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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Focused electron beam induced deposition (FEBID) is a versatile tool to produce nanostructures through electron-induced decomposition of metal-containing precursor molecules. However, the metal content of the resulting materials is often low. Using different Ag(I) complexes, this study shows that the precursor performance depends critically on the molecular structure. This includes Ag(I) 2,2-dimethylbutanoate, which yields high Ag contents in FEBID, as well as similar aliphatic Ag(I) carboxylates, aromatic Ag(I) benzoate, and the acetylide Ag(I) 3,3-dimethylbutynyl. The compounds were sublimated on inert surfaces and their electron-induced decomposition was monitored by electron-stimulated desorption (ESD) experiments in ultrahigh vacuum and by reflection−absorption infrared spectroscopy (RAIRS). The results reveal that Ag(I) carboxylates with aliphatic side chains are particularly favourable for FEBID. Following electron impact ionization, they fragment by loss of volatile CO2. The remaining alkyl radical converts to a stable and equally volatile alkene. The lower decomposition efficiency of Ag(I) benzoate and Ag(I) 3,3-dimethylbutynyl is explained by calculated average local ionization energies (ALIE) which reveal that ionization from the unsaturated carbon units competes with ionization from the coordinate bond to Ag. This can stabilise the ionized complex with respect to fragmentation. This insight provides guidance with respect to the design of novel FEBID precursors.

The Mn-doped compounds Ge 3MnSb2Te7 and Ge3.5Mn0.5Sb2Te7 are prepared from stoichiometric mixtures of the elements (silica ampules, 950 C for 24 h, quenching and subsequent annealing at 550 C for 96 h). The samples are characterized by powder and single crystal XRD, SEM, TEM, EPR, electrical conductivity, Seebeck coefficient, and magnetic measurements. The two compounds crystallize in the cubic space group Fm3m with Z = 4. Mn doping reduces the electrical conductivity of Ge4Sb2Te7, while the Seebeck coefficient increases significantly. The thermoelectric figures of merit of the Mn doped samples do not reach significantly more than 0.5 at any temperature. -(WELZMILLER, S.; HEINKE, F.; HUTH, P.; BOTHMANN, G.; SCHEIDT, E.-W.; WAGNER, G.; SCHERER, W.; POEPPL, A.; OECKLER*, O.; J. Alloys Compd. 652 (2015) 74-82, http://dx.