Ceramics, Volume 7, Issue 3 (September 2024) – 31 articles

Ternary and quaternary compounds offer vast potential for tailoring material properties through compositional adjustments and complex interactions among their constituent elements. However, many of their compositional possibilities still need to be investigated. Energy-dispersive X-ray spectroscopy (EDX) is crucial for determining elemental composition but is inadequate for identifying chemical bonds and physical properties. This work introduces a novel methodology using a stoichiometric deviation vector (SDV) to estimate the physical and compositional feature characteristics of Si, N, and O compounds by comparing actual molar ratios with ideal stoichiometric references. We validated this method by estimating Si-O bonds in silicon oxynitride samples, demonstrating strong agreement with FTIR and refractive index results. We also extended our proof of principle for SiAlON compounds and established an adaptable procedure to analyze compounds with more than three elements. This flexible methodology will significantly value the materials research community, providing valuable compositional features and physical insights by performing elemental EDX characterizations. Full article

The key objective of this study is to determine the effect of interphase boundaries, the formation of which is caused by the variation of Li₂ZrO₃/MgLi₂ZrO₄ phases in lithium-containing ceramics based on lithium metazirconate, on the resistance to near-surface layer destruction processes associated with irradiation with He²⁺ ions. During the observation of the deformation effects that have an adverse impact on the volumetric swelling of the near-surface layers of ceramics, the thermal expansion factor caused by high-temperature irradiation was considered, simulating conditions as close as possible to the operating conditions of these materials as blankets for tritium propagation. During the studies conducted, it was established that an elevation in the contribution of MgLi₂ZrO₄ in the composition of ceramics leads to a rise in resistance to deformation swelling caused by structural distortions of the crystal lattice, due to a decrease in the effect of thermal expansion, alongside the presence of interphase boundaries. The established dependencies of the change in the hardness of the near-surface layer of the studied ceramics made it possible to establish the kinetics of softening caused by the deformation distortion of the crystalline structure, as well as to determine the relationship between volumetric swelling and softening (change in hardness) and a decrease in crack resistance (change in the value of resistance to single compression). Full article

Analyzing the effect of anions on the structure of geopolymers is crucial because anions can significantly influence the material’s chemical stability, mechanical properties, and long-term durability. Understanding these effects helps optimize geopolymer compositions for various applications, such as construction materials and waste encapsulation. This research report describes the effects of nitrate, sulfate, and phosphate anions on alkali-activated blast furnace slag’s structural integrity and properties. Advanced techniques like XRD, FT-IR, Raman spectroscopy, and XPS have been employed to analyze structural modifications caused by anions, providing insights into their interactions and effects. These anions generally decrease compressive strength by disrupting geopolymerization and altering microstructure. For example, sulfate ions lead to the formation of ettringite, while phosphate ions bind calcium into separate phases. We can also observe microstructural changes, such as increased porosity with phosphate, which significantly reduces strength. Nitrate’s effect is less detrimental but still influences the overall structural dynamics. Full article

This study examines the impact of a dual cure activator (DCA) when applied in combination with self-adhesive resin cements on the zirconia. Sixty zirconia were prepared in compliance with the manufacturer’s directions. The specimens were randomly assigned to each group under the dark condition, following DCA and self-adhesive resin cements [RelyX universal resin cement (RXS); Maxcem elite chroma (MAC); Panavia SA cement multi (PSM)]; group 1, RXS; group 2, MAC; group 3, PSM; group 4, DCA + RXS; group 5, DCA + MAC; and group 6, DCA + PSM. The resin composite was fixed to the zirconia, surface-treated, and maintained in a dark container for 30 min. The specimens were kept in an incubator at a temperature of 37 degrees Celsius for 24 h. The universal testing device was employed to compute the shear bond strength (SBS). A stereomicroscope was used to analyze the fractured types. The data were analyzed employing the one-way ANOVA and Tukey’s test. Group 2 had the lowest SBS (4.93 ± 0.53 MPa). Group 1 (11.17 ± 0.86 MPa) and group 3 (11.48 ± 1.17 MPa) were not significantly different in SBS. Group 6 (15.61 ± 0.68 MPa) had the highest SBS but was not significantly different from group 4 (15.45 ± 1.20 MPa). The findings show that treating the zirconia surface with DCA before using the self-curing mode of self-adhesive resin cements is the best way to improve the bond between the zirconia and resin cement. Full article

