Oxygen vacancies in the structure?

[rwooduk]

Please could someone explain to me what is meant by the follow sentence:

"Intrinsic oxygen vacancies in the TiO2 structure might also play important roles as nucleation sites for cavitation."

I understand the nucleation bit but what are "oxygen vacancies in the structure"?

Any help would be appreciated.

 

[DrDu]

Sites in the crystal structure of TiO2 which are usually occupied by O but where an O atom (or ion) is missing.

 

[rwooduk]

Sites in the crystal structure of TiO2 which are usually occupied by O but where an O atom (or ion) is missing.

Ahh I see many thanks! Yes that makes sense as very small crevices in impurities in a liquid is a source of nucleation of cavities when ultrasound is applied. Although I am kind of suprised that this "hole" would be big enough for there to exist a macroscopic gap. Still slightly confused, but I think you are correct. Thanks again!

 

[DrDu]

The vacancy weakens the bonding or cohesion at this site. So it might well be that it acts as a nucleation site, though it certainly isn't a macroscopic gap.