  Low-density amorphous ice (LDA) is involved in critical cosmological
processes and has gained prominence as one of the at least two distinct
amorphous forms of ice. Despite these accolades, we still have an incomplete
understanding of the structural diversity that is encompassed within the LDA
state and the dynamic processes that take place upon heating LDA. Heating the
high-pressure ice VIII phase at ambient pressure is a remarkable example of
temperature-induced amorphisation yielding LDA. We investigate this process in
detail using X-ray diffraction and Raman spectroscopy, and show that the LDA
obtained from ice VIII is structurally different from the more 'traditional'
states of LDA which are approached upon thermal annealing. This new structural
relaxation pathway involves an increase of structural order on the intermediate
range length scale. In contrast with other LDA materials the local structure is
more ordered initially and becomes slightly more disordered upon annealing. We
also show that the cascade of phase transitions upon heating ice VIII at
ambient pressure includes the formation of ice IX which may be connected with
the structural peculiarities of LDA from ice VIII. Overall, this study shows
that LDA is a structurally more diverse material than previously appreciated.
