**7. Conclusions**

The ferroelectric *Pb*0*:*95*Sr*0*:*05ð Þ *Zr*0*:*53*Ti*0*:*<sup>47</sup> *O*<sup>3</sup> þ *x*%*wtCr*2*O*<sup>3</sup> with *x* ¼ 0*:*0, 0*:*1, 0*:*2, 0*:*4 and 0*:*5 samples produce a characterized spectrum well defined by absorption peaks. The signals *B* and *B*<sup>∗</sup> are present in the EPR spectrum for all samples doped with *Cr* and they no have saturation features for microwave power variation from 1 mW to 40 mW at 300*K* and 77*K*. Both *B* and *B*<sup>∗</sup> signals correspond to *Cr*3<sup>þ</sup> ion, with spin *<sup>S</sup>* <sup>¼</sup> <sup>1</sup>*=*2 which is substituting to *Ti*4<sup>þ</sup> or/and *Zr*4<sup>þ</sup> ions at *<sup>B</sup>* sites. One of signals corresponds to octahedron with *Cr*3<sup>þ</sup> ions belong to crystalline cells with tetragonal distortion localize into the grains. The other signal corresponds to octahedrons crystalline cells localize cells in the frontiers between the material grains, i.e., the EPR spectra shows two distinguishable *B* sites, which have been registered by *B* and *B*\* signals. The two *B* sites are similarly to *B* and *B*\* sites of *Mn*4<sup>þ</sup> in *PbTiO*<sup>3</sup> reporter in reference [27]. The microwave power increase does not increase the signals intensity separately, this means that the spectrum is not a superposition of two or more signals corresponding to different paramagnetic centers. The line width and the g-values are not changing with temperature or microwave power variation. The sample 4 shows the same spectrum for 0, 1, 2 and 5 samples. However, the sample 4 shows additionally the *H* and *G* signals forming a "fine triple" structure which indicates the *Cr*<sup>3</sup><sup>þ</sup> presence at weak crystalline field environment in to local octahedral symmetry.
