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Aligned nanotube bundles have been produced by the pyrolysis of ferrocene along with methane, acetylene or butane. Ferrocene–acetylene mixtures are found to be ideal for the production of compact aligned nanotube bundles. The nanotube bundles are associated with iron nanoparticles of diameters in the range 2–13 nm. These nanoparticles are ferromagnetic, showing low saturation magnetization compared to bulk iron. The ferromagnetism of the transition metal nanoparticles is likely to be responsible for the alignment of the nanotubes.
KNO2 has been found to undergo a paraelectric-ferroelectric transition at 40?C. The transformation has been studied by thermal, dielectric and spectroscopic measurements.
The thermal decomposition of several metal nitrates and nitrites, particularly those of rare earths, have been investigated employing infrared spectroscopy to study the nature of the intermediates in these decompositions. The stoichiometry, kinetics, energetics and mechanisms of the decompositions have been discussed. Infrared spectra of metal nitrites have been studied in some detail and the normal vibration analysis of AgNO2 is reported.
PES bands due to ionization from n*, n and π orbitals of the NO group in some aliphatic nitroso compounds have been identified. In nitrosobenzene derivatives only the n*(NO) band can be assigned unequivocally. Substituent effects on the ionization energies in aliphatic and aromatic nitroso compounds have been correlated with substituent constants.
Hydrogen bonding in water has been studied by employing the extended Hückel (EHT) and semi-empirical LCAOSCF(CN DO/2) methods. The hydrogen bond energy as well as proton potential function have been calculated.
A hierarchy of novel zinc oxalates including monomers and dimers has been prepared by reaction of amine oxalates with zinc ions, the amine oxalates having been characterized for the first time. In most of the amine oxalates one of the carboxyl groups transfers a proton to the amino nitrogen, leaving the other carboxyl group free to form hydrogen bonds. The zinc oxalates obtained are composed of a network of ZnO6 octahedra and oxalate units, and possess zero-, one-, two- and three-dimensional structures. The monomer, dimer, and chain zinc oxalates are the first members of the hierarchy of structures. Relationships amongst these various oxalate structures are noteworthy and give indications as to the manner in which these structures are formed. Thus, the three-dimensional structure can be formed by the linking of layers, and the layer structure by condensation of linear chains. The isolation and characterization of a hierarchy of zinc oxalates of differing dimensionalities assumes significance in the light of the recent finding that low-dimensional structures transform to higher, more complex structures in the phosphate family.
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Top-gated field effect transistors (FETs) using Au-gap (5 microm) electrodes on glass substrate and SiO2/Si as gate have been fabricated with undoped and doped nanorods of ZnO as well as with WO2.72 nanorods as active semiconductor elements. The I-V characteristics at different gate voltages show that the nanorods are n-type semiconductors and the derived transfer characteristics show that the FET devices function in the depletion mode. Al-doping (3 at%) enhances the carrier mobility of ZnO nanorods to 128.6 cm2/V x s as against to 0.009 cm2/V x s estimated in the case of the undoped nanorods. Doping with Cd and Mg (3 at%) as well as N (approximately 1 at%) similarly increases the mobility although to a smaller extent. The Cd-doped ZnO nanorods exhibit the high sensitivity (defined as the ratio of the resistance in air to that in the hydrogen) (20) for 1000 ppm of hydrogen. Application of gate voltage decreases the recovery times of the nanorod sensors. FETs based on WO2.72 nanorods also show the depletion mode type characteristics and a carrier mobility of 8.38 cm2/V x s is obtained. The WO2.72 based FETs exhibit good sensitivity (approximately 10) for 1000 ppm hydrogen.
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Titanium oxide lattice parameter changes in 390 to 470 K range studied by X ray crystallography, noting correlation of distension with resistivity changes
Two-dimensional (2D) materials have gained great importance since the discovery of graphene. Of these several 2D materials, PbFCl and BaFCl, have not been exploited for electrochemical applications. Herein, we have prepared single and few-layered nanosheets of PbFCl and BaFCl by exfoliation through ultrasonication in different solvents such as water, dimethylformamide and N-methyl-2-pyrrolidone. The Hansen-Solubility-Parameters of the solvents played an important role in exfoliation of bulk phase of PbFCl and BaFCl. These materials were studied for supercapacitor properties by means of cyclic voltammetry (CV) curves, galvanostatic charge–discharge (GCD) curves and electrochemical impedance spectroscopy (EIS). Exfoliated 1–2 layered PbFCl exhibits a high-specific capacitance of 158 F g −1 at a scan rate of 10 mV s −1 . References: - Geim, A. K. & Novoselov, K. S. The rise of graphene. Nat. Mater. 6 , 183 (2007). Manjunath, K., Servottam, S., Soni, A. & Rao, C. N. R. A study of two-dimensional PbFCl and BaFCl. Bulletin of Materials Science 43 , 1–7 (2020).
The synthesis and structures of metal aminocarboxylates prepared in acidic, neutral, or alkaline media have been explored with the purpose of isolating coordination polymers with linear chain and two-dimensional layered structures. Metal glycinates of the formulae [CoCl2(H2O)2(CO2CH2NH3)] (I), [MnCl2(CO2CH2NH3)2] (II), and [Cd3Cl6(CO2CH2NH3)4] (III) with one-dimensional chain structures have been obtained by the reaction of the metal salts with glycine in an acidic medium under hydro/solvothermal conditions. These chain compounds contain glycine in the zwitterionic form. 4-Aminobutyric acid transforms to a cyclic amide under such reaction conditions, and the amide forms a chain compound of the formula [CdBr2(C4H7NO)2] (IV). Glycine in the zwitterionic form also forms a two-dimensional layered compound of the formula [Mn(H2O)2(CO2CH2NH3)2]Br2 (V). 6-Aminocaproic acid under alkaline conditions forms layered compounds with metals at room temperature, the metal being coordinated both by the amino nitrogen and the carboxyl oxygen atoms. Of the two layered compounds [Cd{CO2(CH2)5NH2}2]2 H2O (VI) and [Cu{CO2(CH2)5NH2}2]2 H2O (VII), the latter has voids in which water molecules reside.
