Ceramics, Volume 9, Issue 2 (February 2026) – 19 articles

Spent fluid catalytic cracking catalysts (E-cat) are a challenging waste from the petroleum refining industry, enriched with heavy metals such as nickel, vanadium, and iron. This study proposes a circular valorization strategy by incorporating E-cat into a chemically bonded iron phosphate ceramic matrix, known for its excellent waste stabilization properties. Composites were synthesized at room temperature using E-cat, hematite, and phosphoric acid, with E-cat contents from 0% to 35%. Characterization by XRF, XRD, SEM, compressive strength, and water absorption tests identified an optimal formulation containing 16% E-cat, achieving a maximum compressive strength of 16.6 MPa, 35% higher than the control. This improvement can be attributed to the dual function of E-cat, acting both as a micro-aggregate that promotes matrix densification and as a pozzolanic component that enhances mechanical reinforcement. These results demonstrate that iron phosphate ceramics represent a low-energy and sustainable strategy for the immobilization of spent catalysts and the production of durable construction composites. Full article

This in vitro study investigated whether piranha solution treatment, applied alone or following sandblasting, enhances the shear bond strength of resin cement to zirconia. Fifty zirconia specimens were assigned to five groups: no treatment, sandblasting (SB), piranha solution (Pi), sandblasting followed by piranha solution treatment (SB + Pi), and double piranha treatment (Pi + Pi). Shear bond strength was measured after 24 h water storage, and failure modes were recorded. The SB + Pi group produced significantly higher bond strength than all other groups. Single treatments (SB, Pi, and Pi + Pi) yielded statistically comparable values, all exceeding the untreated control. Notably, double piranha application offered no benefit over a single application. These findings are preliminary and limited to short-term in vitro conditions; the piranha protocol is not feasible for direct clinical use due to safety constraints, and no aging or surface characterization data were obtained. Full article

To synergistically integrate piezoelectric and varistor functionalities in a single material, PNN-PZT piezoelectric powder (abbreviated as P) and ZnO-based varistor powder (abbreviated as Z) were utilized to fabricate PZT-ZnO composite ceramics (denoted as PZm) via conventional solid-state sintering. The P/Z molar ratio was regulated to 1/0.9, 1/1.05, 1/1.2, 1/1.35, and 1/1.5 to systematically study its influence on the phase composition, microstructure, and electrical properties of the composites. XRD, SEM, EDS characterization, and electrical performance tests were carried out. Results indicate that all PZm samples exhibit the biphasic coexistence of perovskite (piezoelectric phase) and wurtzite (varistor phase) without impurity phases, consisting of large perovskite grains with distinct edges and small wurtzite grains with smooth surfaces. The PZ3 sample (P/Z = 1/1.2) achieves optimal comprehensive properties: d₃₃ = 161 pC/N, k_p = 0.25, Ɛ_r = 2527, tan δ = 3.83%, E_1mA = 1396 V/mm, I_L = 8.2 mA, α = 22.06. This work confirms the synergistic optimization of piezoelectric and varistor properties in PZT-ZnO composites, providing a reliable experimental basis for the formulation design and performance regulation of multifunctional ceramics. Full article

Alumina-spinel refractory bricks, composed of 82 wt.% alumina and 18 wt.% MgAl₂O₄ spinel phases, are used in steel ladles due to their ability to resist chemical attack and thermal shock. Thermal shock resistance is determined, in part, by the thermal conductivity of the material. Thermal conductivity measurements for alumina-spinel refractory, three model alumina ceramics, and single crystal sapphire were made with the laser-flash technique from 20 °C to 1000 °C. At room temperature, these gave 6.5 W m⁻¹ K⁻¹ for the refractory, 5.8 to 22 W m⁻¹ K⁻¹ for the alumina ceramics, and 36 W m⁻¹ K⁻¹ for sapphire, despite all materials containing >81 vol.% of alumina. The differences are explained by the roles of porosity, grain boundary thermal resistance, and the spinel phase (refractory). In order to estimate the thermal conductivity of alumina grains in each material, these microstructural effects are modelled with Landauer’s relation for porosity and thermal resistors in series for grains combined with grain boundaries. For two alumina ceramics, the grains yielded similar behaviour to the single crystal. By taking the spinel phase into account with a two-phase mixture relation, the alumina grains in the refractory were estimated with a value of 31 ± 2 W m⁻¹ K⁻¹, close to sapphire. Full article

In response to the high stiffness and hardness levels of alumina ceramic materials, the traditional SHPB (split Hopkinson pressure bar) experimental setup has been modified. This study analyzes the propagation patterns of stress waves in the SHPB system after adding cushion blocks. Experiments demonstrated that the modified SHPB apparatus can effectively perform dynamic mechanical property tests on alumina ceramics. The JH-2 constitutive damage model parameters for alumina ceramics were determined based on theoretical analysis and static/dynamic experimental data. An LS-DYNA numerical model for the impact compression simulation of alumina ceramics was established to investigate the effects of stress waves with three wavelengths (300 mm, 400 mm, and 600 mm) at the same impact velocity, along with the dynamic fragmentation process. The results indicate that alumina ceramics exhibit strain rate hardening effects in compressive strength, failure strain, and elastic modulus under high strain rates; compressive strength and failure strain show positive correlations with stress wave wavelength under high strain rates; and microcracks initially nucleate preferentially along grain boundaries on the end surfaces, forming annular damage zones symmetrically about the central axis. This study presents a modified SHPB setup that improves test capability for high-hardness ceramics, rather than overturning classical methodologies. The absence of a direct comparison with unmodified setups stems from the known limitations of conventional systems in handling small-diameter alumina specimens without bar damage—a challenge addressed proactively in this work through impedance-matched cushion blocks and refined data processing. Full article

This work analyzes phase transformations in quaternary mixtures (clay–glass–hematite–waste activated sludge (WAS)), processed at 800–1000 °C under conditions of oxygen deficiency. The results of the study showed that, depending on the temperature treatment of mixtures of different compositions, the processes of carbon formation from WAS, carbon participation in reductive processes, and phase transformations in silicate subsystems occur simultaneously. After T_tr = 800 °C the main phases are fayalite and quartz, additional phases are wollastonite and feldspars. After T_tr = 900 °C the main phases are fayalite, quartz, wollastonite, and the additional phases are feldspars. After T_tr = 1000 °C the main phases are wollastonite, iron, quartz, additional phases are hematite, fayalite. Full article

High-purity Zr₃AlC₂ samples (>92 wt%) were synthesized and irradiated at room temperature using 100 keV He⁺ ions at fluences of 2 × 10¹⁶ and 1 × 10¹⁷ ions/cm². As a Zr-based MAX phase, Zr₃AlC₂ is a promising candidate for accident-tolerant fuel cladding due to its compatibility with Zr alloys and the low neutron absorption cross-section of Zr. Our results show that irradiation induces a decrease in the a-lattice parameter and an increase in the c-lattice parameter, along with the formation of anti-site defects and decomposition into ZrC. Cracks preferentially appear along (1000) planes. These findings suggest that Zr₃AlC₂ has limited structural stability under low-temperature helium irradiation. Full article

Longquan celadon represents the pinnacle of Chinese celadon, and there are many kilns in southern China that imitate Longquan celadon. During the Ming Dynasty, Jianyang Bowl Kiln was the representative kiln in Fujian Province for imitating Longquan celadon, while Jingdezhen Kiln was the representative kiln in Jiangxi Province for imitating Longquan celadon. The quality of both is close to that of Longquan celadon, making it difficult to distinguish by ordinary visual observation. This study focuses on Jianyang Bowl Kiln and Jingdezhen Kiln imitating Longquan celadon, comprehensively employing methods such as EDXRF, LA-ICP-MS, and chromaticity analysis to systematically investigate the similarities and differences in the composition of their body and glaze. The results indicate that distinct differences exist in the composition of trace and rare earth elements between the imitations of Longquan celadon produced by Jianyang Bowl Kiln and Jingdezhen Kiln, and authentic celadons from Longquan Kiln, which can serve as important criteria for distinguishing kilns. This provides systematic scientific data support for identifying the technological origins and production locations of Ming Dynasty imitations of Longquan celadon. Full article

