Ceramics

Background: Maxillomandibular bone defects present a complex challenge in regenerative medicine due to anatomical and functional intricacies. Calcium phosphate (CP)-based biomaterials have emerged as promising bone graft substitutes due to their biocompatibility, osteoconductivity, and bioactivity. Aim: This Review highlights recent clinical and experimental advancements in CP-based biomaterials for maxillomandibular bone regeneration, bridging the gap from bench to bedside. Method: An in vitro, in vivo, and clinical literature review was conducted to evaluate the performance of CP ceramics, including hydroxyapatite (HA), tricalcium phosphate (TCP), biphasic ceramics, and novel composites with polymers, growth factors, and nanoparticles. Results: Calcium phosphate-based biomaterials demonstrate excellent bone regeneration potential, with Beta-tricalcium phosphate (β-TCP) and HA being the most widely utilized. Composite scaffolds and 3-dimensional (3D)-printed constructs show enhanced mechanical properties and biological integration. Clinical trials have confirmed the safety and efficacy of CP-based materials, yielding promising outcomes in osteoconduction and defect healing. However, limitations persist regarding mechanical strength and long-term degradation profiles. Conclusions: CP-based biomaterials offer significant clinical promise for maxillomandibular bone regeneration. Continued advancements in scaffold design and biofunctionalization are crucial for overcoming current limitations and fully realizing their therapeutic potential. Full article

NiO-based hole-transport layers are crucial for high-efficiency perovskite solar cells. An industrial deposition method of NiO films is magnetron sputtering using ceramic targets. NiO targets doped with Li contents at 1%, 3%, and 5% were designed, and the doping contents and sintering temperatures were investigated. All the targets have a face-centered cubic phase, dense microstructure, and an average size of a few microns. The NLO targets sintered at an optimal temperature of 1400 °C exhibited high relative density (>98%) and low resistivity (<6 Ω∙cm). These results pave the way for depositing NiO-based hole-transport layer by magnetron sputtering. Full article

This work presents a comprehensive study on the synthesis and application of Al₂O₃ fibers derived from an ammonium aluminum carbonate hydroxide (AACH) precursor. Through a hydrothermal route, the influence of critical synthesis parameters, including aluminum nitrate and urea concentrations, reaction temperature and time, and stirring conditions, on fiber morphology and aspect ratio was systematically investigated. The as-synthesized AACH fibers were subsequently converted into thermodynamically stable α-alumina fibers via controlled annealing. These high-aspect ratio alumina fibers were incorporated into polydimethylsiloxane (PDMS) to produce electrically insulating, thermally conductive composites. The thermal performance of fiber-filled composites was benchmarked against that of particle-filled counterparts, with the former exhibiting significantly enhanced thermal conductivity. Furthermore, the dielectrophoretic alignment of alumina fibers led to an additional increase in thermal conductivity, underlining the importance of high-aspect ratio fillers. This study uniquely combines the controlled synthesis of alumina fibers with their incorporation and alignment in a polymer matrix, presenting a novel and effective approach for engineering anisotropic, thermally conductive, and electrically insulating composite materials. Dielectrophoretic alignment of α-Al₂O₃ fibers synthesized through optimized hydrothermal conditions and incorporated into PDMS composites deliver over 95 % higher thermal conductivity than spherical fillers. Full article

Barium strontium titanates (Ba_1−xSr_xTiO₃, BST) with varying barium-to-strontium ratios were synthesized by the solid-state route (SSR) as well as by the sol–gel process (SGP). In the case of the SSR, the strontium amount x was varied from 0.0 to 0.25 in 0.05 steps, due to the enhanced synthetic effort, and in the case of the SGP, x was set only to 0.05, 0.15, and 0.25. The resulting properties after synthesis, calcination, and sintering, like particle size distribution, specific surface area, particle morphology, and crystalline phase were characterized. The expected tetragonal phase, free from any remarkable impurity, was found in all cases, and irrespective of the selected synthesis method. Pressed pellets were used for the measurement of the temperature and frequency-dependent relative permittivity enabling the estimation of the Curie temperatures of all synthesized BSTs. Irrespective of the selected synthesis method, the obtained Curie temperature drops with increasing strontium content to almost identical values, e.g., in the case of x = 0.15, a Curie temperature range 95–105 °C was measured. Thin BST films could be deposited on different substrate materials applying electrophoretic deposition in a good and reliable quality according to the Hamaker equation. The properties of the BSTs obtained by the simpler solid-state route are almost identical to the ones yielded by the more complex sol–gel process. In future, this result allows for a possible wider usage of BST perovskites for ferroelectric and piezoelectric devices due to the easy synthetic access by the solid-state route. Full article

