Radiation effects, zero thermal expansion, and pressure-induced phase transition in CsMnCo(CN) 6 .

The Prussian blue analogue CsMnCo(CN) 6 is studied using powder X-ray and neutron diffraction under variable temperature, pressure, and X-ray exposure. It retains cubic F 4̄3 m symmetry in the range 85-500 K with minimal thermal expansion, whereas a phase transition to P 4̄ n 2 occurs at ∼2 GPa, driven by octahedral tilting. A small lattice contraction occurs upon increased X-ray dose. Comparisons with related systems indicate that the Cs I ions decrease the thermal expansion and suppress the likelihood of phase transformations. The results improve the understanding of the stimuli-responsive behaviour of coordination polymers.