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Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of alkali gallium hydrides AGaH4 (A = Li, Na) for three different crystal structures, namely tetragonal (P421/C). tetragonal (P42/nmc) and monoclmic (P21,c). Among the considered structures, tetragonal (P421C) phase is found to be the most stable phase for these hydrides at normal pressure. A pressure induced structural phase transition from tetragonal (P421C) to tetragonal (P42/nmc) is observed. The electronic structure reveals that these hydrides are insulators. The calculated elastic constants indicate that these ternary imides are mechanically stable at normal pressure. [ABSTRACT FROM AUTHOR]

Multi-walled carbon nanotubes (MWCNTs) were irradiated by Gamma (γ)-rays in air with absorbed doses of 25 and 50 kGy. As a result of γ-ray irradiation, the inter-wall distance of MWCNTs was decreased and their graphitic order was improved. The reduction in inter-wall distance and structural ordering was improved with the increasing dosage of irradiation. Experimental evidences are provided by powder XRD and micro-Raman analyses. [ABSTRACT FROM AUTHOR]

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of BeAlH5 for monoclinic crystal structures with two different types of space group namely P21 and C2/c. Among the considered structures monoclinic (P21) phase is found to be the most stable at ambient condition. The structural phase transition from monoclinic (P21) to monoclinic (C2/c) phase is observed in BeAlH5. The electronic structure reveals that this compound is insulator. The calculated elastic constants indicate that this material is mechanically stable at ambient condition. [ABSTRACT FROM AUTHOR]

The structural, electronic and mechanical properties of rare earth nitride ErN is investigated by the first principles calculations based on density functional theory using the Vienna ab-initio simulation package. At ambient pressure ErN is stable in the ferromagnetic state with NaCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that ErN is half metallic at normal pressure. A pressure-induced structural phase transition from NaCl (B1) to CsCl (B2) phase is observed in ErN. Ferromagnetic to non magnetic phase transition is predicted in ErN at high pressure. [ABSTRACT FROM AUTHOR]

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of ABeH3 (A = Li, Na) for three different crystal structures, namely orthorhombic (Pnma), monoclinic (P21/c) and triclinic (P-1) phase. Among the considered structures monoclinic (P21/c) phase is found to be the most stable one for all the three hydrides at ambient condition. The electronic structure reveals that these materials are wide band gap semiconductors. The calculated elastic constants indicate that these materials are mechanically stable at ambient condition. [ABSTRACT FROM AUTHOR]

We report ab-initio calculations for the structural and magnetic phase transition of SmHx (x= 1, 2, 3) using the Vienna ab-initio simulation package (VASP). The non-spin polarized (NSP) and spin polarized (SP) calculations are performed for these hydrides at normal and high pressure. It is found that these compounds are stable in ferromagnetic state at normal pressure. The calculated lattice parameters and bulk modulus of these hydrides are in good agreement with the available experimental results. A pressure-induced structural phase transition from cubic to hexagonal phase in SmH and SmH2 and hexagonal to cubic phase in SmH3 is predicted. A pressure-induced ferromagnetic to nonmagnetic phase transition is observed in SmH, SmH2 and SmH3 at the pressures of 104 GPa, 76 GPa and 81 GPa respectively. Ferromagnetism is quenched in mono, di and tri hydrides at high pressures. [ABSTRACT FROM AUTHOR]

The structural, electronic and elastic properties of alkali- metal nitride (KN) is investigated by the first principles calculations based on density functional theory as implemented in Vienna simulation package. At ambient pressure KN is stable in the ferromagnetic state with NaCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that the KN is half metallic ferromagnet at normal pressure. A pressure-induced structural phase transition from NaCl to ZB phase is observed in KN. Half metallicity and ferromagnetism is maintained at all pressures. [ABSTRACT FROM AUTHOR]

The possibility of hydrogen storage in a hybrid system of Titanium dioxide (TiO2) and Tin dioxide (SnO2) functionalized C(10,10) armchair Single Walled Carbon Nanotube (SWCNT), i.e. SWCNT/TiO2/SnO2, is investigated using density functional, first principles study. The TiO2 and SnO2 molecules functionalized on the outer surface of SWCNT do not undergo any dimerization/clustering thus give excellent stability for the hybrid system SWCNT/TiO2/SnO2. The band structure and density of states (DOS) plots suggest that the functionalization transforms the nature (metallic insulator) of the pristine system. The nominal values of H2 storage capacity and binding energies give much hope for using SWCNT/TiO2/SnO2 as a practical and reversible hydrogen storage medium (HSM). [ABSTRACT FROM AUTHOR]

The electronic, structural and mechanical properties of ZrH and ZrH2 are investigated by means of first principles calculation based on density functional theory as implemented in VASP code with generalized gradient approximation. The calculated ground state properties are in good agreement with previous experimental and other theoretical results. Among the six crystallographic structures considered for ZrH, ZB phase is found to be the most stable phase, whereas ZrH2 is energetically stable in tetragonal structure at ambient condition. A structural phase transition from ZB→NaCl at a pressure 10 GPa is predicted for ZrH. [ABSTRACT FROM AUTHOR]

The structural and mechanical properties of CrH and MnH are investigated using first principles calculation based on density functional theory as implemented in VASP code with generalized gradient approximation. The calculated ground state properties are in good agreement with previous experimental and other theoretical results. A structural phase transition from NaCl to NiAs phase at a pressure of 76 GPa is predicted for both CrH and MnH. [ABSTRACT FROM AUTHOR]

The structural and elastic properties of Hafnium dihydride (HfH2) are investigated by first principles calculation based on density functional theory using Vienna ab-initio simulation package (VASP). The calculated lattice parameters are in good agreement with the available results. A pressure induced structural phase transition from CaF2 to FeS2 phase is observed in HfH2 at 10.75 GPa. The calculated elastic constants indicate that this hydride is mechanically stable at ambient condition. [ABSTRACT FROM AUTHOR]

First principles calculation were performed using Tight-binding LMTO method with Local density approximation (LDA) and Atomic sphere approximation (ASA) to understand the electronic properties of CrH. A pressure induced structural phase transition from cubic to hexagonal structure of CrH is predicted. The stability of CrM2H is analyzed. [ABSTRACT FROM AUTHOR]

The elastic and ground state properties of 3d transition metal mono hydrides TMHs (TM = Ti, V), which crystallize in NaCl-type structure, has been performed using DFT based VASP code at ambient pressure. The calculated ground state properties such as lattice constants are compared with the available results. A pressure induced structural phase transition from NaCl phase to hexagonal (NiAs) phase is observed for both TiH and VH. [ABSTRACT FROM AUTHOR]

In this work, hydrogen storage in (10,10) armchair single walled carbon nanotube (SWCNT) functionalized with magnesium hydride (MgH2) has been investigated. As expected, due to light weight of MgH2, the system (SWCNT-MgH2) exhibits a storage capacity of 6.44 wt.%. The hydrogen adsorptions are molecular. The system is stable and thus H2 molecules can be desorbed without affecting the C - Mg attachment. Dimerization of MgH2 molecules has been observed. The binding energies confirm that the system can be used as a practical hydrogen storage medium. [ABSTRACT FROM AUTHOR]

The present work deals with interaction of an anti-cancer drug, carboplatin with single walled carbon nanotube (10, 10). The binding of carboplatin is more stable when it is inside the nanotube. The effect of water molecules on the whole system (single walled carbon nanotube with carboplatin) is examined. The presence of water molecules reduces the binding of carboplatin from the nanotube. This property enables the delivery of this anti-cancer drug from the nanotube at the targeted sites. Overall, this study projects that the single walled carbon nanotubes can be employed as efficient boats for targeted drug delivery. [ABSTRACT FROM AUTHOR]

In this work, hydrogen storage in (10,10) armchair single walled carbon nanotube (SWCNT) functionalized with magnesium hydride (MgH2) has been investigated. As expected, due to light weight of MgH2, the system (SWCNT-MgH2) exhibits a storage capacity of 6.44 wt.%. The hydrogen adsorptions are molecular. The system is stable and thus H2 molecules can be desorbed without affecting the C - Mg attachment. Dimerization of MgH2 molecules has been observed. The binding energies confirm that the system can be used as a practical hydrogen storage medium. [ABSTRACT FROM AUTHOR]

From the first-principle study, it is shown that the introduction of strain in a monolayer graphene enhances its chemical reactivity and hence it becomes more reactive than the pristine one. The intermolecular interaction between graphene and molecular hydrogen increases with increase in strain in the graphene plane leading to adsorption of hydrogen with suitable binding energy. Since graphene sheets can be freely suspended without any substrate we can stretch the sheets by adjusting distance between the clamped edges of the holding frame. In this way stacks of stretched graphene sheets can be constructed and a good hydrogen storage system can be obtained. [ABSTRACT FROM AUTHOR]

