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1.
Hicham Mahfoz Kotb Mohamad Mahmoud Ahmad Sajid Ali Ansari Tarek S. Kayed Adil Alshoaibi 《Molecules (Basel, Switzerland)》2022,27(3)
In the current study, we report on the dielectric behavior of colossal-dielectric-constant Na1/2La1/2Cu3Ti4O12 (NLCTO) ceramics prepared by mechanochemical synthesis and spark plasma sintering (SPS) at 850 °C, 900 °C, and 925 °C for 10 min. X-ray powder diffraction analysis showed that all the ceramics have a cubic phase. Scanning electron microscope observations revealed an increase in the average grain size from 175 to 300 nm with an increase in the sintering temperature. SPS NLCTO ceramics showed a room-temperature colossal dielectric constant (>103) and a comparatively high dielectric loss (>0.1) over most of the studied frequency range (1 Hz–40 MHz). Two relaxation peaks were observed in the spectra of the electrical modulus and attributed to the response of grain and grain boundary. According to the Nyquist plots of complex impedance, the SPS NLCTO ceramics have semiconductor grains surrounded by electrically resistive grain boundaries. The colossal dielectric constant of SPS NLCTO ceramics was attributed to the internal barrier layer capacitance (IBLC) effect. The high dielectric loss is thought to be due to the low resistivity of the grain boundary of SPS NLCTO. 相似文献
2.
Kayed A. Abu Safieh Ahmad M. Abu Mahthieh Mustafa M. El-Abadelah Mikdad T. Ayoub Wolfgang Voelter 《Monatshefte für Chemie / Chemical Monthly》2007,21(9):157-160
A novel method for the synthesis of a new series of 5-substituted 1,3-dimethyl pyrazolo[4,3-e][1,2,4]triazines is described. The new synthetic strategy is based on the classical Bischler 1,2,4-benzotriazine synthesis. This approach involves the preparation of 5-hydrazinopyrazole from 5-chloro-1,3-dimethyl-4-nitropyrazole
followed by acylation and nitro group reduction to form the corresponding 4-amino-3-(acylhydrazino)pyrazoles. Intramolecular
oxidative cyclization of the latter derivatives, using polyphosphoric acid, produced the respective target pyrazolotriazines. 相似文献
3.
Kayed A. Abu Safieh Ahmad M. Abu Mahthieh Mustafa M. El-Abadelah Mikdad T. Ayoub Wolfgang Voelter 《Monatshefte für Chemie / Chemical Monthly》2007,138(2):157-160
Summary. A novel method for the synthesis of a new series of 5-substituted 1,3-dimethyl pyrazolo[4,3-e][1,2,4]triazines is described. The new synthetic strategy is based on the classical Bischler 1,2,4-benzotriazine synthesis. This approach involves the preparation of 5-hydrazinopyrazole from 5-chloro-1,3-dimethyl-4-nitropyrazole
followed by acylation and nitro group reduction to form the corresponding 4-amino-3-(acylhydrazino)pyrazoles. Intramolecular
oxidative cyclization of the latter derivatives, using polyphosphoric acid, produced the respective target pyrazolotriazines. 相似文献
4.
Dr. A. F. Eftaiha Dr. Abdussalam K. Qaroush Ghada G. Kayed Abdel Rahman K. Abdel Rahman Dr. Khaleel I. Assaf Prof. Dr. Matthew F. Paige 《Chemphyschem》2020,21(16):1858-1865
A series of water soluble, surface-active ionic liquids (SAILs), namely, 1-alkyl-3-methyl imidazolium chlorides ([Cn-mim]Cl) and their mixtures with palmitic acid (PA) are investigated in Langmuir monolayers and Langmuir–Blodgett films. It is inferred from the surface pressure-area isotherms that C16-mim-IL mixes non-ideally with PA and stabilizes the binary mixed films. In addition, the residence of mim-IL at the water surface is enhanced as a function of the increasing alkyl side chain length. Generally, the compressional moduli values decrease upon increasing the content of the mim-ILs over a wide range of compositions. Furthermore, film relaxation measurements indicate that the IL component is selectively excluded from the mixed films upon achieving a certain target pressure. Brewster angle microscope images demonstrate minimal changes on the PA domains in the presence of either C4- and C8-mim-ILs, whereas presence of the hexadecyl counterpart results in the formation of condensed sheets. Atomic force microscopy imaging of deposited films show the formation of propeller-like aggregates when C8- or C16-mim-IL is present in the mixed films. 相似文献
5.
