Effects of deposition temperature on the structural and morphological properties of thin ZnO films fabricated by pulsed laser deposition

ZnO thin films were grown on Si(1 0 0) substrates using pulsed laser deposition in O₂ gas ambient (10 Pa) and at different substrate temperatures (25, 150, 300 and 400 °C). The influence of the substrate temperature on the structural and morphological properties of the films was investigated using XRD, AFM and SEM. At substrate temperature of T=150 °C, a good quality ZnO film was fabricated that exhibits an average grain size of 15.1 nm with an average RMS roughness of 3.4 nm. The refractive index and the thickness of the thin films determined by the ellipsometry data are also presented and discussed.     

Design of a Photonic Crystal Fiber with Zero Dispersion Wavelength Near 0.65 μm

The zero dispersion point of an index-guided photonic crystal fiber with triangular lattice of air holes has been shifted to 0.65 μm by varying the diameter of air hole of different rings. Using FDTD method, we have estimated group velocity dispersion, effective refractive index, the fiber parameter, and the mode field of the fundamental mode. It has been realized that the value of zero dispersion point is mainly decided by the air holes of the first ring. This fiber can be used for biomedical application, spectroscopy, and supercontinuum generation.     

Analysis of the photo-thermal excitation in a semiconducting medium under the purview of DPL theory involving non-local effect

Meccanica - Non-local theory comprises a unique characteristics by analyzing the effects of all points of the body on a single point of the material. The present study enlightens the propagation of...     

Ringing non-Gaussianity from inflation with a step in the second derivative of the potential

Pramana - This paper deals with the nonlinear generalised advection–diffusion–reaction (GADR) equation subject to some initial and boundary conditions (BCs). Some exact finite...     

Nearly magic rectangles

Magic squares have been extremely useful and popular in combinatorics and statistics. One generalization of magic squares is magic rectangles which are useful for designing experiments in statistics. A necessary and sufficient condition for the existence of magic rectangles restricts the number of rows and columns to be either both odd or both even. In this paper, we generalize magic rectangles to even by odd nearly magic rectangles. We also prove necessary and sufficient conditions for the existence of a nearly magic rectangle, and construct one for each parameter set for which they exist.     

Light outcoupling efficiency enhancement in organic light emitting diodes using an organic scattering layer

Crystallized 4,7‐diphyenyl‐1,10‐phenanthroline (BPhen) films deposited by convenient vacuum thermal evaporation technique have been found to be an efficient means to extract the substrate wave guided light in organic light emitting diodes (OLEDs). The optimized BPhen film working as organic scattering layer was successfully used with OLEDs for light outcoupling efficiency improvement. Enhancement of 26%, 15% and 6% in efficiency of the blue, green and red OLEDs were obtained, respectively. The achievement was found to be advantageous in terms of simplicity of fabrication method and feasibility for large area OLED applications. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

O,O′-Dialkyl/Alkylene Dithiophosphato Bridged Heterobimetallic Complexes: Synthesis and Spectral Characterization

Heterobimetallic adducts of triphenyltin (IV) O,O'-dialkyl/alkylene dithiophosphate of the formulae [Ph₃SnS(S)P(OCH₂CH₃)₂].MA and [Ph₃Sn {S(S)POCH₂C(C₂H₅)(C₄H₉)CH₂}O13}].MA (MA = CdI₂, AgOCOCF₃, AgOCOCCl₃, AgSCN, Hg(OCOCCl₃)₂, Hg(OCOCF₃)₂, Hg(SCN)₂, HgCl₂, and FeCl₃ were prepared and characterized on the basis of physico-chemical and spectral (FTIR, ¹H, ¹³C, ³¹P, and ¹¹⁹Sn NMR) studies. Heterobimetallic adducts were formed through the coordination of the sulfur atom of triphenyltin (IV) O,O'-dialkyl/alkylene dithiophosphate to metal acceptors.     

Metal ion-induced capacitance modulation in near-isostructural complexes-derived electrochromic coordination polymers

Coordination polymers and metal–organic frameworks have attracted immense attention across different fields of science as materials with numerous functional applications. Herein, we report the use of coordination polymers obtained from near-isostructural metal (Mn²⁺, Fe²⁺, and Co²⁺) bipyridine complexes as electrode materials in a symmetric supercapacitor test cell. The variation in the central metal ion (Mn²⁺ vs. Fe²⁺ vs. Co²⁺) in these nearly identical coordination complexes was found to dictate the capacitive performance of the coordination polymers obtained via Pd(II) cross-linking. The central metal ion not only influences the porosity, Brunauer–Emmett–Teller (BET) surface area (6.5 (Mn), 10.4 (Fe), and 29.7 (Co) m²/g), and the areal capacitance, but also the performance parameters such as the cycling stability and charge–discharge kinetics as well as the charge transfer mechanism. A 3:4:5 ratio for the areal capacitance values (9.1 (Mn), 12.2 (Fe), and 15.4 (Co) mF cm^?2 at a scan rate of 5 mV/s) corroborates the modulative effect of the metal center. The cycling stabilities of these coordination polymers also followed the same order. At higher current densities (>0.50 mA cm^?2), the supercapacitors fabricated from the Mn-coordination polymer were found to charge and discharge at faster rates, whereas those fabricated from Fe- or Co-coordination polymers continued to discharge at similar rates, indicating similar pore volumes for the latter as confirmed by BET surface area measurements. Although the materials used in this study resulted in modest capacitive performance, the possibilities to enhance their surface area and crystallinity is envisaged to result in the development of new, multifunctional non-carbon electrode materials with efficient electrochemical storage characteristics and tunable electro-optical properties.     

Performance modeling of state dependent system with mixed standbys and two modes of failure

The present investigation deals with a multicomponent repairable system with state dependent rates. For smooth functioning of the system, mixed standbys (warm and cold) are provided so that the failed units are immediately replaced by standbys if available. To prevent congestion in the system due to failure of units, permanent along with additional repairmen are provided to restore the failed units. It is assumed that the units may fail in two modes. The units have exponential life time and repair time distributions. The failed unit may balk in case of heavy load of failed units. The failed units may also wait in the queue and renege on finding the repairmen busy according to a pre-specified rule. The Chapman–Kolmogorov equations, governing the model in the form of matrix are constructed using transition flow rates of different states. The steady state solution of queue size distribution is derived using product formula. A cost function is suggested to determine the optimal number of warm and cold standbys units required for the desired level of quality of service. The numerical illustrations are carried out to explore the effect of different parameters on performance measures.