Microcalorimeter x-ray detectors offer the specific advantage of being high -resolution energy -dispersive detectors. Furthermore, they can be designed to cover almost any energy range, from soft x-rays to gamma rays. Many of the current energy values of L, M, and N x-ray lines in the soft x-ray range (below 1.2 keV) have not been established through a chain of calibration. Based on our experience, we propose here a method of measuring the energies of these lines that should establish peak positions to a few tenths of an electron volt. It would involve the calibration of a microcalorimeter detector with diagram line energy values determined by a grating x-ray spectrometer calibrated by a plane grating monochromator using synchrotron radiation. We present L -line spectra from Cu, Co, and Ni obtained with a microcalorimeter detector to demonstrate the feasibility of obtaining high -resolution spectra in the energy range below 1 keV.

Microcalorimeter X-ray detectors employing a transition-edge sensor are capable of very high energy resolution, but achieving this in practice depends on an understanding of the readout process. The combination of thermal cooling and thermoelectric feedback present in most circumstances produces a pulse whose area and amplitude both vary nonlinearly with photon energy. The resolution is further affected by the presence of pileup pulses in the pulse or baseline that need to be detected and rejected down to an arbitrarily small level. We describe here a method that includes both the rejection of pileup pulses and the correction of the nonlinearities. We have implemented the process in a system that accepts pulses from multiple detectors and analyzes them in real time. An initial brief X-ray spectrum from a standard sample supplies sufficient data for pulse characterization and energy calibration. The system is then also enabled to combine pulses from multiple detectors into an energy-calibrated histogram in real time.

Olivine (LiCo1/3Mn1/3Ni1/3PO4) powders were synthesized at 550-600 degrees C for 6 h in air by a sol-gel method using multiple chelating agents and used as a cathode material for rechargeable batteries. Range of chelating agents like a weak organic acid (citric acid - CA), emulsifier (triethanolamine - TEA) and non-ionic surfactant (polyvinylpyrrolidone - PVP) in sal-gel wet chemical synthesis were used. The dependence of the physicochemical properties of the olivine powders such as particle size, morphology, structural bonding and crystallinity on the chelating agent was extensively investigated. Among the chelating agents used, unique cycling behavior (75 mAh/g after 25 cycles) is observed for the PVP assisted olivine. This is due to volumetric change in trapped organic layer for first few cycles. The trapped organic species in the electrode-electrolyte interface enhances the rate of lithium ion diffusion with better capacity retention. In contrast, CA and TEA showed a gradual capacity fade of 30 and 38 mAh/g respectively after multiple cycles. The combination of all the three mixed chelating agents showed an excellent electrochemical behavior of 100 mAh/g after multiple cycles and the synergistic effect of these agents are discussed. (C) 2012 Elsevier Ltd. All rights reserved.

Manganese dioxide (MnO 2 ) appears to be an effective cathode material for a battery system. No studies on lithium insertion in aqueous media are known to the best of our knowledge. However, in one of our previous papers we reported that lithium could be intercalated into a MnO 2 host compound using an aqueous LiOH electrolyte; however simple chemistry suggests that it should not. It is found that a battery with LiOH electrolyte functions quite differently from the cell that uses Li 2 SO 4 . This paper describes the surface modifications that accompany the electrochemical behavior of MnO 2 during redox (discharge) processes in the lithium hydroxide and sulfate media. XPS and SIMS techniques were used to study the resultant surface of the MnO 2 cathode and the spectra reveal that the formation of an insoluble layer of Li 2 CO 3 precedes the process of reduction. SEM was used to study the microstructure of the MnO 2 cathode. Copyright © 2008 John Wiley & Sons, Ltd.

Combined ultrahigh vacuum-electrochemical (UHV-EC) methods were utilized to expose polycrystalline iron and mild steel surfaces to 0.01 m NaOH and for the subsequent transfer back to the UHV analysis chamber without exposure to air. X-ray photoelectron spectroscopy (XPS) was then employed to elucidate a chemical description of the iron surfaces as a function of the emersion potential. The mild steel electrodes display lower corrosion resistance in the alkali solution, underlining a crucial role played by minor alloying components, such as sulfide and/or carbide. Carbonate, an unavoidable contaminant of caustic solutions, is strongly adsorbed to both iron surfaces, its concentration generally being unaffected by a subsequent water wash. Polycrystalline iron extracted in the soluble ferrate domain shows enhanced corrosion resistance, which is suspected to arise through surface impurity enrichment following the anodic leaching of the FeO42- species. In contrast, mild steel extracted in the ferrate domain exhibits poor corrosion resistance, further highlighting the detrimental effect of certain alloying elements. Copyright (c) 2007 John Wiley & Sons, Ltd.