Acetylacetone was successfully used as a precursor of 4-aminomethylpyrazoles and 4-aminomethylisoxazoles in a two step process at ambient temperature. In the first step, acetylacetone was transformed to the corresponding hexahydropyrimidines (1,3-diazinanes) via two consecutive one-pot Mannich aminomethylations. Hexahydropyrimidines were then treated with hydrazine, phenylhydrazine, and hydroxylamine, respectively, to obtain the corresponding 4-aminomethylpyrazoles and 4-aminomethylisoxazoles in good yields. The hexahydropyrimidine ring decomposed providing the title compounds and a reasonable mechanism has been proposed. 相似文献
6.
Bi1.5ZnSb1.5O7 pyrochlore samples were prepared by solid state reaction method. They were examined by x‐ray diffraction and scanning electron microscopy. Single phase, belongs to the cubic pyrochlore structure, with a lattice parameter of 10.442 Å and grain size that varies from 16 to 20 μm was obtained. The electrical properties were measured at different temperatures in the range 15–330 K under different applied magnetic fields up 1.4 T. In our measurements for Hall coefficient, Hall resistivity, and mobility; we noticed an anomalous behavior at two temperatures (around 250 and 310 K) which was supported by the I‐V measurements (double transition of the slope of I‐V characteristics (β) at the same temperatures). This was discussed in terms of polarization phenomenon and mixed ionic‐electronic conduction. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
7.
Kayed A. Abu Safieh Mustafa M. El‐Abadelah Musa H. Abu Zarga Salim S. Sabri Wolfgang Voelter Ccilia M. M
ssmer 《Journal of heterocyclic chemistry》2001,38(3):623-628
The synthesis of some new pyrazolo[3′,4′:6,7]azepino[5,4,3‐cd] indoles (10a‐c) was achieved via regios‐elective cyclization of the respective 3‐(4‐acylaminopyrazol‐5‐yl)indoles (9a‐c) under Bischler‐Napieralski reaction conditions. The latter compounds were obtained by acylation of the corresponding 3‐(4‐aminopyra‐zol‐5‐yl)indoles (8a,b) which, in turn, were prepared by reduction of the 3‐(4‐nitropyrazol‐5‐yl)indoles precursors (7a,b) . The latter synthons were accessible from the reaction of indolylzinc chlorides (5a,b) with 5‐chloro‐1,3‐dimethyl‐4‐nitropyrazole. Ms and nmr spectral data of 10a‐c are in agreement with the assigned azepino‐indole structure as determined for 10a by X‐ray crystal measurements which demonstrate that the azepine ring is almost completely planar with the indole and pyrazole rings. 相似文献
8.
This review deals with the synthesis and reactions of 5-acetylthiazoles. Some of these reactions have been used successfully for the production of biologically important compounds. The main purpose of this review is to present a survey of the literature on the chemistry of 5-acetylthiazoles and to provide useful and up-to-date information on their applications because these compounds have not been previously reviewed. 相似文献
9.
Bader A. Salameh Kayed A. Abu-Safieh Sanaa R. A. Al-Kaabenah Raed A. Al-Qawasmeh 《Research on Chemical Intermediates》2014,40(8):3001-3009
Thioglycosides derivatives of N-phenylmaleimide have been prepared by the reaction of derivatives of 1-thio-d-glucopyranose, d-galactopyranose, d-lactose, and d-maltose with 3,4-dichloro-N-phenylmaleimide. The reaction of 3,4-dichloro-N-phenyl maleimide with sugar thiols (protected or unprotected) took place by displacement of both chlorine atoms by sulfide nucleophile giving the corresponding bis-thioglycoside products. 相似文献
10.
J. Zegenhagen M. A. Kayed K. -G. Huang W. M. Gibson J. C. Phillips L. J. Schowalter B. D. Hunt 《Applied Physics A: Materials Science & Processing》1987,44(4):365-369
We determined the perpendicular overlayer mismatch for type A and type B NiSi2 samples of thicknesses ranging from about 200 to 1000 Å via bulk x-ray diffraction. An increase in the density of dislocations which are formed to release the strain at the growth temperature leads to an increase in the magnitude of mismatch and strain at room temperature. The results on the thinner type A samples show that the perpendicular overlayer mismatch is found to depend on the overlayer thickness even when no dislocations are present at the interface. This may be due to point defects in the epitaxial NiSi2 layers. 相似文献