We report giant reversible barocaloric effects in [(CH₃)₄N]Mn[N₃]₃ hybrid organic–inorganic perovskite, near its first-order cubic-monoclinic structural phase transition at T₀ ∼ 305 K.

In this letter, we investigated the temperature-dependent Raman spectra of CaMn₇O₁₂ helimagnet from room temperature down to 10 K. The temperature dependence of the Raman mode parameters shows remarkable anomalies for both antiferromagnetic and incommensurate transitions that this compound undergoes at low temperatures. The anomalies observed at the magnetic ordering transition indicate a spin-phonon coupling at higher-temperature magnetic transition in this material, while a magnetostriction effect at the lower-temperature magnetic transition.

The [(CH₃)₂NH₂]PbBr₃ perovskite exhibits an unusual thermal expansion, and we propose a novel thermomechanical mechanism that differs from the typical “wine-rack”. Also, we probed the presence of an H-bond between the DMA cation and the framework.

Temperature-dependent Raman scattering and differential scanning calorimetry were applied to the study of the hybrid organic-inorganic azide-perovskite [(CH₃)₄N][Cd(N₃)₃], a compound with multiple structural phase transitions as a function of temperature. A significant entropy variation was observed associated to such phase transitions, |∆S| ~ 62.09 J·kg⁻¹ K⁻¹, together with both a positive high barocaloric (BC) coefficient |δT_t/δP| ~ 12.39 K kbar⁻¹ and an inverse barocaloric (BC) coefficient |δT_t/δP| ~ −6.52 kbar⁻¹, features that render this compound interesting for barocaloric applications. As for the obtained Raman spectra, they revealed that molecular vibrations associated to the NC_4, N₃^– and CH₃ molecular groups exhibit clear anomalies during the phase transitions, which include splits and discontinuity in the phonon wavenumber and lifetime. Furthermore, variation of the TMA⁺ and N₃^– modes with temperature revealed that while some modes follow the conventional red shift upon heating, others exhibit an unconventional blue shift, a result which was related to the weakening of the intermolecular interactions between the TMA (tetramethylammonium) cations and the azide ligands and the concomitant strengthening of the intramolecular bondings. Therefore, these studies show that Raman spectroscopy is a powerful tool to gain information about phase transitions, structures and intermolecular interactions between the A-cation and the framework, even in complex hybrid organic-inorganic perovskites with highly disordered phases.