58 research outputs found
Channelling study of LaSrCoO films on different substrates
The cobalt oxide system LaCoO and its Sr-doped child compounds have been
intensively studied for decades due to their intriguing magnetic and electronic
properties. Preparing thin LaSrCoO (LSCO) films on different
substrates allows for studies with a new type of perturbation, as the films are
subject to substrate-dependent epitaxial strain. By choosing a proper substrate
for a thin film grow, not only compressing but also tensile strain can be
applied. The consequences for the fundamental physical properties are dramatic:
while compressed films are metallic, as the bulk material, films under tensile
strain become insulating. The goal of this work is to determine the strain
tensor in LSCO films prepared on LaAlO and SrTiO substrates by pulsed
laser deposition using RBS/channelling methods. Apart from the composition and
defect structure of the samples, the depth dependence of the strain tensor, the
cell parameters, and the volume of the unit cell are also determined.
Asymmetric behaviour of the strained cell parameters is found on both
substrates. This asymmetry is rather weak in the case of LSCO film grown on
LaAlO, while stronger on SrTiO substrate. The strain is more effective
at the interface, some relaxation can be observed near to the surface
Method development for measurement of elements in Hungarian red wines by inductivelvy coupled plasma optival emission spectrometry (ICP-OES)
ICP-OES (inductively coupled plasma optical emission spectrometry) was used to determine the element content of red wines. Development of the method involves various procedures of sample handling as well as repeatability and reproducibility measurements. Measurements were made for the following 16 elements: Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn. The relative standard deviation of repeatability ranged from 0.41% (potassium) to 27% (cadmium) and that of reproducibility varied between 0.73% (boron) to 52% (cobalt). Recovery of the elements was determined by standard addition with results ranging from 90.6% (phosphorus) to 116.2% (boron). After that, 15 red wine samples were measured. Significant differences were found in the Al, B, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, P, Sr and Zn (P<0.001) concentration of wine samples. Correlation studies revealed parallel changes in phosphorus-potassium, phosphorus-magnesium and zinc-manganese concentrations (r=0.857, 0.875, 0.838). According to principal component analysis, measurements of zinc-, sodium-, boron-, copper- and strontium content gave almost the same results as obtained with 16 different elements. According to a two dimensional non-linear map of absolute values of principal component analysis, wines from Szekszárd and Eger could be differentiated, whereas the analysis of wines from Villány, the Mátra Mountains and Lake Balaton showed overlapping results
The chemical identity of ‘[Ag(py)2]MnO4‘ organic solvent soluble oxidizing agent and new synthetic routes for the preparation of [Ag(py)n]XO4 (X= Mn, Cl, Re, n=2-4) complexes
Single phase a-plane MgZnO epilayers for UV optoelectronics: substitutional behaviour of Mg at large contents
High quality 1 μm thick a-plane MgxZn1−xO layers were produced by molecular beam epitaxy with Mg contents higher than 50%. Resonant Rutherford backscattering spectrometry combined with ion channeling revealed a uniform growth in both composition and atomic order. The lattice-site location of Mg, Zn and O elements was determined independently, proving the substitutional behaviour of Mg in Zn-sites of the wurtzite lattice. X-Ray diffraction pole figure analysis also confirms the absence of phase separation. Optical properties at such high Mg contents were studied in Schottky photodiodes
Evidence of quasi-intramolecular redox reactions during thermal decomposition of ammonium hydroxodisulfitoferriate(III), (NH4)(2)[Fe(OH)(SO3)(2)]center dot H2O
Synthesis of ammonium hydroxodisulfitoferriate(III), (diammonium catena-{bis(mu (2)-sulfito-kappa O,kappa O)-mu (2)-hydroxo-kappa O-2}ferrate(III) monohydrate) (NH4)(2)[Fe(OH)(SO3)(2)]center dot H2O (compound 1) and its thermal behavior is reported. The compound is stable in air. Its thermal decomposition proceeds without the expected quasi-intramolecular oxidation of sulfite ion with ferric ions. The disproportionation reaction of the ammonium sulfite, formed from the evolved NH3, SO2 and H2O in the main decomposition stage of 1, results in the formation of ammonium sulfate and ammonium sulfide. The ammonium sulfide is unstable at the decomposition temperature of 1 (150 A degrees C) and transforms into NH3 and H2S which immediately forms elementary sulfur by reaction with SO2. The formation and decomposition of other intermediate compounds like (NH4)(2)SnOx (n = 2, x = 3 and n = 3, x = 6) results in the same decomposition products (S, SO2 and NH3). Two basic iron sulfates, formed in different ratios during synthesizing experiments performed under N-2 or in the presence of air, have been detected as solid intermediates which contain ammonium ions. The final decomposition product was proved to be alpha-Fe2O3 (mineral name hematite)
Solid-Phase Quasi-Intramolecular Redox Reaction of [Ag(NH3)2]MnO4: An Easy Way to Prepare Pure AgMnO2
Fe-Mg interdiffusion rates in clinopyroxene: Experimental data and implications for Fe-Mg exchange geothermometers
Chemical interdiffusion of Fe-Mg along the c-axis [001] in natural diopside crystals (XDi = 0.93) was experimentally studied at ambient pressure, at temperatures ranging from 800 to 1,200 °C and oxygen fugacities from 10-11 to 10-17 bar. Diffusion couples were prepared by ablating an olivine (XFo = 0.3) target to deposit a thin film (20-100 nm) onto a polished surface of a natural, oriented diopside crystal using the pulsed laser deposition technique. After diffusion anneals, compositional depth profiles at the near surface region (~400 nm) were measured using Rutherford backscattering spectroscopy. In the experimental temperature and compositional range, no strong dependence of DFe-Mg on composition of clinopyroxene (Fe/Mg ratio between Di93-Di65) or oxygen fugacity could be detected within the resolution of the study. The lack of fO2-dependence may be related to the relatively high Al content of the crystals used in this study. Diffusion coefficients, DFe-Mg, can be described by a single Arrhenius relation with (Formula presented). DFe-Mg in clinopyroxene appears to be faster than diffusion involving Ca-species (e.g., DCa-Mg) while it is slower than DFe-Mg in other common mafic minerals (spinel, olivine, garnet, and orthopyroxene). As a consequence, diffusion in clinopyroxene may be the rate-limiting process for the freezing of many geothermometers, and compositional zoning in clinopyroxene may preserve records of a higher (compared to that preserved in other coexisting mafic minerals) temperature segment of the thermal history of a rock. In the absence of pervasive recrystallization, clinopyroxene grains will retain compositions from peak temperatures at their cores in most geological and planetary settings where peak temperatures did not exceed ~1,100 °C (e.g., resetting may be expected in slowly cooled mantle rocks, many plutonic mafic rocks, or ultra-high temperature metamorphic rocks)
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