density of SiO2

physicist888

in the periodic table we have the density of each element ( density(Si) = 2.33), density(O)=1.429). i wonder how we could calculate the density of SiO2 ???

chroot

It isn't possible to simply calculate it, knowing only the densities of the two pure elements. Each compound can form crystals, sometimes many different kinds of crystals, and each will have its own density.

- Warren

physicist888

an how we could calculate it? is there an equation? the density of SiO2 = ????

physicist888

to creat a film of alloy Al and Ti we use to flux of each element and a substrat.
if the flux of Al is double of that of Ti, then we obtain an alloy on the substrat AlTi or what???

f95toli

Try google. Also, SiO2 is so common that the density is listed in most tables of material properties.

physicist888

i know the value, but i need to know how to calculate it

chroot

Didn't I already say that you cannot calculate it only by knowing the density of Si alone and O alone?

- Warren

physicist888

then which other values do we need to calculate it??

chroot

You need to know its bond angles and lengths, crystal organization, etc.

- Warren

physicist888

and you dont know about the other question??
((to creat a film of alloy Al and Ti we use to flux of each element and a substrat.
if the flux of Al is double of that of Ti, then we obtain an alloy on the substrat AlTi or what???))

f95toli

Also almost impossible to answer. What kind of film you end up will depend on many different parameters (including deposition parameters such as temperature, pressure etc). My guess would be that you would end up with a granular film with grains of Al and Ti (Al tends to form small grains so the film might even be quite dense).
But again, that is only a guess.
In order to calculate something like that you would need a reasonably good supercomputer and extensive knowledge of DFT calculations

handsomecat

would it be possible to calculate the density of SiO2 just from the following:

(1) Cell vectors of Unit cell (ie. Volume)
(2) Formula Units per unit cell. (ie. Mass of the atoms in the unit cell)