Synthesis, structure and dielectric characterization of Ln2Ti2−2xM2xO7(Ln=Gd, Er; M=Zr, Sn, Si)

The progress in wireless communications and information access has demanded the use of electronic ceramics exhibiting desired properties. To further our understanding of these properties, compounds in the Ln2Ti2–2xM2xO7 (Ln=Gd, Er; M=Zr, Sn, Si) systems were synthesized by ceramic methods and characterized by powder X-ray diffraction. The ZrO2–doped Gd2Ti2−2xZr2xO7 compounds adopt the pyrochlore structure type and form a complete solid solution. Er2Ti2−2xZr2xO7 forms a pyrochlore solid solution for x<0.1. However, stoichiometric Er2Zr2O7 does not form; instead Er4Zr3O12 forms a with defect fluorite structure. The Sn–doped Ln2Ti2−2xSn2xO7 (Ln=Gd, Er) compounds form complete solid solutions, and the Si compounds adopt the pyrochlore structure up to x=0.05. At ambient temperature, dielectric constants range from 10 to 61 for Er2Ti2−2xZr2xO7 and 16–31 for Gd2Ti2−2xZr2xO7 with low dielectric loss (1×10−3) at 1 GHz.