Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2

Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and the phase separation into mesoscopic magnetic domains with localized spins embedded in a matrix with itinerant electronic character, suggests that the dominant contribution to the specific heat in the region of short-range ordering is mediated by quasi-2D antiferromagnetic clusters, perpendicular to the CoO2 layers

Magnetotransport properties of CaTixRu1-xO3 (x=0, 0.07)

Electrical resistance, transversal magnetoresistance and the Hall effect were studied on polycrystalline CaTixRu1-xO3 (x = 0, 0.07) samples using a conventional Quantum Design PPMS-9 equipment in the temperature range 2-300 K and magnetic field up to 9 T. Substantial differences were found between the two samples: (i) opposite to the metallic character of CaRuO3, the substituted sample has insulating-like electrical resistance; (ii) the magnetoresistance of the substituted sample changes the sign from negative to positive values with increasing temperature. The magnetoresistance of CaRuO3 is negative, the sign reversal is induced by magnetic field and only at temperatures below 15 K, such a behaviour is predicted for clustered systems; (iii) the Hall voltage in pure CaRuO3 also changes sign from negative to positive values above 35 K. This temperature coincides with the observed magnetic transition temperature, indicating that the magnetic state and the carrier character interrelate.13th Czech and Slovak Conference on Magnetism (CSMAG07), Jul 09-12, 2007, Kosice, Slovaki

Ti-induced ferromagnetism and the specific heat of CaTixRu1-xO3 (x=0, 0.005, 0.03)

The influence of Ti substitution on the specific heat of the CaTixRu1-xO3 system at low concentrations x = 0, 0.005, and 0.03 was studied in the temperature range of 2-300 K at magnetic fields tip to 9 T. Small peak was revealed in the C/T vs. T-2 dependence at around 3 K, which are field sensitive (the electronic specific heat coefficient gamma linearly decreases with the increase in magnetic field), and might be connected to some kind of magnetic ordering. The coefficient gamma is suppressed also by Ti substitution.13th Czech and Slovak Conference on Magnetism (CSMAG07), Jul 09-12, 2007, Kosice, Slovaki

Low temperature anomalies in the specific heat and magnetic susceptibility of Na0.7CoO2 samples

We present a comparative study of Na0.7CoO2 samples obtained from three different sources and prepared by different methods. The specific heat and magnetic susceptibility measurements in the temperature range 2-300 K show substantial influence on the observed anomalies, which underlines that the system is extremely sensitive to preparation protocols.13th Czech and Slovak Conference on Magnetism (CSMAG07), Jul 09-12, 2007, Kosice, Slovaki

Processing of eggshell biomaterial by electric discharge assisted mechanical milling (EDAMM) and high energy milling (HEM) techniques

In this study, hen eggshell (ES) biomaterial was treated by two mechanochemical methods. Here we show that using of low-current high-voltage electrical impulses during electrical discharge assisted mechanical milling (EDAMM) or high-energy milling (HEM) are proper tools for ES transformation to materials suitable for the further applications. The decomposition of calcite CaCO3 (the main component of ES) into lime CaO (EDAMM treatment) or calcite-aragonite transformation (HEM treatment) were documented by X-ray diffractometry. The applied techniques bring about solid state transformation, high degree of calcite amorphization, and enhancement of specific surface area of ES samples. As examples of using the transformed ES the uptake of cadmium ions during sorption experiments and the dechlorination of polyvinyl chloride are given. In both cases, the technologically accepted recoveries and kinetics have been obtained

[Portrait of Hector Harrison, 1951] [picture].

Title devised by cataloguer.; Inscription: "Yours sincerely, Hector Harrison, 1951" -- In pencil on mount.; Related material: Papers of Hector Harrison ; National Library of Australia manuscript collection MS 6277.; Related material: Interview with Reverend Hector Harrison ; National Library of Australia oral history collection ORAL TRC 121/46

Thermopower and Surface Magnetic Characterization of Ni Thin Layers

Thermoelectric power and surface magnetic characterization of Ni evaporated layers will be presented, with the comparison with the bulk Ni material. The bulk electrical and magnetic properties are developed gradually, approaching the bulk properties, as the layer thickness increases. Below the thickness of 180 nm, the evaporated layers are amorphous. The epitaxial stresses can appear in both, the anomaly observed in the thermopower and the surface coercivity measurements

Thermodynamic properties of Na0.65CoO2

Specific heat of the layered Na0.65CoO2 powder sample over the temperature region of 3-360 K has been studied. Features hinting at charge ordering below room-temperature were observed. Magnetic phase transition at 28 K as well as signs of short-range ordering confirm the 2D character of magnetism with weak inter-planar coupling in the system. Comparison to different 2D antiferromagnetic models suggests that the magnetic lattice is more square- than triangular-like, what could be favoured by the charge ordering.12th Czech and Slovak Conference on Magnetism, Jul 12-15, 2004, Kosice, Slovaki

Influence of Ti4+ on the magnetic state of CaRu1-xTixO3

In order to shed more light on the character of magnetic correlations at low temperatures in CaRuO3, the delicate effect of substituting nonmagnetic Ti4+ for Ru4+ in low concentrations (0.5-15%) has been investigated by magnetization, AC-susceptibility and specific heat measurements. Despite the clear features in magnetic measurement data at 34K no specific heat anomaly has been observed, nevertheless, two temperature regions with different magnetic characters have been identified. . In pure CaRuO3 sisignificant low-temperature upturn of C/T is visible below 15 K. This feature is suppressed by Ti substitution. (c) 2007 Elsevier B.V. All rights reserved.Joint European Magnetic Symposia (JEMS 06), Jun 26-29, 2006, San Sebastian, Spai