This paper reports the dielectric characterizations of (Ca_0.95Sr_0.05)(Ti_1−xSn_x)O₃ ceramics prepared using a solid-state reaction method with various x values. X-ray diffraction spectroscopy analyses showed that the crystal structure of these pure samples was orthorhombic perovskite. With increasing Sn⁴⁺ content, the lattice constant and unit cell volume increased, while the dielectric constant decreased because of the ionic polarizability decreasing. Moreover, a maximum Q × f value of 5242 (GHz), a dielectric constant (ε_r) of 91.23, and a temperature coefficient (τ_f) of +810 ppm/°C were achieved for samples sintered at 1350 °C for 4 h. The microwave dielectric characterization was found to be strongly correlated with the sintering temperature, and the best performance was achieved for the sample sintered at 1350 °C. (Ca_0.95Sr_0.05)(Ti_1−xSn_x)O₃ possesses a promising potential to be a τ_f compensator for a near-zero τ_f dielectric ceramic applied in wireless communication systems. Full article

Lithium-ion batteries (LIBs) have significantly advanced portable electronics, yet their reliance on flammable organic solvents and lithium dendrite formation pose safety risks. Solid-state batteries (SSBs), utilizing solid electrolytes, offer a safer alternative with higher energy and power densities. This study explores the fabrication of solid electrolytes using ceramic stereolithography, focusing on lithium lanthanum zirconate (LLZ) due to its high ionic conductivity and chemical stability. A photosensitive paste containing 40–43 vol% LLZ was suitable for processing by stereolithography, and optimized processing parameters of 100 mW laser power and 1000 mm/s laser scanning speed with a 50 μm laser spot size were identified for sufficient material curing and interlayer lamination of LLZ. Thin embossed sheets were designed to enhance ion exchange and reduce internal resistance and were fabricated by the ceramic stereolithography method. The effect of cold isostatic pressing (CIP) on the sintered microstructure was investigated, and the potential for CIP to promote solid-phase diffusion during sintering was demonstrated, particularly at 67 MPa. The resulting LLZ-embossed sheets exhibited dense ceramic microstructures. These findings support the potential application of ceramic stereolithography for fabricating efficient solid electrolytes for next-generation telecommunications and mobile devices. Full article

Choosing an appropriate prosthetic material for the superstructure of an implant-supported or tooth-implant supported fixed partial denture (FPD) is crucial for the success of the prostheses. The objective of this study was to examine the effect of prosthetic material type and tooth-to-implant support on stress distribution of FPDs using three-dimensional finite element analysis (3D FEA). Two FEA models were generated, distinguished by their support configurations: Model I representing an FPD supported by implants, and Model II depicting an FPD supported by both a tooth and an implant. Two different restorative materials, porcelain-fused-to-metal (PFM) and monolithic zirconia, were evaluated for stress distribution under axial and oblique loads of 300 N applied to the pontic. Under both axial and oblique loading conditions, the maximum von Mises stress values were observed to be higher in the implant-abutment complex of both zirconia implant-supported and tooth-implant-supported FPDs compared to PFM FPDs. In the case of axial loading, comparable stress values were found in the cortical bone for PFM (12.65 MPa) and zirconia implant-supported FPDs (12.71 MPa). The zirconia tooth-implant-supported FPD exhibited the highest stress values in the implant-abutment system. Full article

Classical (MD) and ab initio (AIMD) molecular dynamics simulations were conducted to investigate the fundamental properties of solid and liquid MgO. AIMD was performed by DFT using the Strongly Conditioned and Appropriately Normed (SCAN) exchange correlation functional. The obtained pair-correlation functions of liquid MgO were used as reference data for the optimization of parameters of classical MD. For the latter, a Born–Mayer–Huggins (BMH) potential was applied, and parameters were adjusted until a best fit of both structural properties was obtained by AIMD and physical properties by experimental data. Different structural, dynamic and thermodynamic properties of solid and liquid MgO were then calculated by classical MD and compared with the literature data. Good agreement was found for the Mg-O bond length, self-diffusion coefficients, density of liquid MgO and for heat content and density of crystalline MgO. Using a void-melting approach, the melting temperature of MgO was found as 3295 ± 30 K, which is in good agreement with the recent experimental work by Ronchi et al. (3250 ± 20 K). The optimized parameters of BMH potential describe well the structural, dynamic and thermodynamic properties of solid and liquid MgO and may be combined with our previous results of a CaO-Al₂O₃-TiO₂ system to calculate the properties of a quaternary CaO-MgO-Al₂O₃-TiO₂ system. Full article

