Fabrication,performance and applications of integrated nanodielectric properties of materials – a review

Abstract

The design and development of modern technological composites for the electrical and electronic applications are highly crucial. The minitualization, performance and durability of nanocomposites are achieved by integrating the nanodielectric properties of materials. In this review article, the entire upcoming trends in the domain of nanodielectric illustrated with important applications co-related to the various fabrication techniques of integrated nanodielectric composites are provided. The factors affecting the nanodielectric due to operating electric field and material interface which exhibit the high dielectric constant, low loss and moderate breakdown voltage. The complete sketch from concept, fabrication, factors co-related and applications of nanodielectric properties with the future scope are taken into consideration for further developments.     

Electronic properties of Cu(In,Ga)Se2 heterojunction solar cells–recent achievements, current understanding, and future challenges

The recent achievements of high-efficiency Cu(In,Ga)Se₂ heterojunction solar cells are reviewed with a special focus on the understanding of the electronic transport properties of the devices. We discuss the basic limitations of the device performance, the present understanding of electronic device analysis, as well as the role of intrinsic defects and of the interfaces for the performance of the solar cells. Received: 12 March 1999 / Accepted: 28 March 1999 / Published online: 24 June 1999     

Heat transfer enhancement—a review of techniques and their possible impact on energy efficiency in the U.K.

There are many techniques for enhancing heat transfer. These may be usefully categorized as active or passive in nature. Approximately 20 enhancement methods are reviewed in this paper, and their status in the United Kingdom discussed. An attempt is made to predict the effect more widespread use of enhancement would have on energy cost savings due to heat recovery. The use of enhancement in other unit operations is briefly discussed. Recent U.S. patents on enhancement methods are reviewed.     

Grain boundaries of nanocrystalline materials – their widths, compositions, and internal structures

Nanocrystalline materials contain many atoms at and near grain boundaries. Sufficient numbers of Mössbauer probe atoms can be situated in grain boundary environments to make a clear contribution to the measured Mössbauer spectrum. Three types of measurements on nanocrystalline materials are reported here, all using Mössbauer spectrometry in conjunction with X-ray diffractometry, transmission electron microscopy, or small angle neutron scattering. By measuring the fraction of atoms contributing to the grain boundary component in a Mössbauer spectrum, and by knowing the grain size of the material, it is possible to deduce the average width of grain boundaries in metallic alloys. It is found that these widths are approximately 0.5 nm for fcc alloys and slightly larger than 1.0 nm for bcc alloys. Chemical segregation to grain boundaries can be measured by Mössbauer spectrometry, especially in conjunction with small angle neutron scattering. Such measurements on Fe-Cu and Fe₃Si-Nb were used to study how nanocrystalline materials could be stabilized against grain growth by the segregation of Cu and Nb to grain boundaries. The segregation of Cu to grain boundaries did not stabilize the Fe-Cu alloys against grain growth, since the grain boundaries were found to widen and accept more Cu atoms during annealing. The Nb additions to Fe₃Si did suppress grain growth, perhaps because of the low mobility of Nb atoms, but also perhaps because Nb atoms altered the chemical ordering in the alloy. The internal structure of grain boundaries in nanocrystalline materials prepared by high-energy ball milling is found to be unstable against internal relaxations at low temperatures. The Mössbauer spectra of the nanocrystalline samples showed changes in the hyperfine fields attributable to movements of grain boundary atoms. In conjunction with SANS measurements, the changes in grain boundary structure induced by cryogenic exposure and annealing at low temperature were found to be somewhat different. Both were consistent with a sharper density gradient between the crystalline region and the grain boundary region.     

Theoretical characterisation and design of D–π–A star-shaped molecules with triphenylamine as core and diketopyrrolopyrroles as arms for organic solar cells

A series of novel D–π–A star-shaped molecules with triphenylamine (TPA) fragments as cores, diketopyrrolopyrrole (DPP) fragments as arms, and different conjugate π-bridges those connect TPA and DPP fragments have been designed for small molecules based organic solar cells (OSCs) applications. The optical, electronic, and charge transporting properties have been systematically investigated by means of density functional theory (DFT) and time-dependent DFT (TD-DFT) methods. The parameters such as energetic driving force ΔE_L-L, adiabatic ionisation potentials (AIP), and adiabatic electron affinities (AEA) were also calculated at the same level to preliminarily evaluate the performance of the OSCs. The results of frontier molecular orbitals (FMOs) show that the designed molecules provide the best match matched energy levels with typical acceptors PCBM, bisPCBM, and PC70BM except for molecule containing benzo[c][1,2,5]thiadiazole unit because of its low energetic driving force ΔE_L-L. It turned out that the FMO energy levels, the band gaps, AIP, AEA, and absorption spectrum can be tuned effectively by the introduction of different groups. Additionally, our results suggest that the designed molecules can act as promising candidates for donor materials and ambipolar charge transport materials for OSCs.     

