Local order of polymer derived amorphous SixCyNz

Abstract

Analysis of geometrical effects on the behavior of transverse and longitudinal modes of amorphous silicon compoundsWe report on the local order of a-Si 39 C 61 , a-Si 40 C 24 N 36 , and a-Si 26 C 40 N 34 . The total structure factors and pair correlation functions obtained by x-ray diffraction as well as the coordination numbers of the first coordination sphere are presented. All materials exhibit a distinct short range order. In the case of a-Si 39 C 61 , a stoichiometric amorphous SiC phase besides an amorphous carbon phase is formed. Also in the case of a-Si 40 C 24 N 36 and a-Si 26 C 40 N 34 phase separation into two amorphous phases is observed.

The influence of Mg substitution for Al on the properties of SiMeRE oxynitride glasses

“…In the case of glasses, an increase in RE coordination with the anions can result in an increase in the fraction of nonbridging anions. Studies of SiAlRE oxynitride glasses revealed that the average coordination number for La with oxygen was 8.8 [30]. Additional studies of the SiAlRE oxide glasses have also shown that the coordination number of oxygen with Y is $6.6, which increased for La [31].…”

Atomic-scale assessment of the crystallization onset in silicon carbonitride

“…[1][2][3] Owing to the strong covalent bonding and structural amorphous nature of PDCs, the ceramics in the ternary system Si-C-N as well as quaternary ceramics Si-M-C-N(O) (M = B, Al, Zr) have excellent structural stability, near-zero steady state creep as well as oxidation and corrosion resistance at high temperatures (1500 • C). 1,[4][5][6][7] Recently, numerous studies of SiCN ceramics have been reported on their amorphous structure and their high-temperature evolution over the ranges of micro to nano-scales. For understanding of the unusual stability of PDCs at high-temperatures, a wide variety of experimental techniques have been implemented such as X-ray and neutron diffractions, 2-5 transmission electron microscopy 6 and nuclear magnetic resonance.…”

Nitridation of Silica Characterized by High‐Energy X‐Ray Diffraction Technique

“…6 However, the changes in the amorphous network structure (usually referred to as medium-range order) during nitridation of silica have not been fully clarified, although there are several studies on the characterization of Si-(O)-N, Si-(O)-C and Si-(O)-C-N system derived from organic precursors. [12][13][14][15][16][17][18][19][20][21] Although local structures may be determined by NMR or EXAFS techniques, the structural information obtained by these methods is not sufficient to determine the nature of the ring-structures in the medium-range order. Diffraction methods (either X-ray or neutron) are commonly used to obtain the atomic arrangement of disordered materials.…”

“…For example, Chino and Okubo have investigated the detailed transformation process from mesoporous silica to mesoporous silicon oxynitride, and clarified the role of surface defect species during nitridation 6 . However, the changes in the amorphous network structure (usually referred to as medium‐range order) during nitridation of silica have not been fully clarified, although there are several studies on the characterization of Si–(O)–N, Si–(O)–C and Si–(O)–C–N system derived from organic precursors 12–21 …”