Raman and infrared spectroscopy study on structure and microstructure of glass–ceramic materials from SiO2–Al2O3–Na2O–K2O–CaO system modified by variable molar ratio of SiO2/Al2O3

The effect of Al2O3 on the high‐temperature oxidation resistance of Si‐B‐C ceramic under air atmosphere

“…The band at ~800/cm can be assigned to the Si‐O stretching of Q 0 and symmetric breathing vibration of the boroxol rings that contains [BO 3 ] . The bands centered at 880‐920, 980‐1010, 1050‐1100, and 1140‐1180/cm are named as Si‐O stretching of Q 1 , Q 2 , Q 3 , and Q 4 or Si‐O‐Al stretching, respectively, As can be observed, at all the oxidation temperatures, with amount of Al 2 O 3 increase, the peak relative intensity at ~800 and ~900/cm decreases, whereas the relative intensity at 1050‐1100 and 1120‐1190/cm increase. As the oxidation temperature rises, for the sample without and with 3% Al 2 O 3 , the former 2 peaks relative intensity are first enhanced and then weakened, meanwhile, the latter 2 peaks are increased first and then weakened.…”

Influence of SrO content on microstructure and crystallization of glazes in the SiO2–Al2O3–CaO–MgO–K2O system

“…After decomposition, the band layout in all spectra is similar. And so, the band at 1116/1080/1177 cm -1 is associated with asymmetric stretching vibrations Si=O (defects), band at 988/982/ 1067 cm -1 with asymmetric stretching vibrations Si-O (Si, Al)-silico-oxygen and alumino-silico-oxygen bridges (bridge bonds) [39][40][41][42][43], bands at 905/904/960 and 855/845/ 884 cm -1 with asymmetric stretching vibrations Si-Oand Al-O -, respectively-broken silico-and aluminooxygen bridges (terminal bonds) [40][41][42][43][44][45], bands at approximately 730 and 690 cm -1 with symmetric Tables 2 and 3), it can be clearly stated that the main difference that should be noted is the much higher integral intensity (surface area under curve) of bands associated with terminal bonds (bands at 904 cm -1 and 845 cm -1 , Fig. 4, Table 3) and lower intrinsic intensity of the band bound to silicon and aluminium bridges (band at 982 cm -1 , Fig.…”

Study of Surface Structure Changes for Selected Ceramics Used in the CAD/CAM System on the Degree of Microbial Colonization, In Vitro Tests

“…Four-coordinated aluminium (together with silica ions) is involved in formation of the glass structure, whereas six-coordinated aluminium breaks it. The introducing of modifying ions (mainly alkali cations) produces the broken silicon-oxygen bridges (Si-O-) [20].…”

“…Bands observed at the highest wave numbers (1135, 1013, 918 cm −1 for Vita Enamic, 1058, 926, 894 cm −1 for IPS Empress, and 1049, 960, 896 cm −1 for IPS Empress Multi) are associated with stretching vibrations of Si-O-Si, Si-O-Al, and Si-O- bridges. For comparison, infrared study of glass-ceramic materials from SiO 2 -Al 2 O 3 -Na 2 O-K 2 O-CaO system modified by variable molar ratio of SiO 2 /Al 2 O 3 showed these bands in the 1180-903 cm −1 spectral range [20]. Bands localized at ~760 cm −1 correspond to the bending modes of Si-O-Si and Si-O-Al units.…”