The current magnetic confinement nuclear fusion power reactor concepts going beyond ITER are based on assumptions about the availability of materials with extreme mechanical, heat, and neutron load capacity. In Europe, the development of such structural and armour materials together with the necessary production, machining, and fabrication technologies is pursued within the EFDA long-term fusion materials programme. This paper reviews the progress of work within the programme in the area of tungsten and tungsten alloys. Results, conclusions, and future projections are summarized for each of the programme´s main subtopics, which are: (1) fabrication, (2) structural W materials, (3) W armour materials, and (4) materials science and modelling. It gives a detailed overview of the latest results on materials research, fabrication processes, joining options, high heat flux testing, plasticity studies, modelling, and validation experiments

The magnetic structures of the hexagonal ${\mathrm{YMnO}}_3$ and ${\mathrm{ScMnO}}_3$ oxides (space group ${P6\mathrm{}}_{3}cm)$ have been studied by neutron-diffraction experiments on powder samples. This study has been complemented with magnetic susceptibility and specific-heat measurements. They confirm that ${\mathrm{YMnO}}_3$ and ${\mathrm{ScMnO}}_3$ become ordered below $T_N\approx 70$ K and $T_N\approx 129$ K, respectively, according to a triangular antiferromagnetic structure. The latter compound undergoes a second magnetic transition below 75 K, corresponding to a spin reorientation. The presence of weak ferromagnetism of Dzialoshinskii-Moriya type is observed in all the ordered region for the Sc material. In both compounds the moments are contained in the $\mathrm{}(a,b)\mathrm{}$ plane and oriented perpendicular $(R=\mathrm{Y})$ or parallel $(R=\mathrm{Sc})$ to the [100] directions. The low-temperature ordered moments are $2.90\left(2\right)\mathrm{}{\mu }_B$ $(R=\mathrm{Y})$ and $3.54\left(3\right)\mathrm{}{\mu }_B$ $(R=\mathrm{Sc})$ at $T=1.7\mathrm{}$ K. The different behavior observed in the thermal evolution of the magnetic structure of both compounds is discussed in terms of geometrical parameters determined from high-resolution structural data. The origin of the weak ferromagnetism in ${\mathrm{ScMnO}}_3$ is also analyzed.

A study of the crystallographic and magnetic structure of ${\text{SrCoO}}_{2.5}$ with a brownmillerite-type structure has been carried out from neutron powder-diffraction (NPD) measurements at temperatures ranging from 10 to 623 K, across the Néel temperature $\left(T_N=537\text{K}\right)$ of this antiferromagnetic oxide. The study has been complemented with differential scanning calorimeter (DSC), $dc$ susceptibility and magnetization measurements. Although the refinement of the crystal structure from NPD data is possible in the orthorhombic $Pnma$ and $Ima2$ space groups, the support of ab-initio band-structure calculations has allowed us to select, without ambiguity, the $Ima2$ space group as the ground state for ${\text{SrCoO}}_{2.5}$ brownmillerite. In $Ima2$ the crystallographic structure of ${\text{SrCoO}}_{2.5}$ is described as layers of corner-sharing $\text{Co}1{\text{O}}_6$ octahedra alternating along the $a$ axis with layers of vertex-sharing $\text{Co}2{\text{O}}_4$ tetrahedra, conforming chains running along the [0 0 1] direction. The magnetic structure below $T_N=537\text{K}$ is $G$-type with the magnetic moments directed along the $c$ axis. This magnetic arrangement is stable from $T_N$ down to 10 K. At $T=10\text{K}$, the magnetic moment values for Co1 and Co2 atoms are $3.12\left(13\right){\mu }_B$ and $2.88\left(14\right){\mu }_B$, respectively, compatible with a ${\text{Co}}^{2+}\underset{̱}{L}$ state, where $\underset{̱}{L}$ stands for a ligand hole. The magnetic susceptibility curves show, below 200 K, a divergence of zero-field cooling and field cooling curves, displaying broad maxima which are interpreted as due to the presence of ferromagnetic clusters embedded into an antiferromagnetic matrix. These inhomogeneities are inherent to the synthesis process, by quenching microcrystalline samples of ${\text{SrCoO}}_{3-x}$ composition from high temperature, where cubic, ferromagnetic perovskites have been identified by diffraction methods.