In this study, Ce₂[Zr_1−x(Ba_1/3Nb_2/3)_x]₃(MoO₄)₉ (0.02 ≤ x ≤ 0.1, CZ_1−xN_x) ceramics were sintered at 600 °C and 700 °C using the traditional solid-state method. An analysis conducted through XRD and Rietveld refinement confirmed that all the CZ_1−xN_x ceramics displayed a single phase with a trigonal structure (space group R-3c). The observed increases in cell volume with increasing x values indicate the successful substitution of (Ba_1/3Nb_2/3)⁴⁺. The high densification of the synthesized phase was validated by the density and SEM results. Additionally, the P-V-L theory demonstrates a strong correlation between the Ce-O bond and ε_r, as well as τ_f, and between the Mo-O bond and Q×f. Notably, the CZ_0.98N_0.02 ceramics demonstrated superior performance at 675 °C, exhibiting ε_r = 10.41, Q×f = 53,296 GHz, and τ_f = −23.45 ppm/°C. Finally, leveraging CZ_0.98N_0.02 ceramics as substrate materials enabled the design of a patch antenna suitable for the 5G communication band, demonstrating its significant potential in this field. Full article

This work presents the study of the rheology ical behavior of Algerian kaolin (DD1) suspensions considering two types of electro-steric dispersants (Hypermer KD1 and Darvan 7) and the evaluation of their effectiveness at neutral pH. The results showed that Darvan 7 exhibits electro-steric behavior at neutral pH, whereas KD1 exhibits purely steric behavior. The addition of a dispersant strongly influenced the rheological behavior of kaolin suspensions. The DD1 suspensions without dispersant exhibited fluidifying plastic behavior (Casson model). The shear stresses decreased significantly with the addition of dispersant, while the significant decrease in viscosity indicated that the dispersant reduced the strength of the particle networks that make up the slurry. The suspensions with 1 wt.% dispersant were consistent with the Bingham model, with a very low yield point. The viscosity of the dispersion reached a minimum when the concentration of the dispersant was 1 wt.%. This value was lower with Darvan 7. The addition of aluminum slag as a source of alumina to KD1 increased its efficiency and lowered the viscosity of the kaolin suspensions. Full article

In this study, we demonstrate the high luminous efficacy of 118 lm/W and the high reliability of white LEDs (WLEDs) through 450 °C thermal aging, utilizing four-inch YAG: Ce³⁺ phosphor-in-glass (PiG) plates designed for vehicle headlights. The sintering process of mixing glass and phosphor typically generates pores, which can scatter light and reduce the luminous efficacy of the fabricated PiG. In this study, we produced four-inch PiG plates under four different fabrication conditions to evaluate their luminous efficacy. Our results revealed that the PiG plate with a thin thickness of 0.08 mm exhibited a 16.83% increase in luminous efficacy compared to the 0.15 mm plate, attributed to reduced light interaction with the pores. Unlike silicone-based phosphor WLEDs, which offer high performance but lower reliability due to the silicone resin’s low transition temperature (150 °C), our novel thin PiG plate achieves high performance and reliability. This advancement suggests that the proposed thin PiG plate could replace traditional silicone-based phosphors, enabling the development of high-quality WLEDs for vehicle headlights in automotive applications. Full article

Bioceramic endodontic cements, known for their antibacterial properties, calcium ion release, and alkaline pH, may come into contact with various irrigants after furcal perforation repair. This study aimed to evaluate the effect of different irrigating solutions and setting times on the shear bond strength (SBS) of Biodentine^® (Septodont, Saint-Maur-des-Fosses Cedex, France) to a self-adhering flowable composite. Sixty Biodentine^® (Septodont, Saint-Maur-des-Fosses Cedex, France) blocks were prepared and divided into two groups based on the setting time: 72 h and 7 days. These were further subdivided into five subgroups based on the irrigation solution applied: distilled water, sodium hypochlorite, ethylenediaminetetraacetic acid, chlorhexidine, and phosphoric acid. They were then restored with Dyad Flow^TM (Kerr^TM, Orange, CA, USA). SBS and failure modes were assessed at 24 h and 6 months. A two-way analysis of variance (ANOVA) test was performed to analyze the effect of the different irrigating solutions and setting times on the SBS of Biodentine^® (Septodont, Saint-Maur-des-Fosses Cedex, France) and Dyad Flow^TM (Kerr^TM, Orange, CA, USA). The level of significance was set at a ≤0.05. At 24 h, SBS was significantly influenced by both the irrigant solution (p = 0.029) and setting time (p = 0.018); at 6 months, SBS was influenced only by the irrigating solutions (p < 0.001). The predominant mode of bond failure was adhesive across all groups. In conclusion, while the setting time did not affect the bond strength, certain irrigating solutions reduced it. Thus, careful consideration of surface treatments applied to Biodentine^® is crucial for successful endodontic and restorative outcomes. Full article

