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 elastic stiffness modulus of α-DIPAB molecular crystals is found to be strongly anisotropic, with exceptionally high values of ~55 GPa. But, the authors did not consider the effect of hydrogen ion deficiency on the properties of DIPA molecules.
Abstract: Elastic stiffness moduli were studied using dispersion-corrected density functional theory. The elastic stiffness moduli of α-DIPAB molecular crystals are found to be strongly anisotropic, with exceptionally high values of ~55 GPa. The magnitude of elastic stiffness modulus is strongly correlated with the relative orientation between the underlying hydrogen-bonding networks of DIPA molecules (“stitched” together by Br ions). These values of elastic stiffness modulus are remarkably high and suggest the design of hydrogen bond networks as a route for rational design of ultra-stiff molecular solids. Furthermore, Young’s modulus of α-DIPAB was found to attain extremely large value of as large as 50 GPa along certain crystallographic directions, while Br-deficient DIPAB has reduced Young’s modulus ( ~18 GPa). Anisotropy of Young’s modulus in α-DIPAB is very large with values below 40% of its maximum along specific spatial directions (and even lower in Br-deficient crystals). α-DIPAB and Br-deficient DIPAB show very different directionality of Young’s modulus due to the change in H-Br bond network upon Br deficiency. Additionally, Poisson’s ratio is strongly anisotropic as well with values ranging between a maximum of 0.4 for certain crystallographic directions and about 0.25 for other directions indicating the directionality of bonding in α-DIPAB. DIPAB systems are brittle based on the ratio between bulk and sheer elastic constants. Thus, DIPAB should be used as an element of composite materials to be used in thin-film flexible electronic application.
5 citations
TL;DR: In this paper, the continuous and uniform deposition of organic diisopropylammonium bromide (DIPAB) film on a single crystalline Si(100) substrate is demonstrated by a thermal evaporation process Structural and optical studies reveal that the film is c-axis oriented with an optical bandgap of 352 eV.
Abstract: Organic diisopropylammonium bromide (DIPAB) is a promising material with superior ferroelectric characteristics However, the DIPAB continuous film, which is essential to explore its application potential, is challenging because its crystallization kinetics favors island-like microcrystalline growth In this work, the continuous and uniform deposition of organic ferroelectric DIPAB film on a single crystalline Si(100) substrate is demonstrated by a thermal evaporation process Structural and optical studies reveal that the film is c-axis oriented with an optical bandgap of 352 eV The topographic image displays well-connected grain-like surface morphology with ∼2 nm roughness The ferroelectric domain studies illustrate the in-plane orientation of the domains, which is in accordance with c-axis oriented film where polarization is along the in-plane b-axis The phase and amplitude responses of the domains display hysteresis and butterfly characteristics, respectively and thereby endorse the ferroelectric nature of the film Importantly, it is demonstrated that the DIPAB film exhibits remarkable self-powered UV-Vis photodetector characteristics with responsivity of 066 mA W−1 and detectivity of 220 × 109 Jones at 1145 mW cm−2 light intensity The fabricated DIPAB film reported in this work can widen its application potential in self-powered photodetector and other optoelectronic devices
5 citations
TL;DR: In this article, the synthesis and characterization of as-grown Diisopropylammonium Bromide (α-DIPAB) thin films are described and an excellent agreement between the measured and calculated structural parameters is obtained.
4 citations
TL;DR: In this article, the temperature dependences of dielectric constant, amplitude of the third harmonic and heat capacity for the organic ferroelectric of diisopropylammonium iodide (C6H16NI) have been investigated.
Abstract: Temperature dependences of dielectric constant, amplitude of the third harmonic and heat capacity for the organic ferroelectric of diisopropylammonium iodide (C6H16NI) have been investigated. The m...
4 citations
TL;DR: In this paper, the properties of the molecular ferroelectric diisopropylammonium bromide (C6H16BrN, DIPAB) particles embedded into a nanoporous opal matrix were studied by high-resolution nuclear magnetic resonance (NMR) in the temperature range from 295 to 450 K.
Abstract: The properties of the molecular ferroelectric diisopropylammonium bromide (C6H16BrN, DIPAB) particles embedded into a nanoporous opal matrix were studied by high-resolution nuclear magnetic resonance (NMR) in the temperature range from 295 to 450 K. The 13C NMR spectra were obtained using CP-MAS technique. The results showed that structural changes in nanostructured DIPAB particles are more complex than it was previously expected. The NMR spectra of DIPAB embedded into the opal matrix revealed the coexistence of two different crystalline structures within a wide temperature range. The monoclinic ferroelectric and orthorhombic non-polar phases were seen in nanoconfined DIPAB at room temperature, meanwhile the orthorhombic phase only was found in the bulk DIPAB crystalline powder. The NMR spectra showed that the transition from the orthorhombic to the ferroelectric phase upon heating is reconstructive. The total nanocomposite transforms into the ferroelectric structure at a temperature much higher than that for the relevant transition in bulk. The size effect also leads to the increase of the temperature of the phase transition from the ferroelectric P21 phase to the P21/m paraphrase.
3 citations
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TL;DR: In this paper, the authors show that lanthanum-substituted bismuth titanate (SBT) thin films provide a promising alternative for FRAM applications, since they are fatigue-free on metal electrodes, they can be deposited at temperatures of ∼650°C and their values of Pr are larger than those of the SBT films.
