Formation of Mn-Co-Ni-O Nanoceramic Microspheres Using In Situ Ink-Jet Printing: Sintering Process Effect on the Microstructure and Electrical Properties

Mn-Co-Ni-O nanoceramic microspheres with high density, uniformity, and size tunability are successfully fabricated using in situ ink-jet printing and two step sintering (TSS) techniques. The microspheres, synthesized by an effective and facile reverse microemulsion method, consist of uncalcined Mn-Co-Ni-O nanocrystallines that show a well formed single tetragonal spinel phase and an average particle size distribution of approximate to 20 nm. The sintering behavior, microstructure, and electrical properties of the Mn-Co-Ni-O nanoceramic microspheres are systematically investigated and characterized. The results indicate that the sintered Mn-Co-Ni-O nanoceramic microspheres show high density and improved electrical properties. The highest R-25, B-25/50, E-a, and alpha(25) values achieved at sintering temperature of 1150 degrees C are 4846.7 K Omega, 4320 K, 0.401 eV, and -5.24% K-1, respectively for these Mn-Co-Ni-O nanoceramic microspheres. Furthermore, the formation mechanism of uncalcined Mn-Co-Ni-O nanocrystallines and an analysis of the TSS procedure of the nanoceramic microspheres are discussed.