Study of ferroelectric characteristics of diisopropylammonium bromide films
TL;DR: In this article, a thick film of diisopropylammonium bromide organic molecular ferroelectric is fabricated on the ITO/glass substrate and a butterfly loop in amplitude and hysteretic character of the phase is revealed, which are the expected characteristics features of ferroelectrics.
Abstract: Organic molecular ferroelectrics are highly desirable due to their numerous advantages. In the present work, a thick film of diisopropylammonium bromide organic molecular ferroelectric is fabricated on the ITO/glass substrate. The grown film shows preferential orientation along the c-axis with a ferroelectric transition at 419 K. The piezoresponse force microscopic measurements are done in a dual ac resonance tracking mode for its switching characteristics. The amplitude and phase images of the oppositely written domain patterns exhibit a clear contrast with 180° phase difference. The dynamical spectroscopic studies reveal a butterfly loop in amplitude and hysteretic character of the phase which are the expected characteristics features of ferroelectrics. In addition, the macroscopic polarization versus electric field hysteresis gives an additional proof for ferroelectric character of the film with the maximum polarization of 3.5 μC/cm2. Overall, we have successfully fabricated diisopropylammonium bromide...
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TL;DR: In this article, the authors explore diisopropylammonium iodide (DPI) for its ferroelectric properties and phase transitions and identify two phase transitions which were identified by differential scanning calorimetry and dielectric and nonlinear optical measurements.
Abstract: In this manuscript, we explore diisopropylammonium iodide (DPI) for its ferroelectric properties and phase transitions. DPI showed two phase transitions which were identified by differential scanning calorimetry and dielectric and nonlinear optical measurements. From detailed structural studies it was found that the first transition at 369 K is from orthorhombic P212121 to monoclinic P21. The polar P21 phase is ferroelectric as evidenced by the pyroelectric data and has a very high value of spontaneous polarization (Ps = 33 μC cm−2), which is probably the highest among other reported bulk organic ferroelectrics. The second transition at 415 K is identified as polar monoclinic P21 space group to non-polar monoclinic P21/m. Thus, DPI has a high Curie temperature of 415 K. The large spontaneous polarization and high Curie temperature make DPI technologically important.
20 citations
TL;DR: In this article, a novel all-organic composite comprising polyvinylidene fluoride (PVDF) and diisopropylammonium bromide (DIPAB) crystal particles with significant dielectric properties has been synthesized via coating method.
Abstract: A novel all-organic composite comprising polyvinylidene fluoride (PVDF) and diisopropylammonium bromide (DIPAB) crystal particles (0–20 mass%) with significant dielectric properties has been synthesized via coating method. The DIPAB crystal nano-particles were prepared in the PVDF matrix by in situ growth method, which were found effective in transforming structure and enhancing the dielectric properties of the composites. X-ray diffraction pattern and Fourier transform infrared spectroscopy confirmed that the DIPAB in situ particles can improve the content of the electroactive β phase nucleation in PVDF matrix, whereas the PVDF matrix could induce the (00l) preferred orientation of the DIPAB nano-crystal. And the dielectric performance of the DIPAB/PVDF composite was significant influenced by the enhanced electroactive β phase and (00l) textured DIPAB. Relative dielectric constants as high as 94 was obtained at 40 Hz with 5 mass% DIPAB filler, which is 11-fold higher than that of the pure PVDF matrix (~8.5). The breakdown strength decreased as the mass fraction of DIPAB increased but still stayed more than 38.9 kV/mm.
13 citations
TL;DR: In this paper, the dielectric properties of Al2O3 oxide films with a pore size of 330 and 60 nm with particles of an organic ferroelectric diisopropylammonium bromide (C6H16BrN, DIPAB) introduced into the pores, aimed at determining the size dependences of phase transition parameters.
Abstract: We present the results of studies of the dielectric properties of nanocomposites based on Al2O3 oxide films with a pore size of 330 and 60 nm with particles of an organic ferroelectric diisopropylammonium bromide (C6H16BrN, DIPAB) introduced into the pores, aimed at determining the size dependences of phase transition parameters. A shift in the phase transition to low temperatures and diffusion of the transition are found, which become more significant for smaller pores. A broadening of the temperature hysteresis of the dielectric constant of nanocomposites during the phase transition was also observed. The decrease in the phase transition temperature in nanocomposites with DIPAB nanoparticles is consistent with theoretical models of the size effects on the structural phase transition.
10 citations
TL;DR: In this paper, the results of a computational first-principles study of the structural and electrical properties of three ferroelectric diisopropylammonium halides containing chlorine, bromine, and iodine were reported.
Abstract: We report the results of a computational first-principles study of the structural and electrical properties of three ferroelectric diisopropylammonium halides containing chlorine, bromine, and iodine. Calculations were carried out using density-functional theory with maximally-localized Wannier functions utilized for computing electrical polarization within the Modern Theory of Polarization formalism. For each of the crystals, the polar properties for all of the relevant polymorphs were evaluated and decomposed into contributions from individual positive diisopropylammonium and negative halogen-ion charge centers. The calculations show that each diisopropylammonium-halide unit in the crystal possesses a substantial dipole moment with magnitude of 10 to 15 Debye, but that these dipoles are arranged in a mutually opposing manner, leading to full cancellation in the paraelectric phase. In the ferroelectric phase, the dipoles cant along a common polar axis, inducing a small net dipole moment in the crystallographic unit cell, with spontaneous polarization ranging from 5 μC cm−2 for the iodide to 6 μC cm−2 for the bromide and 7 μC cm−2 for the chloride, suggesting no strong dependence of the polarization on the chemical identity of the halide counter ion. We propose that structural modifications of the diisopropylammonium-halide system aimed at stabilization of large unit-dipole cantings could produce molecular crystals with greatly increased spontaneous polarization.
8 citations
TL;DR: The study presents experimental results for investigating linear and nonlinear dielectric properties of nanocomposites based on bromide diisopropylammonium and aluminum oxide films and indicated that the phase transition was blurred and shifted toward lower temperatures.
Abstract: The study presents experimental results for investigating linear and nonlinear dielectric properties of nanocomposites based on bromide diisopropylammonium (C6H16NBr, DIPAB) and aluminum oxide films (Al2O3) with pore diameter of 330, 100 and 60 nm. It was indicated that the phase transition was blurred and shifted toward lower temperatures. This anomaly became more significant with decreasing pore size. The reduction of phase transition temperature in the nanocomposites, containing DIPAB, was consistent with theoretical models for the influence of size effects on the structural phase transition.
7 citations
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TL;DR: A thin film of diisopropylammonium perchlorate processed by a spin-coating method shows a good roughness and textured structure that makes DIPAP a candidate in sensing, data storage, electro-optics, and molecular/flexible electronics.
Abstract: Molecular ferroelectric thin films are highly desirable for their easy and environmentally friendly processing, light weight, and mechanical flexibility. A thin film of diisopropylammonium perchlorate (DIPAP) processed by a spin-coating method shows a good roughness and textured structure with (101) orientation in the ferroelectric phase with a space group of P1. Simultaneously, the thin film shows ferroelectricity and ferroelectric relaxivity above room temperature, which is completely different from crystals. These properties make DIPAP a candidate in sensing, data storage, electro-optics, and molecular/flexible electronics.
12 citations