The selective removal of radioactive cesium-137 and strontium-90 from high-salinity radioactive wastewater remains a critical challenge, as competing ions reduce adsorption efficiency and selectivity. In this study, high-performance granulated adsorbents were developed based on alkali-activated geopolymer matrices to enhance sorption performance. The adsorbents were synthesized by inorganic polymerization, and mechanically robust granules with controlled porosity and surface chemistry were obtained. Batch sorption experiments conducted in simulated seawater demonstrated greater than 99% removal efficiencies for cesium and strontium. Isotherm modeling confirmed high maximum sorption capacities (up to 0.41 meq/g for Cs⁺ and 5.07 meq/g for Sr²⁺). Continuous fixed-bed column tests demonstrated sustained removal efficiencies for the optimized adsorbents. Structural analyses, including scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and X-ray diffraction, confirmed uniform elemental distribution and crystalline phases consistent with selective sorption mechanisms. Assessment of mechanical strength revealed sufficient compressive strengths to ensure operational durability under hydraulic stress. These findings demonstrate that the synthesized geopolymer-based granules are a potentially effective and versatile solution for the comprehensive treatment of radioactive wastewater. Full article

Dielectric capacitors, characterized by ultra-fast charge/discharge speeds and high power densities, are widely used in modern electronic power systems. However, their low energy density and poor thermal stability limit applications. In this study, SrBi_3.25La_0.75Ti₄O₁₅ (SBLT) ferroelectric thin films were prepared by the sol–gel method. We systematically investigated the effect of annealing temperature on microstructural evolution, electrical properties, and energy storage performance. The SBLT film annealed at 700 °C exhibited optimal performance, achieving a balanced enhancement in polarization and breakdown strength, with an energy storage density of 48.66 J cm⁻³ and an efficiency of 78%. The material also demonstrated excellent thermal stability (30–175 °C) and frequency stability (0.1–100 kHz). These findings not only validate the potential of SBLT as a next-generation energy storage dielectric but also provide a practical solution for applications in semiconductor technology. Full article

Valorizing construction and demolition waste (CDW) via alkaline activation enables low-carbon binders. This study assesses binary geopolymers formulated with recycled brick powder (PLR) and recycled concrete powder (PCR) in seven precursor ratios (0–100% PCR), activated with a ternary NaOH/Na₂SiO₃/KOH solution (silicate modulus M_s ≈ 3.2) at L/B = 0.15, and cured for 7, 14, and 28 days. Compressive strength (fc), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) were used to link microstructure–phases–properties. A local maximum in fc at ~30% PCR (16.2 MPa at 28 d) was observed versus 0% PCR (14.2 MPa) and ≥50% PCR (13.8 → 10.1 MPa at 28 d). XRD indicated a reduction in inherited crystalline phases and an increased amorphous fraction at ~30% PCR; FTIR (normalized peak position and FWHM of the T–O–Si band, not absolute intensity) suggested higher network extension; SEM-EDS (local/semiquantitative) showed a moderate rise in Ca that supports C-A-S-H domains bridging the N-A-S-H network. At a high PCR, excess Ca simplified mineralogy (quartz/portlandite dominance), promoted competitive routes (C-S-H/carbonation), reintroduced microdefects, and reduced fc. A theoretical oxide balance per mix identified a compositional window where Ca/(Si + Al) ≈ 0.35–0.45 coincides with the mechanical optimum and with XRD/FTIR tracers. Overall, a ~30% PCR window maximizes co-reticulation of N-A-S-H/C-A-S-H and densification without compromising aluminosilicate continuity, providing transferrable design and process-control criteria for CDW-based geopolymer binders. Full article

