Structural measurements have been performed on the La0.7Sr0.3Mn3+0.85Nb5+0.15O3 compound with oxidation state of manganese close to +3. The composition undergoes a structural transition from rhombohedral to orthorhombic symmetry below room temperature. The calculated structural parameters show that the orthorhombic phase is not long-range orbitally ordered and that the structural transition is associated with a steric effect. The compound is ferromagnetic with a Curie point of around 150 K and a magnetic moment of 3.1 μB/Mn. It is suggested that ferromagnetism is originated from superexchange interactions via oxygen. Covalence enhances the positive part of the superexchange interactions whereas structural disorder leads to suppression of ferromagnetism.

Neutron diffraction studies of the La0.5Ba0.5CoO2.8 at the different temperatures has been performed. This solid solution crystallizes in the cubic structure (Pm3m space group) and exhibits below TN ~ 250K G-type antifferomagnetic ordering. Applied pressure suppresses magnetic ordering. Anomalous changes of the lattice parameters under pressure have been found.

The present work shows results on elemental distribution analyses in Cu(In,Ga)Se2 thin films for solar cells performed by use of wavelength-dispersive and energy-dispersive X-ray spectrometry (EDX) in a scanning electron microscope, EDX in a transmission electron microscope, X-ray photoelectron, angle-dependent soft X-ray emission, secondary ion-mass (SIMS), time-of-flight SIMS, sputtered neutral mass, glow-discharge optical emission and glow-discharge mass, Auger electron, and Rutherford backscattering spectrometry, by use of scanning Auger electron microscopy, Raman depth profiling, and Raman mapping, as well as by use of elastic recoil detection analysis, grazing-incidence X-ray and electron backscatter diffraction, and grazing-incidence X-ray fluorescence analysis. The Cu(In,Ga)Se2 thin films used for the present comparison were produced during the same identical deposition run and exhibit thicknesses of about 2 μm. The analysis techniques were compared with respect to their spatial and depth resolutions, measuring speeds, availabilities, and detection limits.

Extended abstract of a paper presented at MC 2007, 33rd DGE Conference in Saarbrücken, Germany, September 2 – September 7, 2007

The frictional response of two opposing polymer brushes subjected to steady shear was studied as a function of solvent condition and degree of compression using the Surface Forces Apparatus (SFA). The brushes were made by preferential adsorption of polyvinylpryridinepolystyrene (PVP-PS) block copolymers adsorbed onto atomically smooth surfaces from a dilute solution of toluene. Extremely parallel lateral motion was imparted to one surface and the response was detected at the opposing brush-covered surface. When the brushes were bathed in a good solvent, it was necessary to strongly compress the layers in order to observe frictional forces transmitted between the surfaces. However, when the solvent was changed to a near-theta solvent, large frictional forces were measured at weaker compressions. The onset of these frictional forces occurred at distances comparable to the distance at which the opposing layers contact one another and rapidly increase as the brushes are compressed. Arguments are advanced that this behavior is attributable to frictional interactions between the polymer chains and the solvent.