Sm Addition to GdCo and TbFe Films for Magneto-Optical Memory
Introduction In order to improve the magnetic properties of rare earthtransition metal alloys being studied for magneto-optical memory media, we added Sm to GdTbFeCo (a quaternary alloy), to make a quinternary alloy. We already reported that both the Kerr rotation angle and the magnetic anisotropy increase with the addition of Sm [1]. In order to study the origin of these improvements, we added Sm to GdCo and TbFe (each a binary alloy) to make ternary alloys. We then investigated their magnetic and magneto-optical properties.
The thermo-magnetic writing and erasing properties and Kerr rotation angle of amorphous TbFe thin film
The compositional dependences of writing, erasing and reading properties of amorphous TbFe thin film were examined in detail. As a result, there was marked differences between Fe-rich and Tb-rich film. That is, the external magnetic field necessary for writing was generally weaker and less dependent on composition in Tb-rich film and the composition range where erasing could be performed by the field of the same intensity as in writing was wider in Tb-rich side. Kerr rotation angle was measured in two different methods and the scattering values between them were observed in Fe-rich film, while there was no significant difference in Tb-rich film. The origins of these compositional dependence were explained by the differences of temperature dependences of M s and H c besides the compositional dependences of rectangular ratio and M s itself. The effects of the adding third elements to TbFe in Kerr rotation angle and minimum writing laser power were also measured. As a result, it was found, among some elements examined in this study, that Sm had effects of not only decreasing writing power but also increasing Kerr rotation angle in some degree.
A Critical Assessment on Functional Attributes and Degradation Mechanism of Membrane Electrode Assembly Components in Direct Methanol Fuel Cells
Direct methanol fuel cells (DMFC) are typically a subset of polymer electrolyte membrane fuel cells (PEMFC) that possess benefits such as fuel flexibility, reduction in plant balance, and benign operation. Due to their benefits, DMFCs could play a substantial role in the future, specifically in replacing Li-ion batteries for portable and military applications. However, the critical concern with DMFCs is the degradation and inadequate reliability that affect the overall value chain and can potentially impede the commercialization of DMFCs. As a consequence, a reliability assessment can provide more insight into a DMFC component’s attributes. The membrane electrode assembly (MEA) is the integral component of the DMFC stack. A comprehensive understanding of its functional attributes and degradation mechanism plays a significant role in its commercialization. The methanol crossover through the membrane, carbon monoxide poisoning, high anode polarization by methanol oxidation, and operating parameters such as temperature, humidity, and others are significant contributions to MEA degradation. In addition, inadequate reliability of the MEA impacts the failure mechanism of DMFC, resulting in poor efficiency. Consequently, this paper provides a comprehensive assessment of several factors leading to the MEA degradation mechanism in order to develop a holistic understanding.