As the operational demands on piezoelectric devices grow increasingly stringent, there is an urgent need for materials capable of delivering stable performance at elevated temperatures. BiFeO₃ (BF), a lead-free piezoelectric oxide with high-temperature resilience, is characterized by its notably high Curie temperature (T_c ∼ 835 °C), rendering it a promising candidate for high-temperature applications. However, its piezoelectric coefficients remain inadequate to satisfy practical requirements. The 0.7BiFeO₃-0.3Ba_(1-x) Sr_xTiO₃ system (abbreviated as BF-BS_xT) was designed to elucidate the roles of chemical disorder and local structural heterogeneities in the enhancement of functional properties through fine-tuning of the Sr content. The phase structure of the samples was carefully examined by X-ray diffraction. Rietveld refinement of the XRD data revealed that all BF-BS_xT ceramics consist of coexisting R and PC phases. Optimized compositional disorder and local heterogeneities led to a moderate enhancement in the piezoelectric coefficient d₃₃ value of 160 pC/N, a high T_c of 495 °C, and a remanent polarization P_r ≈ 22.1 μC/cm² -were achieved in the BF-BS_xT system at x = 0.06. These results indicate that BF-BS_xT ceramics hold good potential for use in high-temperature piezoelectric devices. Full article

The ceramics industry has long embraced the principles of the circular economy, with a strong focus on the reuse and recovery of raw materials essential to the production cycle. This approach reduces costs by reintroducing secondary raw materials—such as production scraps and recycled materials—into the manufacturing process after appropriate recovery treatments. This study aims to contribute to the transition of the ceramic industry toward a circular economy by incorporating industrial by-products into monoporosa ceramic bodies, thereby transforming waste materials into valuable resources. Monoporosa is a porous, single-fired ceramic wall tile characterized by a high carbonate content and low bulk density. However, the role of secondary raw materials in monoporosa formulations, as well as their influence on processing behavior (e.g., during sintering) and on key technological properties, is not yet fully understood. This work investigates a standard monoporosa formulation based on conventional raw materials (sand, calcite, feldspars, and clays) and compares it with new formulations in which industrial waste materials from local and national sources—originating from other industrial processes—are used as partial or total substitutes for some of the traditional raw materials, particularly sand and calcite. The industrial by-products examined include biomass bottom ash, foundry sand, and marble cutting and processing sludge. All materials were characterized using chemical–mineralogical, thermal, and morphological analyses and were incorporated into the ceramic bodies at different substitution levels (10%, 50%, and 100%) to replace natural raw materials. Their behavior within the mixtures was evaluated to determine ceramic suitability and acceptable replacement ratios. Furthermore, the effects of these additions on water absorption, thermal expansion coefficient, and microstructural characteristics were assessed. Based on the positive results obtained, this study demonstrates the feasibility of using, in particular, two secondary raw materials—foundry sand and marble sludge—in monoporosa body formulations, allowing for the complete replacement of the original raw materials and thereby contributing to the development of more sustainable ceramic compositions. Full article

In additive manufacturing technologies, the use of pastes and inks based on materials such as clay to create three-dimensional objects layer by layer has opened new possibilities in fields such as engineering and biomedicine. This review article aims to provide a comprehensive understanding of 3D printing of ceramic pastes through Direct Ink Writing (DIW), also referred to as Robocasting. DIW offers specific advantages for ceramic 3D printing, including the ability to extrude highly loaded pastes with customized rheological properties to accommodate a broad spectrum of ceramic compositions, varying from conventional clays to advanced ceramics. It is characterized by filament deposition control, which facilitates the fabrication of complex, porous, or customized architectures while simultaneously minimizing material waste. Through a bibliometric analysis of the literature published between 2020 and 2024, the most relevant studies regarding printing system architectures, ceramic paste formulations, and adjustment of parameters to obtain high-quality parts were identified. This work presents relevant and accurate explanations of the DIW technology, supporting researchers and industry professionals seeking to initiate or improve ceramic 3D printing processes for a wide range of applications. Full article

