On the Graded Identities for Elementary Gradings in Matrix Algebras over   Infinite Fields
  We find a basis for the $G$-graded identities of the $n\times n$ matrix algebra $M_n(K)$ over an infinite field $K$ of characteristic $p>0$ with an elementary grading such that the neutral component corresponds to the diagonal of $M_n(K)$. 
Diogo Diniz Pereira da Silva e Silva
math.RA