There is a justifiable desire to use slashed zeros for callsigns. It makes identifying callsigns correctly much easier.
However, please do not use some special characters in order to display these slashed zeros. Bad things will happen if you do. You can't easily search for call signs. Sometimes these special characters won't display right for some people. And I won't like you for doing this.
The proper way to display slashed zeros is by using the proper font. This page contains fonts that have slashed zeros.
Personally, my favorite font is Atkinson Hyperlegible.
