A possible solution of the grain boundary problem for applications of   high-Tc superconductors
  It is shown that the critical current density of high-Tc wires can be greatly enhanced by using a threefold approach, which consists of grain alignment, doping, and optimization of the grain architecture. According to model calculations, current densities of 4x10^6 A/cm2 can be achieved for an average grain alignment of 10 degree at 77K. Based on this approach, a road to competitive high-Tc cables is proposed. 
G. Hammerl, A. Herrnberger, A. Schmehl, A. Weber, K. Wiedenmann, C.W.   Schneider, J. Mannhart