Mixedhalide

Mixedhalide refers to chemical species that contain more than one type of halogen atom within the same molecule, salt, crystal lattice, or coordination sphere. Halogens include fluorine, chlorine, bromine, iodine, and astatine; in practice, mixed halide often denotes partial substitution in a halide site of a compound, creating a solid solution with tunable properties. The term is frequently used in inorganic chemistry, materials science, and catalysis.

In solid-state chemistry and materials science, mixed halides are used to tailor structural and electronic properties. A prominent class is mixed halide perovskites with a general formula ABX3, where X is Cl, Br, or I in varying ratios, for example FAPb(I1−xBrx)3. By adjusting halide composition, researchers can tune the bandgap, absorption spectrum, and lattice strain. Mixed halide materials also arise in other metal halide lattices and organometallic complexes, where halide identity influences geometry and reactivity.

Preparation is typically through solution processing or solid-state diffusion, blending halide sources (for example, lead iodide, lead bromide, lead chloride) in precursors and controlling crystallization to form homogeneous solid solutions. Applications include photovoltaic absorbers, light-emitting materials, and photocatalysts. Challenges include phase segregation under illumination in some mixed halide perovskites, which can drive separation into iodide- and bromide-rich domains, affecting stability and performance. Environmental and safety considerations, particularly for lead-containing compounds, are also relevant.