Search Results (592)

Background: This study investigated a new multi-acid-etching formulation for zirconia ceramics, containing hydrochloric, hydrofluoric, nitric, orthophosphoric, and sulfuric acids. The solution was tested on polycrystalline (5Y-TZP zirconia), lithium disilicate, hybrid ceramic, and feldspathic porcelain to assess compatibility, etching selectivity, and surface conditioning. Methods: Two-hundred-and-forty CAD/CAM specimens were etched for 20 s, 60 s, 30 min, or 1 h, and their surface roughness and etching patterns ware evaluated using 3D optical profilometry and scanning electron microscopy (SEM). Results: A positive correlation was observed between etching time and surface roughness (Ra values). The most pronounced changes were observed in lithium disilicate and feldspathic porcelain, with Ra values increasing from 0.733 ± 0.082 µm (Group 5) to 1.295 ± 0.123 µm (Group 8), and from 0.902 ± 0.102 µm (Group 13) to 1.480 ± 0.096 µm (Group 16), respectively. Zirconia increased from 0.181 ± 0.043 µm (Group 1) to 0.371 ± 0.074 µm (Group 4), and the hybrid ceramic from 0.053 ± 0.008 µm (Group 9) to 0.099 ± 0.016 µm (Group 12). Two-way ANOVA revealed significant effects of material and etching time, as well as a significant interaction between the two factors (p < 0.001). SEM observation revealed non-selective etching pattern for the lithium disilicate groups, indicating a risk of over-etching. Conclusions: The tested etching solution increased surface roughness, especially for the lithium disilicate and feldspathic porcelain specimens. In zirconia, one-hour etching improved surface characteristics with minimal observable damage. However, additional studies are necessary to validate the mechanical stability and bond effectives of this approach. Full article

Tissue-engineered scaffolds, particularly composite scaffolds composed of polymers combined with ceramics, bioactive glasses, or nanomaterials, play a vital role in regenerative medicine by providing structural and biological support for tissue repair. As scaffold designs grow increasingly complex, the need for non-invasive imaging modalities capable of monitoring scaffold integration, degradation, and tissue regeneration in real-time has become critical. This review summarizes current non-invasive imaging techniques used to evaluate tissue-engineered constructs, including optical methods such as near-infrared fluorescence imaging (NIR), optical coherence tomography (OCT), and photoacoustic imaging (PAI); magnetic resonance imaging (MRI); X-ray-based approaches like computed tomography (CT); and ultrasound-based modalities. It discusses the unique advantages and limitations of each modality. Finally, the review identifies major challenges—including limited imaging depth, resolution trade-offs, and regulatory hurdles—and proposes future directions to enhance translational readiness and clinical adoption of imaging-guided tissue engineering (TE). Emerging prospects such as multimodal platforms and artificial intelligence (AI) assisted image analysis hold promise for improving precision, scalability, and clinical relevance in scaffold monitoring. Full article

Fine-grained Yb:Y₂O₃ laser ceramics with excellent transmittance and thermal conductivity were fabricated from commercial powders. The process involved aqueous colloidal forming, additive-free air pre-sintering at 1400 °C, and hot isostatic pressing at 1550 °C. Suspensions were prepared with a deionization process to alleviate the hydrolysis issue, which optimizes the microstructure uniformity and enhances the green compacts’ density after consolidation. The microstructure, in-line transmittance, microhardness, and fracture toughness of the Yb³⁺-doped Y₂O₃ ceramics with different concentrations were measured. The 5.0 at% Yb³⁺-doped Y₂O₃ ceramic yielded a superior transmittance of 80.1% at 1100 nm and 83.0% in the mid-infrared region. The average grain size was 752 nm. The sample exhibited a thermal conductivity of 9.94 W·m⁻¹·K⁻¹ while achieving a 1076 nm laser output with a 42 mW peak power and 4.3% slope efficiency. Full article

Recently, the development of nanoparticle pigments has attracted interest in chemical preparation due to their potential functional properties, such as phosphate-based pigments. The present research focuses on the feasibility of synthesising the BaCr₂(P₂O₇)₂ pigment under hydrothermal conditions. The effect of the microstructural features of ceramic pigments (the crystalline structure, morphology, and particle size) on their optical properties (colour and reflectance) was also studied. The BaCr₂(P₂O₇)₂ compound was prepared in different fluid media, including water and NaOH solutions (0.5–1.0 M), at several reaction temperatures (170–240 °C) and intervals (6–48 h). The single-phase BaCr₂(P₂O₇)₂ did not crystallise without by-products (BaCr₂O₁₀, BaCr₂(PO₇)₂) in water and the alkaline solutions, even at 240 °C for 48 h; in these fluids, the ionic Cr³⁺ species oxidised to Cr⁶⁺. In contrast, the BaCr₂(P₂O₇)₂ single-phase crystallisation was favoured by adding urea as a reductant agent (25.0–300.0 mmol). Monodispersed BaCr₂(P₂O₇)₂ fine particles with a mean size of 44.0 nm were synthesised at a low temperature of 170 °C for 6 h with 0.5 M NaOH solution in the presence of 50.0 mmol urea. The phosphate pigment particle grew to approximately 62.0 nm by increasing the treatment temperature to 240 °C. A secondary dissolution–recrystallisation achieved after 24 h triggered a change in the particle morphology coupled with the incrementation of the concentration of NaOH in the solution. The pyrophosphate BaCr₂(P₂O₇)₂ pigments prepared in this study belong to the green colour spectral space according to the CIELab coordinates measurement, and exhibit 67.5% high near-infrared (NIR) solar reflectance. Full article

