Is it a sin to burn the Quran?

There was a tiny Qur'an that was very difficult to read. Also, some of the pages were torn off. We burned the pages instead of burying. We did it because I heard the scholars say that there is no harm in doing so. But I saw on some websites that it would be more appropriate to bury it. Have we committed a sin in this situation? If so, what should we do?