## 3 Results and Discussion
### Characteristics of MFP-Processed Samples
#### 3.2.2 Magnetic Properties of MPF-Processed Samples
As shown in Figure 11b, with the increasing grain alignment for a given composition, \(x\), the increase in \(M_{r}\) always results in the decrease in \(H_{ci}\) for all compositions according to Equation (5). The serious decease in \(H_{ci}\) with improving the grain alignment have also been reported for M-type [46] and Nd-Fe-B [47] magnets. Since it has been suggested that \(H_{ci}\) can be enhanced through simulations on grain boundary diffusion in SrM [48], it may be possible to further improve the \(H_{ci}\) values of MFP samples by using more appropriate sintering additives to ensure smaller average grains and also the presence of a secondary phase at the grain boundary. Figure 12 shows the \(B_{r}\), \(H_{ci}\), and \((BH)_{max}\) values versus \(x\) and also \(B_{r}\) versus \(M_{r}/M_{s}\) for MFP-processed Sr1\({}_{-x}\)La\({}_{x}\)Fe12\({}_{-x}\)Co\({}_{2}\)O\({}_{19}\) samples (\(x\) = 0.0, 0.15, 0.2, and 0.3). The data of MFP-processed samples from Refs. [16; 19] are also plotted on this figure for a comparison. As shown in Figure 12a, our \(B_{r}\) values are comparable to those from [PERSON] et al. [16], who used different sintering additives (SiO\({}_{2}\), CaCO\({}_{3}\), and Al\({}_{2}\)O\({}_{3}\)), but much smaller than those from [PERSON] et al. [19], who employed the same kinds of sintering additives but different amounts (0.4 wt% SiO\({}_{2}\) and 1.4 wt% CaCO\({}_{3}\)); however, their \(M_{s}\) values are almost identical to our \(M_{s}\) values. As previously mentioned, the degree of grain alignment can be evaluated by several different parameters, such as degree of \(c\)-axis orientation, \(w(00l)\); squareness, \(\mathcal{Q}\); and the \(M_{r}/M_{s}\) ratio. All of these parameters are proportional to \(B_{r}\) for a given \(x\). However, for different compositions, only the \(M_{r}/M_{s}\) ratio is proportional to \(B_{r}\). Thus, the much higher \(B_{r}\) values reported by [PERSON] et al. are attributable to the higher degree of alignment indicated by higher \(M_{r}/M_{s}\) values in Figure 12d. Figure 12b shows that our \(H_{ci}\) values are much lower compared with those of previous reports, which are primarily due to the much larger average grain size in our samples. As shown in Figure 10 and Table 4, the highest \((BH)_{max}\) was achievable from the sample of \(x\) = 0.15 among all of our MFP samples. Compared with the previously reported \((BH)_{max}\) values in Figure 12c, we can see that our values are similar to those from [PERSON] et al. [16] but much lower than those from [PERSON] et al. [19], and this is also the case for \(B_{r}\) values. Consequently, the highest \((BH)_{max}\) is obtainable from the highest \(B_{r}\). As shown in Figure 12d, both the \(B_{r}\) and \((BH)_{max}\) values are also proportional to the \(M_{r}/M_{s}\) ratio for all samples with different compositions. Consequently, in comparison with previous reports on MFP-processed\(\text{Sr}_{1-x}\text{La}_{x}\text{Fe}_{12-x}\text{Co}_{x}\text{O}_{19}\) samples [16; 19], our MFP samples exhibit relatively lower values of \(B_{r}\), \(H_{cli}\), and \((BH)_{max}\), and this is largely due to the fact that the processing conditions, such as particle size and distribution, sintering additives, and defoamer, which are closely related to \(c\)-axis grain alignment, have never been optimized yet in such a study. Particularly, [PERSON] et al. [19] reported the highest \((BH)_{max}\) value of 4.86 MGOe for \(x\) = 0.3, suggesting that the \((BH)_{max}\) values in Table 4 could be enhanced by improving the grain alignment through a processing optimization.