Ca-Zr substituted (Bi-YIG) nanopowders with a nominal composition of BiY2-xCaxZryFe5-yO12 (x = y and x varied from 0.00 to 1.25 by the step of 0.25) were prepared by mechanochemical processing (MCP) and subsequent heat treatments. The effect of dopant mol ratios, on garnet phase formation were investigated by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The lattice constant of the samples increased by increasing Zr4+ content (for x <= 1). Mean crystallite,size of the single-phase powders, which was evaluated by Scherrer's formula, was about 35 nm. The experimental results show that the Ca-Zr substitution Bi-YIG lowers the calcining and sintering temperatures for x < 1. The results show that the single-phase nanopowders can be obtained at temperatures below 850 degrees C. The measurements of vibrating sample magnetometer (VSM) show that the saturation magnetization of the samples increases as x increase from 0.00 to 0.25 and then decreases by increasing x to the values greater than 0.25. (C) 2013 Elsevier Ltd. All rights reserved.