Infrared transparent windows found to have applications in demanding defense and space missions. In this paper we report the synthesis of La0.3Y1.7O3 by a modified auto-igniting combustion technique and the sintering of the pellets made from the ultrafine nanostructured powder using resistive heating. The XRD analysis and High Resolution Transmission Electron Microscopic(HR-TEM) studies reveal that the average crystallite size is ~16nm and the lattice planes are well defined. The pure white La0.3Y1.7O3 powder is uniaxially compacted in to pellets in a 14mm diameter steel die and sintered to 98% theoretical density without any sintering additives or applying pressure at 1560oC for 2hours in a conventional furnace which. The transmission spectrum of the sintered pellet in the Uv-Vis region reveals that the material is showing 77% of transmittance in the visible region and 76% in the Mid IR region. The results clearly indicate that the ultra-fine La0.3Y1.7O3 nanopowder synthesized by the modified auto-igniting combustion technique synthesised using single step combustion method followed by resistive heating can be used very effectively for the fabrication of improved infrared transparent windows and domes.