What kind of 'aluminum oxide molecule' are you talking about?

Al2O3 is a solid with a three-dimensional structure and no molecule.

If you could be more specific one might be able to help.

What kind of 'aluminum oxide molecule' are you talking about?

Al2O3 is a solid with a three-dimensional structure and no molecule.

If you could be more specific one might be able to help.

It is not a molecule but a compound with a trigonal structure in general. I would agree with Mr. Oliver Janka that you might be helped efficiently if you could be more specific. In addition, it is an ionic compound and doesn't have to do anything with polarity.

Good luck!

Dear All, i asked this question because in some internet sites ( search with "Is aluminum oxide polar or non-polar?" ) it is given that aluminum oxide is polar covalent and in some other site that it is ionic. Thank you very much for the answers. I am interested in aluminum oxide thin films prepared by ALD.

I think you are talking about the wetting behavior of aluminum oxide. If yes then aluminum oxide behaves like polar molecules and is wetted well by the groups containing polar molecules.

But if we look at the structure its bunch of ions arranged in 3 dimensional pattern

The Al-O is a strange bond, it has 61 % of ionic character and 39 % of covalent character, but Al2O3 have not considering as a molecule. As a ionic character compound, it has affinity by the polar groups as SiOH in the glass because electrostatic interactions.

Thank you Dr.Carlos Daza, Does this 39% covalent character contribute any permanent dipole moment to the material so that the material exhibit oriantational polarization?

I think you may wanna see the review paper by Noguera and Goniakoswky. It is about polar and non polar oxide surfaces. If you don't find the paper I will post the full reference tomorrow for you.

Thank you very much Dr.Erie Morales, I couldn't locate the paper on internet. Could you please send me a copy.

Here is the citation: Polarity of Oxide Surfaces and Nanostructures, Goniakowski, J, Finocchi, F, and Noguera, C. Reports on Progress in Physics vol 71, page 016501, (2008). Read chapters, 1, 2 and 3.4. That should be enough to put you on track. Cheers.

Article Polarity of Oxide Surfaces and Nanostructures

Thank you very much Dr. Morales.

The paper (http://dx.doi.org/10.1016/j.tsf.2013.10.148) discusses effect of low ALD temperature and impurity on non-polarity of Al2O3.

Thank you very much Dr.Md Tashfin Hossain.

Talking with respect to polarity, Al2O3 definitely possesses polar behaviour because of the difference in the electronegativity of the two constituting elements and because of the ionic nature. However, the general concept of polar and non-polar molecules can't be applied to Al2O3 as it is a compound with 3 dimensional array of Al and Oxygen.