Cobalt Disulfide Research Articles

Preparation and characterisation of CoS2 nanomaterial in aqueous cationic surfactant medium of cetyltrimethylammonium bromide (CTAB)

Cobalt disulfide is an important nanomaterial in the field of material chemistry due to its interesting catalytic and electromagnetic properties. We herein report the simple solution phase preparation of nanoparticles of cobalt disulfide in micellar medium of cationic surfactant cetyltrimethylammonium bromide (CTAB) and also by way of capping with thiophenol. The product has been characterized using spectroscopic and electron microscopic and magnetic moment measurements. The presence of disulfide bond is clearly evident from the 480 cm−1 peak in the infrared spectrum. The thiol passivated particles prepared in aqueous and ethanol medium has been found to have different compositions as observed from the ESIMS study.

Fabrication, structure, magnetic properties of highly ordered cobalt disulfide nanowire arrays

Highly ordered arrays of parallel CoS2 nanowires with a diameter of about 50 nm and a length up to about 50μm were synthesized by two electrical fields in an anodized aluminum oxide film. In this letter, fabrication, structure, magnetic properties of highly ordered magnetic cobalt disulfide nanowires arrays were studied. Also, a growth mechanism has been speculated.

A study of novel anode material CoS 2 for lithium ion battery

This paper reports the study of cobalt disulfide as a promising anode material for lithium ion batteries. The crystal structure and surface morphology have been characterized by using X-ray diffraction (XRD), SEM and Brunauer–Emmett–Teller (BET) techniques. The results of XRD show that the sample is a cubic phase with a space group Pa3. The grain size of the sample was 30 μm with a special nano-structured characteristic as observed by means of SEM. Charge–discharge experiments show that the sample with 30 wt.% acetylene black at the current density of 50 mA g −1 has the best performance, it shows that the first discharge capacity is up to 1280 mAh g −1. Ex situ XRD experiments were also carried out to determine the structural changes of delithiated/lithiated anode materials and used to analyze the reaction mechanism. Calculated Gibbs free energy change (Δ rG) and electromotive force (emf, E) values for the reaction CoS 2 + 4Li + + 4e − → Co + 2Li 2S are −146 kJ mol and 1.898 V, respectively. Based on the results, a possible reaction mechanism of CoS 2 anode during intercalation of Li ions was proposed.

Long-life, multi-tap thermal battery development

Abstract This paper describes an effort to develop long-life, multi-tap thermal battery technology with a minimal weight and volume. The effort has several challenging goals. Some of the development goals include an activated life of at least one hour, four voltage sections, and the ability to sustain significant pulse loads at the end of life. In order to meet these goals, advanced materials were chosen for development. The thermal battery chemistry developed consists of lithium–silicon anodes, low-melting eutectic electrolyte/separators, and cobalt disulfide cathodes. Besides evolving the electrochemistry for this battery, there are several other design challenges such as fine-tuning the heat balance so as to allow the battery to sustain the extended duration discharge. In addition, to minimize volume, the battery can is configured in a tapered shape and consequently requires a tapered Min-K™ sleeve for insulation. A new igniter design is also being used. Finally, extremely narrow voltage ranges for each of the four voltage taps have contributed to the challenges facing development engineers. This paper includes a summary of the battery design and presents test data from pre-prototype units.

Long-life, multi-tap thermal battery development

This paper describes an effort to develop long-life, multi-tap thermal battery technology with a minimal weight and volume. The effort has several challenging goals. Some of the development goals include an activated life of at least one hour, four voltage sections, and the ability to sustain significant pulse loads at the end of life. In order to meet these goals, advanced materials were chosen for development. The thermal battery chemistry developed consists of lithium–silicon anodes, low-melting eutectic electrolyte/separators, and cobalt disulfide cathodes. Besides evolving the electrochemistry for this battery, there are several other design challenges such as fine-tuning the heat balance so as to allow the battery to sustain the extended duration discharge. In addition, to minimize volume, the battery can is configured in a tapered shape and consequently requires a tapered Min-K™ sleeve for insulation. A new igniter design is also being used. Finally, extremely narrow voltage ranges for each of the four voltage taps have contributed to the challenges facing development engineers. This paper includes a summary of the battery design and presents test data from pre-prototype units.

