- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
tilt Grain Boundary on Oxygen-ion movement In Yttria-Stabilized Zirconia: Insights from molecular dynamics
摘要： We present a new methodology for investigating the combined effect of the Σ5(310)/[001] symmetric tilt grain boundary (GB) and the local cation environment in polycrystalline yttria stabilized zirconia (YSZ) on two important quantities that determine the ionic conductivity, namely, (i) the local hopping rate of O2- ion and (ii) the probability of O2--ion -vacancy pairs within the YSZ structure. How these quantities vary with distance to the GB core are estimated for the first time using waiting time distributions associated with O2- ion hop events in molecular dynamics simulations. We conclude that indeed fewer hop events occur in the presence of a GB. However, the GB effect can be felt at a far greater distance than previously believed. Most importantly, interactions between the O2- ions, nearby cations and the GB results in a hopping behavior that is different from one observed in single-crystal YSZ. Anisotropy in O2- ion movement in the vicinity of the GB is also studied. These results and the use of our novel technique have a direct implication on the development of improved models for ionic conduction in solid state electrolytes.
关键词： Ionic conductivity,molecular dynamics,yttria stabilized zirconia,grain boundary
更新于2025-09-10 09:29:36
-
Transparent tetragonal-cubic zirconia composite ceramics densified by spark plasma sintering and hot isostatic pressing
摘要： Targeting higher toughness transparent ceramics, tetragonal (3 mol % yttria) and cubic (8 mol % yttria) ZrO2 starting powder mixtures were densified by spark plasma sintering (SPS) in vacuum at 1100°C and post hot isostatic pressing (HIP) in argon at 1100°C. The influence of the ultra-fine microstructure and phase composition on the fracture resistance and light transmission in the visible and infra-red range was assessed. Of special interest was the influence of a thermal annealing step in air on the transparency of the SPS and SPS-HIP ceramics.
关键词： Total Forward Transmission,Hot Isostatic pressing,Spark Plasma Sintering,Ferro-elastic domain switching,Transparent zirconia
更新于2025-09-10 09:29:36
-
Computable translucency as a function of thickness in a multi-layered zirconia
摘要： Statement of problem. Determining the relationship between variable thicknesses and the translucency of dental ceramics is essential for optimizing esthetics in different clinical situations. Purpose. The purpose of this in vitro study was to analyze the relationship between layer thickness and translucency of 2 multi-layered monolithic zirconia materials and to develop an equation by which the grade of translucency can be calculated dependent on the materials’ layer thicknesses in advance. Material and methods. Two semisintered multi-layered zirconia blanks, namely KATANA Zirconia Super Translucent Multi-Layered Disk (Noritake Dental Supply Co, Ltd) and Zirconia Ultra Translucent Multi-Layered Disk (UTML) (Noritake Dental Supply Co, Ltd), were sectioned (N=96) to separate the 4 layers (n=12 per layer): enamel layer, transition layer 1, transition layer 2, body layer. All specimens were sintered in a furnace (M2 Plus; Thermo-Star) at 1500°C for 2 hours and automatically polished under water cooling up to P2400 for the thicknesses of 1.6, 1.3, 1.0, 0.7, and 0.4 mm. Transmittance of visible light was measured using a spectrophotometer (Lambda 35; Perkin Elmer). Data were analyzed using the Kolmogorov-Smirnov, 2-way ANOVA, and Scheffé post hoc tests (a=.01) and curve fitting. Results. Analyzing the fitting of the values of the 8 material groups to the linear, exponential, and logarithmic curves, 7 of the 8 groups (not UTML body layer) fitted the most (R-square value closer to 1.0) to the logarithmic curve. Constants were obtained from the distance to the x-axis and the curvature. Conclusions. The methodology of this study provided the materials’ specific constants a and b by analyzing the translucency behavior of KATANA Super Translucent Multi-Layered Disk and Ultra Translucent Multi-Layered Disk in different thicknesses, allowing further translucency calculation by applying the developed formula and the constants.