The formation of defects, due to drying, in robocasted ceramic objects is an important issue arising from non-uniform shrinkage of the material during this step in the process. Common methods for shrinkage measurement are not well suited to the small size of robocasted cords or the complexity of robocasted objects. Innovative methods for shrinkage measurement were developed using non-destructive optical vision techniques with computer-controlled data acquisition, allowing measurement on millimetric cords and on specific zones of a product. The study of a single porcelain cord revealed an anisometric shrinkage related to the orientation of grains during extrusion. A differential shrinkage at the macroscopic scale was also measured on a robocasted object, indicating a moisture content gradient in the material. The methods presented in this paper are of particular relevance to real-time control of the drying process for robocasted objects. Full article

Herein, this study has examined the influence of Zn²⁺ sources during a biogenic-mediated pathway to synthesize ZnO nanoparticles with highly desirable solar-responsive catalytic properties. Salts of nitrate, acetate and chloride have been utilized. The ZnO powders underwent characterization using diverse analytical tools, including XRD, FTIR, Raman, BET, SEM, TEM with EDS/elemental mapping and UV-vis absorption/emission spectroscopic analyses. Accordingly, precursors have proved to affect crystallinity, morphology, surface characteristics, optical properties and the photocatalytic degradation of methylene blue (MB) model pollutant. It was observed that ZnO derived from zinc acetate precursor (Z-AC NPs) exhibits very fast photocatalytic degradation of MB at pH 11 with superior kinetic estimates of 0.314 min⁻¹ and t_1/2 = 2.2 min over many of recent reports. In contrast, the chloride precursor is not recommended along with the employed biogenic route. The intriguing findings could be directly correlated to the decreased crystal size, augmented surface area, the hexagonal morphology of the crystals, high potency in absorbing visible photons, high efficacy in separating photogenerated charge carriers and producing high amounts of ^•OH radicals. Further testing of Z-AC NPs in photocatalytic remediation of water samples from Dumat Aljandal Lake in Aljouf, Saudi Arabia, contaminated with MB and pyronine Y (PY) dyestuffs, showed high dye photodegradation. Therefore, this work could lead to an extremely fast avenue for decontaminating wastewater from hazmat dyestuff. Full article

This paper presents the results of a study on the morphology, structure, and luminescent properties of ceramics synthesized in the radiation field of MeWO₄ compositions (where Me is Mg, Ca, and Zn). The synthesis of ceramics was carried out by the direct action of the electron flux on an initial mixture of powders of the given stoichiometric composition. WO₃, ZnO, MgO, and CaO powders with particle sizes in the range of 1–50 microns were used for the synthesis of the samples. It was found that the yield of the radiation synthesis reaction (the ratio of the mass of the sample and the charge used), when treated with an electron flux with an energy of 1.4 MeV and a flux power density of 15–18 kW/cm², was in the range of 75–99%. The synthesis of all compositions was carried out under the same radiation treatment modes, although the melting temperatures of the starting materials varied significantly and ranged from 1473 °C (WO₃) to 2825 °C (MgO). The study of the ceramic structure showed that under the radiation effect of powerful radiation fluxes on the charge, a crystalline phase of the appropriate composition formed, regardless of the synthesis modes. The results of XRD studies show that during the radiation treatment of the charge, ceramics are formed mainly with the crystalline phases ZnWO₄, MgWO₄, and CaWO₄. These resulting MeWO₄ ceramics can be used for the same purposes as crystals. Photoluminescence (PL) and cathodoluminescence (CL) were studied under excitation using stationary ultraviolet radiation and nanosecond pulses of electron flux. In general, the PL and CL of synthesized ceramic samples ZnWO₄, MgWO₄, and CaWO₄ showed that their luminescent properties are similar to those of luminescence in corresponding crystalline materials. This indicates the formation of a crystalline phase in synthesized ceramic samples. Full article

