Abstract
A twin-free substrate material, CaYAlO4, was synthesized and used for the epitaxial growth of single crystal YBa2Cu3O7-δ and Tl2Ba2CaCu2O8 thin films for the first time. The lattice parameters of ttus new substrate are a=b=3.648 Å and c=11.89 Å. The dielectric properties, similar to those of LaAlO3, are 20(dielectric constant) and 4×10-5 (loss tangent) at 5 GHz and 77 K. Initial attempts at film growth on this substrate indicate degradation of both superconducting and microwave properties possibly due to interdiffusion.