Synthesis of sub-micron 2SnO·(H₂O) powders using chemical reduction process and thermal calcination

Synthesis of sub-micron 2SnO·(H₂O) powders by chemical reduction process was performed at room temperature as function of viscosity of methanol solution and molecular weight of PVP (polyvinylpyrrolidone). Tin(II) 2-ethylhexanoate and sodium borohydride were used as the tin precursor and the reducing agent, respectively. Simultaneous calcination and sintering processes were additionally performed by heating the 2SnO·(H₂O) powders. In the synthesis of the 2SnO·(H₂O) powders, it was possible to control the powder size using different combinations of the methanol solution viscosity and the PVP molecular weight. The molecular weight of PVP particularly influenced the size of the synthesized 2SnO·(H₂O) powders. A holding time of 1 hr in air at 500 oC sufficiently transformed the 2SnO·(H₂O) into SnO₂ phase; however, most of the PVP (molecular weight: 1,300,000) surface-capped powders decomposed and was removed after heating for 1 h at 700 oC. Hence, heating for 1 h at 500 oC made a porous SnO₂ film containing residual PVP, whereas dense SnO₂ films with no significant amount of PVP formed after heating for 1 h at 700 oC.