关键词： zirconia,translucency,thickness,esthetics,dental ceramics
更新于2025-09-10 09:29:36
-
High-gravity-assisted scalable synthesis of zirconia nanodispersion for light emitting diodes encapsulation with enhanced light extraction efficiency
摘要： Zirconia-based hybrid polymers has become one of the ideal encapsulation material for light emitting diodes (LEDs) with high extraction efficiency due to their proper refractive index to those of semiconductor chips. However, the controlling of the dispersion for zirconia nanoparticles in polymeric hosts to obtain optically transparent hybrid nanocomposites has been one of the major challenges. Herein, we reported the synthesis of zirconia nanodispersion via high-gravity-assisted homogeneous precipitation in an internal circulation rotating packed bed (RPB) reactor followed by two-step modification. An alternative to conventional precipitation in batch stirred tank reactors (STR), the process intensification by high-gravity RPB results in homogeneous micromixing during the nucleation and growth of zirconia particles, which are benefit for continuous and reproducible production of ultrasmall zirconia nanoparticles. The obtained zirconia nanoparticles are purely cubic phase with narrow size-distribution in the range of 3–5 nm according to the X-ray diffraction and transmission electron microscopy characterization, which were similarity to that by the conventional methods. Nevertheless, the average hydrodynamic diameters of zirconia nanoparticles in aqueous solutions obtained by RPB methods were much smaller than those prepared in conventional STR, which enabled easy control and surface modification for highly dispersed nanodispersion in organic solvents and/or polymeric hosts. After two-step surface modification, zirconia nanoparticles with goal-directed structures were obtained, with highly dispersity in various organic solvents (e.g. toluene, trichloromethane, tetrahydrofuran, etc.) and aliphatic epoxy resin, forming transparent hybrid films with tunable refractive indexes. The preliminary applications of these zirconia nanodispersions for LEDs encapsulation were demonstrated. The light extraction efficiency of the LEDs devices packaged with zirconia/epoxy hybrid material increased by 10 percent when the doping content of zirconia nanoparticles was 0.2, compared to the devices encapsulated by original epoxy.
关键词： Rotating packed bed,Hybrid nanocomposite,Zirconia nanoparticles,LED encapsulation
更新于2025-09-09 09:28:46
-
Evaluation of Cure Depth and Geometrical Overgrowth Depending on Zirconia Volume Fraction Using Digital Light Processing
摘要： The optical properties of zirconia photopolymer suspension for DLP (Digital Light Processing) were evaluated. The light source and intensity were set to 395 nm and 30 mW/cm2. Experimental groups were divided into 48, 50, 52, 54, 56 and 58 vol% according to the zirconia volume fraction. The cure depth of all groups was at least 47.35 um when cured for 1 sec, which was higher than layer parameter values of the 3D printer. The geometrical overgrowth showed 28.55% at 48 vol% and 36.94% at 58 vol%. As the volume fraction of zirconia increased, the geometrical overgrowth increased and the cure depth reduced.
关键词： Zirconia,Ceramic 3D Print,Photopolymer Suspension,Additive Manufacturing
更新于2025-09-09 09:28:46
-
In-situ laser Pelletization of advanced ternary thermal barrier coating system
摘要： thermal transformation of cubic (c) phase to tetragonal (t) and monoclinic (m) phases. Powder technology is considered as a product cost effective technology to produce advanced ceramics. A 1 kW CO2 pulsed laser, working at 0.4 and 1.0 kW, 2-200 ms pulsed lengths and 1 mm laser beam diameter, was used to produce pellets from the loose powder of 8 wt% yttria partially stabilized zirconia (YPSZ) containing 8 wt% alumina. SEM equipped with EDS and WDS, X-ray diffraction, X-ray step scanned and Vickers microhardness were employed to evaluate and analyze the dimensions, quality, microstructure, chemical composition, phases, hardness and fracture toughness of the pellets. Homogeneous distribution of a fine scale duplex structure of nontransformable tetragonal (t') + α-alumina was obtained. The rapid solidification which followed the pelletization process after laser melting of the powder mixture prevented phase. Hardness higher than 19 GPa with a fracture toughness higher than 10 MPa.m1/2 was achieved. The results show the possibility of using a pulsed laser to produce completely re-melted and re-solidified spherical pellets with smooth surfaces under wide ranges of processing parameters. Also, it was found that there is a specific interaction time (pulsed length) required for melting and producing pellets at any level of power density. The pulsed lengths needed are in the range of 10-200 ms at power densities and specific energies values of 510 to 1275 W/mm2 and 5-255 J/mm2 respectively. Pellets diameters of 1000-4000 μm were effectively produced. The results clearly demonstrate a high efficiency of laser coupling with ceramic powders. Complete t' phase is formed by athermal transformation with a small amount of rhombohedral (r) phase.
