Application of ceramics powder synthesis through solid and liquid processes to combinatorial chemistry is thought to be of much importance to expansion of material research field. Combinatorial robot system developed in our laboratory has the possibility of performing combinatorial synthesis through a liquid process. The robot system has an automatic arm. Automatic micropipette, attached to the arm, measures and mixes raw materials. Mixed samples were injected and carried to a pallet with many holes where the samples were sucked. The pallet filled with samples was heated in an electrical furnace. In this study, combinatorial powder XRD equipment with position-sensitive proportional counter (PSPC) was developed, which was able to measure a sample in only 2 min. Furthermore, combinatorial robot system and combinatorial X-ray diffraction clarified the influence of dopants on the structural phase transformation temperature of maghemite to hematite in case of using nanoparticle slurries as starting materials. Consequently, it was clarified that the structural phase transformation temperature of maghemite to hematite increased with increasing the adding amount of yttria nanoparticles and the temperature increased from ca. 540 to 820 degreesC by 2 at.% yttria addition.