Elastic properties of scheelite structure molybdates and tungstates

The elastic properties of the four scheelite structure crystals CaMoO4, SrMoO4, PbMoO4 and CaWO4 are compared. Attention is given to the orientation dependence of the elastic behaviour and to how this is related to the atomic arrangement. With respect to the conventional definition of the XYZ axial set employed for scheelites the stiffness constant C16 is negative in all four materials.