This first-principles study deals with chemical functionalization of graphene by nitrogen molecule, N2 and electron deficient boron and electron rich nitrogen atoms. The interaction of these chemical species with the graphene lattice is reflected in the electronic structure of graphene. We can obtain p-type and n-type graphene with the substitution of boron and nitrogen atoms respectively. On co-substitution of these atoms, the band gap closes. The results suggest that complementary doping is also applicable for graphene as in silicon. [ABSTRACT FROM AUTHOR]

First principles calculation were performed using Tight-binding LMTO method with Local density approximation (LDA) and Atomic sphere approximation (ASA) to understand the electronic and magnetic properties of FeH and CoH. Our results indicate that both FeH and CoH is ferromagnetic at normal pressure and a pressure induced magnetic phase transition from ferromagnetic to nonmagnetic phase at high pressure is predicted. At normal pressure, the estimated magnetic moments are 4.99 (μB/FeH) and 1.72 (μB/CoH). It is in agreement with the experimental value. [ABSTRACT FROM AUTHOR]

The adsorption and desorption of hydrogen in SWCNTs functionalized with borane is investigated experimentally. The SWCNTs are functionalized with borane (BH3) using LiBH4 as the precursor. The functionalized samples are hydrogenated and storage capacities of 3.2 wt.% and 3.8 wt.% are achieved at 50°C. Desorption of hydrogen is carried out by thermal annealing. Experimental evidences are provided by FTIR, CHNS and TG/TDS techniques. From the results it is confirmed that the designed hydrogen storage system is suitable for vehicular fuel cells. [ABSTRACT FROM AUTHOR]

The high pressure structural investigations of HfN and ZrN have been studies using ab initio calculations. It is predicted that ZrN undergoes a structural phase transition from NaCl to ZB structure at around 90.17GPa whereas there is no phase transition for HfN. However at higher pressure (at 108.67GPa) HfN undergo a phase transition from ZB to WC structure. Apart from this, the ground state properties, elastic constants and superconducting transition temperature are calculated and compared with the available results. [ABSTRACT FROM AUTHOR]

First principles calculation were performed using ab-initio calculations to understand the electronic properties of transition metal trihydrides. The equilibrium geometries, the total DOS are obtained under various pressures. The most stable structure of the trihydrides is NaCl like structure. We estimated the average electron-phonon coupling constant, electron electron interaction parameter and superconducting Transition Temperature (Tc). Our results indicate that high superconductivity is observed in YH3 at a pressure of 40K. and is in agreement with the experimental value. [ABSTRACT FROM AUTHOR]

We have investigated the adsorption of amino acid alanine on single-walled carbon nanotube using ab initio calculations based on density functional theory. Our study shows that the non-covalent interaction of alanine with nanotube depends upon the functional group nearer to the tube wall. Interaction through the amine group of alanine seems to be the most favourable adsorption pathway. The functionalization does not significantly change the metallic property of the nanotube. [ABSTRACT FROM AUTHOR]

We have investigated the formation of ripples in graphene using two-dimensional vibrating membrane model. We have chosen both armchair and zigzag graphene sheets with different sizes. The amplitude of vibrational modes of each graphene sheet is determined using this model. We observed that the vertical displacement (amplitude of the ripples) of the graphene sheet reaches a maximum height of about 0.99 nm from the mean plane in certain graphene sheets (nanoribbons) whose lengths are integral multiple of the basic armchair/zigzag units. [ABSTRACT FROM AUTHOR]

We have done the experimental investigation of hydrogen storage in functionalized single-walled carbon nanotubes (SWCNTs). The SWCNTs having the average diameter of 22 nm are deposited on alumina substrates by drop casting method. The functionalization of SWCNTs with BH3 using LiBH4 as the precursor, over the surface of SWCNTs is done by the same chemical method. Further, the functionalized samples are hydrogenated in the hydrogenation chamber. The samples are characterized through FTIR, XPS and CHNS studies. A hydrogen storage capacity of 0.87 wt % at 100 °C is observed. [ABSTRACT FROM AUTHOR]

Ab initio calculations are performed to investigate the structural stability, electronic structure and mechanical properties of BeAlH5 for monoclinic crystal structures with two different types of space group namely P21 and C2/c. Among the considered structures monoclinic (P21) phase is found to be the most stable at ambient condition. The structural phase transition from monoclinic (P21) to monoclinic (C2/c) phase is observed in BeAlH5. The electronic structure reveals that this compound is insulator. The calculated elastic constants indicate that this material is mechanically stable at ambient condition. [ABSTRACT FROM AUTHOR]