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11.
Pb(Zr0.50Ti0.50)O3 solid solution was prepared using lead acetate and transition metal n-propoxides in n-propanol or n-butoxides in n-butanol. The complex solutions were hydrolysed with an excess of H2O. The resultant powders were calcined up to 700°C for 30 minutes in a flowing oxygen atmosphere. Scanning electron microscope analysis showed different morphologies of the resultant powders. The n-propoxide derived powder consisted of gel fragments, while the n-butoxide derived one had agglomerated submicrometre particles. EDS analysis of the powders revealed no chemical heterogeneities in the examined samples upon calcining up to 600°C, notwithstanding the type of precursor used. Both samples, calcined at 700°C, exhibited a slight deficiency of lead in the pyrochlore type phase as compared to the perovskite phase. 相似文献
12.
A novel, ultrafast, mild and scalable amide bond formation strategy in methanol using simple thioacids and amines is described. The mechanism suggests that the coupling reactions are initially mediated by CuSO(4)·5H(2)O and subsequently catalyzed by in situ generated copper sulfide. The pure peptides were isolated in satisfactory yields in less than 5 minutes. 相似文献
13.
R. B. Kadam G. G. Mali B. S. Mohite 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):501-511
A selective and effective chromatographic separation method for thorium(IV) has been developed by using poly [dibenzo-18-crown-6] as stationary phase. The separations are carried out from glycine medium. The sorption of thorium(IV) was quantitative from 1 × 10?2 to 1 × 10?4 M glycine. The elution of thorium(IV) was quantitative with 2.0–8.0 M HCl, 4.0–7.0 M HBr, 1.0–2.0 M HClO4 and 5.0 M H2SO4. The capacity of poly [dibenzo-18-crown-6] for thorium(IV) was found to be 0.215 ± 0.01 mmol/g of crown polymer. The effect of concentration of glycine, metal ion, foreign ion and eluents has been studied. Thorium(IV) was separated from a number of cations in ternary as well as in multicomponent mixtures. The applicability of the proposed method was checked for the determination of thorium(IV) in real as well as geological sample. The method is simple, rapid, and selective with good reproducibility (approximately ±2 %). 相似文献
14.
D. M. Todorović J. Zakrzewski M. Maliński T. Grozdić F. Firszt 《The European physical journal. Special topics》2008,154(1):263-266
The results of experimental studies of optical and
structural properties in bulk crystals of
Zn1-xBexTe (x = 0.02, 0.06 and 0.12) were presented. The
amplitude and phase photoacoustic (PA) spectra were measured and analyzed in
dependence on the wavelength of the excitation optical beam, at different
frequencies of modulation, using the PA microphone (PAmic) and PA
piezoelectric (PApze) spectroscopy methods. The differences in PA spectra of
as grown and annealed in zinc vapor samples were observed. 相似文献
15.
16.
The core level binding energies of simple metals, Mg and Al have been calculated by employing a single shot, add on self interaction correction proposed by Perdew and Norman. The correction applies to the eigenvalue of the single particle like Kohn-Sham equation. The calculations have been performed using atom in jellium model. The corrected eigenvalues show a marked improvement over the Kohn-Sham eigenvalues bringing them closed to the ΔSCF binding energies reported by Nieminen and Puska. 相似文献
17.
Xin?YangEmail author Mali?Gong Lei?Huang Ping?Yan Haitao?Zhang 《Optical and Quantum Electronics》2004,36(12):1079-1088
In this paper, the authors investigate the performance of recently presented run-length limited (4, 18) code for high density optical storage systems. The construction of the code is described simply. The code has code rate R = 1/3 and density ratio (DR) = 1.67. The bit error rate (BER) performance for decision feedback equalizer (DFE) and partial response maximum likelihood (PRML) detector are simulated, considering signal-to-noise ratio (SNR) and optical channel jitter. The result shows that the performance of the code is acceptable. The encoder and decoder of the code are implemented by complex programmable logic device (CPLD) chip and the hardware resources required for encoder and decoder arelow. 相似文献
18.
Suter A Mali M Roos J Brinkmann D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,143(2):266-273
We present a NMR pulse double-irradiation method which allows one to separate magnetic from quadrupolar contributions in the spin–lattice relaxation. The pulse sequence fully saturates one transition while another is observed. In the presence of a Δm = 2 quadrupolar contribution, the intensity of the observed line is altered compared to a standard spin-echo experiment. We calculated analytically this intensity change for spins I = 1,
,
, thus providing a quantitative analysis of the experimental results. Since the pulse sequence we used takes care of the absorbed radiofrequency power, no problems due to heating arise. The method is especially suited when only one NMR sensitive isotope is available. Different cross-checks were performed to prove the reliability of the results obtained. The applicability of this method is demonstrated by a study of the plane oxygen 17O (I =
) in the high-temperature superconductor YBa2Cu4O8: the 17O spin–lattice relaxation rate consists of magnetic as well as quadrupolar contributions. 相似文献
19.
Sawanta S. Mali Hyungjin Kim Chang Su Shim Pramod S. Patil Chang Kook Hong 《固体物理学:研究快报》2013,7(12):1050-1054
Quaternary kesterite‐type Cu2ZnSnS4 (CZTS) nanoparticles (NPs) were successfully synthesized by a single‐step solvothermal process. Semiconductor CZTS nanoparticles were obtained from ethylene glycol (EG) and CZTS precursor after solvothermal process at 180 °C for 30 h in polyvinylpyrrolidone (PVP) medium. The synthesized CZTS NPs were further annealed at 450 °C in nitrogen atmosphere and used for further characterizations. The CZTS NPs were characterized using X‐ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), micro Raman spectroscopy, high resolution transmission electron microscopy (HRTEM) and X‐ray photoelectron spectroscopy (XPS). The optical properties of the CZTS NPs were recorded by UV–vis absorption spectroscopy. The results showed that the synthesized CZTS nanoparticles are kesterite‐type CZTS, with good crystallinity and a stoichiometric composition. Moreover, the prepared nanoparticles have a size ranging from 5–7 nm and a band gap of ~1.5 eV.
20.
Dr. Mirta Rubčić Dr. Krunoslav Užarević Dr. Ivan Halasz Nikola Bregović Momir Mališ Dr. Ivica Đilović Zoran Kokan Dr. Robin S. Stein Prof. Robert E. Dinnebier Prof. Vladislav Tomišić 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(18):5620-5631
The Schiff base derived from salicylaldehyde and 2‐amino‐3‐hydroxypyridine affords a diversity of solid forms, two polymorphic pairs of the enol‐imino ( D1 a and D1 b ) and keto‐amino ( D2 a and D2 b ) desmotropes. The isolated phases, identified by IR spectroscopy, X‐ray crystallography, and 13C cross‐polarization/magnetic angle spinning (CP/MAS) NMR spectroscopy, display essentially planar molecular conformations characterized by strong intramolecular hydrogen bonds of the O? H???N ( D1 ) or N? H???O ( D2 ) type. A change in the position of the proton within this O???H???N system is accompanied by substantially different molecular conformations and, subsequently, by divergent supramolecular architectures. The appearance and interconversion conditions for each of the four phases have been established on the basis of a number of solution and solvent‐free experiments, and evaluated against the results of computational studies. Solid phases readily convert into the most stable form ( D1 a ) upon exposure to methanol vapor, heating, or by mechanical treatment, and these transformations are accompanied by a change in the color of the sample. The course of thermally induced transformations has been monitored in detail by means of temperature‐resolved powder X‐ray diffraction and infrared spectroscopy. Upon dissolution, all forms equilibrate immediately, as confirmed by NMR and UV/Vis spectroscopy in several solvents, with the equilibrium shifted far towards the enol tautomer. This study reveals the significance of peripheral groups in the stabilization of metastable tautomers in the solid state. 相似文献