Yttria-stabilized zirconia (Y-TZP) ceramics with a drastically reduced yttria content have been introduced by different manufacturers, aiming at improving the damage tolerance of ceramic components. In this study, an alumina-doped 1.5Y-TZP was axially pressed, pressureless sintered in air at 1250–1400 °C for 2 h and characterized with respect to mechanical properties, microstructure, and phase composition. The material exhibits a combination of a high strength of 1000 MPa and a high toughness of 8.5–10 MPa√m. The measured fracture toughness is, however, extremely dependent on the measurement protocol. Direct crack length measurements overestimate toughness due to trapping effects. The initially purely tetragonal material has a high transformability of >80%, the transformation behavior is predominantly dilational, and the measured R-curve-related toughness increments are in good agreement with the transformation toughness increments derived from XRD data. Full article

Yb:CaF₂ transparent ceramics represent a promising laser gain medium for ultra-short lasers due to their characteristics: low phonon energy, relatively high thermal conductivity, negative thermo-optical coefficient, and low refractive index. Compared to single crystals, Yb:CaF₂ ceramics offer superior mechanical properties, lower cost, and it is easier to obtain large-sized samples with proper shape and uniform Yb³⁺ doping at high concentrations. The combination of air pre-sintering and Hot Isostatic Pressing (HIP) emerges as a viable strategy for achieving high optical quality and fine-grained structure of ceramics at lower sintering temperatures. The properties of the powders used in ceramic fabrication critically influence both optical quality and laser performance of Yb:CaF₂ ceramics. In this study, the 5 atomic percentage (at.%) Yb:CaF₂ transparent ceramics were fabricated by air pre-sintering and hot isostatic pressing (HIP) using nano-powders synthesized through the co-precipitation method. The co-precipitated powders were optimized by studying air calcination temperature (from 350 to 550 °C). The influence of calcination temperature on the microstructure and laser performance of Yb:CaF₂ ceramics was studied in detail. The 5 at.% Yb:CaF₂ transparent ceramics air pre-sintered at 625 °C from powders air calcined at 400 °C and HIP post-treated at 600 °C exhibited the highest in-line transmittance of 91.5% at 1200 nm (3.0 mm thickness) and the best laser performance. Specifically, a maximum output power of 0.47 W with a maximum slope efficiency of 9.2% at 1029 nm under quasi-CW (QCW) pumping was measured. Full article

Inorganic dielectric films have attracted extensive attention in the field of microelectronic and electrical devices because of their wide operating temperature range, small size, and easy integration. Here, we designed and prepared eco-friendly (1-x)Bi_0.45Na_0.45Ba_0.1TiO₃-xBi(Mg_1/3Nb_2/3)O₃ multifunctional ferroelectric thin films for energy storage and photovoltaic. The results show that Bi(Mg_1/3Nb_2/3)O₃ can effectively improve the energy storage performance. At x = 0.05, the energy storage density and efficiency are as high as 73.1 J/cm³ and 86.2%, respectively, and can operate stably in a wide temperature range. The breakdown field strength of the thin films increased significantly, and the analysis showed that the addition of Bi(Mg_1/3Nb_2/3)O₃ caused a change in the internal conduction mechanism. At the same time, the generation of polar nanoregions increases the relaxation characteristics, thus improving the energy storage properties. In addition, the thin film material also has excellent ferroelectric photovoltaic properties. This work represents a new design paradigm that can serve as an effective strategy for developing advanced multi-functional materials. Full article

Porous α-Al₂O₃ ceramics are a highly sought-after material with a multitude of applications; for example, they are used as filters, substrates, biomedicine materials, etc. Despite the availability of raw materials, a challenge associated with this technology is the high energy budget caused by sintering above 1500 °C. For the cold sintering processing (CSP) of ceramics, lowering the α-Al₂O₃ sintering temperature is one of the most urgent challenges in the background of its rapid development. This paper is the first to demonstrate a solution to this problem using the CSP of α-alumina ceramics in the presence of pure water as a transient liquid. The manufactured materials were examined using XRD analysis; the evolution of their microstructures during CSP was revealed by SEM; and the porosity was evaluated using the Archimedes method. Ceramics with an open porosity up to 36% were produced at 380–450 °C and 220 MPa in 30 min. An increase in the pressure was found to impede α-Al₂O₃ formation from γ-AlOOH. The development of the microstructure was discussed within the framework of the dissolution–precipitation model and homogenous nucleation. The results of the SEM study pointed to the coalescence of γ-AlOOH grains during CSP. Full article

