We propose to study the structural and magnetic properties of three double perovskites Ca2-xLaxFeRuO6. Room temperature PXRD has revealed that all these compounds are orthorhombic with the space group Pbnm with disordered corner sharing FeO6 and RuO6 sublattices. Magnetic susceptibility measurements showed that the magnetic behaviour and antiferromagnetic ordering temperatures vary with the substitution of the alkaline earth by rare earth metals at A-position. The structural and magnetic effects will be investigated in detail to understand the role of valence-changing non-magnetic substituents in double perovskites. This will provide a clear idea how the charge degree of freedom influences the magnetic behaviour. In the proposed neutron powder diffraction study at instruments E2 and E9 we would like to investigate in detail the magnetic ordering as a function of temperature. Further, we would like to investigate structural changes caused by magnetostriction effects.