The effects of SiO 2 and K 2O on glass forming ability and structure of CaOTiO 2P 2O 5 glass system

Ahmadi Mooghari, H. R ; Sharif University of Technology | 2012

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  1. Type of Document: Article
  2. DOI: 10.1016/j.ceramint.2011.12.034
  3. Publisher: 2012
  4. Abstract:
  5. The effects of SiO 2 and K 2O were investigated on the glass forming ability (GFA) and structural characteristics of CaOTiO 2P 2O 5 system. Differential thermal analyzer (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and 31P magic angle spinning NMR methods were applied for characterizations of the system. Unwanted crystallization in the initial three components base glass composition was observed by adding SiO 2 and crystalline phases such as TiP 2O 7, rutile (TiO 2) and cristobalite (SiO 2) were formed in it. The results showed that K 2O prevents crystallization of glasses and promotes the formation of glass. FT-IR and X-ray diffraction showed that the addition of K 2O caused the formation of phosphate-silicate network as POSi, and formation of isolated droplet phases (rich of Si and P) separated from the phosphate matrix. The optimum amounts of SiO 2 and K 2O in phosphate structure were respectively 6 and 2 wt.%, 0 in accordance with glass forming ability (GFA) parameters. Despite addition of SiO 2 along with K 2O; the 31P MAS NMR and infrared spectrums of glasses show that no Q 2 sites were in the phosphate network. The Q 1 and the pyrophosphate groups was the predominant structural unit in these glasses
  6. Keywords:
  7. DTA ; NMR ; Cristobalites ; Crystalline phasis ; Differential thermal analyzers ; Droplet phasis ; FT-IR ; Glass compositions ; Glass forming ability ; Glass forming ability parameters ; Glass systems ; Infrared spectrum ; Magic angle spinning NMR ; MAS NMR ; Scanning electron microscopies (SEM) ; Structural characteristics ; Structural unit ; Three component ; TiO ; Differential thermal analysis ; Glass ; Magic angle spinning ; Nuclear magnetic resonance ; Nuclear magnetic resonance spectroscopy ; Oxide minerals ; Scanning electron microscopy ; Silicate minerals ; Titanium dioxide ; X ray diffraction ; Silicon compounds
  8. Source: Ceramics International ; Volume 38, Issue 4 , 2012 , Pages 3281-3290 ; 02728842 (ISSN)
  9. URL: http://www.sciencedirect.com/science/article/pii/S0272884211011011