Bismuth layer-structured ferroelectrics (BLSFs) are core candidates for high-temperature piezoelectric applications owing to their excellent thermal stability and fatigue resistance, yet traditional Bi₄Ti₃O₁₂ (BiT)-based ceramics suffer from limited piezoelectric performance. To address this, MBi₄Ti₄O₁₅-Bi₄Ti₃O₁₂ (M=Ba, Sr, Ca) symbiotic structure bismuth-layered piezoelectric ceramics were fabricated via the conventional solid-state reaction method. Their crystal structure, microstructure, and electrical properties were systematically characterized using a X-ray diffractometer, scanning electron microscope, high-temperature dielectric spectrometer, and quasi-static d₃₃ meter to explore the effects of different A-site divalent elements. Results show that all samples form a pure-phase symbiotic structure with the P2₁am space group, without secondary phases. The lattice constant decreases with increasing A-site ionic radius, while symbiosis-induced lattice mismatch and long-range disorder refine grains, reduce aspect ratio, lower conductivity, enhance spontaneous polarization, and improve piezoelectric properties. The ceramics exhibit d₃₃ of 10 to 15 pC/N and T_C of 502 to 685 °C, with SrBi₄Ti₄O₁₅-Bi₄Ti₃O₁₂ showing optimal comprehensive performance (d₃₃ ≈ 15 pC/N, T_C = 593 °C, tanδ = 0.6% at 1 kHz/475–575 °C, and a low AC conductivity of 5.3 × 10⁻⁵~4.8 × 10⁻⁴ S/m). This study improves bismuth-layered ceramics’ performance via A-site regulation and symbiotic structure design, offering theoretical and technical support for high-performance lead-free high-temperature piezoelectric ceramics. Full article

Alumina ceramics used in semiconductor plasma environments require high densification, microstructural homogeneity, and stable performance under increasingly aggressive processing conditions. However, systematic studies linking slurry processing parameters to the plasma resistance of alumina ceramics remain limited. In this study, the effects of slurry preparation parameters—specifically milling and aging—and sintering atmosphere on the densification, mechanical strength, and plasma etching resistance of slip-cast alumina ceramics were systematically investigated. Optimal dispersion stability was achieved under 12 h milling and 12–24 h aging conditions, resulting in homogenized green body packing and a high relative sintered density exceeding 99%. Mechanical strength and plasma resistance were strongly influenced by slurry aging and sintering atmosphere. Specimens aged for 48 h and sintered under a low oxygen partial pressure (N₂ at 1.0 L/min) exhibited the highest flexural strength and significantly improved resistance to SF₆/Ar plasma etching, with reduced etch depth and suppressed surface roughening. These results demonstrate that coordinated slurry processing and sintering atmosphere control is an effective strategy for designing high-reliability, plasma-resistant alumina ceramics for high-demand semiconductor manufacturing environments. Full article

Archaeological research on Santiago Island (Cape Verde) offers a strategic framework for investigating ceramic material culture shaped by Iberian and African interactions during the early modern period. This study presents first-stage results from a non-destructive archaeometric analysis of pottery fragments recovered from early colonial sites and curated at the Museu de Arqueologia in Praia. Using portable X-ray fluorescence spectroscopy (pXRF), low-fired, handmade vessels associated with African technological traditions were analysed to determine their elemental composition and potential provenance. The work also focused on sugar moulds, containers used in the refining of this product, one of the most important in Atlantic colonisation. The resulting geochemical data is compared with established reference groups from the Iberian Peninsula, Atlantic Africa, and Macaronesia. Elemental variability indicates the use of diverse clay sources and production techniques, reflecting hybrid technological practices shaped by cultural interaction and provisioning constraints. These results contribute to ongoing research within the CERIBAM (Iberian Atlantic Expansion in North Africa and Macaronesia) and Palarq-funded projects, which aim to reconstruct early colonial ceramic networks and sociotechnical dynamics. By integrating archaeometric data with archaeological and historical perspectives, this study aims to demonstrate the utility of non-invasive analytical protocols for understanding ceramic technology, intercultural exchange, and Atlantic material connectivity in early Creole formations while preserving the integrity of the collections. Full article

