**5. