“…In many papers (see, e.g., [1,10,14,15,19,24,58,64,78,95,97,99,102,104,109,110,112,113,[119][120][121]128,154,158,159,201,202]), the lower-energy emission bands of Bi 3+ -doped compounds were ascribed to the {Bi 3+ -Bi 3+ } pairs or the clusters of Bi 3+ ions. The characteristics of this luminescence are presented in Table 4.…”