We synthesized the current evidence from the literature and conducted a 2 × 3 factorial experiment to quantify the impact of thermocycling on the Vickers microhardness (HV) of dental CAD/CAM materials: VITA ENAMIC (VE, polymer-infiltrated ceramic network) and CERASMART (CS, nanofilled resin-matrix). Sixty polished specimens (n = 10 per Material × Cycles cell; 12 × 2 × 2 mm) were thermocycled at 5–55 °C (0, 10,000, 20,000 cycles; 30 s dwell, ≈10 s transfer) and tested as HV0.3/10 (300 gf, 10 s; five indentations/specimen with standard spacing). Assumptions regarding the model residuals were met (Shapiro–Wilk W ≈ 0.98, p ≈ 0.36; Levene F(5,54) ≈ 1.12, p ≈ 0.36), so a two-way ANOVA (Type II) with Tukey’s HSD post hoc (α = 0.05) was applied. VE maintained consistently higher HV than CS at all cycle levels and showed a smaller drop from baseline: VE (mean ± SD): 200.2 ± 10.8 (0), 192.4 ± 13.9 (10,000), and 196.7 ± 9.3 (20,000); CS: 60.8 ± 6.1 (0), 53.4 ± 4.7 (10,000), and 62.1 ± 3.8 (20,000). ANOVA revealed significant main effects from the material (η²p = 0.972) and cycles (η²p = 0.316), plus a Material × Cycles interaction (η²p = 0.201). Results: Thermocycling produced material-dependent changes in microhardness. Relative to baseline, VE varied by −3.9% (10,000) and −1.7% (20,000), while CS varied by −12.2% (10,000) and +2.1% (20,000); from 10,000→20,000 cycles, microhardness recovered by +2.2% (VE) and +16.3% (CS). Pairwise comparisons were consistent with these trends (CS decreased at 10,000 vs. 0 and recovered at 20,000; VE only showed a modest change). Conclusions: Thermocycling effects were material-dependent, with smaller losses and better retention in VE (PICN) than in CS. These results align with the literature (resin-matrix/hybrids are more sensitive to thermal aging; polished finishes mitigate losses). While HV is only one facet of performance, the superior retention observed in PICN under thermal challenge suggests the improved preservation of superficial integrity; standardized reporting of aging parameters and integration with wear, fatigue, and adhesion outcomes are recommended to inform indications and longevity. Full article

This study reports the development of electrospun poly(methyl methacrylate) (PMMA) fiber mats incorporating ibuprofen (IBU)-intercalated layered double hydroxides (LDH) for enhanced transdermal drug delivery systems (TDDS). IBU, in its anionic form, was successfully intercalated into LDH, which possesses anion exchange capabilities, and subsequently embedded into PMMA fibers via electrospinning. In vitro drug release experiments demonstrated that UPMMA–LDH–IBU fibers exhibited significantly higher IBU release than PMMA–IBU controls. This enhancement was attributed to the improved hydrophilicity and water absorption imparted by the LDH, as confirmed by contact angle and water uptake measurements. Furthermore, artificial skin permeation tests revealed that the UPMMA–LDH–IBU fibers maintained comparable release rates to those observed during buffer immersion, indicating that the rate-limiting step was the diffusion of IBU within the fiber matrix rather than the interface with the skin or buffer. These findings highlight the critical role of LDH in modulating drug release behavior and suggest that UPMMA–LDH–IBU electrospun fiber mats offer a promising and efficient platform for advanced TDDS applications. Full article

This study investigated the effect of piranha solution etching duration on the shear bond strength of zirconia ceramics bonded to resin cement, comparing it to conventional sandblasting treatment. Fifty fully sintered zirconia specimens (6.0 mm diameter, 4.0 mm thickness) were prepared and randomly divided into five groups (n = 10): sandblasting control and piranha solution treatment for 1, 2, 3, and 4 min. Piranha solution was prepared by mixing 98% H₂SO₄ and 35% H₂O₂ in a 3:1 ratio. All specimens were bonded to resin composite cylinders using dual-cure resin cement. Shear bond strength testing was performed using a universal testing machine at a 0.5 mm/min crosshead speed. Failure modes were analyzed using a stereomicroscope and classified as adhesive, cohesive, or mixed failures. One-way ANOVA revealed significant differences between groups (p < 0.05). Tukey’s post hoc test showed that 1-min piranha treatment produced significantly lower bond strength (7.64 ± 2.02 MPa) compared to all other groups. The 2-min (15.17 ± 2.79 MPa), 3-min (14.99 ± 3.27 MPa), and 4-min (18.34 ± 3.15 MPa) piranha treatments showed no significant differences compared to sandblasting (15.41 ± 2.61 MPa). Failure mode analysis revealed 100% adhesive failures for the 1-min group, while all other groups showed 80% adhesive and 20% mixed failures. Piranha solution treatment duration significantly affected zirconia bonding performance. While 1-min treatment proved inadequate, 2–4 min treatments achieved bond strengths comparable to sandblasting. The findings suggest that piranha solution treatment for 2–4 min represents a viable alternative to sandblasting for zirconia surface preparation, with the 2-min protocol being the most efficient choice for clinical application. Full article

