Reactive fabrication of spherical ZnO–MgO solid‐solution submicrometer particles by pulsed laser melting in liquid

Abstract Pulsed laser irradiation with an appropriate laser fluence (50–200 mJ pulse −1 cm −2 ) onto photo‐absorptive ceramic or metallic nanoparticles dispersed in liquid can induce a rapid rise in the local temperature to 1000–3000 K of the particles, instantaneous generation of melt droplets, and formation of spherical particles of high‐temperature materials via quenching. Such space‐selective pulsed heating through optical absorption may enable reactive powder processing through mimicking of conventional high‐temperature ceramic or metallurgical‐reaction processes. Here, by combining photo‐absorptive ZnO and non‐photo‐absorptive MgO as raw particles, the laser irradiation technique for high‐temperature powder reaction was applied to check whether submicrometer spherical ZnO–MgO solid‐solution particles can be generated. Various raw‐particle mixtures obtained by mechanical milling, coprecipitation from inorganic salts, and thermolysis of organic salts were tested; the produced particles were characterized to reveal the effects of temperature on the composition of MgO included in ZnO host crystals. The raw‐particle mixtures composed of small particles tended to transform into ZnO–MgO particles with high MgO content. Physicochemical calculations and experimental results revealed the importance of appropriate particle sizes of photo‐absorptive ZnO and non‐photo‐absorptive MgO, their mutual close contact, and laser irradiation conditions in the reactive fabrication of ZnO–MgO submicrometer particles.