Sahoo Shradhanjali, Ravindran T R, Rajaraman R, Srihari V, Pandey K K, Chandra Sharat
Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam 603102, Tamil Nadu, India.
High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
J Phys Chem A. 2020 Mar 12;124(10):1993-2000. doi: 10.1021/acs.jpca.9b11325. Epub 2020 Feb 27.
Diisopropylammonium salts have drawn attention in recent years due to their room-temperature ferroelectric properties. Triclinic diisopropylammonium perchlorate (DIPAP) exhibits ferroelectricity at room temperature. We have carried out density functional theory calculations to assign the phonon modes in DIPAP. High-pressure Raman spectra of DIPAP are recorded up to ∼3 GPa. Discontinuity in the NH bending and stretching mode frequencies and the appearance of new bands at 0.7 GPa suggest a phase transition by a rearrangement in the hydrogen network. Broadening of lattice modes at 1.3-1.7 GPa indicates a loss of crystalline nature above 1.7 GPa. High-pressure synchrotron X-ray diffraction of DIPAP shows an isostructural phase transition at 0.6 GPa and confirms amorphization at 1.5 GPa that may lead to a loss of ferroelectricity above this pressure. The ambient phase becomes reversible after releasing the pressure. The bulk modulus of DIPAP is determined to be 16.5 GPa.
近年来，二异丙基铵盐因其室温铁电特性而备受关注。三斜晶系的高氯酸二异丙基铵（DIPAP）在室温下表现出铁电性。我们进行了密度泛函理论计算以确定DIPAP中的声子模式。记录了DIPAP高达约3 GPa的高压拉曼光谱。NH弯曲和拉伸模式频率的不连续性以及在0.7 GPa处出现新带表明通过氢网络的重排发生了相变。在1.3 - 1.7 GPa处晶格模式变宽表明在1.7 GPa以上晶体性质丧失。DIPAP的高压同步加速器X射线衍射显示在0.6 GPa处发生同结构相变，并证实在1.5 GPa处非晶化，这可能导致在此压力以上铁电性丧失。释放压力后，常压相变得可逆。DIPAP的体积模量确定为16.5 GPa。
