The influence of growth conditions on the characteristics of Bi-based whiskers

The influence of growth conditions, such as growth time, temperature, Pb doping, the state of the substrate and the growth atmosphere, on the whisker growth have been investigated. It was found that the maximum length of the whiskers is proportional to the growth time at the initial stage; however, after passing a certain growth time, the maximum length stays constant. The high- T_c phase emerges when the growth time is prolonged for the whiskers whose starting compositions are near the stoichiometry of the high- T_c phase. The optimum temperatures for whiskers growth are in a very narrow range. An appropriate amount of Pb doped into the starting materials and a steady stream of oxygen atmosphere play catalytic roles in the whisker growth.