Print Email Facebook Twitter On the relations between the bandgap, structure and composition of the M–Si–N (M = alkali, alkaline earth or rare-earth metal) nitridosilicates Title On the relations between the bandgap, structure and composition of the M–Si–N (M = alkali, alkaline earth or rare-earth metal) nitridosilicates Author ten Kate, O.M. (TU Delft ChemE/Product and Process Engineering) Zhang, Zhijun (Shanghai University) Hintzen, H.T.J.M. (TU Delft RST/Fundamental Aspects of Materials and Energy) Date 2017-10 Abstract Relations between the bandgap and structural properties and composition of the M–Si–N nitridosilicates (M = alkali, alkaline earth or rare earth metal) have been obtained, using experimental data collected from literature; and qualitative models are presented to explain the observed trends. Compounds with a higher degree of condensation, i.e. a higher Si/N ratio, generally have longer M–N bonds and shorter Si–N bonds. The observations can be explained based on the effective charge of N, dependent on its coordination with Si (NSix). With increasing Si/N ratio the coordination number of N by Si increases, making the effective charge of the nitrogen atom less negative, resulting in a longer and less covalent M–N bond. This also shifts the N 2p levels down in energy, lowering the top of the valence band (mainly composed of N orbitals); while decreasing the Si–N distance shifts the bottom of the conduction band (mainly composed of Si and M orbitals) upward. Some nitridosilicates show deviations to the general trends, such as γ-Si3N4 and several Li-containing compounds. These deviations have been discussed and possible explanations have been given based on peculiarities in their structural characteristics. To reference this document use: http://resolver.tudelft.nl/uuid:fee046a7-6358-4a58-aa7b-3dc0c7e1f3be DOI https://doi.org/10.1039/C7TC04259K ISSN 2050-7526 Source Journal of Materials Chemistry C: materials for optical and electronic devices, 5 (44), 11504-11514 Part of collection Institutional Repository Document type journal article Rights © 2017 O.M. ten Kate, Zhijun Zhang, H.T.J.M. Hintzen Files PDF c7tc04259k_2.pdf 2.93 MB Close viewer /islandora/object/uuid:fee046a7-6358-4a58-aa7b-3dc0c7e1f3be/datastream/OBJ/view