Effects of Interaction in Mixtures of Ferroelectric Powders C 6 H 16 NBr and PbTiO 3
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OELECTRICITY
Effects of Interaction in Mixtures of Ferroelectric Powders C6H16NBr and PbTiO3 S. V. Baryshnikova, b and A. Yu. Milinskiia, * a
Blagoveshchensk State Pedagogical University, Blagoveshchensk, Russia b Amur State University, Blagoveshchensk, Russia *e-mail: [email protected] Received May 25, 2020; revised May 25, 2020; accepted June 10, 2020
Abstract—Phase transitions in the mixture of powders C6H16NBr (DIPAB) and PbTiO3 and composites xbTiO3–(1 – x)C6H16NBr at x from 0.05 to 0.45 have been studied by the differential thermal analysis (DTA) method. The DTA signal is compared to the temperature dependence of dielectric permittivity ε'(T) of the xPbTiO3–(1 – x)C6H16NBr composites. The addition of lead titanate to C6H16NBr is shown to lead to the appearance of new phase transition in both the composites and the powder mixture. Keywords: ferroelectric, composite, diisopropilammonium bromide, DIPAB, dielectric permittivity DOI: 10.1134/S1063783420110074
1. INTRODUCTION Great interest to studying composites is caused by the fact that such structures can have unusual properties as compared to homogeneous materials. One of the aims of such studies is the revealing of changes in the properties of micro- and nanoparticles in mixtures. According to the existing concepts, the cause of the ferroelectric state in crystals is the long-range dipole–dipole interaction that is responsible for the separation of crystals into domains and the influence of dipole impurities on the properties of ferroelectrics. [1–3]. The study of cooperative phenomena in disordered systems shows that the incorporation of eccentric impurities in strongly polarized matrices can lead to the formation of a ferroelectric phase [2, 3]. Unlike crystals, dipole particle in ferroelectric composites are arranged at significant states; however, it was found in some works [4–8] that a mutual influence of the components on the properties of one other is possible also in such systems. For ferroelectric composites xBaTiO3–(1 – x)KNO3 and xKNbO3–(1 – x)KNO3, the region of existence of the ferroelectric potassium nitrate phase is expanded [4, 5]. For the xBaTiO3– (1 – x)NaNO2 composites, the interaction effect leads to an increase in the temperature range of existence of the inconsistent sodium nitrite phase [6]. In [7], it was found that the Curie temperature of AgNa(NO2)2 in the 0.1BaTiO3–0.9AgNa(NO2)2 composite is significantly shifted. In [8], it was shown that the mechanisms of influence of interstitial particles on the Curie temperature of thiurea in composites
0.1BaTiO3–0.9SC(NH2)2, 0.1PbTiO3–0.9SC(NH2)2, and 0.1LiNbO3–0.9SC(NH2)2 are dependent not only on the spontaneous polarization of incorporated particles, but also on their dielectric permittivity. Recently several organic ferroelectrics belonging to the family of C6H16NA salts, where A = Cl–, Br–, and I– [9–11]. Such ferroelectrics are diisopropilammonium chloride (DIPAC), having spontaneous polarization Ps ~ 8.2 μC cm–2 and the Curie temperature TC = 440 K [9], diisopropilammonium bromide
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