I'm an engineering student, and in my Materials Science course we are currently learning about ceramics. Anyway, one type of ceramic the book talks about is AX-Type crystal structures. Bascially this is a type of ionic bonding where there are the same number of anions and cations in a unit cell.

As one of the examples of an AX-type crystal structure the book gives FeO. So, my first question is this "Rust"? Secondly if it is rust, does that mean that rust is ceramic? Since ceramics are generally brittle is that why rust is typically unwanted in a material?

ummm..... i think its FeO3 and FeO2 because theres 2 specific types of rust, rather iron has 2 oxidatied states. rusts consists of a mixture of these two

Ok so it's not rust then. I knew rust was a reaction between Iron and Oxygen, but I didn't know the chemical formula. So this ceramic that is FeO, what is it?

my old chemistry book says rust is Fe2O3 . h2o

hydrated? anyhow, the fe2+ ion goes to fe3+ and then to "rust" although i'm sure its all just called rust if its iron oxide. the equation my book quotes is the complete oxidation. notice how rust is first black, then bright orange? is FeO is black? i remember using the stuff. i'm thinking it could be iron(2) oxide as opposed to iron(3) oxide