We demonstrate that liquid-feed flame spray pyrolysis (LF-FSP) processing provides non-aggregated nanopowders that can be used immediately to tape cast, producing thin films (<100 mu m) of Li+ ion conducting membranes when sintered. Glass-ceramic or sol-gel processing methods are commonly used for such but require additional high-energy milling and/or calcining to obtain powder feedstock. Li1+x+yAlxTi2-xSiyP3-yO12 (x = 0.1, 0.3/y = 0.2, 0.4) nanopowders were prepared by LF-FSP with a primary focus on the effects of Al-0.3/Si-0.4 doping on conductivities. Furthermore, the effects of excess Li2O on Al-0.3/Si-0.4 doped materials were studied. Li1.7Al0.3Ti1.7Si0.4P2.6O12 pellets sintered to 93-94% of theoretical density and samples with varying excess Li2O contents all show superionic conductivities of 2 -3 x 10(-3) S cm(-1) at room temperature. Li2O lowers both the crystallization temperatures and temperatures required to sinter. Total conductivities range from 2 x 10(-3) to 5 x 10(-2) S cm(-1) in the temperature span of 25 degrees-125 degrees C. Small grain sizes of 600 +/- 200 nm were produced. Initial attempts to make thin films gave-films with thicknesses of 52 +/- 1 mu m on sintering just to 1000 degrees C. Measured conductivities were 3-5 x 10(-4) S cm(-1); attributed to final densities of only approximate to 88%. (C) 2014 Elsevier B.V. All rights reserved.