Microbalance studies in flow reactors: design of experimental equipment

Studies have been made of the effect of the nature of the reactor surface on the gaseous, liquid and solid products of hydrocarbon pyrolysis at high temperatures. This has necessitated the development of a tubular and a jet-stirred reactor, which can be used together with a microbalance to record weight changes resulting from the formation of carbon.The results show that there is a significant effect of the nature of the reactor surface on the kinetics of formation of different products. This effect tends to approach a common value as individual surfaces become covered with carbon. If carbon encapsulation is prevented, for example by gasification by hydrogen, the particular effect of an individual surface continues to influence the product spectra.     

Large negative magnetoresistance effects in Co2Cr0.6Fe0.4Al

Materials, which display large changes in resistivity in response to an applied magnetic field (magnetoresistance) are currently of great interest due to their potential for applications in magnetic sensors, magnetic random access memories, and spintronics. Guided by striking features in the electronic structure of several magnetic compounds, we prepared the Heusler compound Co₂Cr_0.6Fe_0.4Al. Based on our band structure calculations, we have chosen this composition in order to obtain a half-metallic ferromagnet with a van Hove singularity in the vicinity of the Fermi energy in the majority spin channel and a gap in the minority spin channel. We find a magnetoresistive effect of 30% in a small magnetic field of 0.1 T at room temperature. This demonstrates the feasibility of a cheap and simple magnetic sensor based on polycrystalline, intermetallic material.     

Contemporary superconducting materials

Superconductors currently under active study are briefly described from a chemical perspective. The author's current views on those superconductors, the role of theory in searching for new superconductors, and possibilities for new superconducting materials that might be found in the future are presented.     

Orbital dependence of the fermi liquid state in Sr2RuO4

We have used angle-resolved photoemission spectroscopy to determine the bulk electronic structure of Sr(2)RuO(4) above and below the Fermi liquid crossover near 25 K. Our measurements indicate that the properties of the system are highly orbital dependent. The quasi-2D gamma band displays Fermi liquid behavior while the remaining low energy bands show exotic properties consistent with quasi-1D behavior. In the Fermi liquid state below 25 K, the gamma band dominates the electronic properties, while at higher temperatures the quasi-1D beta and alpha bands become more important.