Hydrostatic pressure influence on electric relaxation response of bismuth manganite ceramics

Abstract

Electrical impedance of bismuth manganite ceramics was studied under ambient and high hydrostatic pressure. Local disorder of crystal lattice was confirmed using XRD and DSC. Two relaxation processes were discerned. One was attributed to small polarons, which showed a changeover from variable range hopping features related to Fermi glass and structural disorder to the nearest neighbor hopping behavior in higher temperature range related to uniform distribution of energy levels. Hydrostatic pressure shortened relaxation times that would be interesting for applications. The second process, which was assigned to the nearest neighbor hopping of polarons, also exhibited a changeover to glassy features in a high‐temperature range.

Vis and NIR Diffused Reflectance Study in Disordered Bismuth Manganate ‒ Lead Titanate Ceramics

“…The estimated Egap(Vis) fluctuated in 0.13-0.36 eV range when the PT content increased, showing no clear tendency. Such narrow Egap corresponds to the measured activation energy of electrical conductivity at room temperature reported in literature: Ea = 0.20 eV [35], and 0.24 eV for BM [39] and 0.34-0.40eV for BM-PT compounds [40,41]. The correspondence to the Egap = 0.33 eV calculated for the stoichiometric BiMnO3 [32] and Egap = 0.45eV calculated for the oxygendeficient BiMnO3-x [34] should also be noticed.…”

“…Electrical conductivity was attributed to the polaronic mechanism, and simultaneously high values of permittivity occurred. What is more, the electrical conductivity relaxations, showing changeover to properties dominated by glassy features, were assigned to the strain-stress effect [36][37][38][39].…”

“…A series of (1-x) BM-x PT, (x = 0.0, 0.02, 0.04, 0.08, 0.12, 0.16, 0.24) ceramics was sintered [39,41,44]. In this work, we studied diffused reflectance in the Vis-NIR range to determine the PT content influence on the BM-PT composite absorption coefficient and optical Egap magnitude.…”

Toward the Undiscovered Dielectric Properties of Hybrid Acetamidinium Manganese Formate under High Pressure

“…Following this observation, it was stated that ferroelectricity can be reduced or even can vanish in ABO 3 perovskite materials at high-pressure conditions; however, an opposite effect has also been observed . Moreover, the phenomenon of pressure-induced polarization enhancement has been found for formate-bridged hybrid organic–inorganic perovskite-like formates [NH 4 ]­[Cd­(HCOO) 3 ] and [C 2 H 5 NH 3 ]­[Na 0.5 Cr 0.5 (HCOO) 3 ]. − Finally, after application of an external pressure, relaxation processes can shift toward lower frequencies and higher frequencies, or even may be characterized by a pressure invariance. ,, …”

“…26−28 Finally, after application of an external pressure, relaxation processes can shift toward lower frequencies and higher frequencies, or even may be characterized by a pressure invariance. 25,29,30 Encouraged by the lack of such studies, we decided to choose acetamidinium manganese formate, AceMn, as a model compound to analyze the complex dielectric behavior of organic−inorganic hybrids under high-pressure conditions. Particularly, we focus on the issue of how and to what extent the external pressure affects the dipole relaxation process, its activation energy, and molecular dynamics of acetamidinium cations.…”