Preparation of complex oxide (Pr0.8Y0.2)0.6Ca0.4CoO3 from Pr–Y–Ca–Co gel synthesized by ultrasonic irradiation and its metal–insulator transition characteristics

We previously reported that a swollen gel with a uniform composition and prolonged stability can be conveniently prepared by simple ultrasonic irradiation of an ethanol suspension of calcium acetate, which is poorly soluble in ethanol. In this study, the same gel synthesis method was used to prepare the complex oxide (Pr1−y Y y )1−x Ca x CoO3 (PYCCO), which undergoes a metal–insulator phase transition. Calcination of the Pr–Y–Ca–Co swollen gel at 800 °C for 12 h in air afforded PYCCO nanoparticles with good crystallinity, thus realizing a faster and more convenient route compared with conventional solid-phase reactions or sol–gel methods.