Structure and bonding in TiNiSi type LaMgSnH intermetallic hydride

The work was aimed on reaching a better understanding of the effect of magnesium as a component of the hydride-forming LaMgSn intermetallic compound crystallising with the orthorhombic TiNiSi type of structure on the hydrogenation behaviours, crystal structure and bonding interactions with hydrogen. The LaMgSn structure is significantly...

Exploring the negative thermal expansion and magnetocaloric effect in Fe₂(Hf,Ti) Laves phase materials

The transition-metal based Laves phase materials represent an extended family of alloys with rich and fascinating physical properties. In this work, we have investigated the negative thermal expansion and magnetocaloric effect in arc-melted and melt-spun Fe₂Hf_1-_xTi_x (x = 0.15, 0.27, 0.30, 0.33, 0.36...

Enhanced reversibility of the magnetoelastic transition in (Mn,Fe)₂(P,Si) alloys via minimizing the transition-induced elastic strain energy

Magnetocaloric materials undergoing reversible phase transitions are highly desirable for magnetic refrigeration applications. (Mn,Fe)₂(P,Si) alloys exhibit a giant magnetocaloric effect accompanied by a magnetoelastic transition, while the noticeable irreversibility causes drastic degradation of the magnetocaloric properties...

Towards low-cost PEM fuel cells: Interfacial effects and material dynamics of a non-PGM electrocatalyst

In this thesis several aspects of PEM fuel cells are discussed. From an atomic scale, e.g. crystal and electronic structure of a non-noble metal material, e.g. (H)zLiMn2O4 (protonated spinel lithium manganese oxide) for electrocatalysis and its dynamics, to meso-macro scale effects such as those concerning transport resistances at the membrane...

Tuning the magneto-elastic transition of (Mn,Fe,V)₂(P,Si) alloys to low magnetic field applications

The first-order magneto-elastic transition in the Mn–Fe–P–Si alloys can be tailored by vanadium substitution. Alloys with a suitable V substitution provide an excellent magnetocaloric effect with minor hysteresis in low magnetic fields up to 1.2 T. Mössbauer measurements show that the hyperfine field is reduced by V substitution. Neutron...

Structural and thermodynamic study of Cs₃Na(MoO₄)₂: Margin to the safe operation of sodium cooled fast reactors

Neutron diffraction measurements of the double molybdate Cs₃Na(MoO₄)₂ have been performed for the first time in this work and the crystal structure refined using the Rietveld method. The thermal expansion of this trigonal phase, in space group P3¯m1, measured using high temperature X-ray diffraction (XRD),...

Combined effect of annealing temperature and vanadium substitution for mangetocaloric Mn_1.2-xV_xFe_0.75P_0.5Si_0.5 alloys

Approaching the border of the first order transition and second order transition is significant to optimize the giant magnetocaloric materials performance. The influence of vanadium substitution in the Mn_1.2-xV_xFe_0.75P_0.5Si_0.5 alloys is investigated for annealing temperatures of 1323,...

Magnetoelastic Coupling in Mn-Fe-P-Si Compounds

Mn-Fe-P-Si compounds are, to date, the most promising materials for refrigeration and energy conversion applications due to the combination of giant magnetocaloric effect (GMCE) and low material cost. The nature of magneto-elastic transition was studied on both length- and time-scales using neutron diffraction, muSR and Mӧssbauer spectroscopy...

Non-destructive bulk analysis of the Buggenum sword by neutron resonance capture analysis and neutron diffraction

Two neutron based techniques, neutron resonance capture analysis (NRCA) and time-of-flight neutron-diffraction (TOF-ND) have been used to determine the elemental composition and structure of a precious and very well preserved all-metal sword from the Bronze Age. This Buggenum sword was on loan from the National Museum of Antiquities (NMA) in...