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Highly pure biogenic silica can be obtained from rice husk ash if agglomeration and ash melting during combustion can be avoided. In the present study, the effects of fuel pretreatment and combustion temperature on the properties of the ash samples from rice husk combustion were investigated. In this respect, the chemical compositions of the bulk and outer surface and morphology of the obtained rice husk ash were evaluated. Compositions of the bulk ashes were analyzed with X-ray fluorescence and inductively coupled plasma with optical emission spectroscopy, while surface compositions were obtained from X-ray photoelectron spectroscopy. Images from a scanning electron microscope were used to evaluate the morphologies of the ash samples. Results showed that the concentrations of metal impurities on the surfaces of the ashes were higher than in the bulks. In pretreated rice husk ash samples, the levels of metal impurities decreased considerably on the surfaces. Consequently, ash melting was obviated, and powdery ashes without any agglomeration were obtained.

Prussian Blue analogues (PBAs) are a promising class of electrode active materials for batteries. Among them, copper nitroprusside, Cu[Fe(CN)5NO], has recently been investigated for its peculiar redox system, which also involves the nitrosyl ligand as a non-innocent ligand, in addition to the electroactivity of the metal sites, Cu and Fe. This paper studies the dynamics of the electrode, employing surface sensitive X-ray Photoelectron spectroscopy (XPS) and bulk sensitive X-ray absorption spectroscopy (XAS) techniques. XPS provided chemical information on the layers formed on electrode surfaces following the self-discharge process of the cathode material in the presence of the electrolyte. These layers consist mainly of electrolyte degradation products, such as LiF, LixPOyFz and LixPFy. Moreover, as evidenced by XAS and XPS, reduction at both metal sites takes place in the bulk and in the surface of the material, clearly evidencing that a self-discharge process is occurring. We observed faster processes and higher amounts of reduced species and decomposition products in the case of samples with a higher amount of coordination water.

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This work is concerned with the structural compatibility of perovskite BaTiO3 on garnet substrates Gd3Ga5O12 and Y3Fe5O12. Thin films (200 and 500 nm nominal thickness) have been deposited by pulsed...