  We report synchrotron x-ray powder diffraction measurements of
Ce0.8La0.1Th0.1 subject to pulsed magnetic fields as high as 28 Tesla. This
alloy is known to exhibit a continuous volume collapse on cooling at ambient
pressure, which is a modification of the gamma -> alpha transition in elemental
cerium. Recently, it has been suggested on the basis of field-cooled
resistivity and pulsed field magnetization measurements that the volume
collapse in this alloy can be suppressed by the application of magnetic fields.
Conversely, our direct diffraction measurements show a robust collapsed phase,
which persists in magnetic fields as high as 28 Tesla. We also observe
nanoscale disorder in the collapsed phase, which increasingly contaminates the
high temperature phase on thermal cycling.