Synthesis of cobalt disulfide nanoparticles in polymer matrix

Amorphous rod-like and needle-like nanoparticles of cobalt disulfide were prepared by the reaction of CoCl 2·6H 2O with thiourea in the presence of some hydrazine in aqueous solution. The reaction was undertaken in an open reflux system at a relatively low temperature. Polycrystalline cobalt disulfide nanorods were obtained by a similar reaction in an alcohol/water mixed solution. The products were characterized by Fourier transform infrared spectrometer (FTIR), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The effects of solvent, temperature and time of the reaction on the formation of cobalt disulfide nanocrystalline were discussed. It was found that hydrazine played an important role in shaping rod- or needle-like nanoparticles, and the reflux temperature and time mainly influenced the crystallization of nanoparticles. In addition, the microwave (wavelength λ=3 cm) absorption property of this nanocomposite at room temperature was also investigated.

The synthesis and morphological control of nanocrystalline pyrite nickel disulfide and cobalt disulfide

Abstract Nanocrystalline CoS 2 and NiS 2 have been successfully prepared through a solventothermal synthetic route at 130°C. The final products are characterized by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The sulfur-to-metal ratio of the as-prepared products is ca. 1.99–1 and 1.98–1 for CoS 2 and NiS 2 , respectively. TEM shows that with the change of solvents, the morphologies of the as-prepared sulfides can be controlled.

Solvent–thermal preparation of nanocrystalline pyrite cobalt disulfide

Nanocrystalline pyrite cobalt disulfide has been successfully prepared using the solvent–thermal method by the reaction of anhydrous CoCl 2 with Na 2S 3 at 180 °C, which is similar to the well known hydrothermal process, except that toluene is substituted for water. The sulfur-to-metal ratio of the as-prepared product is 1.99:1, which is determined by chemical analysis. X-ray diffraction analysis indicates that the product is a single phase of pyrite cobalt disulfide. No Co–O vibrations are found in the IR spectra. Transmission electron microscopy shows that the average particle size is about 22 nm.

Preparation and properties of poorly crystallized cobalt disulfide and ruthenium disulfide

Preparation and properties of poorly crystallized cobalt disulfide and ruthenium disulfide

Electrical resistivity of cobalt disulfide

The electrical resistivity of a metallic ferromagnet CoS 2 shows an anomalous temperature dependence in the vicinity of Curie point, which suggests a band-structure effect.

Preparation and magnetic properties of cobalt disulfide

A sample of CoS 1.97 was prepared by reacting CoS and S in an evacuated silica tube. Single crystals were grown by chemical transport using iodine as the transport agent. The ferro- magnetic transition temperature was found to be 122°K and from the saturation magnetization value of 38 e.m.u./g a magnetic moment of 0.84 μ B /molecule at 0°K was obtained.

Preparation and magnetic properties of cobalt disulfide

A B2 Fe–40 at% Al–Zr–B iron aluminide was subjected to shock-wave (explosive) loading at ∼6 GPa shock pressure. The applied shock pressure was sufficient to generate high dislocation density in the material which, in turn, gave rise to primary static recrystallization process upon subsequent isothermal annealing at 700, 750 and 800°C for various lengths of time. At various annealing temperatures recrystallization occurs rather inhomogeneously. Nucleation occurs mostly at the triple points and grain boundaries, showing tendency for clustering. Recrystallization kinetics follows a general behavior according to the Johnson, Mehl, Avrami and Kolmogorov theory (JMAK) with the Avrami exponent, n∼2.3–2.9. The estimated apparent activation energy for recrystallization, ∼259 kJ/mol, is very close to the activation energy for self-diffusion in pure iron and iron in FeAl. The results of microhardness studies of partially recrystallized specimens indicate that the average Vickers microhardness values for recrystallized and unrecrystallized areas differ significantly, the former having higher microhardness. This phenomenon is discussed in terms of higher density of retained sinks for quenched-in vacancies in the unrecrystallized areas and lower efficiency of vacancy hardening.