Our combined experimental/theoretical study expands the known Allotropy for element fourteen and the unique high-pressure precursor synthesis methodology demonstrates the potential for new materials with desirable properties. This new allotrope possesses a quasidirect bandgap near 1.3 eV. The Cmcm structure of Si24, which has 24 Si atoms per unit cell (oC24), contains open channels along the crystallographic a-axis that are formed from six- and eight-membered sp3 silicon rings. First, a Na4Si24 precursor was synthesized at high pressure5 second, sodium was removed from the precursor by a thermal ‘degassing’ process. Here, we report the formation of a new orthorhombic allotrope of silicon, Si24, using a novel two-step synthesis methodology. The most stable form of silicon at ambient conditions takes on the structure of diamond (cF8, d-Si) and is an indirect bandgap semiconductor, which prevents it from being considered as a next-generation platform for semiconductor technologies1, 2, 3, 4. Silicon is ubiquitous in contemporary technology. Its structure contains open channels and it possesses a quasidirect bandgap near 1.3 eV.
A new orthorhombic allotrope of silicon, Si_24, is demonstrated using a two-step synthesis. The Cmcm structure of Si_24, which has 24 Si atoms per unit cell ( o C24), contains open channels along the crystallographic a -axis that are formed from six- and eight-membered sp ^3 silicon rings. First, a Na_4Si_24 precursor was synthesized at high pressure^ 5 second, sodium was removed from the precursor by a thermal ‘degassing’ process. Here, we report the formation of a new orthorhombic allotrope of silicon, Si_24, using a novel two-step synthesis methodology. The most stable form of silicon at ambient conditions takes on the structure of diamond (cF8, d -Si) and is an indirect bandgap semiconductor, which prevents it from being considered as a next-generation platform for semiconductor technologies^ 1, 2, 3, 4. quasi-direct bandgap of open-framework allotrope Si 24 ) allows us to suggest future applications. The pressure-temperature range of their formation is suitable for large-volume synthesis and future industrial scaling. Our recent high-pressure studies of the chemical interaction and phase transformations in the Na- Si system, revealed a number of interesting routes to new and known silicon compounds and allotropes.
This justifies intensive theoretical and experimental research for the direct-bandgap forms of silicon. However, conventional diamond-like Si is an indirect gap semiconductor and cannot absorb solar photons directly. It is not a pollutant and, therefore, an ideal candidate to replace the actual materials in photovoltaics, such as compounds based on the arsenic and heavy metals. quasi-direct bandgap of open-framework allotrope Si24) allows us to suggest future industrial applications.Ībstract Silicon is essential for today's electronics because of its ability to show various electronic behaviors that are relevant to numerous fields of cutting-edge applications. That justifies the attempts to create silicon materials with direct gap that can absorb and emit light. This puts it apart from the next-generation applications (light diode, high-performance transistor). It has not replaced them so far because Si is an indirect gap semiconductor and cannot absorb directly the solar photons without thermal agitations of crystal lattice (phonons). Moreover, silicon is not a pollutant and, therefore, is an ideal candidate to replace the actual materials in photovoltaics, like compounds based on the arsenic and heavy metals. It is essential for today's electronics because of its ability to show various electronic behaviors that allow covering the numerous fields of cutting-edge applications. Silicon is the second abundant element, after oxygen, in the earth crust.