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Extraordinary Changes in the Electronic Structure and Properties of CdS and ZnS by Anionic Substitution: Cosubstitution of P and Cl in Place of S 下载免费PDF全文
Summayya Kouser S. R. Lingampalli Dr. P. Chithaiah Anand Roy Sujoy Saha Prof. Umesh V. Waghmare Prof. C. N. R. Rao 《Angewandte Chemie (International ed. in English)》2015,54(28):8149-8153
Unlike cation substitution, anion substitution in inorganic materials such as metal oxides and sulfides would be expected to bring about major changes in the electronic structure and properties. In order to explore this important aspect, we have carried out first‐principles DFT calculations to determine the effects of substitution of P and Cl on the properties of CdS and ZnS in hexagonal and cubic structures and show that a sub‐band of the trivalent phosphorus with strong bonding with the cation appears in the gap just above the valence band, causing a reduction in the gap and enhancement of dielectric properties. Experimentally, it has been possible to substitute P and Cl in hexagonal CdS and ZnS. The doping reduces the band gap significantly as predicted by theory. A similar decrease in the band gap is observed in N and F co‐substituted in cubic ZnS. Such anionic substitution helps to improve hydrogen evolution from CdS semiconductor structures and may give rise to other applications as well. 相似文献
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Shahnaz Kouser Muhammad Nouman Sarwar Qureshi Khalid Hussain Shah Hassan Amir Shah 《等离子体物理论文集》2020,60(10):e202000058
In this paper, we have studied the propagation of non-linear ion-acoustic waves in a plasma comprising of (r, q) -distributed electrons and kappa-distributed positrons. We have investigated the effect of complete electron distribution profile on the propagation of small, as well as arbitrary, amplitude solitons (via pseudopotential technique) by using generalized (r, q) distribution, which exhibits a spiky and flat top nature at low energies and a super-thermal tail at high energies. Interestingly, for negative values of r , solitons are formed with both polarities, positive (compressive) and negative (rarefactive), separately within a small amplitude limit and exist simultaneously in an arbitrary amplitude limit. We also found that the propagation of solitons has been affected by the change in parameters r , q , positron concentration, and electron to positron temperature ratio. The results presented in this study add to the fundamental understanding of the complete profile of the electron distribution function, high- and low-energy parts, and in the formation of compressive and rarefactive small and finite amplitude solitons in both space and astrophysical plasmas. 相似文献
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Ion population fraction calculations using improved screened hydrogenic model with l-splitting 下载免费PDF全文
Amjad Ali G Shabbir Naz Rukhsana Kouser Ghazala Tasneem M Saleem Shahzad Aman-ur-Rehman M H Nasim 《中国物理 B》2018,(10)
Ion population fraction(IPF) calculations are very important to understand the radiative spectrum emitted from the hot dense matter. IPF calculations require detailed knowledge of all the ions and correlation interactions between the electrons of an ion which are present in a plasma environment. The average atom models, e.g., screened hydrogenic model with l-splitting(SHML), now have the capabilities for such calculations and are becoming more popular for in line plasma calculations. In our previous work [Ali A, Shabbir Naz G, Shahzad M S, Kouser R, Rehman A and Nasim M H 2018 High Energy Density Phys. 26 48], we have improved the continuum lowering model and included the exchange and correlation effects in SHML. This study presents the calculation of IPF using classical theory of fluctuation for our improved screened hydrogenic model with l-splitting(I-SHML) under local thermodynamic equilibrium conditions for iron and aluminum plasma over a wide range of densities and temperatures. We have compared our results with other models and have found a very good agreement among them. 相似文献
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G. L. Balaji K. Rajesh Shabana Kouser Ali V. Vijayakumar 《Research on Chemical Intermediates》2013,39(4):1807-1815