The adsorption of ferric and ferrous iron onto the native oxide of the SiO 2 /Si(111) surface has been evaluated using X‐ray photoelectron spectroscopy (XPS). Through a series of immersion experiments, performed at room temperature and pH 1, it has been shown that the ferric species is strongly adsorbed onto the hydrophilic surface, while ferrous iron remains in solution. Dehydroxylation of the silica surface by etching with hydrofluoric acid reduces the concentration of receptive Si‐OH groups, thereby limiting iron adsorption. The experiments were reproduced in a combined ultrahigh vacuum‐electrochemical system (UHV‐EC), which allowed a carbon‐free surface to be prepared before contacting the iron solutions, and confirmed the strong affinity of ferric iron towards the SiO 2 /Si(111) surface. Copyright © 2007 John Wiley & Sons, Ltd.

The electrochemical behavior of titanium dioxide (TiO 2 ) in aqueous lithium hydroxide (LiOH) electrolyte has been investigated. Cyclic voltammetry shows that electroreduction results in the formation of a number of products. X-ray diffraction of the electroreduced TiO 2 shows that Li x TiO 2 , Ti 2 O 3 , Ti 2 O and TiO are formed. The formation of Li x TiO 2 is confirmed through X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) studies of the electroreduced TiO 2 . The formation of Li x TiO 2 is electro reversible. In this respect, the electrochemical behavior of TiO 2 in concentrated aqueous lithium hydroxide electrolyte is similar to that for lithium perchlorate (LiClO 4 ) non-aqueous media.

Intercalation of lithium into the vacant sites of a host compound can be achieved electrochemically using non-aqueous electrolytes. The use of aqueous electrolyte is less common because of the reactivity of many lithium intercalation compounds with water. Here we propose that lithium could be intercalated using aqueous solutions, lithium hydroxide as the electrolyte. The X-ray photoelectron spectroscopy (SIMS) data on the discharged material indicate that lithium is intercalated into the host structure of EMD without the destruction of its core structure. A significant improvement on cell performance was obtained by adding small amounts (<3 wt%) of titanium disulphide (TiS2) to the cathode.

The electrochemical behavior of olivine-type lithium manganese phosphate (LiMnPO4) as a cathode material was investigated in a saturated aqueous lithium hydroxide electrolyte. The crystal structure and surface characterization of the olivine type LiMnPO4 and the products which are formed on its oxidation and subsequent reduction were studied. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and secondary ion mass spectrometry were used for these investigations. LiMnPO4 was found to be reversibly delithiated/lithiated on electro-oxidation/reduction. (c) 2006 The Electrochemical Society.

The redox behavior and surface characterization of LiFePO4 in aqueous lithium hydroxide (LiOH) electrolyte have been investigated. The objective of this work is to investigate the electrochemical behavior of LiFePO4 in an aqueous lithium hydroxide electrolyte and its comparison with that in non-aqueous lithium ion electrolytes. Cyclic voltammetry results show that LiFePO4 undergoes partially reversible oxidation/reduction. The products formed on electrooxidation and subsequent reduction of LiFePO4 were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). It is found that lithium extraction from LiFePO4 occurs during oxidation. The products formed on subsequent reduction consist of LiFePO4 and Fe3O4.

The electrochemistry of olivine-type iron phosphate (FePO4) as a battery cathode material, in aqueous lithium hydroxide (LiOH), has been investigated. The material forms intercalated LiFePO4 reversibly on electroreduction/oxidation. The formation of Fe3O4 phase, in addition to the regeneration of FePO4 during reverse oxidation of LiFePO4, also occurs. In this regard, the mechanism of FePO4 discharge/charge in aqueous LiOH differs from that in non-aqueous solvents.