关键词： Pellets,t’-phase,α-alumina,Zirconia-yttria-alumina,Laser pelletization
更新于2025-09-09 09:28:46
-
Influence of UV irradiation and cold atmospheric pressure plasma on zirconia surfaces: an in vitro study
摘要： Purpose: To compare the influence of ultraviolet (UV) irradiation and cold atmospheric pressure plasma (CAP) treatment on surface structure, surface chemistry, cytocompatibility, and cell behavior on zirconia in vitro. Materials and Methods: Zirconia samples (TZ-3YSB-E) were treated by UV irradiation, oxygen plasma, or argon plasma for 12 minutes each and compared with the nontreated samples. Surface analysis was conducted using scanning electron microscopy, roughness analysis, and x-ray photoelectron spectroscopy. Cell proliferation, viability, and cell attachment as well as cytotoxicity were evaluated using MC3T3-E1 murine osteoblasts cultivated directly on the zirconia samples. Results: Surface structure and roughness were not affected by the surface treatments. CAP and UV irradiation significantly reduced organic material and increased the surface oxidation on the zirconia samples. Furthermore, CAP and UV treatment significantly decreased the contact angle on the zirconia samples, indicating superhydrophilicity. Cell attachment was significantly increased on oxygen plasma-treated zirconia samples compared with the nontreated samples at all times (P < .001). After 24 and 48 hours, cell proliferation and viability (P < .001) were significantly increased on oxygen plasma-treated samples in comparison with the nontreated, UV-treated, and argon plasma-treated samples. Neither UV nor CAP treatment led to cytotoxicity. Conclusion: In vitro, surface treatment by UV irradiation or CAP causes a significant reduction of organic material, increases the hydrophilicity of zirconia, and improves the conditions for osteoblasts. Results stipulate that treatment of zirconia surfaces with oxygen plasma may favor cell proliferation.
关键词： UV light,Implant surface,Cold atmospheric pressure plasma,Photofunctionalization,Dental implant,Zirconia
更新于2025-09-04 15:30:14
-
Investigation of Interface Diffusion in Sputter Deposited Gd0.1Ce0.9O1.95 Thin Buffer Layers on Y-Stabilized Zirconia Crystalline Substrates for Solid Oxide Cells Applications
摘要： This paper presents the results concerning the investigation of the morphological and structural properties of Gd0.1Ce0.9O1.95 layers deposited on crystalline (111) YSZ subtrates by RF magnetron sputtering. Room temperature as-grown samples have been annealed at different temperatures from 600°C to 1300°C. Atomic Force Microscopy analysis shows an increase in the average grain size dimensions with increasing annealing temperatures. X-Ray Diffraction measurements indicates a preferential growth of the grains along the (111) direction with a decrease in the evaluated c-axis as a function of the annealing temperature, probably related to an over-oxidation of the samples. X-Ray Reflectivity studies, performed on thin layers annealed at temperatures from 700-1000°C, points out the presence of zones with different densities and roughness at the layer/substrate interface and at the layer/vacuum surface. The behaviour of these zones as a function of temperature has been investigated. The obtained results seem to exclude the presence of consistent inter-diffusion phenomena at the GDC/YSZ interface.
关键词： Solid oxide cells,X-ray reflectivity,Reciprocal space map,RF magnetron sputtering,Yttrium stabilized Zirconia,Gadolinium doped Ceria,Interdiffusion
更新于2025-09-04 15:30:14