Phase evolution, structure and microwave dielectric properties of Li2+Mg3SnO6 (x = 0.00–0.12) ceramics

Abstract In this study, the Li 2+ x Mg 3 SnO 6 (L x MS) ceramic systems were prepared by solid-state reaction using novel atmosphere-controlled sintering ( x = 0.00–0.12). The influences of extra lithium contents on the phase evolution, crystal structure and microwave dielectric properties of Li 2+ x Mg 3 SnO 6 (L x MS) ceramics were systematically investigated. As samples were calcined from 800 to 1000 °C, the Li 2 Mg 3 SnO 6 phase was formed from the chemical reaction between Li 2 SnO 3 and MgO phase. Pure Li 2 Mg 3 SnO 6 phase could be observed for samples calcined at 1000–1100 °C. But when it was exposed to high temperature air over 1100 °C, the Li 2 Mg 3 SnO 6 decomposed into Mg 2 SnO 4 , MgO and Li 2 O. Because of the protective atmosphere and extra lithium, the e r , Q×f and τ f were significantly improved by the suppression of secondary phase and pores for 0.00 ≤ x ≤ 0.08 . However, comprehensive microwave characteristics were deteriorated for 0.08 x ≤ 0.12 , which were correlated with dielectric polarization, bond valence, FWHM, packing fraction and octahedral distortion. The excellent microwave characteristics of L x MS ( x = 0.08) sintered at 1350 °C in novel controlled atmosphere were obtained : e r = 12.7, Q×f = 168,330 GHz and τ f = −27.4 ppm/°C.