Translucency and color stability are key factors for the long-term success of dental ceramics. The aim was to compare the translucency parameter (TP) and color stability (ΔE) of CAD/CAM ceramics, including a lithium disilicate (E; IPS e.max CAD), a zirconia-reinforced lithium-silicate (S; VitaSuprinity), and a zirconia-based ceramic (Z; Ceramill Zolid HT+), before and after low-grade hydrothermal aging (134 °C and 2 bars for 20 h). Ninety disks (n = 30/group, A2, 1.2 ± 0.02 mm) were fabricated and their L*, a*, and b* values were recorded against black and white backgrounds to calculate TP, contrast ratio (CR), and opacity (OP). ANOVA, Bonferroni post hoc, and paired t-tests (α = 0.05) showed that after aging, the Z group showed ↓L and ↑a values; the E group showed ↓L with ↑ a and b; and the S group showed only ↑a. All ceramics exhibited ΔE values below the clinical acceptability threshold of 3.7. E presented the highest TP, whereas Z demonstrated the highest CR and masking ability. Aging significantly increased CR and OP but did not alter TP. Within the limitations of this study, all tested ceramics maintained clinically acceptable shade stability and translucency, with E showing superior initial translucency and Z offering improved masking potential. Full article

In this paper, 316 stainless steel/TiC coatings with different LaB₆ contents (0%, 2%, 4%, 6%) were prepared on the surface of 45 steel by laser cladding technology. The effects of the LaB₆ content on the phase composition, microstructure, microhardness, and wear resistance of the coatings were studied. The results show that without the LaB₆ addition, the coating is composed of Austenite and TiC phases, with defects such as pores and cracks, and the microstructure is mainly equiaxed grains. With the addition of LaB₆, Fe-Cr phases are formed in the coating, and the microstructure transforms into columnar grains and dendritic grains. The grains are first refined and then coarsened, among which the coating with 4% LaB₆ (C4) has the smallest grain size. The experimental results indicate that the microhardness of the coatings first increases and then decreases with the increase in the LaB₆ content, and the C4 coating has the highest microhardness (594HV_0.2). The wear rate shows the same variation trend. The C4 coating has the lowest wear rate and the best wear resistance. This is attributed to the synergistic effect of the fine grain strengthening and TiC particle dispersion strengthening. Full article

The mass transfer phenomenon of contained impurities causes differences in the morphologies, densification processes, and heat resistance of ceramics. Of these, in this paper, differences in the heat resistance of ceramic fibers are discussed. Third-generation SiC polycrystalline fibers demonstrated excellent heat resistance. However, at temperatures above 1800 °C, sintered fiber (Tyranno SA) and non-sintered fiber (Hi-Nicalon Type S) showed remarkable differences in heat resistance. At temperatures above 1800 °C, the non-sintered fiber underwent structural changes, including the formation of a surface carbon layer and abnormal SiC grain growth, whereas the sintered fiber maintained its stable polycrystalline structure. Until now, these differences and a detailed description of them have not been discussed. Here, we first explain the dramatic differences in heat resistance that occurred at high temperatures in relation to the mass transfer of excess carbon. Our findings should be widely used for the development of much more stable structures and for the long-term use of materials at higher temperatures in applications such as airplane engines and turbines. Full article

Binary oxide ceramics have emerged as key materials in solar energy research due to their versatility, chemical stability, and tunable electronic properties. This study presents a comparative analysis of seven prominent oxides (TiO₂, ZnO, Al₂O₃, SiO₂, CeO₂, Fe₂O₃, and WO₃), focusing on their functional roles in silicon, perovskite, dye-sensitized, and thin-film solar cells. A bibliometric analysis covering over 50,000 publications highlights TiO₂ and ZnO as the most widely studied materials, serving as electron transport layers, antireflective coatings, and buffer layers. Al₂O₃ and SiO₂ demonstrate highly specialized applications in surface passivation and interface engineering, while CeO₂ offers UV-blocking capability and Fe₂O₃ shows potential as an absorber material in photoelectrochemical systems. WO₃ is noted for its multifunctionality and suitability for scalable, high-rate processing. Together, these findings suggest that binary oxide ceramics are poised to transition from supporting roles to essential components of stable, efficient, and environmentally safer next-generation solar cells. Full article