Coal combustion in power plants for electric power generation produces millions of tons of residues that are generally disposed of in landfills or ponds occupying vast land, resulting in serious environmental pollution. Fly ash (FA) is one of the main solid wastes generated in coal-based thermal power plants, representing the largest fraction of coal combustion residues (65–95%). Unfortunately, the enormous amount of FA residue is utilized only partly, mainly in the cement industry and building materials field. An alternative approach to using FA is its incorporation into ceramic, glass and glass–ceramic production, aligning with circular economy principles and reducing the environmental footprint of both the energy and ceramic sectors. In this review article, the topics of the composition, properties, classification, and utilization of fly ashes from thermal power plants are discussed. The main objective of this work is a critical analysis of the experimental trials directed to the involvement of FA as a raw material in the fabrication of glass–ceramics and porous ceramic composites. Full article

Over the past decades, Na_0.5Bi_0.5TiO₃ (NBT)-based ceramics have received increasing attention in energy storage applications due to their high power density and relatively large maximum polarization. However, their high remnant polarization (P_r) and low breakdown field strength are detrimental for their practical applications. In this paper, a new solid solution (1−x)Na_0.5Bi_0.5TiO₃–xCaHfO₃ (x = 0.04, 0.08, 0.12, 0.16) was constructed by introducing CaHfO₃ into NBT, and thus was prepared using a conventional solid-state reaction. With the addition of CaHfO_3, the disorder of the structure increased, A-site vacancies formed, and thus oxygen vacancies were suppressed due to the replacement of the Na⁺ by Ca²⁺, resulting in the enhanced relaxation behavior and the reduced P_r, the refined grain, and improved breakdown strength. Furthermore, an optimal recoverable energy storage density (W_rec) of 1.2 J/cm³ was achieved in 0.92Na_0.5Bi_0.5TiO₃–0.08CaHfO₃ ceramics under the breakdown strength of 140 kV/cm, which is mainly attributed to the resultant defect of Na⁺ vacancy_. Full article

In this study, we successfully obtained crystalline silicon from silica powder using a metal-induced crystallization method. For this purpose, powders were first prepared from organosilicon compounds and finely dispersed aluminum particles, then their metal-induced crystallization was carried out by annealing at the temperature of 570 °C. Powders of organosilicon compounds (tetraethoxysilane and polyethylhydrosiloxane) were prepared by different technological operations in order to determine precisely the presence of carbon in the product. The results showed that the presence of carbon in silica powder affects the production of crystalline silicon. In silica powders containing no carbon, the formation of crystalline substances does not occur at the annealing temperature of 570 °C. The results of this study are of great importance for the production of polycrystalline silicon powders obtained at reduced temperatures. Full article

Bone loss is a major burden for society and impacts people’s health all over the world. In a changing world looking toward a more conscious use of raw materials, efforts are being made to increasingly consider new promising biomaterials that account for, on one side, the ability to provide specific functional biological activities and, on the other, the feature of being well tolerated. In this regard, the use of phenolic compounds in the field of bone-related bioengineering shows a rising interest in the development of medical solutions aimed at taking advantage of the multiple beneficial properties of these plant molecules. In this work, the anti-bacterial and anti-inflammatory power of a biphasic calcium phosphate synthetic bone filler coated with a mixture of phenolic compounds was investigated by evaluating the minimal inhibitory concentration (MIC) value against Streptococcus mutans and Porphyromonas gingivalis and the expression of genes involved in inflammation and autophagy by real-time reverse transcription polymerase chain reaction (RT-qPCR) on J774a.1 murine macrophage cells. Results show a MIC of 0.8 μg/mL, a neat anti-inflammatory effect, and induction of autophagy key genes compared to a ceramic bone filler. In conclusion, functionalization with a polyphenol-rich extract confers to a ceramic bone filler anti-bacterial and anti-inflammatory properties. Full article

