Epitaxial films of Ga:YIG (gallium substituted yttrium iron garnet) deposited on GGG (gadolinium gallium garnet) substrates often fracture. This is especially noticeable for the gallium compositions which are favorable for the formation of bubble domains. A consideration of the conditions which lead to fracture indicates that fracture will not take place unless film thickness is greater than the length of a Griffith crack. This conclusion has led us to modify the lattice parameter of the Ga:YIG to ensure that the Griffith crack length is larger than the thickness of the film. This has been achieved by substituting Gd or Eu for some of the Y. It has eliminated the fracture problem and yet the magnetic properties required for the formation of stable bubble domains have been retained. In this work an x‐ray diffraction technique was used for the measurement of the epitaxial strains. This technique and the results of the strain measurement will be described.