The polymorphous nature of cubic halide perovskites

Abstract

It has been long known that numerous halide and oxide perovskites can have non-ideal octahedra, showing tilting, rotation, and metal atom displacements. It has also been known that compounds that have at low temperatures a single structural motif ("monomorphous structures") could become disordered at higher temperatures, resulting in non-ideal octahedra as an entropy effect. What is shown here is that in many cubic halide perovskites and some oxides compounds a distribution of different low-symmetry octahedra ("polymorphous networks") emerge already from the minimization of the systems internal energy, i.e., they represent the intrinsic, preferred low temperature pattern of chemical bonding. Thermal disorder effects build up at elevated temperatures on top of such low temperature polymorphous networks. Compared with the monomorphous counterparts, the polymorphous networks have lower predicted total energies (enhanced stability), larger band gaps and dielectric constants now dominated by the ionic part, and agrees much more closely with the observed pair distribution functions. The nominal cubic perovskites (Pm-3m) structure deduced from X-Ray diffraction is actually a macroscopically averaged, high symmetry configuration, which should not be used to model electronic properties, given that the latter reflect a low symmetry local configuration.

20 pages; 7 figures; 94 references

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Cited by in corpus (24)

• Anharmonic electron-phonon coupling in ultrasoft and locally disordered perovskites
• Anharmonic lattice dynamics via the special displacement method
• Leveraging Low-Energy Structural Thermodynamics in Halide Perovskites
• Limits of the phonon quasi-particle picture at the cubic-to-tetragonal phase transition in halide perovskites
• Understanding Electronic Peculiarities in Tetragonal FeSe as Local Structural Symmetry Breaking
• Mixed Formamidinium-Methylammonium Lead Iodide perovskite from first-principles: Hydrogen-bonding impact on the electronic properties
• Bulk NdNiO2 is thermodynamically unstable with respect to decomposition while hydrogenation reduces the instability and transforms it from metal to insulator
• Quantifying Dynamic Tilting in Halide Perovskites: Chemical Trends and Local Correlations
• Mass enhancement in 3d and s-p perovskites from symmetry breaking
• Intrinsic local symmetry-breaking in nominally cubic paraelectric BaTiO3
• Static and Dynamic Disorder in Formamidinium Lead Bromide Single Crystals
• Dynamic Nanodomains Dictate Macroscopic Properties in Lead Halide Perovskites
• The Disorder Origin of Raman Scattering In Perovskites Single Crystals
• Direct, indirect, and self-trapped excitons in Cs${}_2$AgBiBr${}_6$
• Microscopic picture of paraelectric perovskites from structural prototypes
• Three-Dimensional to Layered Halide Perovskites: A Parameter-Free Hybrid Functional Method for Predicting Electronic Band Gaps
• Multiple lattice instabilities and complex ground state in Cs${}_2$AgBiBr${}_6$
• Density Functional description of spin, lattice, and spin-lattice dynamics in antiferromagnetic and paramagnetic phases at finite temperatures
• Mixed-anion mixed-cation perovskite (FAPbI${}_3$)${}_{0.875}$(MAPbBr${}_3$)${}_{0.125}$: an ab-initio molecular dynamics study
• Impact of Surface Adsorbates and Dimensionality on Templating of Halide Perovskites
• Efficient First-Principles Framework for Overdamped Phonon Dynamics and Anharmonic Electron-Phonon Coupling in Superionic Materials
• Local structural disorder in crystalline materials
• How to choose efficiently the size of the Bethe-Salpeter Equation Hamiltonian for accurate exciton calculations on supercells
• Anharmonic thermodynamics redefines metastability and parent phases in ferroelectric HfO2