The ceramic Sr(NiNb)_0.5O₃, incorporating silver doping in the A site, was synthesized using a sol–gel route and subjected to comprehensive analysis through various experimental techniques. X-ray diffraction data analysis indicates a rhombohedral crystal structure. Scanning electron microscopy (SEM) examination reveals densely packed grains with minimal surface porosity. A thorough investigation of electrical properties, encompassing dielectric constant, loss tangent, electrical impedance, modulus, conductivity, etc., was conducted across a wide frequency range (10³–10⁶ Hz) and temperature range (260–340 K). This analysis provided valuable insights into structure–property relationships and conduction mechanisms. The discussion highlights the significance of interface effects, space charge polarization, and Maxwell–Wagner dielectric relaxation in achieving the material’s high dielectric constant at low frequencies and elevated temperatures. Examination of temperature dependence through Nyquist plots elucidates the contributions of grain behavior to the material’s resistive and capacitive properties. The dielectric permittivity, dissipation of energy, and electrical characteristics like impedance, modulus and conductivity are notably influenced by the frequency of the applied electric field and temperature. Overall, the material exhibits promising potential for industrial applications such as energy storage, given its intriguing properties. Full article

The study aimed to assess the effects of different surface conditionings on hybrid ceramics (HBC). Hydrofluoric acid was combined with a silane (HFA+S), low-level laser therapy activated Malachite green (LLLT-MG), Ho: YAG laser, and non-thermal plasma (NTP) as surface conditioning methods for HBC. Eighty-four HBC discs were prepared and divided into four groups according to surface conditioning methods. The total number of samples (n = 21) for each group was further split into two for the non-thermocycling and thermocycling subgroups. After surface treatment, all samples were examined to study the effect of color change and surface roughness. The shear bond strength (SBS) test of HBC was performed on thermo-cycled samples. Statistical analysis using ANOVA with Tukey post hoc was performed to observe any significant difference among tested groups, p > 0.05. The HFA+S and Ho: YAG surface-treated samples showed higher SBS than other surface-treated samples due to higher surface roughness. All surface conditioning methods, except NTP, induced noticeable color change, making them less suitable for aesthetical purposes in clinical settings. Overall, surface conditioning methods are critical in affecting shear bond strength through surface roughness and color change. Full article

Photocatalysis based on titanium dioxide (TiO₂) has become a promising method to remediate industrial and municipal effluents in an environmentally friendly manner. However, the efficiency of TiO₂ is hampered by problems such as rapid electron–hole recombination and limited solar spectrum absorption. Furthermore, the sensitization of TiO₂ through heterojunctions with other materials has gained attention. Vanadium, specifically in the form of ammonium vanadate ((NH₄)₂V₃O₈), has shown promise as a photocatalyst due to its ability to effectively absorb visible light. However, its use in photocatalysis remains limited. Herein, we present a novel synthesis method to produce lamellar (NH₄)₂V₃O₈ as a sensitizer in a supramolecular hybrid photocatalyst of TiO₂–stearic acid (SA), contributing to a deeper understanding of its structural and magnetic characteristics, expanding the range of visible light absorption, and improving the efficiency of photogenerated electron–hole separation. Materials, such as TiO₂–SA and (NH₄)₂V₃O₈, were synthesized and characterized. EPR studies of (NH₄)₂V₃O₈ demonstrated their orientation-dependent magnetic properties and, from measurements of the angular variation of g-values, suggest that the VO₂⁺ complexes are in axially distorted octahedral sites. The photocatalytic results indicate that the 2D/2D heterojunction layered TiO₂/vanadate at a ratio (1:0.050) removed 100% of the methylene blue, used as a model contaminant in this study. The study of the degradation mechanism of methylene blue emphasizes the role of reactive species such as hydroxyl radicals (^•OH) and superoxide ions (O₂^•−). These species are crucial for breaking down contaminant molecules, leading to their degradation. The band alignment between ammonium vanadate ((NH₄)₂V₃O₈) and TiO₂–SA, shows effective separation and charge transfer processes at their interface. Furthermore, the study confirms the chemical stability and recyclability of the TiO₂–SA/(NH₄)₂V₃O₈ photocatalyst, demonstrated that it could be used for multiple photocatalytic cycles without a significant loss of activity. This stability, combined with its ability to degrade organic pollutants under solar irradiation, means that the TiO₂–SA/(NH₄)₂V₃O₈ photocatalyst is a promising candidate for practical environmental remediation applications. Full article

