Sol–gel preparation of a new compound with Ca3Ga2Ge4O14 structure: La3Al5.5Ta0.5O14

Langatate (La3Ga5.5Ta0.5O14 (LGT)) and its isomorphs are promising piezoelectric materials for surface acoustic waves (SAW) and BAW use. A new compound La3Al5.5Ta0.5O14 (LAT) that has the same crystal structure with LGT was reported in this paper. Nanosized LAT was successfully prepared by a simple citrate sol–gel technique with La2O3, Al(NO3)3·9H2O and tantalum citrate as starting materials. The powder of the dried gel was heat treated at different elevated temperatures and the effect of the temperatures on the particle size was investigated. The nanoscaled LAT was produced by calcining the citrate precursor powder at 900 °C for 6 h. The crystallinity of the calcined powder increased with the calcination temperature. Thermogravimetry-differential thermal analysis (TG-DTA) was employed to investigate the transformation process from gel to LAT powder. The phase contents were studied by X-ray powder diffraction (XRPD). At the same time, the lattice parameters were calculated, revealing a=0.8127 nm, c=0.4985 nm and V=0.2851 nm3. Particle size and morphology were studied by transmission electron microscopy (TEM).