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71.
L.C. Souza A.C.A. Silva N.O. Dantas P.C. Morais S.W. da Silva 《Ceramics International》2018,44(1):208-215
Successful fabrication of glass-based hybrid nanocomposites (GHNCs) incorporating Ag, core-shell CdSe/CdS and CdSxSe1?x nanoparticles (NPs) is herein reported. Both metallic (Ag) and semiconductor (CdSe/CdS) NPs were pre-synthesized, suspended in colloids and added into the sol-gel reaction medium which was used to fabricate the GHNCs. During fabrication of the nanocomposites a fraction (20–60%) of core-shell CdSe/CdS NPs was alloyed into CdSxSe1?x (0.20 < x < 0.35) NPs without changing morphology. Modulation of in situ alloying is possible via the relative content of organics added into the sol-gel protocol. Within colloids Ag (core-shell CdSe/CdS) NPs presented average diameter and polydispersity index of 49.5 nm (4.2 nm) and 0.41 (0.21), respectively. On the other hand, the Ag (core-shell CdSe/CdS) NPs’ average diameter and polydispersity index assessed from the GHNCs were respectively 51.5 nm (4.1 nm) and 0.43 (0.25), revealing negligible aggregation of the nanophases within the glass template. The new GHNCs herein introduced presented two independent excitonic transitions associated to homogenously dispersed semiconductor NPs, peaking around 420 nm (core-shell CdSe/CdS) and 650 nm (CdSxSe1?x) and matching the plasmonic resonance (Ag NPs) in the 400–500 nm range. We envisage that the new GHNCs represent very promising candidates for superior light manipulation while illuminated with multiple laser beams in quantum interference-based devices. 相似文献
72.
He Qi Ruzhong Zuo Jing-feng Li Longtu Li 《Journal of the European Ceramic Society》2018,38(16):5341-5347
A morphotropic phase boundary (MPB) between rhombohedral (R) and tetragonal (T) phases was identified in a few (0.9-x)NaNbO3-0.1BaTiO3-xABO3 (x?=?0–0.05) lead-free systems. Critical roles of R-phase inducers were specially evaluated in terms of phase boundary position, microstructure and piezoelectric responses. The results indicate not only the tolerance factor of the ABO3 additive but also its ferroelectricity and corresponding volume change would influence the formation of phase boundary and further determine dielectric and ferroelectric responses. The piezoelectric coefficient d33 of MPB compositions was compared with theoretically-calculated d33-cal according to d33?=?2Pr·ε33·Q33, demonstrating that the piezoelectric response of these systems should be determined by combined effects of the phase coexistence, nano-scale domains and particularly enhanced dielectric responses. The largest d33 ~305 pC/N, the highest ε33T/εo ~2815 and the lowest Pr ~14.7 μC/cm2 were achieved in the MPB composition with 3.75% SrZrO3. These experimental results provide a valuable reference for designing new NaNbO3-based lead-free piezoelectric materials. 相似文献
73.
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75.
Preethi Balasubramanian Teresa Büttner Valentina Miguez Pacheco Aldo R. Boccaccini 《Journal of the European Ceramic Society》2018,38(3):855-869
Boron is considered to influence the performance of several metabolic enzymes and boron deficiency is associated with impaired growth and abnormal bone development. As such, boron is a beneficial bioactive element for animals and humans. It is also well known that boron stimulates wound healing and improves bone health. The addition of boron in different proportions to bioactive glasses has significant effects on glass structure, glass processing parameters, biodegradability, biocompatibility, bioactivity and cytotoxicity. Different compositions of bioactive glasses (BGs) containing boron, including boron-doped, borosilicate and borate glasses, are being investigated for bone and soft tissue engineering under the premise that these BGs are suitable carriers of boron, indicating controlled release of B species in the biological environment. This paper reviews up to date research and applications of borate, borosilicate, and boron doped silicate and phosphate BGs focussing on their physical, structural, degradation and biological properties for hard and soft tissue regeneration. 相似文献
76.
