SiBr4--prediction and determination of crystal structures

Area of Science:

• Solid-state chemistry
• Crystallography
• Materials science

Background:

• The crystal structure of silicon tetrabromide (SiBr4) has not been previously reported.
• Understanding the solid-state structures of simple inorganic compounds is fundamental to materials science.

Purpose of the Study:

• To predict and experimentally determine the crystal structures of SiBr4.
• To investigate the phase transition behavior of SiBr4.

Main Methods:

• Global lattice-energy minimization using force-field methods for structure prediction.
• Experimental determination of crystal structures using X-ray synchrotron powder diffraction.
• Temperature-dependent X-ray powder diffraction to study phase transitions.

Main Results:

• Ten potential crystal structures for SiBr4 were identified within an energy range of 5 kJ mol(-1) above the global minimum.
• The low-temperature beta phase was determined to crystallize in the P2(1)/c space group.
• The high-temperature alpha phase was determined to crystallize in the Pa3 space group.
• A phase transition between the alpha and beta phases was observed at 168 K.

Conclusions:

• The crystal structures of SiBr4 have been successfully predicted and experimentally validated.
• SiBr4 exhibits polymorphism, existing in at least two distinct crystalline phases.
• The identified phase transition provides crucial data for understanding SiBr4's behavior under varying temperatures.