Silicon oxycarbide coatings are the subject of research due to their exceptional optical, electronic, anti-corrosion, etc., properties, which make them attractive for a number of applications. In this article, we present a study on the synthesis and characterization of thin SiOC:H silicon oxycarbide films with the given composition and properties from a new organosilicon precursor octamethyl-1,4-dioxatetrasilacyclohexane (²D₂) and its macromolecular equivalent—poly(oxybisdimethylsily1ene) (POBDMS). Layers from ²D₂ precursor with different SiOC:H structure, from polymeric to ceramic-like, were produced in the remote microwave hydrogen plasma by CVD method (RHP-CVD) on a heated substrate in the temperature range of 30–400 °C. SiOC:H polymer layers from POEDMS were deposited from solution by spin coating and then crosslinked in RHP via the breaking of the Si-Si silyl bonds initiated by hydrogen radicals. The properties of SiOC:H layers obtained by both methods were compared. The density of the cross-linked materials was determined by the gravimetric method, elemental composition by means of XPS, chemical structure by FTIR spectroscopy, and NMR spectroscopy (¹³C, ²⁹Si). Photoluminescence analyses and ellipsometric measurements were also performed. Surface morphology was characterized by AFM. Based on the obtained results, a mechanism of initiation, growth, and cross-linking of the CVD layers under the influence of hydrogen radicals was proposed. Full article

The current investigation evaluated a novel acid-etching solution containing hydrochloric acid (HCl), hydrofluoric acid (HF), nitric acid (HNO₃), orthophosphoric acid (H₃PO₄), and sulfuric acid (H₂SO₄) designed for etching zirconia ceramics. Achieving reliable bonding to zirconia is challenging due to its chemical inertia, unlike lithium disilicate, which can be effectively conditioned with HF etching. One hundred and twenty specimens of zirconia and lithium disilicate underwent etching with the experimental solution for six different durations: control, 20 s, 60 s, 5 min, 30 min, and 1 h. Surface roughness was assessed using 3D optical profilometry and scanning electron microscopy (SEM). The roughness of both materials increased with etching time; however, lithium disilicate demonstrated a significantly greater response, with Ra values rising from 0.18 µm (control) to 1.26 µm (1 h), while zirconia increased from 0.21 µm to 0.60 µm. ANOVA revealed significant effects depending on the ceramic type, time, and their interaction (p < 0.001). SEM images revealed non-selective etching of lithium disilicate, suggesting potential over-etching. The novel acid-etching solution improved surface roughness, especially in lithium disilicate ceramics. An application duration of one hour appears optimal for zirconia, improving surface characteristics while reducing damage; however, further research is required to assess its clinical safety and long-term effects on the mechanical properties of this dental ceramic. Full article

In the aerospace, energy and nuclear energy sectors, dynamic pressure measurement of power equipment and pressure vessels in high-temperature environments is critical for validating design, manufacturing processes and operational condition monitoring. The existing electric sensors are resistant to temperature. It is difficult to meet the pressure measurement requirements of high temperature and high-frequency responses. In this paper, combining the material properties of high-temperature co-fired ceramics (HTCC) with the structural characteristics of Fabry–Perot, an all-ceramic fiber-optic Fabry–Perot high-temperature pulsating pressure sensor based on a HTCC pressure- sensing diaphragm and ceramic high-temperature sintering process, is proposed. Experimental results show that in the pressure range of 6 MPa, the static pressure sensitivity of the sensor is 1.30 nm/MPa, and the linear goodness of fit reaches 0.99913. The dynamic response frequency of the sensor reaches 598.5 kHz. The survival time at high temperature of 800 °C is more than 80 h. The sensitivity to temperature is 0.00475 nm/°C. Full article