Boro-antimonite glasses doped with Eu³⁺ and having the general composition (90-x) Sb₂O₃–xB₂O₃–10Li₂O-0.5Eu₂O₃ (x = 0 to 60 in 10 mol. % increment) were prepared using the melt quenching method. The influence of B₂O₃/Sb₂O₃ substitution on the spectroscopy and photoluminescence of Eu³⁺ ions was analyzed by studying the measured and calculated properties of these glasses. The relative value of a given property was shown to increase or decrease by up to 26% with the addition of up to 60 mol. % B₂O₃, while the number of Eu³⁺ ions per unit volume increased by approximately 32%. Strong emissions were obtained in association with the transitions of Eu³⁺ (⁵D₀→⁷F_j, j = 1–4). A weak, broad emission centered at 450 nm was also detected. This emission is clearly linked to the glass composition. It originates from a potential presence of Eu²⁺ ions. This enhances ⁵D₀ level emission via charge transfer. The radiative and experimental lifetimes of the ⁵D₀ level increase linearly with B₂O₃ content. This results in high quantum efficiency (η) ranging from 74 to nearly 84%. Tunable chromaticity, as defined by the CIE 1931 standard, was achieved, resulting in a warm orange-red color with high brightness. These new glasses have a variety of potential laser-related applications. Full article

Digital Light Processing (DLP), which operates through a layer-by-layer deposition, has proven to be a promising technique for obtaining complex and customized architectures. However, there are still numerous unresolved challenges in ceramics additive manufacturing, among which is delamination due to suboptimal adhesion between the layers, which threatens the structural integrity and properties of samples. According to recent findings, excess surface hydroxyl groups were identified as being responsible for this defect; a suitable calcination pre-treatment of the ceramic powder could be effective in significantly mitigating delamination flaws in mullite DLP printed bodies. Therefore, in addition to optimizing the printable slurry formulation and printing parameters (mainly in terms of curing energy and layer resolution), this work aimed at investigating the influence of the calcination of a commercial mullite powder (added with magnesium nitrate hexahydrate, as a precursor of the sintering aid MgO) as a simple and effective treatment to additively shape ceramic bodies with limited flaws and enhanced density. The surface characteristics evolution of the mullite powder was investigated, specifically comparing samples after magnesium nitrate hexahydrate addition and ball-milling in water (labeled as BM), and after an additional calcination (BMC). In particular, the effect of the superficial -OH groups detected by FTIR analysis in the BM powder, but not in the BMC sample, was studied and correlated to the properties of the respective ceramic slurry in terms of rheological behavior and curing depth. The hydrophilicity of BM powders, due to superficial hydroxyls groups, affects ceramic powder dispersion and wettability by the resin, causing a weak interface. At the same time, it promotes photopolymerization of the light-sensitive resin, thus inducing the as-printed matrix embrittlement. Anyhow, its photopolymerization degree, equal to 67% and 55% for BM and BMC, respectively, was enough to guarantee the printability of both slurries. However, the use of BMC significantly reduced flaw occurrence in the as-printed bodies and the final density of the samples sintered at 1450 °C (without an isothermal step) was increased (approx. 60% and 50% of the theoretical value for BMC and BM, respectively). Thus, the target porosity of the ceramic bodies was guaranteed, and their structural integrity achieved without any increase in sintering temperature but with a simple powder treatment. Full article