Morphology-tunable synthesis and formation mechanism of SnO2 particles and their application in Ag–SnO2 electrical contact materials.

SnO 2 powders with four distinct morphologies of prismoids, hollow rhomboidal tubes, solid rhomboidal rods, and needles have been prepared through morphology-conserved transformation from SnC 2 O 4 precursors. The SnC 2 O 4 precursors were synthesized by a facile oxalate precipitation method. A controllable periodic bond chain (PBC) growth was found to be critical for the formation of these SnC 2 O 4 samples. In the case of forward titration, SnC 2 O 4 prismoids were generated because the formed Sn 3 O(OH) 2 SO 4 was attached on { 1 - 01} polar facets and inhibited the PBC growth along the c axis. By contrast, in the case of reverse titration, SnC 2 O 4 samples preferably formed one-dimensional shapes. Dissolution and ripening were observed during the formation of hollow tubes in the case of low molar ratio of Sn2+ to C 2 O 4 2−. Further, the formation of SnC 2 O 4 needles was ascribed to the selective coordination of polyvinylpyrrolidone (PVP) on the side surface. The as-prepared SnO 2 powders were used as reinforcement of Ag–SnO 2 electrical contact materials, and a good adhesion was observed at the Ag (111)/SnO 2 (200) interface. Further, the characterization results revealed that the sample reinforced by SnO 2 tubes (with one-dimensional shape and hollow structure) had the lowest degradation rate under cathode arc erosion, which might be attributed to its good resistance to the dual action (heat and force) of cathode arc. [ABSTRACT FROM AUTHOR]