Dielectric properties of an organic ferroelectric of bromide diisopropylammonium embedded into the pores of nanosized Al 2 O 3 films.
04 Dec 2019-Journal of Physics: Condensed Matter (J Phys Condens Matter)-Vol. 31, Iss: 48, pp 485704-485704
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.
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TL;DR: In this article, the influence of hydrogen bonds on dielectric relaxation properties of classical hydrogen-bonded ferroelectrics (triglycine sulfate, Rochelle salt) is clarified.
Abstract: This present work is devoted to clarifying the influence of hydrogen bonds on dielectric relaxation properties of classical hydrogen-bonded ferroelectrics (triglycine sulfate, Rochelle salt...
5 citations
TL;DR: In this article, phase transitions in new organic ferroelectric DIPA embedded into porous alumina and in bulk DIPAI were studied. But the phase transitions do not show noticeable thermal hysteresis.
Abstract: We studied phase transitions in new organic ferroelectric DIPAI embedded into porous alumina and in bulk DIPAI. Complex permittivity and third harmonic generation coefficient were measured within a wide temperature range. The increase in the third harmonic generation indicates the emergence of the polar phase. Two phase transitions were seen in bulk DIPAI upon heating from room temperature after preliminary heating up to 420 K while only a transition was found upon cooling accompanied with pronounced thermal hysteresis. The ferroelectric phase was observed in the range between two transitions upon heating and below the transition upon cooling. In contrast, two phase transitions occur in DIPAI confined to porous alumina upon heating and cooling. The transitions do not show noticeable thermal hysteresis. It was suggested that different behavior of bulk and confined DIPAI results from slow kinetics of phase transitions in bulk upon cooling. The noticeable shift of the transition temperatures for DIPAI within alumina pores of different diameters was treated using the theories of size effects in ferroelectrics.
4 citations
TL;DR: In this article, the temperature dependences of the linear dielectric permittivity and the third harmonic coefficient γ3ω for nanocomposites obtained by embedding a KNO3 melt into the pores of Al2O3 oxide films with diameters of 330, 190, and 100 nm are investigated.
Abstract: The temperature dependences of the linear dielectric permittivity e′ and the third harmonic coefficient γ3ω for nanocomposites obtained by embedding a KNO3 melt into the pores of Al2O3 oxide films with diameters of 330, 190, and 100 nm are investigated. The measurements were carried out in the heating and cooling modes in the range from room temperature to 463 K. It was found that the structural phase transition from phase II to phase I of potassium nitrate in Al2O3 films shifts towards higher temperatures as compared to bulk KNO3. For KNO3, the ferroelectric phase appears in the pores of 190 and 100 nm both upon heating and upon cooling.
2 citations
TL;DR: In this paper, the properties of new organic ferroelectric diisopropylammonia iodide (DIPAI) introduced into porous aluminum oxide films have been studied in comparison with a bulk DIPAI.
Abstract: Linear and nonlinear dielectric properties of new organic ferroelectric diisopropylammonia iodide (DIPAI) introduced into porous aluminum oxide films have been studied in comparison with the properties of a bulk DIPAI In DIPAI, in pores 300 and 60 nm in diameter, it has been found that the ferroelectric phase forms on heating and on cooling in the temperature range between two structural phase transitions above room temperature No marked temperature hysteresis is observed for both the phase transitions The boundaries of the intermediate polar phase in the nanostructured DIPAI is shown to shift to lower temperatures as the pore size decreases For the bulk DIPAI, two structural transitions are observed on heating with the formation of an intermediate polar phase and only one transition below which the ferroelectricity forms is observed on cooling This transition temperature is significantly lower than the corresponding temperature on heating It is assumed that the observed differences of the phase transition in DIPAI in pores and in the bulk DIPAI are related to an acceleration of the kinetics of the phase transitions in the nanoconfinement conditions
1 citations
TL;DR: In this paper , the dielectric permittivity, the third harmonic coefficient, and the DTA signal for Al2O3 nanoporous matrices filled with rubidium nitrate are presented.
Abstract: Abstract The results of studying the dielectric permittivity, the third harmonic coefficient, and the DTA signal for Al2O3 nanoporous matrices filled with rubidium nitrate are presented. A shift of the phase transition T c ≈ 437 K by 3 K to the low-temperature region and an increase in the temperature hysteresis of the phase transition from 14 K for polycrystalline RbNO3 to 33 K for RbNO3 in the pores of the Al2O3 oxide film were found.
References
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888 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 paper, the size effects on the Curie temperature and spontaneous polarization in spherical particles are studied using Landau phenomenological theory and the extrapolation length is shown to be size dependent.
Abstract: Size effects on the Curie temperature and spontaneous polarization in spherical particles are studied using Landau phenomenological theory. The extrapolation length is shown to be size dependent. The spatial distribution of polarization is obtained. The size dependence of the polarization is calculated whereby a size-driven phase transition is demonstrated. The Curie temperature as a function of particle size is calculated. Theoretical results are compared with the experimental in the literature and good agreement is obtained.
454 citations
01 Jan 2017
TL;DR: In this paper, the authors proposed a method to identify the most likely SiH3 + SiH4 SiH 4 + Si H4 + H2 + H3 + H 2 + H 3 + H 4
Abstract: ion SiH3 + SiH4 SiH4 + SiH3 H + SiH4 H2 + SiH3
348 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