  At ambient pressure, lithium molybdenum purple bronze (Li0.9Mo6O17) is a
quasi-one dimensional solid in which the anisotropic crystal structure and the
linear dispersion of the underlying bands produced by electronic correlations
possibly bring about a rare experimental realization of Tomomaga-Luttinger
liquid physics. It is also the sole member of the broader purple molybdenum
bronzes family where a Peierls instability has not been identified at low
temperatures. The present study reports a pressure-induced series of phase
transitions between 0 and 12 GPa. These transitions are strongly reflected in
infrared spectroscopy, Raman spectroscopy, and x-ray diffraction. The most
dramatic effect seen in optical conductivity is the metallization of the
c-axis, concomitant to the decrease of conductivity along the b-axis. This
indicates that high pressure drives the material away from its quasi-one
dimensional behavior at ambient pressure. While the first pressure-induced
structure of the series is resolved, the identification of the underlying
mechanisms driving the dimensional change in the physics remains a challenge.
