A new approach to synthesize LiAsF6 and other lithium based fluorochemicals for rechargeable lithium cells

A new method to synthesize inorganic lithium based fluorinated compounds like LiAsF₆ (Lithium hexafluoro arsenate) has been developed by a low temperature solid state procedure. LiAsF₆ is used extensively in the lithium cells because of its stability to withstand high voltages during cycling. The procedure developed to synthesize lithium based fluorinated compounds is a single step procedure and fluorination is done in-situ. This is an environmentally friendly method and is less expensive than the other known procedures.     

Thin film characterisation using backscattering spectrometry

The use of proton resonance backscattering spectrometry for the estimation of carbon as thin films formed on a target material is discussed. Conventional He backscattering experiments were also carried out on TiVN films formed on beryllium backing but the determination of stoichiometry of these films were difficult using conventional software for depth resolution.     

Gamma ray induced sensitization in CaSO4: Dy and competing trap model

Gamma ray induced sensitization in CaSO₄ :Dy has been compared for different temperatures during irradiation (25° 120° and 250°C). Enhanced sensitization at elevated temperatures seems to support the competing trap model for supralinearity and sensitization in CaSO₄ :Dy.     

A one-step procedure to prepare LiAsF6 and other allied lithium-based fluoro compounds used as electrolyte in lithium cells

A low-temperature all-solid-state thermal method has been developed to synthesize electrolytes like LiAsF₆, LiPF₆ and allied lithium-based fluoro-chemicals useful for lithium secondary cells. This developed procedure is simple and environmentally friendly compared with the existing procedures, which are poisonous and hazardous to health due to the use of obnoxious gases or liquids like F₂, AsF₃, PF₃, BF₃, AsF₃, or AsF₅, which are difficult to handle. In this proposed procedure, all chemicals are taken as analytical grade. Lithium salts and all other required salts are mixed well in required proportions and heated in between 300–400 °C to get the products examined by X-ray. The chemical reactions proposed for the preparation are given below.

1. 2LiOH + As₂O₅ + 12NH₄F → 2LiAsF₆ + 12NH₃ + 7H₂O
2. LiOH + (NH₄)₂HPO₄ + 6NH₄F → LiPF₆ + 8NH₃ + 5H₂O
3. 2LiOH + B₂O₃ + 8NH₄F → 2LiBF₄ + 8NH₃ + 5H₂O

     

Boron-doped diamond electrodes for the mineralization of organic pollutants in the real wastewater

The presence of recalcitrant organic compounds in wastewater poses a serious threat to the ecosystem and human health. Electrochemical advanced oxidation processes constitute a promising way for the mineralization of persistent organic compounds. They are commonly used for the transformation of organic pollutants into more biodegradable compounds or their complete removal from water. In this review, we present the recent advances in the use of boron-doped diamond (BDD) electrodes in the anodic oxidation process for the mineralization of real wastewater. First, the characteristic properties of BDD electrodes are discussed followed by the degradation mechanism. In addition, an overview on the application of BDD electrodes for mineralization of real wastewater is provided.     

Three-photon annihilation of positrons—Application to chemical characterization

The measurement of three-photon annihilation of positrons could provide not only an enhanced specificity in the determination of elements that have positron emitters as products, but also chemical (state) information on the environment of that element in the sample. The tree-photon yields have been determined for several compounds containing copper, in addition to the pure metal and a few alloys. The observations have been corraborated by angular correlation and Doppler broadening measurements and further substantiated by magnetic quenching in the angular correlation measurements.     

A search for rare and other trace elements in different stages of a copper mill by NAA

A method has been developed for the determination of Re, Se, As, Sb, Pt, Au, Te and Rare Earth elements in samples collected at various stages during the production of copper. Instrumental neutron activation analysis, along with a multielement sequential procedure for radiochemical separation of these analytes has been worked out and the results for various samples are discussed.     

Mode-locked fiber laser based on an attenuation-imbalanced nonlinear optical loop mirror

We propose a mode-locked figure-eight fiber laser by utilizing an attenuation-imbalanced nonlinear optical loop mirror (AI-NOLM) for the first time. Stable self-starting passively mode-locked pulses as short as 296 fs are obtained. We have also confirmed that the pulse width of the laser can be varied by changing the amount of attenuation in the AI-NOLM.