000169061 001__ 169061
000169061 005__ 20181221101943.0
000169061 02470 $$2ISI$$aA1996UV56100002
000169061 037__ $$aCONF
000169061 245__ $$aRaman spectroscopic study of structural changes in calcium aluminate (CaAl2O4) glass at high pressure and high temperature
000169061 269__ $$a1996
000169061 260__ $$c1996
000169061 336__ $$aConference Papers
000169061 520__ $$aThe Raman spectrum of calcium aluminate (CaAl2O4) glass has been obtained as a function of pressure at ambient temperature to similar to 15 GPa, and as a function of temperature at room pressure to 1650 K. On increasing pressure at 300 K, the Raman spectrum changes drastically between 8 and 10 GPa. The intensity of the overall spectrum weakens, the intensity of the 580-cm(-1) band decreases markedly, and a new broad band centered near 750 cm(-1) begins to dominate the spectrum. We interpret these spectral changes as due to the formation of highly coordinated Al species through the involvement of bridging oxygens (i.e. formation of O-[3] species). Upon decompression, the pressure-induced spectral changes are mostly reversible. However, the decompressed samples do not relax completely to their normal ambient state, and the spectra reflect important changes in the inter-tetrahedral AlOAl linkages. These changes are consistent with some high-coordinate species being retained in the decompressed sample. On increasing temperature through the glass transformation range (T-g = 1178 K) at room pressure, our Raman spectra show evidence for important configurational changes, after vibrational effects are removed. The major spectral change consists of growth of a broad band between 600 and 1100 cm(-1), appearing immediately above T-g. We suggest that these configurational changes concern the removal of O2- ions from the fully polymerized aluminate framework, with the resulting formation at high temperature of O-[3] species (''triclusters''), coordinated by three tetrahedral aluminate groups.
000169061 6531_ $$aInduced Coordination Changes
000169061 6531_ $$aAl-27 Nmr-Spectroscopy
000169061 6531_ $$aX-Ray-Diffraction
000169061 6531_ $$aSilicate Melts
000169061 6531_ $$aSio2-Al2O3 Glasses
000169061 6531_ $$a5-Coordinated Silicon
000169061 6531_ $$aSio2 Glass
000169061 6531_ $$aMas Nmr
000169061 6531_ $$aLiquids
000169061 6531_ $$aViscosity
000169061 700__ $$aMcMillan, P.F.
000169061 700__ $$0244692$$aGillet, P.$$g199993
000169061 700__ $$aPoe, B.T.
000169061 700__ $$aDaniel, I.
000169061 7112_ $$a5th Silicate Melt Workshop$$cLA PETITE PIERRE, FRANCE$$dApr 04-08, 1995
000169061 773__ $$j128$$q5-15$$tChemical Geology
000169061 909C0 $$0252407$$pEPSL
000169061 909c0 $$xU12330
000169061 909CO $$ooai:infoscience.tind.io:169061$$pconf$$pSB
000169061 937__ $$aEPFL-CONF-169061
000169061 973__ $$aOTHER$$rREVIEWED$$sPUBLISHED
000169061 980__ $$aCONF