Linear magnetoresistivity in the ternary AM2B2 and A3Rh8B6 phases (A = Ca, Sr; M = Rh, Ir)

We studied the magnetoresistivity of the AM2B2 and A3Rh8B6 (A = Ca, Sr; M = Rh, Ir) compounds within the ranges 1.8<=T<=300 K and 0<=H<=50 kOe. The zero-field resistivity {\rho}0(T) is metallic and follows closely the Bloch-Gr\"uneisen description. A positive, nonsaturating, and dominantly linear-in-H magnetoresistivity was observed in all samples, including the ones with a superconducting ground state. Such {\Delta}{\rho}T(H)/{\rho}T(0), reaching 1200% in favorable cases, was found to be much stronger for the AM2B2 compounds and to decrease with temperature as well as when Ca is replaced by Sr, or Rh is replaced by Ir. Finally, the general features of the observed magnetoresistivity will be discussed in terms of the Abrikosov model for the linear magnetoresistivity in inhomogeneous materials.