Abstract: Non-volatile memory devices are so named because they retain information when power is interrupted; thus they are important computer components. In this context, there has been considerable recent interest1,2 in developing non-volatile memories that use ferroelectric thin films—‘ferroelectric random access memories’, or FRAMs—in which information is stored in the polarization state of the ferroelectric material. To realize a practical FRAM, the thin films should satisfy the following criteria: compatibility with existing dynamic random access memory technologies, large remnant polarization (Pr) and reliable polarization-cycling characteristics. Early work focused on lead zirconate titanate (PZT) but, when films of this material were grown on metal electrodes, they generally suffered from a reduction of Pr (‘fatigue’) with polarity switching. Strontium bismuth tantalate (SBT) and related oxides have been proposed to overcome the fatigue problem3, but such materials have other shortcomings, such as a high deposition temperature. Here we show that lanthanum-substituted bismuth titanate thin films provide a promising alternative for FRAM applications. The films are fatigue-free on metal electrodes, they can be deposited at temperatures of ∼650 °C and their values of Pr are larger than those of the SBT films.
2,008 citations
TL;DR: It is shown that a large piezoelectric response can be driven by polarization rotation induced by an external electric field, and the computations suggest how to design materials with better performance, and may stimulate further interest in the fundamental theory of dielectric systems in finite electric fields.
Abstract: Piezoelectric materials, which convert mechanical to electrical energy (and vice versa), are crucial in medical imaging, telecommunication and ultrasonic devices. A new generation of single-crystal materials, such as Pb(Zn1/3Nb2/3)O3-PbTiO3 (PZN-PT) and Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), exhibit a piezoelectric effect that is ten times larger than conventional ceramics, and may revolutionize these applications. However, the mechanism underlying the ultrahigh performance of these new materials-and consequently the possibilities for further improvements-are not at present clear. Here we report a first-principles study of the ferroelectric perovskite, BaTiO3, which is similar to single-crystal PZN-PT but is a simpler system to analyse. We show that a large piezoelectric response can be driven by polarization rotation induced by an external electric field. Our computations suggest how to design materials with better performance, and may stimulate further interest in the fundamental theory of dielectric systems in finite electric fields.
1,789 citations
TL;DR: DIPAB is a molecular alternative to perovskite ferroelectrics and ferroelectric polymers in sensing, actuation, data storage, electro-optics, and molecular or flexible electronics and exhibits good piezoelectric response and well-defined ferro electric domains.
Abstract: Molecular ferroelectrics are highly desirable for their easy and environmentally friendly processing, light weight, and mechanical flexibility. We found that diisopropylammonium bromide (DIPAB), a molecular crystal processed from aqueous solution, is a ferroelectric with a spontaneous polarization of 23 microcoulombs per square centimeter [close to that of barium titanate (BTO)], high Curie temperature of 426 kelvin (above that of BTO), large dielectric constant, and low dielectric loss. DIPAB exhibits good piezoelectric response and well-defined ferroelectric domains. These attributes make it a molecular alternative to perovskite ferroelectrics and ferroelectric polymers in sensing, actuation, data storage, electro-optics, and molecular or flexible electronics.
641 citations
TL;DR: In this article, the authors summarize the recent progress in applications of piezoresponse force microscopy (PFM) for imaging, manipulation and spectroscopy of ferroelectric switching processes.
Abstract: Ferroelectrics and multiferroics have recently emerged as perspective materials for information technology and data storage applications. The combination of extremely narrow domain wall width and the capability to manipulate polarization by electric field opens the pathway toward ultrahigh (>10 TBit inch−2) storage densities and small (sub-10 nm) feature sizes. The coupling between polarization and chemical and transport properties enables applications in ferroelectric lithography and electroresistive devices. The progress in these applications, as well as fundamental studies of polarization dynamics and the role of defects and disorder on domain nucleation and wall motion, requires the capability to probe these effects on the nanometer scale. In this review, we summarize the recent progress in applications of piezoresponse force microscopy (PFM) for imaging, manipulation and spectroscopy of ferroelectric switching processes. We briefly introduce the principles and relevant instrumental aspects of PFM, with special emphasis on resolution and information limits. The local imaging studies of domain dynamics, including local switching and relaxation accessed through imaging experiments and spectroscopic studies of polarization switching, are discussed in detail. Finally, we review the recent progress on understanding and exploiting photochemical processes on ferroelectric surfaces, the role of surface adsorbates, and imaging and switching in liquids. Beyond classical applications, probing local bias-induced transition dynamics by PFM opens the pathway to studies of the influence of a single defect on electrochemical and solid state processes, thus providing model systems for batteries, fuel cells and supercapacitor applications.
405 citations
TL;DR: A simple organic salt, diisopropylammonium chloride, shows the highest ferroelectric phase transition temperature among molecule-based ferroelectrics with a large spontaneous polarization, making it a candidate for practical technological applications.
Abstract: A simple organic salt, diisopropylammonium chloride, shows the highest ferroelectric phase transition temperature among molecule-based ferroelectrics with a large spontaneous polarization, making it a candidate for practical technological applications.
292 citations