Role of Donor and Acceptor Ions in the Dielectric Loss Tangent of (Zr0.8Sn0.2)TiO4 Dielectric Resonator Material

The role of donor and acceptor ions in the dielectric loss tangent of (Zr,Sn)TiO₄ was investigated at frequencies from 0.1 kHz to 9 GHz. When a specimen was doped with Fe₂O₃, the loss tangent increased drastically at microwave frequencies. This increase is explained by a large concentration of Fe³⁺ ions and oxygen vacancies in the grains. When the specimen was doped with Ta₂O₅ and then annealed in a reducing atmosphere, electrical resistivity decreased and tan δ increased extremely at low frequencies but trivially at microwave frequencies. The high microwave Q value of Tadoped specimens is explained by assuming the Ta ions in the crystal to be tetravalent. Dielectric loss is determined predominantly by space charge polarization at low frequencies and by the disordered charge distribution at microwave frequencies.