Ionic conductivity and crystallographic data for Na2-xCa1-xAlxSiO4 and Na2-xCaSi1-xPxO4 carnegieite phases

Abstract Single crystals of Na 2 CaSiO 4 prepared at 30 kbar and 1500°C are cubic with a = 22.456 A . The polycrystalline compositions Na 1.9 Ca 0.9 Al 0.1 SiO 4 and Na 1.8 CaSi 0.8 P 0.2 O 4 can also be indexed using a = 22.458 and 22.471 A , respectively. The Ca carnegieites Na 2 CaSiO 4 , Na 1.9 Ca 0.9 Al 0.1 SiO 4 , and Na 1.8 CaSi 0.8 P 0.2 O 4 have Na ion conductivities of only 5−8 × 10 −6 ( ω -cm) −1 at 300°C.