A new Li-based ceramic of Li4MgSn2O7: Synthesis,phase evolution and microwave dielectric properties

A pure-phase Li₄MgSn₂O₇ (L₄MS) was successfully synthesized through optimizing the calcination condition. Microwave dielectric properties of the L₄MS ceramic with the phase evolution were investigated together with its low-temperature sintering. The sample maintains a single L₄MS phase as sintered below 1200?°C, such that τ_f remains a constant value of ～12.4?ppm/°C. Accompanied by the appearance of impurity phases (Li₂SnO₃)_ss and especially (MgO)_ss at higher sintering temperatures, excellent microwave dielectric properties of ε_r?=?13.1–13.5, Q?×?f?=?106,800–126,810?GHz and τ_f ?=?0–?4.2?ppm/°C are obtained in samples sintered at 1215–1260?°C for 4?h. Reduction of sintering temperature using LiF sintering aid also helps achieve pure-phase dense L₄MS ceramic. The L₄MS?+?x wt.% LiF ceramic exhibits ε_r～13.7, Qxf～97,000?GHz (x?≤?3) and τ_f ～8–13?ppm/°C sintered at 850?°C for potential LTCC applications, and ε_r ～13.9, Qxf～146,000?GHz and τ_f ～1.5–6?ppm/°C (x?≥?4) as sintered 1000?°C, exhibiting large potentials for microwave dielectric candidates.