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 powder s were obtained by a metallorganic polymeric method. Calcining and granulat ing resulted in green compacts with uniform powder packing and a narrow por e-size distribution (pore size 19 nm). Dense ceramic bodies (> 99% of theor etical) were fabricated by normal liquid-phase sintering at 850 degrees and 940 degreesC for 1-5 h. Apparently, the low pore-coordination number allow ed a uniform filling of the small pores by the liquid formed in the early s tages of sintering, and, consequently, high shrinkage and rapid densificati on 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 c oefficient, 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 electric al performance of the doped-ZnO dense ceramics was attributed to liquid-pha se recession on cooling, which enhanced the ZnO-ZnO direct contacts and the potential barrier effect.