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《Ceramics International》2021,47(20):28487-28492
In this work, the microwave dielectric properties of Ba4(Nd1-yBiy)28/3Ti18-x(Al1/2Ta1/2)xO54(0≤x≤2, 0.05≤y≤0.2) ceramics co-substituted by A/B-site were studied. Firstly, (Al1/2Ta1/2)4+ was used for substitution at B-site. At 0≤x≤1.5, the above mentioned ceramic was found to exist in single-phase tungsten bronze structure, but at x = 2.0, the secondary phase appeared. Although the dielectric constant decreased by doping the (Al1/2Ta1/2)4+, but the quality factor was observed to improve by 40% and the temperature coefficient of resonant frequency decreased by 75%. Based on the above results, Bi3+ was introduced to Ba4Nd28/3Ti17(Al1/2Ta1/2)O54. The introduction of Bi3+ reduced the sintering temperature, greatly improved the dielectric constant, and ultimately decreased the temperature coefficient of resonant frequency, but it led to deterioration of quality factor. At last, with appropriate site-substitution content control (x = 1.0,y = 0.15), excellent comprehensive properties (εr = 89.0, Q × f = 5844 GHz @ 5.89 GHz,TCF = +8.7 ppm/°C) were obtained for the samples sintered at 1325 °C for 4 h. 相似文献
83.
《Journal of the European Ceramic Society》2021,41(13):6722-6728
Extensive researches on scintillators have been executed to satisfy the excellent radiation detection materials in broad applications. However, practical application of conventional scintillators is limited due to the limitations of high cost, time-consuming fabrication process and insufficient radioluminescence. Herein, high density precursor glass doped with Tb3+ was designed to absorb X-ray efficiently and produce green emission. Molecular dynamics simulation was used to simulate the phase separation process in melting process. Then, Tb3+-doped Ba0.84Gd0.16F2.16 glass ceramics (GCs) with excellent structural and optical properties were elaborated by melt quenching technic and further heat treating. Their structural properties, photoluminescence (PL) and X-ray excited luminescence (XEL) were explored detailedly. The internal quantum efficiency of PL is 64 % in GCs. The XEL intensity is 192 % of that of Bi4Ge3O12 (BGO) commercial scintillator. Our results suggest that Ba0.84Gd0.16F2.16:Tb3+ GCs might have potential application in X-ray detection. 相似文献
84.
Amyloid precursor protein (APP) is a type 1 transmembrane glycoprotein, and its homologs amyloid precursor-like protein 1 (APLP1) and amyloid precursor-like protein 2 (APLP2) are highly conserved in mammals. APP and APLP are known to be intimately involved in the pathogenesis and progression of Alzheimer’s disease and to play important roles in neuronal homeostasis and development and neural transmission. APP and APLP are also expressed in non-neuronal tissues and are overexpressed in cancer cells. Furthermore, research indicates they are involved in several cancers. In this review, we examine the biological characteristics of APP-related family members and their roles in cancer. 相似文献
85.
Rebecca L. Walton Michael J. Brova Beecher H. Watson Elizabeth R. Kupp Mark A. Fanton Richard J. Meyer Gary L. Messing 《Journal of the European Ceramic Society》2021,41(3):1945-1953
Direct writing is a unique means to align anisotropic particles for the fabrication of textured ceramics by templated grain growth (TGG). We show that alignment of tabular barium titanate (BT) template particles (20–40 μm width and 0.5–2 μm thickness) in a PIN-PMN-PT matrix powder (d50 = 280 nm) is significantly improved during direct writing using anisotropic nozzles at high printing rates. The particle orientation distribution in as-printed filaments, and the texture orientation distribution in sintered ceramic filaments are shown to directly correlate with COMSOL Multiphysics-predicted torque distributions for direct writing with aspect ratio 2, 3 and 5 oval nozzles. Electromechanical strain properties of the textured piezoelectric ceramics significantly improved relative to random ceramics when printed with anisotropic nozzles. Simulations of aspect ratio 20 nozzles and nozzles with interior baffles demonstrate significantly increased torque and near elimination of constant shear stress cores (i.e. plug flow). 相似文献
86.
Guangran Zhang Iva Milisavljevic Karina Grzeszkiewicz Piotr Stachowiak Dariusz Hreniak Yiquan Wu 《Journal of the European Ceramic Society》2021,41(6):3621-3628
Highly transparent X2O3 sesquioxide ceramics were obtained from a solid solution of five different oxides (Lu2O3, Y2O3, Yb2O3, Gd2O3, and Dy2O3), mixed in an equal molar ratio according to the principle of high-entropy. The fabricated (Lu, Y, Yb, Gd, Dy)2O3 ceramics achieved 99.97 % of the relative density and exhibited a high degree of optical transparency with the in-line transmittance of almost 80 % in the visible wavelength range. Emissions of Gd3+ (6PJ → 8S7/2 at 312 nm), Dy3+ (4F9/2 → 6H15/2 at 492 nm and 4F9/2 → 6H13/2 at 572 nm), and Yb3+ (2F5/2 → 2F7/2 at 1031 nm) suggested a potential application of the high-entropy ceramics as multi-wavelength emission phosphor transparent ceramics. High-entropy ceramics also exhibited lower specific heat and thermal conductivity compared to single-element sesquioxide ceramics. This work demonstrated that highly transparent oxide ceramics, with complex chemical compositions and good optical properties, could be obtained using the high-entropy principle. 相似文献
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