Microwave dielectric properties of YAG ceramics prepared by sintering pyrolysised nano-sized powders

YAG ceramics with good dielectric properties were prepared via a modified pyrolysis method, with yttrium nitrate as the yttrium source and combined aluminium sulphate and aluminium nitrate as aluminium sources, and subsequent sintering in a muffle furnace. The effects of the different aluminium sources on the powder characteristic and the impact of sintering temperature , sintering aids (TEOS) and additive (TiO 2 ) on the dielectric properties of the ceramics were studied. The results show that well-dispersed pure YAG nano-powders can be obtained after calcination at 1000   °C with an aluminium sulphate and aluminium nitrate molar ratio of 1.5:2. The relative density, permittivity ( ε r ) and quality factor ( Q × f ) of the YAG ceramics increase with sintering temperature and TEOS addition. TiO 2 can greatly promote τ f to near-zero but decreases Q × f . The relative density, ε r , Q × f and τ f of the YAG–1   wt% TEOS–1   wt% TiO 2 ceramic obtained at 1520   °C are 97.6%, 9.9, 71, 738   GHz and −30   ppm/°C, respectively.