Zirconia is widely used in prosthodontics due to its excellent biocompatibility, mechanical properties, and esthetic characteristics. This article reviews the fundamentals of sintering zirconia for prosthodontic applications. Various sintering techniques, including conventional, spark plasma, high-speed, and microwave sintering, are discussed regarding their influence on translucency, strength, and microstructure. This review aims to provide a comprehensive reference for the sintering methods of zirconia currently used or may be used for dental prosthodontics. Full article

Due to its good thermal conductivity and small thermal expansion coefficient, aluminum nitride (AlN) is an excellent material for thermal shock resistance. Recently, carbon (C) doping has emerged as a potential strategy for tailoring the properties of AlN, but its effects on the mechanical properties and thermal conductivity of AlN remain unclear. In the present study, the mechanical properties and thermal conductivity of C-doped AlN (C@AlN) with various C-doping densities were investigated using first-principles calculations based on density functional theory. The results suggest that C doping often leads to an increase in the c lattice constant. When the C-doping concentration reaches 12.5%, the structural symmetry of 4C@AlN is fully broken. In addition, as the C-doping density increases, the strength and stiffness of C@AlN generally decrease while the ductility increases. Moreover, the thermal conductivity of C@AlN generally decreases as the C-doping density increases, mainly because of the structural distortion. Meanwhile, as the C-doping density reaches 12.5%, the thermal conductivity of 4C@AlN anomalously increases, due to the symmetry breakage. Full article

In line with circular economy principles and the reduction of primary material exploitation, waste-to-energy (WtE) by-products such as bottom ash (BA) are increasingly being used as raw materials in cement and ceramics manufacturing. However, it is critical to verify that the final product presents not only adequate technical properties but also that it does not pose negative impacts to the environment and human health during its use. This study investigates the environmental compatibility of the use of ceramic porcelain stoneware tiles manufactured with BA as partial replacement of traditional raw materials, with a particular focus on the leaching behavior of the tiles during their use, and also after crushing to simulate their characteristics at their end of life. To evaluate the latter aspect, compliance leaching tests were performed on crushed samples and compared with Italian End-of-Waste (EoW) thresholds for the use of construction and demolition waste as recycled aggregates. Whereas, to assess the environmental compatibility of the tiles during the utilization phase, a methodology based on the application of monolithic leaching tests to intact tiles, and the evaluation of the results through multi-scenario human health risk assessment and the analysis of the main mechanisms governing leaching at different stages, was employed. The results of the study indicate that the analyzed BA-based tiles showed no significant increase in the release of potential contaminants compared to traditional formulations and fully complied with End-of-Waste criteria. The results of the monolith tests used as input for site-specific risk assessment, simulating worst-case scenarios involving the potential contamination of the groundwater, indicated negligible risks to human health for both types of tiles, even considering very conservative assumptions. As for differences in the release mechanisms, tiles containing BA exhibited a shift toward depletion-controlled leaching and some differences in early element release compared to the ones with a traditional formulation. Full article

The stability of ceramic suspensions is a key factor in the preparation and shaping of ceramic bodies. The presented work offers an experimental determination of ceramics suspensions stability using the LUMiSizer analytical centrifuge, focusing on kinetic behaviour using transmission profiles and instability indexes. Multiple ceramic systems comprising corundum, metakaolin, and zirconia suspensions were experimentally examined under varying solid contents, dispersant dosages, and additive concentrations. Results showed that highly loaded corundum suspensions with dispersant (Dolapix CE64) achieved excellent stability, with an instability index below 0.05. Compared to classical sedimentation tests, which are time-consuming and not highly sensitive, LUMiSizer offers a suitable alternative by guaranteeing correct kinetic data and instability indexes indicating suspension behaviour using centrifugal force. Comparisons of the LUMiSizer results and data obtained using the modified Stokes law confirmed increased terminal velocities in experiments with metakaolin suspensions, indicating the sensitivity of the centrifuge to the effect of dispersion medium shape. The influence of porogen (waste coffee grounds) on the stability of corundum suspensions was also investigated, followed by slip casting to create and characterize a ceramic body, confirming the possibility of shaping based on stability results. Furthermore, instability indices are suggested as a rapid, quantitative method for comparing system stability and as an auxiliary criterion to the rheological measurements. Optimal dispersant concentration for zirconia-based photocurable suspensions was identified as 8.5 wt.%, which minimized viscosity and, at the same time, assured maximal kinetic stability. Integrating the LUMiSizer analytical centrifuge with standard methods, including sedimentation tests and rheological measurements, highlights its value as a powerful tool for characterizing and optimizing ceramic suspensions. Full article

