Li6.75La3Zr1.75Nb0.25O12 (LLZNb) was synthesized using the coprecipitation method. X-ray powder diffraction patterns of LLZNb after calcination at 600 degrees C or higher indicate a cubic phase with a garnet-type structure. Transmission electron microscopy revealed primary LLZNb particles formed by coprecipitation with sizes in the range of 50-100 nm. Sintering of LLZNb was possible at relatively low temperatures of 1000 and 1100 C under an air atmosphere due to the small-sized primary particles, although LLZNb powder synthesized by solid-state reaction did not sinter under the same conditions due to the large size of the primary particles. The total lithium ion conductivity of an LLZNb pellet sintered at 1000 degrees C was measured using AC impedance to be 1.0 x 10(-4) S cm(-1). (C) 2013 Elsevier B.V. All rights reserved.