“…The substitution can take place either at the Ca-site or at the Co-site. There have been a number of reports on partially substituted elements at Ca-site, for instance, Na [11][12][13][14], Y [8], Ag [15][16][17][18], Bi [12,19], Ba [18], Nd [14], Gd [20], Yb [21], and other rare earth elements [22][23][24]. The effect of partial substitution at the Ca-site is mainly to change the charge carrier concentration which results in a change in resistivity.…”