Ultrasound-promoted reaction of substituted 2,4-dichloroquinolines (1) with ethyl 4-(3-hydroxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxylate (2) in the presence of K2CO3 as mild base at moderate temperatures leads to 2-chloroquinolin-4-pyrimidine carboxylate derivatives (3) with high regioselectivity. All the compounds synthesized were characterized by use of spectral data and screened for their antibacterial activity against two Gram-positive (Staphylococcus aureus, Bacillus cereus) and two Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Activity was moderate. 相似文献
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Rukhsana Kouser G Tasneem Muhammad Saleem Shahzad S Sardar Amjad Ali M H Nasim M Salahuddin 《中国物理 B》2017,26(7):75201-075201
We present the preliminary results of our code OPAQS(opacity calculation using quantum statistical model) that is based on the self consistent Hartree-Fock-Slater model for the average atom. The code is capable of performing robust calculations of average charge state, frequency-dependent and mean opacities. The accuracy of the atomic model is verified by comparing the calculations of average charge state with various published results. The monochromatic opacities for iron computed at different sets of temperatures and densities are compared with LEDCOP. The Rosseland and Planck opacities for iron and aluminum are validated with some state-of-the-art codes. The results are in good agreement with the published data. 相似文献
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Dr. Nitesh Kumar M. B. Sreedhara Summayya Kouser Prof. Umesh V. Waghmare Prof. C. N. R. Rao 《Chemphyschem》2015,16(13):2745-2750
The effect of N‐doping on the paramagnetic–antiferromagnetic transition associated with the metal–insulator (M–I) transition of V2O3 at 150 K has been studied in bulk samples as well as in nanosheets. The magnetic transition temperature of V2O3 is lowered to ~120 K in the N‐doped samples. Electrical resistivity data also indicate a similar lowering of the M–I transition temperature. First‐principles DFT calculations reveal that anionic (N) substitution and the accompanying oxygen vacancies reduce the energy of the high‐temperature metallic corundum phase relative to the monoclinic one leading to the observed reduction in Nèel temperature. In the electronic structure of N‐substituted V2O3, a sub‐band of 2p states of trivalent anion (N) associated with its strong bond with the vanadium cation appears at the top of the band of O(2p) states, the 3d‐states of V being slightly higher in energy. Its band gap is thus due to crystal field splitting of the degenerate d‐orbitals of vanadium and superexchange interaction, which reduces notably (ΔEg=?0.4 eV) due to their hybridization with the 2p states of nitrogen. A weak magnetic moment arises in the monoclinic phase of N‐substituted V2O3 with O‐vacancies, with a moment of ?1 μB/N localized on vanadium atoms in the vicinity of oxygen vacancies. 相似文献
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Gangaiah Mettela Summayya Kouser Chaitali Sow Prof. Sokrates T. Pantelides Prof. Giridhar U. Kulkarni 《Angewandte Chemie (International ed. in English)》2018,57(29):9018-9022
Conventional gold comprising the cubic lattice is universally known for its stability. However, well known to chemists and metallurgists, this nobility is challenged by reagents such as aqua regia, which dissolve gold to form a salt solution. Among metals, mercury blends with gold to form amalgam, otherwise transition metals such as copper tend to interact with gold surfaces in electrochemical media. Herein, we report a combined experimental and theoretical investigation of the stability of Au microcrystallites bearing unconventional crystal lattices that exhibit enhanced stability towards Hg and aqua regia and practically no interaction with Cu during electroless plating. The unconventional gold is undoubtedly nobler. 相似文献
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Farzana Kouser Vijay Kumar Sharma Masood Rizvi Shaista Sultan Neha Chalotra Vivek K. Gupta Utpal Nandi Bhahwal Ali Shah 《Tetrahedron letters》2018,59(22):2161-2166
A visible light mediated radical addition of thiophenols on 4-phenylbut-3-enoic acids to give diastereoselective synthesis of 3,4-disubstituted γ-lactones is reported. The reaction precludes the conventional prerequisite of conjugate addition. Furthermore, the lactones were successfully utilized in the synthesis of γ-ketoamides. 相似文献
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