Update: with version 4.5 (2014/04/08) chemformula has a basic native support for Kröger-Vink notation. It must be enabled with the option kroeger-vink=true:
\documentclass{article}
\usepackage{chemformula}[2014/04/08]
\begin{document}
\setchemformula{kroeger-vink}
\ch{Al_{Al}^x}
\ch{Ni_{Cu}^x}
\ch{V_{Cl}^{*}}
\ch{Ca_i^{**}}
\ch{e'}
\ch{Cl_i'}
\ch{O_i''}
\ch{O_O^x + Zn_{Zn}^x <-> 1/2 O2 + Zn_i^. + e^{-1}}
\end{document}

Original answer:
I've never heard from the Kröger Vink notation before... but from what a quick web search shows me the following should be correct. I use chemformula (from the chemmacros bundle) because it let's you customize the size of the dots and the amount of horizontal shift of superscripts:
\documentclass{article}
\usepackage{chemformula}
\begin{document}
\setchemformula{
radical-radius = .3ex , % a larger `radical' dot
charge-hshift = 0pt % don't shift superscripts to the right if subscripts
% are present
}
\ch{Al_{Al}^{$\times$}}
\ch{Ni_{Cu}^{$\times$}}
\ch{V_{Cl}^{.}}
\ch{Ca_i^{..}}
\ch{e^{$\prime$}}
\ch{Cl_i^{$\prime$}}
\ch{O_i^{$\prime\prime$}}
\ch{O_O^{$\times$} + Zn_{Zn}^{$\times$} <-> 1/2 O2 + Zn_i^. + e^{-1}}
\end{document}

A question related to the “dot” symbol is How to get the the dot symbol in Chemistry? which may give you some more hints
\documentclass{...}and ending with\end{document}. – Mar 23 '14 at 09:37