From these maps one can also nd that BTparticles are tensile strained (as shown by the green color),which is reasonable considering that the lattice parameters ofBT are smaller than those of BTS (as manifested by the slightshi of XRD peaks for the BT phase to higher angles ascompared to those for BTS, as shown in Fig. 1), and when BTparticles combine with BTS through the interfaces, tensilestress is produced in BT, leading to tensile strains in BT particles, with the largest strain reaching 2%, as shown in Fig. 4.