Order-disorder phase transition and molecular dynamics in the hybrid perovskite [(CH3)3NH][Mn(N3)3]

[Display omitted] •Hybrid organic–inorganic perovskite compound [(CH3)3NH][Mn(N3)3] was obtained by the solution-diffusion method.•Clausius-Clapeyron indirect method was applied to estimate the barocaloric coefficient (δTt/δP) of [(CH3)3NH][Mn(N3)3] in ∼3.17 K kbar−1 for the first-order phase transition at 359 K.•A correlation between the hydrogen bond strengths and the order–disorder processes of framework and TrMA cations was observed.•The temperature dependence of intermolecular interactions between the TrMA+ cations, azido-bridges, and intramolecular bonds were discussed.•Linewidth anomalies of the δNC3 and νasNC3 modes evidenced the molecular dynamics of encapsulated cations. We present a temperature-dependent Raman scattering study of a [(CH3)3NH][Mn(N3)3] hybrid organic–inorganic azide-perovskite, in which we have analysed in detail the wavenumber and full width at half-maximum (FWHM) of lattice modes and internal modes of the NC3 skeleton, N3– and CH3 molecular groups. In general, the modes exhibited unusual behaviour during the phase transitions, including discontinuity in the phonon wavenumber, bandwidth, and unconventional shifts upon temperature variation. Spectral features on heating reveal the absence of significant distortions in the NC3 skeleton and a relatively restricted order–disorder process of the TrMA+ cations. On the other hand, linewidth anomalies of the δNC3 and νasNC3 modes have been attributed to the molecular dynamics of encapsulated cations. The unconventional blue shift of the symmetric stretching modes of azide ligands indicates the weakening of the intermolecular interactions between the TrMA+ cations and azido-bridges, and the strengthening of the intramolecular bonds. Additionally, we have used differential scanning calorimetry to confirm the subtle monoclinic to monoclinic (P21/c → C2/c) phase transition at around 330 K; and the phase transition to trigonal structure (R3¯m) above 359 K, whose associated entropy variation turns to be |ΔS| ∼ 22.3 J·kg−1 K−1 and displays a barocaloric (BC) tunability |δTt/δP| ∼ 3.17 K kbar−1, according to our estimations using the Clausius-Clapeyron method. Although the obtained values of entropy change and BC tunability are very close to those reported on formate-perovskites and other important caloric materials, those parameters are much lower than the giant entropy change of ∼80 Jkg−1 K−1 and large BC tunability ∼12 K kbar−1 observed for the analogue azide-perovskite [(CH3)4N][Mn(N3)]3 (T