Gold nanoparticles (AuNPs) were synthesised using ultrasonic spray pyrolysis (USP) with the addition of polyvinylpyrrolidone (PVP) as a stabilising agent and subsequently dried via lyophilisation. The resulting dried AuNPs were redispersed in ethanol and homogenised to ensure uniform dispersion. This AuNP dispersion was then deposited onto a ceramic substrate—aluminum oxide (Al₂O₃)—using plasma jet printing. Comprehensive characterisation of the dispersion, AuNPs, and the resulting printed lines was performed using the following methods: inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-Vis), dynamic light scattering (DLS), measurements of dispersion viscosity and printed line roughness. ICP-OES confirmed consistent gold content in the AuNP dispersion, while the SEM and EDS analyses revealed predominantly spherical AuNPs with minimal aggregation and similar size distributions. TEM, SAED, and STEM/EDS confirmed that the crystalline structure and elemental composition of the AuNPs had diverse morphologies and strong gold signals. The UV-Vis, DLS, and zeta potential measurements indicated moderate colloidal stability, and thermogravimetric analysis (TGA) verified the AuNPs dispersion’s composition. The AuNP dispersion exhibited thixotropic behaviour favourable for printing applications, while confocal microscopy confirmed smooth, uniform printed traces, with an average surface line roughness of 1.65 µm. The successful use of plasma printing with the AuNP dispersion highlights its potential for functional material applications in electronics. Full article

Lithium disilicate ceramics (LDSs) are widely used in restorative dentistry for their excellent aesthetic and mechanical properties. Variants like zirconia-reinforced lithium silicate (ZLS) and advanced lithium disilicate (ALD) were developed to enhance these characteristics. However, differences in their physical and optical properties, as well as the influence of processing techniques (heat pressing vs. CAD-CAM), remain unclear. This study aimed to evaluate the physical and aesthetic properties of LDS, ZLS, and ALD ceramics. A systematic review and meta-analysis following PRISMA guidelines were conducted. Studies published in the last ten years were retrieved from PubMed, Web of Science, Scopus, Cochrane, and Scielo. The inclusion criteria encompassed in vitro studies analyzing LDS, ZLS, and ALD ceramics with quantitative data on mechanical and aesthetic properties. Meta-analyses were performed using a random-effects model, with subgroup analyses based on ceramic type and processing technique. Twenty-two studies met the inclusion criteria. Meta-analyses showed significant differences in flexural strength, hardness, surface roughness, wear, and translucency. The processing technique influenced these properties, with CAD-CAM materials exhibiting distinct performance compared to heat-pressed ceramics. Publication bias was assessed using Egger’s test and the Trim and Fill method, and heterogeneity via meta-regression. LDS showed the highest fracture resistance and least wear, while ALD had greater roughness depth. Heat pressing enhanced hardness and reduced roughness, whereas CAD-CAM improved flexural strength. Considering these findings and study limitations, LDS appears the most suitable option for clinical use due to its superior mechanical performance. Full article

Zirconia ceramics are widely used in dentistry, but maintaining long-term color stability remains challenging. This study investigated the combined effects of specimen thickness, immersion duration, and aging of coloring solutions on the color stability of two multilayer commercial zirconia materials: TT ONE Multilayer (TT) and DD cubeX² ML (DD). Discs (1.0–2.5 mm thick) were immersed in A2-shade coloring liquids for 30 s, 1 min, 3 min, and 5 min and evaluated after three months of solution aging. Color parameters (L*, a*, b*, C*, ΔE) were assessed, along with pH variation and Fe/Er ion concentrations using ICP-MS. Thinner specimens showed higher ΔE values and greater chromatic shifts than thicker ones. Aging of the coloring solutions increased L* values and discoloration, particularly in TT. ICP-MS revealed rising Fe and declining Er levels, correlating with observed optical changes. DD showed greater chemical and optical stability under identical conditions. These findings highlight the need to control zirconia thickness and coloring solution aging to preserve long-term esthetics. Full article

This paper systematically investigated the influence of sintering atmospheres, vacuum, and oxygen, on the microstructure and optical properties of Y₂O₃ ceramics. Compared with vacuum sintering, sintering in flowing oxygen atmosphere can effectively inhibit the grain growth of Y₂O₃ ceramics at the final stage of sintering and improve the uniformity of microstructure. After hot isostatic pressing, the samples pre-sintered at oxygen atmosphere showed good in-line transmittance from a visible-to-mid-infrared wavelength range (0.4–6.0 μm) except in the range of 2.8–4.1 μm. Spectral analysis showed that an obvious broadband absorption peak (2.8–4.1 μm) of characteristic hydroxyl groups is detected in the above samples. However, before densification, a low-temperature heat treatment at 600 °C under vacuum can effectively diminish the hydroxyl groups in Y₂O₃ ceramics. However, laser experiments in the ~1 μm wavelength range showed that although the Yb:Y₂O₃ ceramic carrying hydroxyl had obvious absorption in the 2.8–4.1 μm range, it had little effect on its laser oscillation in the ~1 μm wavelength. Yb:Y₂O₃ ceramics pre-sintered in an oxygen atmosphere at 1460 °C followed by hot isostatic pressing at 1440 °C achieved 12.85 W continuous laser output at room temperature, with a laser slope efficiency of 84.4%. Full article

