Mixed Phase Composition Research Articles

Origin of manganese carbonates in Jurassic red shale, central Japan

ABSTRACTManganese carbonate deposits in Japanese Jurassic sedimentary rocks were studied petrogeochemically. The deposits are characteristically composed of spheroidal micronodules, up to 1 mm in diameter, and always contain well‐preserved radiolarian shells. Chemical elemental composition and mineralogical characteristics indicate that the micronodules contain rhodochrosite in a mixed carbonate phase composition (Mn86.7−92.2Ca2.2−2.9Mg2.6−6.7Fe2.6−5.6)CO3 Carbon and oxygen isotope values, which range from −7.99 to −4.78‰ and −4.05 to 0.28‰ relative to PDB, respectively, suggest that the manganese carbonate was precipitated in a suboxic zone. The micronodules closely resemble agglutinated benthic foraminifera in shape. We suggest that agglutinated foraminiferal tests composed of radiolarian shells accumulated selectively on the sediment surface during redeposition of bottom sediments and were replaced by manganese carbonate in suboxic diagenetic conditions of manganese reduction.

Compositional and magnetic properties of iron nitride thin films

The compositional and magnetic properties of iron-nitride thin films deposited by dc reactive magnetron sputtering under various nitrogen partial pressure conditions have been investigated by x-ray diffraction, Mössbauer and Auger electron spectroscopy as well as magnetic measurements. The x-ray diffraction patterns indicate a mixed phase composition. 57Fe Mössbauer spectroscopy shows that part of the nitrogen atoms are randomly distributed on interstitial sites with the formation of nonstoichiometric compounds. The excessive width of the Mössbauer lines indicates the degree of disorder of the different iron nitride precipitates. The nitrogen concentration as a function of depth is obtained by sputter-etched Auger electron spectroscopy. Furthermore, the ferromagnetic films show moderate saturation magnetization and coercivities at room temperature as compared with pure iron thin films.

Chromatographic resolution on mixed stationary phases; the choice of the optimum composition

A method to establish the optimum composition of mixed stationary phases used in GC is given for the case when only the retention times on the individual phases are known. The method has been empirically tested for the resolution of chlorinated C1−C3 hydrocarbons.

Choice of preferred stationary phases for gas chromatography. Part II

The regularities of changes of the polarity factors with the composition of mixed stationary phases are discussed. Values of the polarity factors of active solids, partitioning liquids and also colloidal stationary phases are compared.

Observations of repeated Curie-point writing effects on MnBi films

Curie-point writing on MnBi films with a focused laser beam provides a means of substantially improving the packing density of magnetic recording. The MnBi film, however, has two crystallographic phases with different Curie temperatures. This causes the laser power requirement for writing to become a function of the operating history of the data bit location. Fortunately, the normal room-temperature phase has a higher laser power requirement than the quenched or mixed phase compositions. Therefore, the initial conditions for writing are suffieient for any subsequent condition. The time constants for these trasformations and the resulting optical memory characteristics have been observed and measured. Long-term operational lifetime has also been examined. The results show that when the laser writing power is 10% above writing threshold, the readout signal remains constant indefinitely; whereas when the writing laser power is more than 20% above the threshold value, continual degradation occurs. These experiments further confirm MnBi as a practical magneto-optic storage medium.

The use of binary stationary phases in gas-liquid partition chromatography

The theoretical basis of choice of optimal composition of the binary mixed stationary phase for a given separation problem is described; a number of practical applications is presented. The possibility of the application of binary solvent systems in gas chromatography is considered for the investigation of the energy effect due to deviations from ideality of binary liquid mixtures. In the experimental part a method of calculation of excess free enthalpies of mixing solvents g E ( m) is given, together with an experimental illustration. The values of g E ( m) have been calculated from the deviations from linearity of the relationship log Xk ′ = mixed phase). The values of partition numbers ( k′) determined from retention times have been used for the calculation of partition coefficients ( K) of solutes at column temperature. The results obtained are compared with partition coefficients calculated from other retention data.

On the relation between the composition of the mixed stationary phase and the retention time in gas-liquid partition chromatography

On the relation between the composition of the mixed stationary phase and the retention time in gas-liquid partition chromatography