Learn More
[1] Pure ferrimagnetic greigite (Fe3S4) has been synthesized by reacting ferric chloride with thiourea and formic acid at 170 C. Sample purity was confirmed by X-ray diffraction, neutron diffraction and Mössbauer spectroscopy, coupled with magnetic measurements. Scanning electron microscope observations indicate clear cubo-octahedral and polyhedral crystal(More)
Raman scattering measurements were carried out in self-organized Ge quantum dot superlattices. The samples consisted of 25 periods of Ge quantum dots with different dot sizes sandwiched by 20 nm Si spacers, and were grown using solid-source molecular-beam epitaxy. Optical phonon modes were found to be around 300 cm, and a dependence of the Raman peak(More)
[1] We report the magnetic properties of pure synthetic pseudo-single-domain (PSD) and multi-domain (MD) greigite and the grain size dependence of the magnetic properties of greigite for the first time. The dominantly PSD-like and MD-like behavior are demonstrated by hysteresis, first-order reversal curve diagrams, lowtemperature cycling (LTC) of room(More)
[1] We provide comprehensive low-temperature magnetic results for greigite (Fe3S4) across the spectrum from superparamagnetic (SP) to multidomain (MD) behavior. It is well known that greigite has no lowtemperature magnetic transitions, but we also document that it has strong domain-state dependence of magnetic properties at low temperatures. Blocking of SP(More)
[1] We have investigated greigite (Fe3S4) using a combination of neutron powder diffraction and polarized neutron diffraction to give the first unambiguous assignment of its magnetic structure. Our results confirm that greigite has a collinear ferrimagnetic structure with antiferromagnetic coupling between the tetrahedral (A) and octahedral (B) sites. Our(More)
This paper presents a method for optimizing the geometrical pa.rameters of a refrigeration twin-screw compressor. The method optimizes rotor profile and discharge port position etc., by making use of two efficient computer programs; the geometrical parameter calculation program and the performance prediction program. Two new parameters; relative blow hole(More)
In this paper a mathematical model for the process of heat interaction between the com~ pressed gas and the screws in a twin screw compressor is presented and discussed. The simulation process is based on the results of the working process simulation which was developed previously at the University of Strathclyde.The simultaneous influence of geometrical(More)
In a comment on our recent letter, Yu first pointed out that there was strong alloying between the Ge dots and Si barrier layers because of the appearance of Si–Ge modes as also observed in SiGe alloys. It is correct that the Ge dot samples reported in our letter have some degrees of alloying due to interdiffusion. This was due to the fact that the samples(More)
This paper presents a parameter study for optimum rotor geometrical parameter combinations of a refrigeration helical twin screw compressor with four commonly used lobe combinations and five different length/diameter ratios and wrap angles. The volumetric and indicated efficiencies of the compressor are important. So also are other factors such as rotor(More)