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81.
《Ceramics International》2015,41(4):5607-5613
Doped barium cerate is a promising solid electrolyte for intermediate temperature fuel cells as a protonic conductor. In the present paper, the nanocrystalline Gd-doped barium cerate (BaCe0.7Gd0.1Y0.2O2.9) thin films have been successfully deposited on alumina substrate by spray pyrolysis technique. The films deposited from 0.1 M concentration and annealed at five different temperatures were characterized with different physio-chemical techniques. The BCGY is crystallized in orthorhombic perovskite structure with slight shift to the lower 2θ value compared with barium cerate (BC) and yttrium doped barium cerate (BCY). The grain growth and hence densification is also investigated by using SEM and AFM. The grain growth is almost complete at 1000 °C and the surface of the film appears to be smooth with typical roughness of 152 nm. Raman spectrum of BCGY film shows intense band at 463.8 cm−1 compared to pure BC and BCY indicating the presence of more oxygen vacancies due to Gd doping. The proton conductivity of BCGY thin film in moist atmosphere is 1×10−3 Scm−1. 相似文献
82.
83.
《Ceramics International》2023,49(15):25302-25311
Calcium phosphate ceramics are widely used as bone repair materials owing to their excellent biocompatibility, bone conductivity, bone induction, and degradability. Although there are many methods for synthesizing calcium phosphate and controlling its phase composition, it is necessary to explore effective preparation methods by understanding the formation of calcium phosphate and its influencing factors. In this study, calcium phosphate powders with controllable phase compositions were synthesized using a wet chemical precipitation method by adjusting the process parameters (aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration). Subsequently, a certain biphasic proportion of (biphasic calcium phosphate, BCP) products was prepared, and pure (β-tricalcium phosphate, β-TCP) can be obtained according to the customer's requirements. BCP ceramics with desired phase compositions were obtained by pressing and sintering different calcium-deficient powders. Specifically, β-TCP powder with a purity of 99.83 wt% was obtained when the aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration were 0 h, 50% ethanol, 1, 0.27 M, and 0.0135 M, respectively. The BCP synthesized in this study shows great application potential in the field of bone tissue repair materials. 相似文献
84.
《Ceramics International》2023,49(19):31152-31162
There is still a problem of low energy storage density in dielectric capacitors which is a core component of power systems. For the improvement of the energy storage density, the linear dielectric material CaTiO3 (CT) was introduced in Na0.5Bi0.5TiO3 (NBT) ceramics in this paper. By modifying the A site, a new relaxor ferroelectric ceramic was successfully synthesized and attained a recoverable density (Wrec) of 2.34 J/cm3 at x = 0.18. Moreover, the preparation process was optimized in this paper. Through the viscous polymer process (VPP) route, the energy density (WA) of 82NBT-18CTVPP ceramic further reaches 6.45 J/cm3 at 340 kV/cm, with efficiency (η) up to 75% and a Wrec of 4.82 J/cm3. At the same time, the change of Wrec is small at temperature (30–150 °C) and frequency (1 Hz–300 Hz), which demonstrates its excellent stability. The discharge power density reaches about 180 MW/cm3 and the discharge time is 0.117 μs, which indicates its excellent pulse discharge performance. The results show that 82NBT-18CT lead-free relaxation ferroelectric material is expected to become ideal for high-energy storage applications. 相似文献
85.
《Journal of the European Ceramic Society》2023,43(9):3988-3997
Composites of Cf/Ti5Si3 were prepared by spark plasma sintering a mixture of TiC-coated short carbon fiber and pre-synthesized Ti5Si3 powder. The TiC coating protects the Cf and mediates a mild interdiffusion process between Cf and Ti5Si3, rather than an exothermic reaction. Compared with traditional in-situ fabrication, the use of a pre-synthesized Ti5Si3 powder as a raw material mitigated heat release from the Ti-Si reaction and consequent grain overgrowth. The spark plasma sintering process was completed within 15 min and the relative density of the product reached 99.2 %. The Cf/Ti5Si3 composite achieved a high fracture toughness of 7.57 MPa m1/2 and a flexural strength of 518.3 MPa, which reflected increases of 255 % and 270 %, respectively, compared with those properties of monolithic Ti5Si3. These improvements are attributable to the effects of the carbon fiber reinforcement, the TiC protective coating on the Cf, inhibition of grain overgrowth, and control of interfacial reaction. 相似文献
86.
