Łukasz Wolański | Searcharxiv

arXiv2025

Chemical capacitor: its concept, functionalities and limits

We use density functional theory calculations to study simple but diverse stoichiometries within the novel chemical capacitor (CC) setup. We look at main effects occurring in this device, extremes of the physicochemical properties, and we study limits of applicability of this nano-object. In the cases studied, CC permits achieving charge transfer of up to 1.74 e per atom. Tuning of the charge transfer may be achieved via judicious choice of chemical constituents of the CC as well as use of a ferroelectric material as a separator layer. Different classes of chemical systems may be doped, including metallic and nonmetallic elements, and chemical compounds, in certain cases leading to the appearance of superconductivity.

cond-mat.mtrl-sci↗

arXiv2022

Structural phase transitions and magnetic superexchange in MIAgIIF3 perovskites at high pressure

Pressure induced phase transitions of MIAgIIF3 perovskites where M = K, Rb, Cs, have been predicted theoretically for the first time for pressures up to 100 GPa. The sequence of phase transitions for M = K and Rb consists of an orthorhombic to monoclinic and back to orthorhombic transition, associated with progressive bending of infinite chains of corner sharing [AgF6]4 minus octahedra and their mutual approaching via secondary Ag...F contacts. In stark contrast, only a single phase transition i.e. tetragonal to triclinic, is predicted for CsAgF3, associated with substantial deformation of the Jahn Teller-distorted first coordination sphere of AgII and association of the infinite [AgF6]4 minus chains into a polymeric sublattice. The phase transitions markedly decrease the coupling strength of intra-chain antiferromagnetic superexchange in MAgF3 hosts lattices.

cond-mat.mtrl-sci↗