In the first series. the compacts w

In the first series. the compacts were sintered at 1450℃ for 0.5 h in 0, atmosphere and then water quenched. With little Bi2O3 added in this series. it was easier to trap the liquid inside the grain. Some specimens were further heat-treated at 1050℃ for 20 h to observe the shape change of the trapped liquid with temperature. In the second series, the compacts of 92ZnO-7Bi2O3-iLi2O were placed with sintcred scraps on Pt plate within an alumina crucible and sintered for 2 h at l000 and 1400℃, respectively. During sintcring, O2 gas was used during heating up stage and then changed to air (as soon as the sintcring tcmpcrature was reached). Such an atmosphere change during liquid phase sintcring has been dcmonstratcd to lower the residual porosity of the specimen by enhancing the diffusion of trapped oxygen in the pores [14]. The heating and cooling rate for sintering was 4℃/min.