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.

Manganite with a double perovskite structure is an attractive material because of its interesting magnetoelectric and dielectric responses. In particular, colossal dielectric constant (CDC) behavior has been observed in La₂CoMnO₆ (LCMO) at radio frequencies and at room temperature. In this paper, we used infrared-reflectivity spectroscopy to study a LCMO ceramic obtained through a modified Pechini's method to determine the phonon contribution to the intrinsic dielectric response of the system and to investigate the CDC origin. The analysis of the main polar modes and of the obtained phonon parameters indicate that the CDC effect of LCMO is of pure extrinsic origin. In addition, we estimated the dielectric constant and the quality factor of the material in the microwave region to be ε′_s ∼ 16 and Q_u × f ∼ 124 THz, which verifies that LCMO is appropriate for application in microwave devices and circuitry.