](q075 "fig:"){width="1\columnwidth"} ![\[fig:detailscan\] The dispersion of the TA2 phonons softens and hardens at $q = (\overline{0.075}\ 0.075\ 0)$ (top) and $q = (\overline{0.5}\ 0.5\ 0)$ (bottom), respectively, when approaching the cubic-tetragonal phase transition near $T_{OO} = 63$ K from high temperatures. For $q = (\overline{0.3}\ 0.3\ 0)$ (middle) there is no change in phonon energies in the $T > T_{OO}$ region. Please note that at MIRA we measured using neutron energy gain ($-E$) for reasons of analyser efficiency and angular constraints at the instrument. The physics of the system is unaffected by this choice. ](q3 "fig:"){width="1\columnwidth"} ![\[fig:detailscan\] The dispersion of the TA2 phonons softens and hardens at $q = (\overline{0.075}\ 0.075\ 0)$ (top) and $q = (\overline{0.5}\ 0.5\ 0)$ (bottom), respectively, when approaching the cubic-tetragonal phase transition near $T_{OO} = 63$ K from high temperatures. For $q = (\overline{0.3}\ 0.3\ 0)$ (middle) there is no change in phonon energies in the $T > T_{OO}$ region. Please note that at MIRA we measured using neutron energy gain ($-E$) for reasons of analyser efficiency and angular constraints at the instrument. The physics of the system is unaffected by this choice. ](35_45_0 "fig:"){width="1\columnwidth"}

 \[sec:linewidths\] Phonon linewidths 
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Having established the presence the softening 