L Besra, M. Liu/Progress in Materials Science 52(2007)1-61 Film B 6007 Fig. 2. SEM images of YBCO film electrophoretically deposited on silver electrode from its suspension in acetone 80s(film A: mean particle size =3 um; film B: mean particle size =0.06 um). The films were sintered h and annealed at 500C for 6 h [4]- the morphology of the YBCO superconducting film fabricated by electrophoretic deposi tion suggesting that it is a useful technique to minimize cracking of deposits 3. 1.2. Dielectric constant of liquid Powers [32] investigated beta-alumina suspensions in numerous organic media and determined the incidence of deposition as a function of the dielectric constant of the liquid and the conductivity of the suspension. A sharp increase in conductivity with dielectric constant was noted; which apparently refers to the liquid in their pure state. It should also be noted that impurities, in particular water, affects the conductivity and that conductivity of milled suspension is very different to that of pure liquid, as a consequence of dissociative or adsorptive charging modes. Powers [32] obtained deposits only with liquid for which the dielectric constant was in the range of 12-25. With too low a dielectric constant, depo- ition fails because of insufficient dissociative power, whilst with a high dielectric constant, the high ionic concentration in the liquid reduces the size of the double layer region and consequently the electrophoretic mobility. Consequently, the ionic concentration in the liquid must remain low, a condition favoured in liquids of low dielectric constant. Thethe morphology of the YBCO superconducting film fabricated by electrophoretic deposi￾tion suggesting that it is a useful technique to minimize cracking of deposits. 3.1.2. Dielectric constant of liquid Powers [32] investigated beta-alumina suspensions in numerous organic media and determined the incidence of deposition as a function of the dielectric constant of the liquid and the conductivity of the suspension. A sharp increase in conductivity with dielectric constant was noted; which apparently refers to the liquid in their pure state. It should also be noted that impurities, in particular water, affects the conductivity and that conductivity of milled suspension is very different to that of pure liquid, as a consequence of dissociative or adsorptive charging modes. Powers [32] obtained deposits only with liquid for which the dielectric constant was in the range of 12–25. With too low a dielectric constant, depo￾sition fails because of insufficient dissociative power, whilst with a high dielectric constant, the high ionic concentration in the liquid reduces the size of the double layer region and consequently the electrophoretic mobility. Consequently, the ionic concentration in the liquid must remain low, a condition favoured in liquids of low dielectric constant. The Fig. 2. SEM images of YBCO film electrophoretically deposited on silver electrode from its suspension in acetone at 10 V for 180 s (film A: mean particle size = 3 lm; film B: mean particle size = 0.06 lm). The films were sintered at 945 C for 1 h and annealed at 500 C for 6 h [4]. L. Besra, M. Liu / Progress in Materials Science 52 (2007) 1–61 7