to the development of durable solar steam generators.

Rational Design of Ruddlesden-Popper Perovskite Ferrites as Air Electrode for Highly Active and Durable Reversible Protonic Ceramic Cells.

Reversible protonic ceramic cells (RePCCs) hold promise for efficient energy storage, but their practicality is hindered by a lack of high-performance air electrode materials. Ruddlesden-Popper perovskite Sr3Fe2O7-δ (SF) exhibits superior proton uptake and rapid ionic conduction, boosting activity. However, excessive proton uptake during RePCC operation degrades SF's crystal structure, impacting durability. This study introduces a novel A/B-sites co-substitution strategy for modifying air electrodes, incorporating Sr-deficiency and Nb-substitution to create Sr2.8Fe1.8Nb0.2O7-δ (D-SFN). Nb stabilizes SF's crystal, curbing excessive phase formation, and Sr-deficiency boosts oxygen vacancy concentration, optimizing oxygen transport. The D-SFN electrode demonstrates outstanding activity and durability, achieving a peak power density of 596 mW cm-2 in fuel cell mode and a current density of - 1.19 A cm-2 in electrolysis mode at 1.3 V, 650 °C, with excellent cycling durability. This approach holds the potential for advancing robust and efficient air electrodes in RePCCs for renewable energy storage.

Ultralow-Permittivity and Temperature-Stable Ba1-xCaxMg2Al6Si9O30 Dielectric Ceramics for C-Band Patch Antenna Applications.

Ca-substituted Ba1-xCaxMg2Al6Si9O30 ceramics were prepared to explore the relationships among their crystal structural parameters, phase compositions, dielectric properties, and coefficients of thermal expansion and applications in C-band antenna. The maximum solubility of Ba1-xCaxMg2Al6Si9O30 was located at x = 0.25, and Ba1-xCaxMg2Al6Si9O30 ceramics (0 ≤ x ≤ 0.25) crystallized in the space group P6/mcc. In Ba1-xCaxMg2Al6Si9O30 single-phase ceramics, εr was dominated by ionic polarizability and "rattling effects" of Ba2+ and Al(2)3+; Q × f was controlled by the roundness of [Si4Al2O18] inner rings and total lattice energy; and τf was affected by the bond valence of Si/Al(1)-O(1). Notably, the low average coefficients of thermal expansion (2.668 ppm/°C) at -150 °C ≤ T ≤ 850 °C and near-zero coefficients of thermal expansion (1.254 ppm/°C) at -150 °C ≤ T ≤ 260 °C were achieved for the Ba1-xCaxMg2Al6Si9O30 (x = 0.1) ceramic. Optimum microwave and terahertz dielectric properties were obtained for the Ba1-xCaxMg2Al6Si9O30 (x = 0.1) ceramic with εr = 5.80, Q × f = 31,174 at 13.99 GHz, τf = -7.10 ppm/°C, and εr = 5.71-5.85 at 0.2 THz ≤ f ≤ 1.0 THz. Also, the Ba1-xCaxMg2Al6Si9O30 (x = 0.1) ceramic substrate had been designed as a C-band patch antenna with a high simulated radiation efficiency (87.76%) and gain (6.30 dBi) at 7.70 GHz (|S11| = -38.41 dB).

Effects of Internal Stress and Hydrogen Penetration on the Performance of Er2O3 Coatings as Hydrogen Permeation Barriers.

Ceramic coatings that can effectively prevent hydrogen permeation have a wide range of applications in hydrogen energy and nuclear fusion reactors. In this study, for the first time, the internal stress of Er2O3 coatings was found to be a key factor that could determine their hydrogen permeation resistance and lifespan. The internal stress was controlled by designing layered Er2O3 coatings. The internal stress increased with an increasing number of Er2O3 layers. When the number of layers was below 15, the increased internal stress did not adversely affect the coating performance and might help to increase its hydrogen permeation resistance. Although the overall thickness of the 15-layer Er2O3 coating was only 97 nm, its hydrogen permeation reduction factor (PRF) reached the highest value of 626, whereas a further increase in the internal stress detrimentally affected the ability of the coating to reduce hydrogen permeation. In addition, the experimental observations and simulation results revealed that the performance of the Er2O3 coatings was related to the hydrogen atoms that penetrated the coating, which weakened the Er-O bonds and consequently decreased the Er2O3 fracture limit. This study provides insights into the effects of internal stress and hydrogen penetration on the performance of ceramic coatings as hydrogen permeation barriers and will help guide strategies for the structure design of hydrogen permeation barriers possessing high PRFs and long lifespans.