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1.
《Ceramics International》2022,48(14):20134-20145
M-type calcium hexaferrite- CaFe12O19 (CaM) has been prepared in presence of Azadirachta indica, and Murraya koenigii leaves extracts, followed by calcination at 650 °C for 3h. It was observed that the presence of phytochemicals in both leaves extract plays a vital role in deciding the structural, optical, microstructural, magnetic, and dielectric properties of prepared CaM hexaferrites. Prepared samples were characterized using FT-IR, XRD, UV–Vis, SEM, VSM, and dielectric measurements. FTIR, UV– Vis, and antioxidant assay confirmed the presence of phenolic content and antioxidant property of plant extract. This further resulted in the formation of a pure hexagonal phase as revealed by the XRD analysis. The surface morphology of prepared ferrites modified through this greener route was illustrated by the spongy appearance of ferrites in SEM micrographs.The saturation magnetization for the CaM powder prepared using Murraya koenigii leaves extract is 11.78 Am2/kg, while that prepared from Azadirachta indica leaves extract is 3.56 Am2/kg. Both samples show a magnetically soft nature, with a multidomain structure. The energy bandgap was also observed to be 2.01 eV. Moreover, the calcium ferrite synthesized by Murraya koenigii leaves had ε’max ~ 25 and that synthesized in presence of Azadirachta indica leaves had ε’max ~ 200 at ~20 Hz. 相似文献
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含偶氮基团的不对称弯曲型液晶分子的合成及其光谱特性 总被引:2,自引:2,他引:0
合成了6个含偶氮基团的具有不同苯环个数的不对称弯曲型液晶分子,用1 H NMR、HRMS表征其结构,采用差示扫描量热法(DSC)和偏光显微镜(POM)研究其液晶性能。考察结果表明:所有化合物均出现了液晶相,特别是含有3个苯环的分子在较低温度下出现了向列相;偶氮基团的吸收光谱在330~360nm出现了较强的由π-π*电子跃迁引起的吸收,在430~450nm出现了较弱的由n-π*电子跃迁引起的吸收,其吸收波长的变化表明分子的弯曲形状和电子分布使分子吸收波长有较大的变化。 相似文献
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通过乳液聚合法制备纳米聚苯胺,使用十二烷基苯磺酸(DBSA)作为掺杂剂,在聚苯胺链上引入直链烷基,得到可溶性纳米聚苯胺(PANI-DBSA)复合物。研究了DBSA含量对PANI-DBSA复合物溶解度和电导率的影响,及制备过程中聚苯胺的生成和最终产物的紫外-可见光特征。结果表明:聚苯胺颗粒分散性好,粒径为20~100nm,当DBSA与苯胺单体摩尔比为3.0时,聚合物在甲苯中的溶解度最高为3.76%,当DBSA与苯胺单体摩尔比为1.0,聚合物导电性最好,电导率为250.4S/m。PANI-DBSA复合物在波长300~800nm具有良好的吸收性能。 相似文献
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Ghazali MS Zakaria A Rizwan Z Kamari HM Hashim M Zaid MH Zamiri R 《International journal of molecular sciences》2011,12(3):1496-1504
The optical band-gap energy (E(g)) is an important feature of semiconductors which determines their applications in optoelectronics. Therefore, it is necessary to investigate the electronic states of ceramic ZnO and the effect of doped impurities under different processing conditions. E(g) of the ceramic ZnO + xBi(2)O(3) + xTiO(2), where x = 0.5 mol%, was determined using a UV-Vis spectrophotometer attached to a Reflectance Spectroscopy Accessory for powdered samples. The samples was prepared using the solid-state route and sintered at temperatures from 1140 to 1260 °C for 45 and 90 minutes. E(g) was observed to decrease with an increase of sintering temperature. XRD analysis indicated hexagonal ZnO and few small peaks of intergranular layers of secondary phases. The relative density of the sintered ceramics decreased and the average grain size increased with the increase of sintering temperature. 相似文献
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聂海 《上海电力学院学报》2010,(6)
采用循环伏安(CV)法结合紫外-可见(UV-Vis)吸收光谱表征了4种新型电致发光材料三芳胺聚合物TPD(PTPD)的能带结构,并对引入的基团及分子结构对其能带结构的影响进行了探讨。结果表明,从聚合物TPD和小分子TPD的UV-VIS吸收光谱的最大吸收来看,聚合后TPD的能带结构没有太大的改变。从循环伏安图看出,材料的具有较好电化学稳定性。并制成了ITO(氧化铟锡)/PTPD/Alq3(8-羟基喹啉铝)/Mg:Ag异质结电致发光器件,与典型的ITO/TPD/Alq3/Mg:Ag器件进行了比较,研究发现其器件的稳定性有的明显提高。 相似文献
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Dearomatization levels during electrochemical oxidation of p-methoxyphenol (PMP) and p-nitrophenol (PNP) have been determined through UV-Vis spectroscopy using solid phase extraction (UV-Vis/SPE). The results show that the method is satisfactory to determine the ratio between aromatic compounds and aliphatic acids and reaction kinetics parameters during treatment of wastewater, in agreement with results obtained from numerical deconvolution of UV-Vis spectra. Analysis of solutions obtained from electrolysis of substituted phenols on antimony-doped tin oxide (SnO2Sb) showed that an electron acceptor substituting group favored the aromatic ring opening reaction, preventing formation of intermediate quinone during oxidation. 相似文献
10.
The application of in situ Raman, IR, and UV-Vis DRS spectroscopies during steady-state methanol oxidation has demonstrated
that the molecular structures of surface vanadium oxide species supported on metal oxides are very sensitive to the coordination
and H-bonding effects of adsorbed methoxy surface species. Specifically, a decrease in the intensity of spectral bands associated
with the fully oxidized surface (V5+) vanadia active phase occurred in all three studied spectroscopies during methanol oxidation. The terminal V = O (∼1030 cm−1) and bridging V–O–V (∼900–940 cm−1) vibrational bands also shifted toward lower frequency, while the in situ UV-Vis DRS spectra exhibited shifts in the surface
V5+ LMCT band (>25,000 cm−1) to higher edge energies. The magnitude of these distortions correlates with the concentration of adsorbed methoxy intermediates
and is most severe at lower temperatures and higher methanol partial pressures, where the surface methoxy concentrations are
greatest. Conversely, spectral changes caused by actual reductions in surface vanadia (V5+) species to reduced phases (V3+/V4+) would have been more severe at higher temperatures. Moreover, the catalyst (vanadia/silica) exhibiting the greatest shift
in UV-Vis DRS edge energy did not exhibit any bands from reduced V3+/V4+ phases in the d–d transition region (10,000–30,000 cm−1), even though d–d transitions were detected in vanadia/alumina and vanadia/zirconia catalysts. Therefore, V5+ spectral signals are generally not representative of the percent vanadia reduction during the methanol oxidation redox cycle,
although estimates made from the high temperature, low methoxy surface coverage IR spectra suggest that the catalyst surfaces
remain mostly oxidized during steady-state methanol oxidation (15–25% vanadia reduction). Finally, adsorbed surface methoxy
intermediate species were easily detected with in situ IR spectroscopy during methanol oxidation in the C–H stretching region
(2800–3000 cm−1) for all studied catalysts, the vibrations occurring at different frequencies depending on the specific metal oxide upon
which they chemisorb. However, methoxy bands were only found in a few cases using in situ Raman spectroscopy due to the sensitivity
of the Raman scattering cross-sections to the specific substrate onto which the surface methoxy species are adsorbed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献