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Journal of the American Ceramic Society, Vol.84, No.8, 1661-1668, 2001
Sintering behavior and electrical properties of nanosized doped-ZnO powders produced by metallorganic polymeric processing
Homogeneous and nanosized (28 nm crystallite size) doped-ZnO ceramic powders were obtained by a metallorganic polymeric method. Calcining and granulating resulted in green compacts with uniform powder packing and a narrow pore-size distribution (pore size 19 nm). Dense ceramic bodies (> 99% of theoretical) were fabricated by normal liquid-phase sintering at 850 degrees and 940 degreesC for 1-5 h. Apparently, the low pore-coordination number allowed a uniform filling of the small pores by the liquid formed in the early stages of sintering, and, consequently, high shrinkage and rapid densification occurred in a short temperature interval (825 degrees -850 degreesC). At these sintering temperatures, limited grain growth occurred, and the grain size was maintained at <1 mum. Ceramics so-fabricated showed a nonlinear coefficient, alpha, of greater than or equal to 70, and a breakdown voltage, V-b (1 mA/cm(2)), of greater than or equal to 1500 V/mm. The high electrical performance of the doped-ZnO dense ceramics was attributed to liquid-phase recession on cooling, which enhanced the ZnO-ZnO direct contacts and the potential barrier effect.