SINGLE CBYSTAL OROWTH AND OBSERVATION ON FERROELECTRIC DOMAINS IN (K_(1-x)Na_x)_(0.4) (Sr_(1-y)Ba_y)_(0.8)Nb_2O_6 TUNGSTEN BRONZE TYPE STRUCTURE CRYSTALS

• 钨青铜型结构铁电体(K_(1-x)Na_x)_(0.；4)(Sr_(1-y)Ba_y)_(0