Ferroelectric phases and phase transitions in CsGeBr_3 induced by mechanical load
arxiv(2024)
摘要
First-principles-based atomistic simulations are used to reveal ferroelectric
phases and phase transitions induced in a semiconductor ferroelectric,
CsGeBr_3, by external loads: hydrostatic pressure, uniaxial and biaxial
stresses, and misfit strain. Hydrostatic pressure was found to suppress the
Curie point at the rate -0.45T_C(0) K/GPa, where T_C(0) is the zero
pressure Curie temperature. Stresses and misfit strains were found to induce
additional ferroelectric phase transitions and phases not available under
normal conditions. We find that tensile load significantly enhances both the
Curie temperature and spontaneous polarization, while compressive load has the
opposite effect but with the difference that the Curie temperature is only
slightly suppressed. The isothermal dependencies of polarization on pressure
and stresses are highly nonlinear, which could result in large nonlinear
piezoelectric responses. The phase diagrams reveal the diversity of the phases
accessible through mechanical load, which include tetragonal, orthorhombic and
monoclinic symmetries in addition to the rhombohedral and cubic ones realizable
under normal conditions. We believe that this work reveals the potential of
Ge-based halide perovskites for applications in energy converting devices,
which is especially significant in the current pursuit of environmental
friendly lead-free technologies.
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