Yiguang Jiang Benxue Jiang Qihua Zhu Nan Jiang Pande Zhang Shuilin Chen Xu Hu Ge Zhang Jintai Fan Liangbi Su Jiang Li Long Zhang 《Journal of the European Ceramic Society》2018,38(5):2404-2409
Different deformation rates of Nd,Y-codoped CaF2 transparent ceramics were prepared by ceramization of single crystals. The deformation rate effects on the crystallization behaviors, microstructures, mechanical properties, and optical performances were investigated for the first time. The results indicate that the comprehensive performances of Nd,Y-codoped CaF2 ceramic (△a?=?62%) are the most optimal compared with other ceramics having different deformation rates (△a?=?34%, 40%, 50%, and 75%). In further investigations of the optical properties, the Nd,Y-codoped CaF2 ceramic (△a?=?62%) sample exhibited a high transparency (Ta?>?91%, 3-mm thick,250?~?1200?nm), low light scattering, superior fracture toughness (K1c?~?0.71?MPa·m1/2), strong fluorescence emission, long lifetime (τ?=?348.72?μs), and broad FWHM (29.2?nm), promising a good candidate for high-power laser material. 相似文献
77.
Tao Li Zehui Du Nobumichi Tamura Mao Ye Saikumar Inguva Wei Lu Xierong Zeng Shanming Ke Haitao Huang 《Journal of the European Ceramic Society》2018,38(4):1488-1497
(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 ((1-x)PZN-xPT in short) is one of the most important piezoelectric materials. In this work, we extensively investigated (1-x)PZN-xPT (x = 0.07–0.11) ferroelectric single crystals using in-situ synchrotron μXRD, complemented by TEM and PFM, to correlate microstructures with phase transitions. The results reveal that (i) at 25 °C, the equilibrium state of (1-x)PZN-xPT is a metastable orthorhombic phase for x = 0.07 and 0.08, while it shows coexistence of orthorhombic and tetragonal phases for x = 0.09 and x = 0.11, with all ferroelectric phases accompanied by ferroelastic domains; (ii) upon heating, the phase transformation in x = 0.07 is Orthorhombic → Monoclinic → Tetragonal → Cubic. The coexistence of ferroelectric tetragonal and paraelectric cubic phases was in-situ observed in x = 0.08 above Curie temperature (TC), and (iii) phase transition can be explained by the evolution of the ferroelectric and ferroelastic domains. These results disclose that (1-x)PZN-xPT are in an unstable regime, which is possible factor for its anomalous dielectric response and high piezoelectric coefficient. 相似文献
78.
In this study, we present an effective strategy to enhance the energy storage properties of Ba0.4Sr0.6TiO3 (BST) lead-free ceramics by the addition of Bi2O3-B2O3-SiO2 (BBS) glass, which were prepared by the conventional solid state sintering method. The phase structure, microstructure and energy storage properties were investigated in detail. It can be found that the Ba0.4Sr0.6TiO3-x wt%(Bi2O3-B2O3-SiO2) (BST- x wt%BBS, 0 ≤ x ≤ 12) ceramics possess large maximum polarization (Pmax), low remanent polarization (Pr) and slim polarization electric field (P-E) hysteresis loops. The breakdown strength (BDS), recoverable energy storage density (Wrec) and energy storage efficiency (η) are enhanced obviously with the addition of BBS glass. The BST-9 wt%BBS ceramic is found to exhibit excellent energy storage properties with a Wrec of 1.98 J/cm3 and a η of 90.57% at 279 kV/cm. These results indicate that the BST-x wt%BBS ceramics might be good candidates for high energy storage applications. 相似文献
79.
80.
Chloride-induced corrosion of highway bridges constitutes a critical form of environmental deterioration and may result in significant escalation of seismic life-cycle costs due to increased fragility during earthquake events. Most of existing literature tends to adopt simplistic uniform area loss assumptions in lieu of potentially complex, yet realistic and more detrimental, pitting corrosion models for seismic vulnerability analysis. Since the degree of deterioration depends on the severity and duration of exposure, there exists a need to investigate the influence of uniform vs. pitting corrosion assumption on seismic life-cycle costs for varied chloride exposure conditions. A case-study example of a highway bridge in Central and Southeastern US reveals consideration of pitting corrosion as critical for extreme exposures compared to relatively minor settings. Subsequently this study provides recommendations to aid bridge engineers and stakeholders to balance between computational cost and accuracy of results to aid prompt decisions on rehabilitation of ageing bridges in different exposure conditions. A framework is also included to compute seismic life-cycle costs from generic measures of corrosion, independent of assumed exposure scenario. This framework is particularly helpful for seismic loss assessment of highway bridges in chloride exposure zones with periodic field measurements to estimate the extent of structural deterioration. 相似文献