《Journal of the European Ceramic Society》2023,43(11):4774-4781
BiFeO3-based lead-free ferroelectric is considered a potential candidate for energy storage applications owing to its high spontaneous polarization. To tackle the compromise between high polarization and energy storage density, NaNbO3 (NN) was introduced into 0.7BiFeO3-0.3Ba(Hf0.05Ti0.95)O3 (BF-BHfT) ceramics, where Nb5+ ions enter the BF-BHfT lattices and enhance resistivity, while Na+ ions occupied on the A-sites and smash the long-range ferroelectric order into polar nanoregions. Consequently, the ceramics could maintain high maximum polarization and low remanent polarization. High recoverable energy density (Wrec) of 5.2 J/cm3 and efficiency (88%) were recorded in 0.53BF-0.3BHfT-0.17NN ceramics. Besides, it exhibited good thermostability up to 120 °C (Wrec variation < 5%), frequency stability from 10 to 200 Hz (Wrec variation < 7%) and excellent fatigue resistance after 104 cycles (Wrec variation < 0.2%). Under different electric fields the efficiency still maintains nearly constant. In charge-discharge test a Wdis of 3.7 J/cm3 was recorded, which proved 0.53BF-0.3BHfT-0.17NN ceramics a promising candidate for energy storage applications. 相似文献
87.
《Journal of the European Ceramic Society》2023,43(9):3981-3987
Silicon nitride (Si3N4) is an excellent engineering ceramic with high strength, fracture toughness, wear resistance, and good chemical and thermal stability. Recently, the enhanced thermal conductivity enables Si3N4 to have potential application prospects in the electronic and orthopedic fields. Metal bonding with Si3N4 is often the key to these applications. Here we report a facile approach for the titanium-activated Cu bonding on Si3N4 substrates using an atmosphere plasma spray (APS) process. With X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) observation, it was shown that the interaction between the pre-bonded Ti (by APS) on Si3N4 promoted the adhesion and high bonding strength of APS Cu on Si3N4. The interfacial structure and phases were characterized, and tensile strength, electrical resistivity, thermal conductivity, and residual stress of Cu bonded Si3N4 were measured accordingly. The APS deposited Cu layer is dense, has a high purity, and is joined firmly with Ti pre-bonded Si3N4 substrate. The maximum tensile strength between Cu and Si3N4 is as high as 89.4 MPa. The Si3N4 substrate bonded with highly dense Cu demonstrates a low surface resistivity of 8.72 × 10−4 Ω∙mm, and high thermal conductivity of 98.12 W/m·K, which shows potential applications in electronic devices. 相似文献
88.
《Journal of the European Ceramic Society》2023,43(9):3905-3916
In this work, pure ZrB2-SiC composite powders were obtained using ZrO2, SiO2, B4C and carbon black as raw materials via a boro/carbothermal reduction (BCTR) reaction process at 1500 °C for 2 h in vacuum condition. Based on this finding, porous ZrB2-SiC ceramics were in-situ synthesized via a novel and facile boro/carbothermal reaction process templated pore-forming (BCTR-TPF) method. The phase composition, linear shrinkage, and pore size distribution were also methodically studied. Results show that the porous ZrB2-SiC ceramics with controllable porosity of 67–78%, compressive strength of 0.2–9.8 MPa and thermal conductivity of 1.9–7.0 W·m−1K−1 can be fabricated by varying of ZrO2 and B4C particle sizes. The formation of ZrB2 grains was controlled via solid-solid and solid-liquid-solid growth mechanisms, the growth process of SiC grains was mainly regulated by solid-solid, vapor-vapor and vapor-solid growth mechanisms during the overall synthesis process. Finally, the pore-forming mechanism of porous samples prepared via the BCTR-TPF method was gases combined with template pore-forming mechanism, i.e., B4C and carbon black acted as pore-forming templates, and gaseous products generated in the BCTR reaction were also applied as gas pore-forming agent. 相似文献
89.
90.