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Ba(Fe$_{1/2}$Nb$_{1/2}$)O$_3$ (BFN) ceramics are considered to be promising for technological applications owing to their high dielectric constant over a wide range of temperatures. However, there exists considerable discrepancy over the structural details. We address this discrepancy through a combined x-ray diffraction at room temperature and neutron powder diffraction measurements in the range from 5K up to room temperature, supplemented by a comparative analysis of the earlier reported structures. Our study reveals a cubic structure with space group Pm$\bar{3}$m at all measured temperatures. Further, the x-ray near edge structure and the extended x-ray absorption fine structure studies on the local environment of the Fe ions is consistent with the cubic symmetry. An appropriate value of $U$ for DFT+$U$ calculations is obtained by comparison with x-ray absorption spectroscopy, which agrees well with the earlier reported electronic properties., Comment: 15 pages, 9 figures

Ba2ScSbO6 (BSS) has been synthesized in polycrystalline form by solid state reaction. Structural characterization of the compound was done through X-ray diffraction (XRD) followed by Riedvelt analysis of the XRD pattern. The crystal structure is cubic, space group Fm-3m (No. 225. Optical band-gap of the present system has been calculated using the UV-Vis Spectroscopy to be 4.2eV. A detailed study of the electronic properties has also been carried out using the Full-Potential Linear Augmented Plane Wave (FPLAPW) as implemented in WIEN2k. BSS is found to be a large band-gap insulator with potential technological applications, such as dielectric resonators and filers in microwave applications, Comment: 4 pages, 3 figures. arXiv admin note: text overlap with arXiv:1309.6785

The paper aims to do a survey along with a comparative analysis of the various cryptography libraries that are applicable in the field of Internet of Things (IoT). The first half of the paper briefly introduces the various cryptography libraries available in the field of cryptography along with a list of all the algorithms contained within the libraries. The second half of the paper deals with cryptography libraries specifically aimed for application in the field of Internet of Things. The various libraries and their performance analysis listed down in this paper are consolidated from various sources with the aim of providing a single comprehensive repository for reference to the various cryptography libraries and the comparative analysis of their features in IoT., Comment: 5 pages, 14 tables

This paper is a comprehensive survey of the various operating systems available for the Internet of Things environment. At first the paper introduces the various aspects of the operating systems designed for the IoT environment where resource constraint poses a huge problem for the operation of the general OS designed for the various computing devices. The latter part of the paper describes the various OS available for the resource constraint IoT environment along with the various platforms each OS supports, the software development kits available for the development of applications in the respective OS along with the various protocols implemented in these OS for the purpose of communication and networking., Comment: 5 pages, 7 tables

This paper analyses the various authentication systems implemented for enhanced security and private re-position of an individual's log-in credentials. The first part of the paper describes the multi-factor authentication (MFA) systems, which, though not applicable to the field of Internet of Things, provides great security to a user's credentials. MFA is followed by a brief description of the working mechanism of interaction of third party clients with private resources over the OAuth protocol framework and a study of the delegation based authentication system in IP-based IoT., Comment: 5 pages, 2 figures

This paper is a general survey of all the security issues existing in the Internet of Things (IoT) along with an analysis of the privacy issues that an end-user may face as a consequence of the spread of IoT. The majority of the survey is focused on the security loopholes arising out of the information exchange technologies used in Internet of Things. No countermeasure to the security drawbacks has been analyzed in the paper., Comment: 7 pages, 3 figures

The supercooled liquid silicon, modeled by Stillinger-Weber potential, shows anomalous increase in heat capacity $C_p$, with a maximum $C_p$ value close to 1060 K at zero pressure. We study equilibration and relaxation of the supercooled SW Si, in the temperature range of 1060 K--1070 K at zero pressure. We find that as the relaxation of the metastable supercooled liquid phase initiates, a straight line region (SLR) is formed in cumulative potential energy distributions. The configurational temperature corresponding to the SLR is close to 1060 K, which was earlier identified as the freezing temperature of 4-coordinated amorphous network. The SLR is found to be tangential to the distribution of the metastable liquid phase and thus influences the broadness of the distribution. As the bath temperature is reduced from 1070 K to 1060 K, the effective temperature approaches the bath temperature which results in broadening of the metastable phase distribution. This, in turn, causes an increase in overall fluctuations of potential energy and hence an increase of heat capacity. We also find that during initial stages of relaxation, 4-coordinated atoms form 6-membered rings with a chair--like structure and other structural units that indicate crystallization. Simultaneously a strong correlation is established between the number of chair-shaped 6-membered rings and the number of 4-coordinated atoms in the system. This shows that all properties related to 4-coordinated particles are highly correlated as the SLR is formed in potential energy distributions and this can be interpreted as a consequence of `freezing' of amorphous network formed by 4-coordinated particles., Comment: Submitted to a Peer-reviewed Journal on 28 January 2014

With increasing temperature, ${\rm Sr}_2{\rm ScSbO}_6$ undergoes three structural phase transitions at approximately ${\rm 400K}$, ${\rm 560K}$ and ${\rm 650K}$, leading to the following sequence of phases: $P2_1/n \rightarrow I2/m \rightarrow I4/m \rightarrow Fm\bar{3}m$, making it an ideal candidate to study the effects of octahedral tilting keeping other parameters fixed. To ascertain the isolated effects of octahedral distortions, the electronic and optical properties of the monoclinic $P2_1/n$ (at room temperature), monoclinic $I2/m$ (at ${\rm 430K}$), tetragonal $I4/m$ (at ${\rm 613K}$) and the cubic $Fm\bar{3}m$ (at ${\rm 660K}$) phases have been studied in terms of the electronic structure, dielectric constant, optical conductivity and electron energy loss spectroscopy using density functional theory. ${\rm Ca}_2{\rm ScSbO}_6$, on the other hand, shows only a $P2_1/n$ phase at room temperature and its properties have been been compared with the corresponding ${\rm Sr}$ compound. UV-Vis spectroscopic studies of the optical properties of the room-temperature phase of these $d^0$ double perovskite have been performed and presence of large direct bandgap for both the compounds have been reported. The electronic bandgaps for the room temperature phases is found to be in good agreement with the corresponding experimental values obtained using the Kubelka-Munk function. Interestingly, in contrast to other Sc-based $d^0$ double perovskites, with increasing octahedral distortions, the effective $t_{\rm 2g}$ bandwidth remains unaffected while the states forming the band change due to changes in unit cell orientation, leading to small effects on the electronic and optical properties., Comment: 27 pages, 8 figures

Ba2CoWO6 (BCoW) has been synthesized in polycrystalline form by solid state reaction at 1200C. Structural characterization of the compound was done through X-ray diffraction (XRD) followed by Rietveld analysis of the XRD pattern. The crystal structure is cubic, space group Fm-3m (No 225) with the lattice parameter, a=8.210A. Optical band-gap of the present system has been calculated using the UV-Vis Spectroscopy and Kubelka-Munk function, its value being 2.45 eV. A detailed study of the electronic properties has also been carried out using the density functional theory (DFT) techniques implemented on WIEN2k. Importance of electron-electron interaction between the Co ions leading to half-metallic behavior, crystal and exchange splitting together with the hybridization between O and Co, W has been investigated using the total and partial density of states., Comment: 3 pages, 3 figures, submitted to 58th DAE-SSPS 2013

We report here the preparation and measurements on the susceptibility, sound velocity and internal friction for Ni-Pt systems. We then compare these experimental results with the first principle theoretical predictions and show that there is reasonable agreement with experiment and theory., Comment: 9 pages, 5 figures. submitted to Journal of Magnetism and Magnetic Materials