Local structure and dielectric behavior of tetragonal tungsten bronzes β-SrTa₂O₆ and β′-SrTa₂O₆

Abstract

The dielectric properties of polymorphic tungsten-bronzes, ¢-SrTa 2 O 6 and ¢¤-SrTa 2 O 6 , were measured using phase pure ceramic specimens. The room temperature dielectric constant (¬) of ¢-SrTa 2 O 6 and ¢¤-SrTa 2 O 6 were µ26 and µ104, respectively, which were relatively constant over the ac frequency range, 10 2 10 6 Hz. The markedly distinct ¬ of ¢-and ¢¤-SrTa 2 O 6 were attributed to local structural details, where the displacive Sr disorder in ¢¤-SrTa 2 O 6 was emphasized. Both ¢-and ¢¤-SrTa 2 O 6 exhibited a temperature dependent transition of ¬ with diffuse maxima at 4080 K.