Particular periodic solutions to a nonintegrable system of Schrödinger nonlinear equations and their eigenvalues

Particular solutions to the general case of a nonintegrable system of Schrödinger nonlinear equations in the form of a family of cnoidal waves are found on the assumption of linear relationship between the squared moduli of the orthogonal components of a vector field. The domains of existence of solutions and the corresponding spectra of eigenvalues are determined.     

Sonochemical degradation of poly- and perfluoroalkyl substances – A review

Poly- and perfluoroalkyl substances (PFAS) have received considerable attention from environmental scientists and engineers because of their stability and widespread. Sonochemical process has been widely used in the environmental field to remove pollutants due to its advantages in terms of operational simplicity, no secondary pollutant formation and safety. Currently, many studies have reported sonochemical degradation of various PFAS in laboratory settings and showed excellent removal potential. This article reviewed the effects of different power densities, ultrasonic frequencies, temperatures, atmosphere conditions, additives, and initial concentration and chemical properties of PFAS on the sonochemical degradation of PFAS. Sonochemical methods combined with conventional techniques for PFAS removal were elaborated as well. Additionally, this article discussed the challenges and prospects of using sonochemical approaches for PFAS remediation.     

Classical solutions ofℂP n−1 models and their generalizations

We discuss finite action solutions ofP ^n–1 models, of their Grassmannian generalizations and of a classical fermion — boson model based on the supersymmetric extension of theP ^n–1 model.Invited talk presented at the International Symposium Selected Topics in Quantum Field Theory and Mathematical Physics, Bechyn, Czechoslovakia, June 14–19, 1981.I would like to thank Dr. A. M. Din for his collaboration with me on all the topics discussed here. Also I would like to thank E. F. Corrigan, D. B. Fairlie, M. Günyadin, J. Lukierski, I. Singer, R. Stora and many others for discussions and constructive criticisms and Professor J. Niederle for his invitation to present this talk at the symposium and for hospitality in Czechoslovakia.     

Electroweak phase transition and some related phenomena – a brief review

Pramana - In this review we have outlined a very brief history of the Higgs boson search and the development of the strategies for searching for the Higgs boson in its diphoton decay channel. We...     

Painlevé integrability of a generalized fifth-order KdV equation with variable coefficients: Exact solutions and their interactions

By means of singularity structure analysis, the integrability of a generalized fifth-order KdV equation is investigated. It is proven that this equation passes the Painlevé test for integrability only for three distinct cases. Moreover, the multisoliton solutions are presented for this equation under three sets of integrable conditions. Finally, by selecting appropriate parameters, we analyze the evolution of two solitons, which is especially interesting as it may describe the overtaking and the head-on collisions of solitary waves of different shapes and different types.     

Hydrogen adsorption and desorption on the Pt and Pd subnano clusters – a review

In this review, we present our recent first principles studies on the sequential H₂ dissociative chemisorption and H desorption on the Pt_n and Pd_n clusters (n=2-9, 13). Upon full saturation by H atoms, the calculated H₂ dissociative chemisorption energy and H desorption energy on Pt₁₃ and Pd₁₃ clusters are similar to the corresponding values on smaller close-packed clusters. Indeed, the catalytic performances of these subnano clusters do not vary significantly with the particle sizes or shapes. Instead, they are dependent on the surface metal atoms which can be accessed by H atoms. In addition to the coverage dependency of the H₂dissociative chemisorption and H sequential desorption energies, the phase transition of both Pt₁₃ and Pd₁₃from the icosahedral to fcc-like structures at certain H coverage was also investigated.     

