Temperature Variation Of Susceptibility Research Articles

Magnetomineralogy of the cordierite gneiss from the magnetic anomaly at Humpolec, Bohemian Moldanubicum (Czech Republic)

Magnetic properties as well as the magnetomineralogy were investigated in rocks underlying a 7 km long aeromagnetic anomaly situated in the Moldanubian crystalline unit of the Bohemian Massif. The anomaly is caused by highly magnetic cordierite gneiss forming a stripe of NE — SW direction east of the town of Humpolec, eastern Bohemia. Magnetic susceptibility and its anisotropy (AMS), natural remanent magnetization, field and temperature variations of susceptibility were measured. Optical study of thin sections, electron microprobe and Mossbauer studies were also used to reveal the carrier of the high susceptibility and the high NRM. There appear to be two major generations of Fe-Ti oxides: older hematite with ilmenite exsolutions (Ti-hematite) which is the dominant remanence phase, and younger magnetite, the dominant susceptibility phase, usually associated with rutile. This indicates a reaction Hematite + Ilmenite → Magnetite + + Rutile; the trace elements in magnetite, as well as texture and morphology of the oxide grains support this assertion. An additional minor portion of maghemite is revealed by Mossbauer and thermomagnetic results. The Ti-hematite belongs to the oldest mineral assemblage in the rock, despite its anhedral morphology. Inclusions in Ti-hematite, among which corundum and abundant paragonite occur, record a strongly peraluminous and probably disequilibrium association during the crystallization of the Ti-hematite.

XRD and magnetic studies on Ti-substituted MgZn ferrites

The ferrites of the compositions Zn xMg (1−x)+tTi tFe 2−2tO 4 are prepared by a standard ceramic method. The spinel structure is confirmed for these ferrites, however impurity lines for higher concentration of Mg have been observed. Compositional variation of lattice parameter has shown non linearity on addition of zinc which is explained by the combined effect of cation size on repulsion parameter and of the A-site charge on Madelung constant. Temperature variation of susceptibility has shown peaks which gradually disappear on addition of Zn. This is explained on SD-SP transition. The peak temperatures and Curie temperatures from X-T variation and obtained experimentally decrease on addition of Zn which is attributed to reduction of A-B interactions. The magnetisation studies have shown Neels two sublattice and three sublattice models applicable to the system. The values of M:M s and H c decrease on addition of Zn which is attributed to SD-MD transformation.

A radio frequency method for the measurement of initial magnetic susceptibility

A method of displaying simultaneously the real and imaginary parts of the complex initial susceptibility of rocks and rock powders is described. A Q-multiplier in conjunction with two feedback loops separates distinctly and linearly the contributions of the real component, X' and imaginary component X of a given sample. Temperature variations of susceptibility may also be studied using a furnace. In the absence of the furnace the sample's coupling factor and hence the signal-to-noise ratio of the instrument is substantially enhanced. At present the noise level of the X loop is equivalent to +or-5*10-12 m3 and that of the X loop is equivalent to +or-1.4*10-11 m3 with the furnace in position. The sample volumes are 0.2 cm3 or less.

Temperature variations of susceptibility and magnetization for nickel

Temperature variations of paramagnetic susceptibility and the magnetization for nickel are calculated in the band model. The value of high-field susceptibility at 0 K is also estimated.

A simple method for the measurement of the temperature variation of initial magnetic susceptibility between 77 and 1000 K

Two identical multi-layered solenoids each enclosing a water jacket are used in an a.c. bridge circuit so that inclusion of a sample in either coil produces an out of balance signal proportional to the susceptibility of the sample. This signal is then amplified with low noise field effect transistors, converted to direct current with a phase sensitive detector, and displayed against temperature on an XY recorder. The water jacket of one solenoid contains a furnace capable of reaching 700°C, while the other contains a cooling assembly for use between liquid nitrogen and room temperature. The temperature variation of susceptibility allows determination of Curie and transition temperatures.

The magnetic susceptibility of some carbides of uranium and thorium

The magnetic susceptibilities of the monocarbides and dicarbides of both thorium and uranium have been measured at room temperature, and the temperature variation of susceptibility has also been determined in the range 90-1100°K for both thorium and uranium carbides. The susceptibilities of uranium carbide-rich, uranium carbide-thorium carbide compounds have also been measured in the same temperature range for specimens of nominal composition 1, 3, 8, 15 and 20% thorium carbide by weight. All the compounds show little variation of susceptibility in the range investigated. The susceptibility of each of the mixed carbides and uranium carbide is independent of temperature in the low temperature region. The slight curvature observed in this region for thorium carbide and thorium dicarbide is attributed to the presence of ferromagnetic impurity; the measurements do not fit a Curie-Weiss law. The variation of susceptibility may be explicable in terms of a band model, but at present the data are not sufficiently extensive.

Electric susceptibility of ethyl chloride in the centimetre region

Electric susceptibility of ethyl chloride has been determined in the microwave region at 8,780 mc/s over a pressure range of 10 cm to 75 cm of mercury, and a temperature range of 263° K to 353° K. It has been found that the total susceptibility, at constant temperature, varies almost linearly with pressure. The contribution due to quantised transitions to total susceptibility has been calculated from the data on absorption measurements and it is found to be 0·45 × 10−3. Since most of this contribution is due to zero frequency transitions, no measurable dispersion is observed in this region. It has been found possible to determine the values of dipole moment and the sum of atomic and electronic polarisations from the data on temperature variation of susceptibility. The values are μ=2·06 × 10−18 e.s.u and (P A +P E )=22·70. These results are in fair agreement with those obtained earlier

The Temperature Variation of Susceptibility of Tantalum

The Temperature Variation of Susceptibility of Tantalum

A new inductive method for the determination of the temperature variation of susceptibility of rocks

A new apparatus for determining the temperature variation of susceptibility of rocks is described, along with a brief outline of an essential piece of subsidiary equipment.