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Junwei Liu Xin Wei Yongfu Lian Qiaoli Liu Xingzu Xu Dayong Lu 《Ceramics International》2021,47(13):18669-18676
Sr-modified Cu/Nb co-doped BaTiO3 ceramics were prepared using solid-state reactions and the structures and dielectric properties were studied. All the samples had single-phase perovskite structures with no detectable secondary phases. In the low-temperature range, the dielectric constant decreased as the Sr content increased in the high- and low-frequency ranges. Two dielectric constant plateaus accompanied by dielectric relaxation peaks were present in the loss curves, and the relaxation process deviated from the Arrhenius law at low temperatures. The dielectric constants of different plateaus were related to inhomogeneous structures such as grain interiors and grain boundaries. The polarization strength of the grain boundaries in the low-frequency range increased with the temperature and that of the grain interiors demonstrated paraelectric behaviour in high-temperature ranges. An analysis of the electric modulus spectra indicated a close relationship between the relaxation process and resistivity of the grains for high-frequency relaxation. The impedance spectra at high temperatures consist of three electrical responses, corresponding to the effects of grains, grain boundaries, and electrodes. The dielectric relaxation appeared in high temperature range was related to the electrical properties of the grain boundaries. 相似文献
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White-light-emitting phosphors based on phosphate host matrix, KSrPO_4 doped with Dy~(3+), were prepared by solid state reaction and their VUV luminescent properties were firstly investigated. The excitation band peaking at 125-153 nm corresponding to the absorption of PO_4~(3-) group exhibits very strong absorption. The phosphors emit warm-white luminescence under vacuum ultraviolet excitation of 147 nm, which consists of three main emission peaks located at 475, 570 and 662 nm, respectively.According to the luminescence and color chromaticity of the optimal sample KSrPO_4:1 mol%Dy~(3+),1.3 mol%Li~+, it can be a potential candidate for mercury-free fluorescent lamps. 相似文献
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AbstractThe impacts of using radio frequency (RF) energy to dry purple-fleshed potatoes were investigated and compared to infrared radiation (IR) and microwave (MW) drying techniques. The gelatinization rate, color, flavor, morphological, and structural characteristics, thermodynamic properties, as well as antioxidant capacity were examined. The results indicated that the drying time of RF (70?min) and MW (21?min) were shorter than IR (105?min). The gelatinization ratio of MW, RF, and IR were 94.4?±?2.0, 88.3?±?1.4, and 64.5?±?1.1%, respectively. The degree of crystallization of purple-fleshed potato powder decreased with all three drying methods. RF-dried potatoes were able to retain higher polyphenols (loss rate: 4.3%), total anthocyanin (3.7%), and total flavonoid content (35.1%), whereas IR showed the lowest retention. The content of polyphenols also decreased significantly. Furthermore, after RF heating, the scavenging of free radicals was higher compared to MW and IR. 相似文献
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以OMS-2粉体催化剂为基础,对催化剂进行挤出成型,考察粘结剂种类、粘结剂用量、润滑剂和孔结构改进剂用量、焙烧温度对成型催化剂机械强度的影响。得到最佳成型工艺条件为,粘结剂硅溶胶用量为OMS-2粉体催化剂质量的105%~110%、辅助粘结剂纳米ZrO_2用量为OMS-2粉体催化剂质量的30%~35%、润滑剂田菁粉用量为OMS-2粉体催化剂质量的2. 5%~3. 0%、孔结构改进剂柠檬酸用量为OMS-2粉体催化剂质量的5%~6%,焙烧温度450℃。成型后催化剂机械强度可达150 N·cm~(-1),满足工业化应用对催化剂强度的要求。将成型催化剂应用于催化湿式氧化印染废水处理,经过432 h活性评价时间,COD平均去除率约91. 6%,反应结束后催化剂结构完整,平均机械强度约144 N·cm~(-1),表现出良好的水热稳定性。 相似文献
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Xu Zhi-Zheng Jiang Feng Zhong Chong-Quan Gou Yong-Jie Teng Hong-Fei 《Structural and Multidisciplinary Optimization》2020,61(1):207-223
Structural and Multidisciplinary Optimization - The overall layout optimization design of an orbital propellant depot involves the optimization of shape, size, and positions of propellant tanks in... 相似文献
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针对高强度采动巷道围岩控制难题,从实验室岩样尺度和现场巷道尺度研究了湾图沟煤矿13405工作面回风平巷围岩稳定性特征。结合单轴压缩试验和声波测试分析了干燥、自然及饱和状态下3组岩样的力学行为差异特征。利用钻孔成像,分析了高强度采动影响巷道围岩裂隙发育分段特征。结果表明:干燥、自然及饱和状态下岩样的单轴抗压强度和弹性模量依次降低,水分的存在极大地降低了岩石的强度和刚度。实煤体段围岩仅在深度1 m范围内发现少量纵向裂隙。高静压段两帮维护效果较差,煤帮裂隙极为发育,存在高量值的离层。动压段巷道顶板完整性较好,两帮均发现较大离层,且超出了锚杆正常锚固范围,严重影响了巷道锚固结构的稳定性。 相似文献