On fractional systems with Riemann-Liouville derivatives and distributed delays – Choice of initial conditions,existence and uniqueness of the solutions

A comparative analysis among the possible types of initial conditions including (or not) derivatives in the Riemann-Liouville sense for incommensurate fractional differential systems with distributed delays is proposed. The provided analysis is essentially based on the possibility to attribute physical meaning to the initial conditions expressed in terms of Riemann-Liouville fractional derivatives. This allows the values of the initial functions for the mentioned initial conditions to be obtained by appropriate measurements or observations. In addition, an initial problem with non-continuous initial conditions partially expressed in terms of Riemann-Liouville fractional derivatives is considered and existence and uniqueness of a (1 ? α)-continuous solution of this initial problem is proved.     

Crystal growth,spectral, thermal and optical properties of an organic single crystal – Dye doped hippuric acid

A new organic dye doped hippuric acid (DHA) single crystals have been grown from aqueous solution of acetone by doping with rhodamine using slow evaporation technique. Rhodamine is a dye, an organic molecule well-studied in laser physics and nonlinear optics for its fluorescent properties. Dyeing of crystals is a practice that was developed particularly for quantum optical applications because of the very significant increase in surface area achieved in growing crystals. In the present work, The DHA single crystals were successfully grown by the slow evaporation method. Good quality single crystals were harvested after 5 days. The grown crystal was characterized by various techniques namely Single crystal X-ray diffraction, FT-IR, UV–vis, NLO and thermal analysis. The FT-IR analysis confirms the presence of various functional groups available in DHA. The optical transmission study and Kurtz and Perry SHG measurement shows the suitability of doped crystals for NLO applications.     

Hamilton’s equations of motion of a vortex filament in the rotating Bose–Einstein condensate and their “soliton” solutions

The equation of motion of a quantized vortex filament in a trapped Bose–Einstein condensate [A. A. Svidzinsky and A. L. Fetter, Phys. Rev. A 62, 063617 (2000)] has been generalized to the case of an arbitrary anharmonic anisotropic rotating trap and presented in the variational form. For condensate density profiles of the form ρ = f(x² + y² + ReΨ(x + iy)) in the presence of the plane of symmetry y = 0, the solutions x(z) describing stationary vortices of U and S types coming to the surface and solitary waves have been found in quadratures. Analogous three-dimensional configurations of the vortex filament uniformly moving along the z axis have also been found in strictly cylindrical geometry. The dependence of solutions on the form of the function f(q) has been analyzed.     

Tannic acid NPs – Synthesis and immobilization onto a solid surface in a one-step process and their antibacterial and anti-inflammatory properties

Tannic acid nanoparticles were synthesized from an aqueous solution without the use of stabilizers via a sonochemical process. In order to avoid the dissolution of the formed nanoparticles, the sonochemical reaction was performed in the presence of a cotton fabric: following their formation, the tannic acid nanoparticles were embedded into the cotton substrate in a one-step process. The bioactive properties of the tannic acid coated surface were examined towards the inhibition of myeloperoxidase and collagenase, two major enzymes related with inflammatory processes. In addition, the antibacterial activity of the tannic acid nanoparticles coated textiles was evaluated against Staphylococcus aureus and Pseudomonas aeruginosa.     

On some exact solutions of slightly variant forms of Yang’s equations and their graphical representations

The equations obtained by Yang while discussing the condition of self-duality of SU(2) gauge fields on Euclidean four-dimensional space have been generalized. Exact solutions and their graphical representations for the generalized equation (for some particular values of the parameters) have been reported. They represent interesting physical characteristics like waves with spreading solitary profile, spreading wave packets, waves with pulsating solitary profile (between zero and a maximum), waves with oscillatory solitary profile and chaos.      

Metastable decay of DNA components and their compositions – a perspective on the role of reactive electron scattering in radiation damage

Here we review recent studies on the metastable fragmentation of individual DNA and RNA building blocks and their compositions using matrix assisted laser desorption/ionization mass spectrometry (MALDI). To compare the fragmentation channels of small DNA components with larger compositions we have studied the metastable fragmentation of the deprotonated nucleobases, ribose, ribose-monophoshates, the nucleosides, the nucleoside 5′-monophosphates and selected oligonucleotides. Both previously published and unpublished data are reported. To gain a comprehensive picture of the fragmentation of individual components, metastable fragmentation of native components are in many cases compared to chemically modified components and isotopic labelling is used to unambiguously identify fragments. Furthermore, to shed light on the underlying fragmentation mechanisms we complement the experimental studies with classical dynamics simulations of the fragmentation of selected compounds. For the DNA and RNA components where dissociative electron attachment studies have been conducted we compare these to the metastable fragmentation channels observed here.