The study of the relationship between the composition and mechanical properties of structural ceramics based on zirconium, magnesium and aluminum oxides is an important scientific and technological task. In this study, ceramics of the composition x·ZrO₂-(90−x)·MgO-10·Al₂O₃ (x = 10–80 wt.%) were obtained using standard ceramic technology. XRD, SEM, Vickers hardness and biaxial flexural strength measurements were performed to determine the effect of concentration x on the phase composition, microstructure and mechanical characteristics of the sintered samples. The results show that with an increase in the starting concentration x in experimental samples, the fraction of the stabilized ZrO₂ phase grows, and the grain size decreases. These two factors determine the values of microhardness and biaxial bending strength. Experimental investigation on the ternary oxide ceramics shows that for ceramics sintered at 1500 °C, the microhardness values varied within the range of 815–1300 HV1 and the biaxial bending strength of 110–250 MPa. Full article

Metal–organic frameworks (MOFs) are promising materials for drug delivery due to their structural tunability and high surface area. This work reports on the synthesis of ZIF-8 for the in situ encapsulation of hesperidin, a flavonoid with poor water solubility used in the treatment of circulatory system disorders, as a gastric-targeted drug delivery system (DDS). A 2³ full factorial design was used to optimize drug loading, investigating the effects of DMSO concentration, 2-MIm/Zn²⁺ molar ratio, and final solution volume (water content). The materials were characterized by ATR-FT-IR, TG, XRD, and SEM analyses, confirming successful ZIF-8 synthesis and partial hesperidin encapsulation. Drug release kinetics were evaluated at pH 1.0 and 6.86. The system showed a faster and more pronounced release at pH 1.0, driven by MOF degradation, demonstrating its potential as a gastric-targeted DDS. This study confirms the feasibility of ZIF-8 to improve hesperidin solubility and bioavailability, highlighting a novel strategy for its therapeutic application. Full article

(Y_xGd_3−x)(Al_yGa_5−y)O₁₂:Ce and (Lu_xGd_3−x)(Al_yGa_5−y)O₁₂:Ce ceramics were synthesized for the first time by direct exposure of a powerful electron flux to a mixture of the corresponding oxide components. Five-component ceramics were obtained from oxide powders of Y₂O₃, Lu₂O₃, Gd₂O₃, Al₂O₃, Ga₂O₃, and Ce₂O₃ in less than 1 s, without the use of any additional reagents or process stimulants. The average productivity of the synthesis process was approximately 5 g/s. The reaction yield, defined as the mass ratio of the synthesized ceramic to the initial mixture, ranged from 94% to 99%. The synthesized ceramics exhibit photoluminescence when excited by radiation in the 340–450 nm spectral range. The position of the luminescence bands depends on the specific composition, with the emission maxima located within the 525–560 nm range. It is suggested that under high radiation power density, the element exchange rate between the particles of the initial materials is governed by the formation of an ion–electron plasma. Full article

Porous acicular mullite was fabricated at 1300 °C starting from Al₂O₃ and mixture of SiO₂ and MoO₃ obtained by previous oxidation of waste MoSi₂. It was found that the presence of MoO₃ favors formation of acicular (prism-like) mullite grains with sharp edges. The effect of addition of Fe₂O₃ (4–12 wt.%) on phase composition, compressive strength, thermal conductivity and microstructure was studied. The addition of Fe₂O₃ improved the compressive strength from approximately 25 MPa in pure mullite to about 76 MPa in samples containing 12 wt.% Fe₂O₃, while the open porosity decreased from 55.4% to 51.8%. The presence of Fe₂O₃ caused a decrease in mullite formation temperature owing to the formation of liquid phase and accelerated diffusion. The solubility of iron oxide in mullite lattice was between 8 and 12 wt.% Fe₂O₃. The incorporated iron ions also promoted the rounding of sharp edges in prismatic mullite grains, leading to a reduced specific surface area of 0.55 m²/g in the sample with 12 wt.% Fe₂O₃. The thermal conductivity of mullite increased with addition of 12 wt.% Fe₂O₃ reaching value of 1.17 W/m·K. Full article