Glassy Musings.

[High Bridge Pottery]

To hopefully be able to ask my question I am going to talk about pure silica glass. I am still not sure if I am asking the right question.

 

Lets say I can get to the temperatures needed to melt silica. I start with my quartz which is a massive covalently bonded structure. I then heat it up until it melts and then cool it quickly into a vitreous silica (glass).

 

 

"A glassy structure suggest that chemical bonds among atoms must be partially covalent and partially ionic. This is because covalent bonds have well defined angles and distances (incompatible with glassy structure) while ionic bonds are non-directional."

 

So when I am melting the silica the electrons must transfer from being shared by each atom to being completely transferred to the other atom? I imagined that when melting the electron would go back to the atom where it came from but this doesn't seem to be the case. I need to have ions if I want to make a glass so electron transfer must be happening?

 

Is it that the melt is an electron soup where electrons are being shared with every atom at once and given enough time this would form crystalline structures but when crash cooled the ions get trapped as ions?

 

Source of confusion : http://digitalfire.com/4sight/education/the_chemistry_physics_and_manufacturing_of_glaze_frits_340.html

[Chantay]

Can I assume you read the whole paged you linked to? I am unable to copy paste. It seems further down the page your question is answered.

[High Bridge Pottery]

Took me around three hours to get through it 

 

Is this the part you mean ? 

 

"Silica melts at 1710C and the glass melt is highly viscous, it is too refractory to be melted in a normal furnace. When we adjust the composition of a frit we are, in effect, modifying this hypothetic molten silica original glass by adding different elements in order to obtain suitable characteristics. Glassy silica is comprised of a network of tetrahedron SiO4^4- units and when we add modifiers or intermediate elements the continuous three-dimensional network is broken (and weakened) and the tetrahedrons connect to form different structures like chains, rings layers, etc."

 

It says glassy silica is comprised of a network of SiO₄^4- groups but how do all these come together by themselves to make glass. There must be Si⁴⁺ and SiO₂^2- and other ions in there somewhere. Is it that there are not many ions which is why it's a highly viscous melt? Are we adding in other crystals that form better ions at lower temperatures? Am I confusing everything?