摘要
The valences of Cu in Y_(1-x)Ca_(x)Ba_(2)Cu_(3)O_(6+y) have been investigated by using complex chemical bond theory.The results for the valences of Cu(1)and Cu(2)in the calculation suggest that the holes introduced by calcium substitution only reside in CuO_(2) planes,and there is a competition mechanism for the hole density in CuO_(2) planes between Ca doping and oxygen depletion.These conclusions are satisfactorily in agreement with experiments.
