Pressure induced phase transformations in diisopropylammonium bromide

High-Pressure Structural Phase Transformation of Ferroelectric Bis-benzylammonium Lead Tetrachloride Studied by Raman Spectroscopy and X-ray Diffraction

“…In the ambient phase, pressure–volume data of BALC were fitted to second-order Birch–Murnaghan equation of state and the bulk modulus was found to be 14.5 ± 0.3 GPa which is comparable to the analogous compound BALB which has bulk modulus 10 GPa (Figure ). Also, the bulk modulus value is comparable to other 2-D perovskite structures ,− and molecular solids. − After the phase transition in the new phase, the bulk modulus was obtained to be 19.1 ± 0.7 GPa which is higher than the ambient phase (Figure ). We have carried out linear fits of the form a 0 + a 1 P for a , b , and c values in phase-I to understand the behavior of lattice parameters.…”

Pressure-Induced Amorphization of Diisopropylammonium Perchlorate Studied by Raman Spectroscopy and X-ray Diffraction

“…12,13,20 Our earlier investigations on diisopropylammonium bromide (DIPAB) revealed a pressureinduced structural transformation from the ambient monoclinic (m-II) ferroelectric phase to a centrosymmetric, nonpolar triclinic structure that indicated a weakening or loss of ferroelectricity at a high pressure. 21 As a function of increasing temperature, DIPAP shows two phase transitions from P21/c to P1 at 296 K and subsequently to P21/c at 338 K. The phase transitions are reversible with some hysteresis, which was confirmed using Raman and XRD measurements. 13,14,22 The low-temperature and high-temperature phases are isostructural; only the P1 (triclinic) intermediate phase exhibits ferroelectricity at room temperature.…”

“…The bulk modulus of phase-I before the transition is 16.5(2) GPa. Molecular organic solids generally possess bulk modulus values of less than 20 GPa. , DIPAP has a higher bulk modulus value than DIPAB (7.3) and ammonium perchlorate (15.2), but much lower than inorganic ferroelectrics, such as BaTiO 3 (162 GPa) and PbTiO 3 (144 GPa) …”

“…Molecular organic solids generally possess bulk modulus values of less than 20 GPa. 24,43 DIPAP has a higher bulk modulus value than DIPAB (7.3) 21 and ammonium perchlorate (15.2), 44 but much lower than inorganic ferroelectrics, such as BaTiO 3 (162 GPa) and PbTiO 3 (144 GPa). 45 To understand the behavior of lattice parameters in phase-I, we carried out linear fits of the form a 0 +a 1 P for a, b, and c values.…”

“…Experimentally, it is found that diisopropylammonium bromide (DIPAB) has a spontaneous polarization ( P s ) of 26 μC/cm 2 , DIPAC has a value of 8.2 μC/cm 2 , and diisopropylammonium perchlorate (DIPAP) has a value of only 1 μC/cm 2 , whereas according to density functional theory (DFT) calculations, the value of P s should be ∼20 μC/cm 2 for all of these salts, along with a large dielectric constant of ∼10 3 , which is comparable to that of conventional BaTiO 3 . ,, These materials are lead-free, low cost, flexible, and have strong potential for device applications. Diisopropylammonium perchlorate (DIPAP) belongs to the family of diisopropylammonium salts that have recently drawn the attention of researchers due to their room-temperature molecular ferroelectric character. ,, Our earlier investigations on diisopropylammonium bromide (DIPAB) revealed a pressure-induced structural transformation from the ambient monoclinic (m-II) ferroelectric phase to a centrosymmetric, nonpolar triclinic structure that indicated a weakening or loss of ferroelectricity at a high pressure . As a function of increasing temperature, DIPAP shows two phase transitions from P 21/ c to P 1 at 296 K and subsequently to P 21/ c at 338 K. The phase transitions are reversible with some hysteresis, which was confirmed using Raman and XRD measurements. ,, The low-temperature and high-temperature phases are isostructural; only the P 1 (triclinic) intermediate phase exhibits ferroelectricity at room temperature.…”