This article presents a computational study of the influencing parameters on the solidification of the thermoplastic beryllium oxide slurry in an annular forming cavity. The main purpose of this paper is to study the effect of cooling and casting conditions on the solidification of the BeO suspension by considering the temperature-dependent rheological and physical properties. The results of calculations of the Bingham–Papanastasiou rheological model with experimental data in the intervals of phase transitions with different casting rates of beryllium ceramics have been validated. The use of the regularization parameter made it possible to approximate the flow of the slurry at all levels of its shear rates as highly viscous, followed by a continuous transition to a solid state. The speed of heat removal from the molding during the solidification period is determined by the speed of movement of the slurry and the temperature field on which the width of the transition region depends. The process of solidification of the slurry mass has been evaluated by changing its heat flow distribution and density along the length of the concentric channel. The obtained model calculation results make it possible to control the casting process and eventually realize a uniform structure of castings. Full article

Yttria stabilized zirconia materials are frequently used in mechanical engineering and biomedical applications. Demanding loading conditions require materials combining a high level of strength and fracture toughness. A ready-to-press alumina doped 2 mol% yttria-stabilized zirconia powder was shaped by axial pressing and sintering in air at 1250–1500 °C for 2 h. At 1350 °C the best combination of strength (1450 MPa) and toughness (7.8 MPa√m) was achieved. Materials sintered in the middle of the chosen temperature range combine full density, high transformability and small grain size. Toughness measurements by direct crack length measurements delivered unrealistically high fracture toughness values. Full article

This study investigates the impact of curing conditions, porosity and shaping techniques on the mechanical properties of metakaolin-based geopolymers. Geopolymers offer versatility in shaping, including 3D printing, yet the influence of curing conditions after printing on mechanical properties remains unclear. This is assessed by measuring the bending properties of 3D-printed metakaolin-based geopolymer filaments cured under varied humidity and temperature conditions. The influences of porosity and of shaping technique are observed by comparing the compression properties of molded and 3D-printed samples of various porosity. Samples cured at low humidity exhibit unusually high mechanical properties, which decrease when moved from a dry to a humid environment. This behavior may be due to the presence of PEG within the composition and/or to residual stresses due to the too rapid evacuation of water. High humidity is therefore necessary to ensure optimal curing and stable properties. Increasing the curing temperature helps accelerate geopolymerization without significantly compromising mechanical properties. Direct ink writing offers design flexibility and suitable porosity, but the samples appear to exhibit different failure mechanisms than the molded samples. Additional studies are necessary to understand the interactions between PEG and the geopolymer as well as to better identify the fracture mechanisms within the different samples. Full article

Rare earth (RE) aluminosilicate glasses exhibit several favorable chemical, mechanical and thermal properties. As such, they are considered to be model systems for long-half-life actinides and are candidate containment materials for long-term immobilization of radioactive wastes. The aim of the present study was to investigate the effect of the substitution of sodium oxide on the glass transition temperature and structure of lanthanum aluminosilicate glasses. The primary objective was to elucidate the relationship between the substitution of Na₂O for La₂O₃ on the Tg reduction and structural characteristics of lanthanum aluminosilicate glass, including identifying changes in the main Qn species and local environments of Si and Al. The structure of SiO₂–Al₂O₃–La₂O₃–Na₂O glasses has not been studied previously, and, thus, this investigation is the first to assess the structural changes occurring when La₂O₃ is substituted by Na₂O. Three glasses were prepared with general composition (mol.%): 55SiO₂–25Al₂O₃–20M₂O_n (M = La or Na; n = 3 or 1). Glass G1 contains 20 mol.% La₂O₃; in G2, 15 mol.% of La₂O₃ was substituted by 15 mol.% Na₂O; and Glass G3 contains 20 mol.% Na₂O. The glasses were characterized by DSC to determine glass transition temperatures. As expected, as Na is substituted for La, T_g decreases substantially. Structural studies were carried out by FTIR spectroscopy, ²⁹Si, and ²⁷Al MAS NMR. As Na is substituted for La in these aluminosilicate glasses, the main goals that were achieved were the identification of Qⁿ species and also changes in the local environments of Si and Al: {Qⁿ_Si(mAl)} and {Qⁿ_Al(mSi)}. Full article