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931.
Sauvik Chatterjee Dr. Arnab Palui Sayantan Chongdar Dr. Shyamal Roy Prof. Dr. Aswini Ghosh Prof. Dr. Asim Bhaumik 《化学:亚洲杂志》2021,16(16):2261-2266
Zinc oxide is one of the most widely studied semiconductor metal oxides, which predominantly crystallizes as hexagonal wurtzite and often cubic zinc-blende phases. Here we report the transformation of the highly stable wurtzite ZnO to a new triclinic phase NZO-2 by using metformin as a template during post-synthesis hydrothermal treatment. This crystalline phase of the material NZO-2 has been identified through the refinement of the powder XRD data. NZO-2 possesses porous rod like particle morphology consisting of the self-assembly of 3–7 nm size spherical nanoparticles and interparticle nanoscopic voids spaces. NZO-2 has been surface phosphorylated and the resulting material displayed good proton conductivity. Further, NZO-2 displayed ultra-low band gap of 1.74 eV, thereby responsible for red emission under high energy laser excitation and this may open new opportunities in optoelectronic application of ZnO. 相似文献
932.
G. Szenes 《辐射效应与固体损伤》2020,175(3-4):241-256
ABSTRACTThe role of various materials parameters in track formation is discussed. Experimental information is utilized showing a direct quantitative relationship in different solids between the melting points Tm and the ion-induced track radii Re without involving other materials parameters. It is shown for Θ?=?Tm???Tir (Tir – irradiation temperature) that Θ~exp{?Re2/w2} for Se/N?=?constant, where Se and N are the electronic stopping power and the number density of atoms and w?=?4.5?nm. The validity of this universal-type relation is demonstrated for 14 different insulators including LiNbO3 and BaFe12O19. It is shown that the thermal diffusivity D, the heat of fusion L the band gap energy Eg and the absorption radius αe of the electron distribution must not affect the track sizes as this would not be coherent with this identical behavior. Original reports on LiNbO3 and BaFe12O19 with opposite conclusions are critically analyzed. It is shown that an arbitrary value of the ion energy was used in the analysis that modified substantially the results leading to an undue justification of the contribution of L and Eg in apparent agreement with the experimental data. 相似文献
933.
Thomas Bjørn Egede Grønbech Kasper Tolborg Helle Svendsen Jacob Overgaard Yu-Sheng Chen Bo Brummerstedt Iversen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(39):8651-8662
FeSb2 exhibits a colossal Seebeck coefficient ( ) and a record-breaking high thermoelectric power factor. It also has an atypical shift from diamagnetism to paramagnetism with increasing temperature, and the fine details of its electron correlation effects have been widely discussed. The extraordinary physical properties must be rooted in the nature of the chemical bonding, and indeed, the chemical bonding in this archetypical marcasite structure has been heavily debated on a theoretical basis since the 1960s. The two prevalent models for describing the bonding interactions in FeSb2 are based on either ligand-field stabilization of Fe or a network structure of Sb hosting Fe ions. However, neither model can account for the observed properties of FeSb2. Herein, an experimental electron density study is reported, which is based on analysis of synchrotron X-ray diffraction data measured at 15 K on a minute single crystal to limit systematic errors. The analysis is supplemented with density functional theory calculations in the experimental geometry. The experimental data are at variance with both the additional single-electron Sb−Sb bond implied by the covalent model, and the large formal charge and expected d-orbital splitting advocated by the ionic model. The structure is best described as an extended covalent network in agreement with expectations based on electronegativity differences. 相似文献
934.
How much different genders contribute to citations and whether we see different gender patterns between STEM and non-STEM researchers are questions that have long been studied in academia. Here we analyze the research output in terms of citations collected from the Web of Science of males and females from the largest Croatian university, University of Zagreb. Applying the Mann–Whitney statistical test, for most faculties, we demonstrate no gender difference in research output except for seven faculties, where males are significantly better than females on six faculties. We find that female STEM full professors are significantly more cited than male colleagues, while male non-STEM assistant professors are significantly more cited than their female colleagues. There are ten faculties where females have the larger average citations than their male colleagues and eleven faculties where the most cited researcher is woman. For the most cited researchers, our Zipf plot analyses demonstrate that both genders follow power laws, where the exponent calculated for male researchers is moderately larger than the exponent for females. The exponent for STEM citations is slightly larger than the exponent obtained for non-STEM citations, implying that compared to non-STEM, STEM research output leads to fatter tails and so larger citations inequality than non-STEM. 相似文献
935.
Jie Wang Dr. Huapeng Ruan Zhaobo Hu Wenqing Wang Dr. Yue Zhao Prof. Xinping Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202103897
The one-electron reduction of indeno[2,1-a]fluorene-11,12-dione ( IF ) with various alkali metals prepare the radical anion salts. The data about different structures, properties, and characterization was obtained by single-crystal X-ray diffraction, electron paramagnetic resonance (EPR) spectroscopy, superconducting quantum interference device (SQUID) measurements, and physical property measurement system (PPMS). Compound IF .−K+(18-c-6) is regarded as a one-dimensional magnetic chain through C−H⋅⋅⋅C interaction. Theoretical calculations and magnetic results showed that [ IF .−K+(15-c-5)]2 is a dimer with an open-shell ground state. Compounds IF .−Na+(15-c-5) and IF .−K+(cryptand) are monoradical anion salts: IF 2.−Li+ possesses unique π-stack structure with an interplanar separation less than 3.46 Å, making it a semiconductor (δRT=1.9×10−4 S ⋅ cm−1). This work gives insights into multifunctional radical anions, and describes the design and development of different functional radicals. 相似文献
936.
937.
Dr. Hui Wang Sen Jin Prof. Dr. Xiaodong Zhang Prof. Dr. Yi Xie 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(51):23024-23035
Owing to the intrinsically low dielectric properties, robust Coulomb interactions between photoinduced electrons and holes lead to dramatically strong exciton effects in polymeric photocatalysts. Such effects endow polymeric matrixes with nontrivial photoexcitation processes determining photocatalytic energy utilization. In this Minireview, we describe recent progress in the investigation of the excitonic effect in polymeric photocatalysts. On the basis of the understanding of excitonic effects in polymeric systems, we outline the relationships between excitonic behaviors and photocatalytic performance. Advances in optimizing the excitonic effect for gaining high-efficiency polymer-based photocatalysis are summarized. We also discuss the challenges in the field and forecast the directions for future research. 相似文献
938.
Dr. Andrej Jančařík Daniel Mildner Dr. Yuuya Nagata Dr. Marzena Banasiewicz Joanna Olas Dr. Boleslaw Kozankiewicz Dr. Jan Holec Dr. André Gourdon 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(48):12388-12394
Acenes, polyaromatic hydrocarbons composed of linearly fused benzene rings have received immense attention due to their performance as semiconductors in organic optoelectronic applications. Their appealing physicochemical properties, such as extended delocalization, high charge carrier mobilities, narrow HOMO-LOMO gaps and partially radical character in the ground state make them very attractive targets for many potential applications. However, the intrinsic synthetic challenges of unsubstituted members such as high reactivity and poor solubility are still limiting factors for their wider exploitation. Herein, we report a simple general synthesis of a new family of angularly fused acenoacenes with improved stability compared to their isoelectronic linear counterparts. The synthesis and comprehensive characterization of pentacenopentacene, pentacenohexacene and hexacenohexacene, with lengths between decacene and dodecacene, are disclosed. 相似文献
939.
940.