Abstract
Three pure phases Li4NbO4F, Li4MgNbO5F and Li6.5MgTiNbO8F1.5 oxyfluorides were successfully prepared using the way of solid-state reaction method at 650 °C, 600 °C and 725 °C, respectively. According to the XRD data and Rietveld refinement results, these three types of ceramics crystallized in a cubic rock salt structure with space group [Fm-3 m(225)]. The grain sizes, theoretical εtheo and packing fraction were calculated to help with the evaluation of these three ceramics. The oxyfluoride ceramics Li4NbO4F, Li4MgNbO5F and Li6.5MgTiNbO8F1.5 sintered at 875 °C, 900 °C and 900 °C exhibited outstanding microwave dielectric properties: εr = 16.8, 16.4 and 17.3, Q × f = 76,200, 97,300 GHz and 92,600, and τf = ?48.6, ? 40.5 and ? 41.3 ppm/°C, respectively. The compatibility with Ag powders shows that the Li4NbO4F, Li4MgNbO5F and Li6.5MgTiNbO8F1.5 ceramics are potential candidates for low temperature co-fired ceramic technology.
NSTL
Elsevier