should look like. They can compare this simulated pattern to their experimental samples to verify which phase ( , or mixed) they have successfully synthesized in the lab.
| Feature | α-FAPbI₃ (Black, Active) | δ-FAPbI₃ (Yellow, Inactive) | | :--- | :--- | :--- | | | Pm-3m (No. 221) | P6₃mc (No. 186) | | Dimensionality | 3D Cubic | 1D Hexagonal (chains) | | Tolerance Factor | ~0.99 (Ideal) | >1.0 (Distorted) | | Bandgap | ~1.48 eV | ~2.4 eV |
The most scientifically plausible interpretation of "fapbi3" is (Formamidinium Lead Iodide).
Once you locate the correct CIF (assuming you are looking for the $\alpha$-phase), here is what you should expect to see inside the file: fapbi3 cif file
If you download a CIF for FAPbI₃ from a general database (e.g., CCDC), you might accidentally retrieve the stable . Here is its signature:
The complexity of the FAPbI₃ CIF file lies in its . Depending on temperature and synthesis conditions, the material can exist in several phases:
The thermodynamically stable "non-perovskite" phase at room temperature. -phase Intermediate Tetragonal Occurs as the material cools below -phase Orthorhombic/Trigonal Emerges below with restricted cation motion. Challenges in Modeling: The FA Cation should look like
Pulse. Pause. Pulse. Pause.
A CIF file is the universal text-based standard established by the International Union of Crystallography (IUCr) for sharing structural data. For FAPbI3, the file bridges the gap between raw experimental X-ray diffraction (XRD) data and 3D atomic visualization software.
The material is known for its complex polymorphism. FAPbI₃ can exist in several distinct crystallographic phases: 221) | P6₃mc (No
Unlike the simpler cesium cation, the formamidinium (FA) molecule is a large, non-spherical organic cation. In a standard cubic CIF, the FA molecule often appears because it rotates rapidly within the lead-iodide "cage". This requires researchers to choose between a "time-averaged" CIF (useful for standard XRD refinement) and a "frozen" or relaxed structure (often derived from DFT calculations ) for modeling electronic band structures. Strategic Importance FAPbI3.cif - WMD-group/hybrid-perovskites - GitHub
There is no single "official" CIF file. The structure can vary slightly depending on temperature and synthesis conditions. Here are the most reliable sources to download CIF files for your research, ranging from public databases to specialized repositories.
Plugging the coordinates into supercomputers to predict how the material will react to heat, moisture, or pressure. X-Ray Fingerprinting:
Once you have fapbi3.cif , you must check for errors. Bad CIFs lead to non-physical DFT energies.
Obtaining a reliable CIF file requires checking the right databases: for theoretical optimizations, COD/ICSD for experimental validation, and the Supporting Information of journals for high-quality refined data. As perovskite solar cell research pushes toward 30% efficiency, the precision of these structural files will remain a cornerstone of modern materials innovation.