Pulsed laser deposition of CdWO4CdWO_4 thin films

Thin $CdWO_4$ films were produced on various substrates by pulsed laser deposition. A method of producing transparent films of high structural and optical quality on MgO substrate was developed. It is based on deposition of an amorphous film from a non-stoichiometric $CdWO_4$–CdO target and a consequent crystallization of the film in oxygen atmosphere at 750 °C. The quality of the films produced was verified by x-ray diffraction, electron probe microanalysis, scanning electron microscopy, Raman and optical spectroscopy

Trace Metal Distributions in Nickel Slag Cleaning

https://www.springerprofessional.de/trace-metal-distributions-in-nickel-slag-cleaning/16054078To capture efficiently the valuable trace metals from nickel slag using electric furnace, it is important to study their distributions between the slag and metallic phases in the furnace. It is impossible to calculate accurately these distributions without experimental measurements. Therefore, in this work, selected trace metal distributions and phase equilibria between K2O containing iron-silicate slags and a metallic Ni-Fe-Cu alloy in nickel slag cleaning furnace conditions were studied. The experimental method developed and applied during the work, involved a modified quenching technique that included equilibration of the samples in semi-sealed quartz ampoules in an inert atmosphere and metallic Fe saturation. The use of the semi-sealed quartz ampoule prevents the escape of volatile elements from the sample during equilibration. Chemical compositions of the phases and the trace elements were analysed by EPMA. From the measured compositions, the trace metal distribution coefficients between the molten Ni-Fe-Cu alloy and slag were calculated.Peer reviewe

Transparent and conductive Sb-doped tin oxide SPM tips prepared by sol-gel method

The rapid progress in scanning probe microscopy (SPM) techniques in the last decade has induced an increasing need for manufacturing advanced SPM tips. One important case is conductive and transparent tips. For such tips, only a few techniques have been proposed. which are either expensive or have poor reproducibility. We here propose a simple and cheap sol-gel technique to prepare fibers with a suitably sharp apex so that they can be used as SPM tips. The fibers were spinned off from a high-viscosity solution of tin alkoxide and SbCl3 hydrolysed in hurnid air and baked at 520 degreesC for several hours. The radii of the resulting tips were estimated by transmission electron microscopy to be less than 50 am. The resistivity of the transparent fibers was measured using different Sb-doping (0.5-1 wt.%) of the tin oxide, The temperature dependence of the conductivity and light absorption were investigated down to liquid He temperatures

Tuning the electronic properties of naturally nanostructured compounds

Tuning of band gaps in materials by changing the ionic content of nanopores (in the case of 12CaOcenterdot7Al2O3) and nanochannels (in Ca-phosphate apatite) was demonstrated using low-temperature luminescence spectroscopy methods under vacuum ultraviolet excitation. Luminescence excitation spectra enabled us to conclude that the replacement of O2− ions with F− in the cages of 12CaOcenterdot7Al2O3 shifts the absorption edge from ≈ 5.1 to ≈ 5.8 eV. Non-homogeneously broadened 2p states of O2− ions inside cages of 12CaOcenterdot7Al2O3 form the dominating trapping levels for valence band holes and their replacement with F− ions facilitates efficient self-trapping of holes at the framework oxygen ions. In the case of Ca-phosphate apatite, the replacement of OH− groups with F− ions shifts the onset of host absorption from ≈ 7.8 to ≈ 8.4 eV. The intrinsic emissions of Ca-phosphate apatites revealed in the UV region were tentatively interpreted as radiative decay of Frenkel-type self-trapped excitons, where the hole component is localized on oxygen ions of PO4 tetrahedra

Metal oxide based SPM tips prepared by sol-gel method

Up to date SNOM tips have. been prepared from SiO2 based materials using etching or locally melt fibre's stretching for tip sharpening [1,2] Usage of other metal oxides has been restricted because of the lack Of methods for obtaining the tips with suitable geometrical configuration. In our previous work we have proposed the technique for preparing transparent and electroconductive SnO2 fibres and tips by sol-gel method [3]. In the present investigation we have demonstrated that the sol-gel method provides the wide range of metal oxides to obtain SPM fibre tips. The new method of preparation enables to study tips based on oxide or oxide mixtures to create sensors with new properties for different applications. We propose some methods for preparing suitable precursors for spinning of pure and mixed TiO2, SnO2, SiO2 fibres. In those new methods the sharpening of tips is achieved in fibre drawing procedure. That is carried out at room temperature in humid atmosphere and then fibres are baked at 300-700degreesC for crystallisation of the material