*2.3.3.4 Koga's and Kolodiazhnyi's data comprehended in Kugimiya's data*

Koga's data [24] and Kolodiazhnyi's [29] data are comparable with Kugimiya's BMT data [22]. The area (I) and the H-CT with the highest *Qf* as shown in **Figures 22** and **24**, respectively, are located on the opposite side of Kugimiya's data against the BMT-Ba5Ta4O15 tie-line (**Figure 21**). These compositions will be comparable with that of the ideal crystal structure Ba1+*α*(Mg1/3Ta2/3+4*<sup>α</sup>*/5*Vα*/5) O3+3*α*, as stated before in section (2.3.3.1) [22]. The formula is rewritten as Ba(Mg1/3−*<sup>α</sup>*/3Ta2/3+2*<sup>α</sup>*/15*Vα*/5)O3 solid solutions on the tie-line BMT-Ba5Ta4O15. The crystal structure in the composition region is ideal, without defects, and with an intrinsic high compositional density as described above. Surendran et al. [66] also reported a composition with high *Qf* deviated from stoichiometric BMT reviewed in detail in Intech Open Access Book [21].
