Microwave dielectric properties, chemical bonds and infrared reflection spectra of La2Sn2O7 ceramics with pyrochlore structures

The La 2 Sn 2 O 7 ceramic was synthesized using the solid−phase reaction method. The crystal structure, sintering characteristics, and microwave dielectric properties of the La 2 Sn 2 O 7 ceramics were studied. XRD analysis shows that La 2 Sn 2 O 7 ceramics possess a pyrochlore structure with a space group of F d 3 ¯ m . As the sintering temperature increases, the ε r and relative density show the same trend of change. The Q × f of ceramics has a strong correlation with the packing fraction. The P−V−L theory shows that La−O and Sn−O bonds have certain effects on the ε r and Q × f . The intrinsic dielectric properties of ceramics were analyzed using infrared reflection spectra. At 1350 °C, La 2 Sn 2 O 7 ceramic obtained the largest relative density and optimum microwave dielectric properties (ε r = 15.65, Q × f = 73,804 GHz and τ f = −18.58 ppm/°C).