A new class of ordered langasite structure compounds, namely, Sr3NbGa3Si2O14 (SNGS), Sr3TaGa3Si2O14 (STGS), Ca3NbGa3Si2O14 (CNGS) and Ca3TaGa3Si2O14 (CTGS), have been reported [1]. Lower acoustic loss is expected among these compounds, We report our effort to produce 3" diameter single crystals for acoustic applications. We also report the effort to extract material constants of these compounds, Preliminary result based on inter-digital SAW transducer (IDT) on Y-cut wafers shows many attractive properties. Comparing with published data on LGS, LGN and LGT, these crystals have significantly lower dielectric constants (epsilon(11) epsilon(33)), much higher SAW velocity (comparable to quartz) and higher electro-mechanical coupling constants (2x that of LGS for SNGS.). Current effort is concentrated on the search for the orientation with zero TCD.