This study focuses on addressing the reflectivity reduction issue in La_1–xSr_xTiO_3+δ during high-temperature preparation, which is caused by oxygen vacancy generation. Bulk samples of CeO₂-doped La_1–xSr_xTiO_3+δ with varying doping contents as a second phase and sintering temperatures were prepared. The phase composition, reflectivity, and valence states were thoroughly investigated. Introducing 10 wt.%CeO₂ significantly suppressed the formation of oxygen vacancies. Thus, the occurrence of impurity levels caused by oxygen vacancies was reduced. This can further mitigate the reflection decrease caused by impurity levels as photon absorption traps. Additionally, the reduced pore structure achieved at 1450 °C contributed to improved reflectivity compared to pure La_1–xSr_xTiO_3+δ. The findings suggest that this approach has great potential for reducing oxygen vacancies sensitivity in high-reflection ceramics under high-temperature conditions and preserving their optical properties. Full article

The color stability of dental ceramics in the oral cavity is influenced by multiple factors, including the patient’s dietary habits and oral hygiene practices, which can affect the optical and surface properties of resin-containing dental restorative materials. The purpose of this study was to evaluate the effects of surface finishing procedures and simulated tooth-brushing on the surface roughness, surface gloss, and color stability of resin matrix ceramics before and after coffee immersion. Forty specimens were prepared from a resin matrix ceramic and divided into four experimental groups according to surface finishing procedures, coffee immersion, and simulated tooth-brushing. The surface roughness, surface gloss, and color stability of the tested material were measured, and the data were statistically analyzed at a significance level of p < 0.05. The surface finishing procedures, measurement times, and application sequences affected surface roughness, surface gloss, and color stability. The most significant color differences occurred after coffee immersion; however, tooth-brushing had a more significant effect on the surface roughness and surface gloss. Coffee caused perceivable and clinically unacceptable color differences in the resin matrix ceramics. Tooth-brushing had a positive impact on the tested parameters. This study presents a novel approach by integrating both chemical (coffee immersion) and mechanical (tooth-brushing simulation) degradation processes to assess their combined and isolated effects on a resin matrix ceramic material. The findings provide clinically relevant insights into how finishing procedures and oral hygiene may influence the long-term esthetic performance of such restorative materials. Full article

Micromixing is a crucial process in microfluidic systems. In biochemical and chemical analysis, the sample is usually tested with reagents. These solutions must be well mixed for the reaction to be possible, generally using micromixers manufactured with sophisticated and expensive technology. The present work shows the design and evaluation of micromixers fabricated with LTCC (low-temperature co-fired ceramics) and FDM (fused deposition modeling) technologies for the development of functional and complex geometries. Two-dimensional planar serpentine and 3D chaotic convection serpentine micromixers were manufactured and implemented in an automated microanalytical system using photometric methods. To evaluate the performance of the micromixers, flow, mixing and absorbance measurements were carried out. Green tape and PP materials were used and showed good resistance to the acidic chemical solutions. The devices presented achieved mixing times in seconds, a reduced dispersion due to their aspect ratio, high sensitivity, and precision in photometric measurement. The optical sensing cells stored sample volumes in a range of 10 to 600 µL, which allowed the reduction of reagent consumption and waste generation. These are ideal characteristics for in situ measurement, portable, and low-cost applications focused on green chemistry and biochemistry. Full article

BiFeO₃ is a fascinating material with a rhombohedral crystal structure (R3c) at room temperature. This unique structure makes it suitable for use in solar cells, as the interaction of light with the polarized octahedral enhances electron movement. Evaluating its properties on different substrates helps to identify the specific characteristics of thin films. The thin films presented in this work were deposited using reactive RF cathodic sputtering with a homemade 1-inch diameter ceramic target. Their morphology, phase composition, optical, piezoelectric, and ferroelectric properties were evaluated. Fluorine Tin Oxide (FTO) and Indium Tin Oxide (ITO) substrates were used for the presented thin films. The thin films deposited on FTO displayed the “butterfly” behavior typically associated with ferroelectric materials. A d₃₃ value of 2.71 nm/V was determined using SSPFM-DART mode. In contrast, the thin films deposited on ITO at 550 °C reached a maximum saturation polarization of 40.89 μC/cm² and a remnant polarization of 44.87 μC/cm², which are the highest values recorded, but did not present the typical “butterfly” behavior. As the grain size increased, the influence of charge defects became more pronounced, leading to an increase in the leakage current. Furthermore, the presence of secondary phases also contributed to this behavior. Full article