Compounds with the general composition Ni2+xMn1-xGa belong to the
group of ferromagnetic shape memory alloys. These materials have
recently attracted a considerable amount of interest due to their potential
for applications. Ferromagnetic shape memory alloys, in contrast to
conventional shape memory materials, offer the possibility to initiate a
change of shape with the application of an external magnetic field of
modest magnitude in addition to shape changes induced via a shift in
In this thesis the magnetic and crystallographic properties of
Ni2+xMn1-xGa alloys are investigated within the range 0 < x < 0.17.
Structural investigations using both X-ray as well as neutron scattering
have been carried out. The low temperature phase has been determined
and structural information has been obtained within the transition region
for the first time. Magnetic properties have been investigated using a
SQUID magnetometer within the temperature range of T = 2 K to 360 K
and using magnetic fields up to 5.5 Tesla. The locations of phase
transitions were investigated using DSC and resistivity measurements for
both heating as well as cooling. The composition dependence of the
martensitic and ferromagnetic transition temperatures have been
confirmed. The first order nature of the martensitic phase transformation
has been confirmed in DSC, magnetisation and resistivity measurements.
A Master's Thesis. Submitted in partial fulfilment of the requirements for the award of Master of Philosophy at Loughborough University.