Mixed valency in cerium oxide crystallographic phases: Determination of valence of the different cerium sites by the bond valence method

We have applied the bond valence method to cerium oxides to determine the oxidation states of the Ce ion at the various site symmetries of the crystals. The crystals studied include cerium dioxide and the two sesquioxides along with some selected intermediate phases which are crystallographically well characterized. Our results indicate that cerium dioxide has a mixed-valence ground state with an f-electron population on the Ce site of 0.27 while both the A- and C-sesquioxides have a nearly pure f^1 configuration. The Ce sites in most of the intermediate oxides have non-integral valences. Furthermore, many of these valences are different from the values predicted from a naive consideration of the stoichiometric valence of the compound

Superconducting phases of f-electron compounds

Intermetallic compounds containing f-electron elements display a wealth of superconducting phases, that are prime candidates for unconventional pairing with complex order parameter symmetries. For instance, superconductivity has been found at the border of magnetic order as well as deep within ferro- and antiferromagnetically ordered states, suggesting that magnetism may promote rather than destroy superconductivity. Superconductivity near valence transitions, or in the vicinity of magneto-polar order are candidates for new superconductive pairing interactions such as fluctuations of the conduction electron density or the crystal electric field, respectively. The experimental status of the study of the superconducting phases of f-electron compounds is reviewed.Comment: Rev. Mod. Phys. in print; 75 pages, 23 figures; comments welcom

Investigating webcasting as an intervention technique for International MSc. Students

This study explored the feasibility of using webcasting as a possible intervention technique to deal with the late arrival of International students who are unable to attend University on day one of their postgraduate programmes. To put this lateness into context the planning department of the University was contacted and data was provided which allowed this to be quantified in terms of number of days late. Information was collected from a number of companies producing webcasting solutions and this report briefly describes their usage in a small scale pilot run. After the trial run survey data was collected from student attendees to gather their views with regard to the viability of using such products whilst being back home. The following suggested benefits were considered: • online collaborative opportunities with peers and staff; • access to an archive of programme material; • helping students make the transition from home to here

Co-learning in the collaborative mathematics classroom

Co-learning agreements between researchers and practitioners have been suggested as a way of generating research findings that are useful to improving schools and informing classroom practice. In this chapter we describe how a co-learning agreement was developed as a basis for researching aspects of the learning of mathematics in the classroom of a teacher whose pedagogy emphasised collaborative problem-solving as a major vehicle for learning mathematics. A study of co-operative group work in mathematics found that the perceptions of high achieving students (in terms of the purpose and benefits of group work) were more in line with those of their teacher than those of low achieving students. In contrast, the research reported in this chapter of a collaborative mathematics classroom revealed no such differences between students. In using a co-learning approach both authors felt that they learnt more about the processes of collaborating in researching and learning mathematics than they would have done with either a more traditional ‘data gathering’ approach led by the researcher or as a piece of action research by the teacher. The chapter suggests that co-learning can be a useful way of collaborating and describes the benefits such an approach can offer when researching classroom processes