How can a compound said to be glass?

[jied]

regards,
i m doing my MSc in glass ceramic, i ve read in journals saying that when glass are heated above its crystallization temperature, it can be considered to transformed into glass ceramics, and of course if has to undergo XRD or FTIR or FESEM to confirm it, but how can we say that it is glass? what is the glass component?
i m using lithium acetate, aluminium oxide, titanium oxide and ammonia dihydrogen phosphate as starting material.

Thanks in advance :cool:

[Sybren]

do an absorption spectrum of the material.

[Andy Resnick]

regards,
i m doing my MSc in glass ceramic, i ve read in journals saying that when glass are heated above its crystallization temperature, it can be considered to transformed into glass ceramics, and of course if has to undergo XRD or FTIR or FESEM to confirm it, but how can we say that it is glass? what is the glass component?
i m using lithium acetate, aluminium oxide, titanium oxide and ammonia dihydrogen phosphate as starting material.

Thanks in advance :cool:

If I understand your question, a glassy state is defined as having short-range order but long-range disorder; crystals have long-range order.

That said, the glass transition is considered one of the most outstanding unanswered questions in physics.

http://en.wikipedia.org/wiki/Glass_transition

does that help?

[jied]

do an absorption spectrum of the material.

yes, thank you. and i understand FTIR is one of the method for this technique. i m waiting for the result as we speak :smile:

what i do not understand is the glass component. for example, if we use chitosan to make a sample, then we say that the sample is a polymer. i ve searched every journals, and many books i read doesnt state a glass component.

Andy, thanks for reviewing my question, and it sure help. i m actually doing a glass ceramic conducting material, which needs me to understand glass transitions, but i still cant get myself clear.

[johng23]

In a melt, the molecules are randomly aligned. In order to crystallize, they need to orient themselves into a regular, periodic array. Below a certain temperature, the necessary movements can not occur, and the molecules are "frozen in". This temperature is the glass transition. If cooling occurs quickly enough, the molecules are stuck in an amorphous configuration, without the long range order or periodicity of a crystal. We call this phase glass.

Chitosan is a polymer because of its chemical bonding. You can have glassy polymers, but generally polymers are considered a separate category. Disregarding that, there's no "component" that defines a glass. There are even metallic glasses, although again, these may be considered a separate category.

[jied]

In a melt, the molecules are randomly aligned. In order to crystallize, they need to orient themselves into a regular, periodic array. Below a certain temperature, the necessary movements can not occur, and the molecules are "frozen in". This temperature is the glass transition. If cooling occurs quickly enough, the molecules are stuck in an amorphous configuration, without the long range order or periodicity of a crystal. We call this phase glass.

Chitosan is a polymer because of its chemical bonding. You can have glassy polymers, but generally polymers are considered a separate category. Disregarding that, there's no "component" that defines a glass. There are even metallic glasses, although again, these may be considered a separate category.

Thanks so much. i can now relate what i have read about glass transition. we can only be sure that the samples are glass, thought its structure, if i understand your explanation.

thank you so much for the replies and help. Only God knows how much this has helped me. :smile: