The relationship between structural transformations and colour centres creation is discussed for deeply coloured hydrogen tungsten bronzes and for pure WO) powders, acquiring less intense colour after mechanical treatments of variable duration. A comparative study on coloration is made also for mixed compounds (l-x)WO].y·xRe01, where anevidence of a resonance effect for a particular Raman band at 970 ern", attributed to the color centres, is observed. Besides, it is found that even moderate milling treatments result in a quite different structural evolution of tungsten trioxide uponcooJing.
Color Centres and Polymorphism in Pure WO(3) and Mixed (1-x)WO(3-y)center dot xReO(2) Powders
MARIOTTO, Gino;
1999-01-01
Abstract
The relationship between structural transformations and colour centres creation is discussed for deeply coloured hydrogen tungsten bronzes and for pure WO) powders, acquiring less intense colour after mechanical treatments of variable duration. A comparative study on coloration is made also for mixed compounds (l-x)WO].y·xRe01, where anevidence of a resonance effect for a particular Raman band at 970 ern", attributed to the color centres, is observed. Besides, it is found that even moderate milling treatments result in a quite different structural evolution of tungsten trioxide uponcooJing.
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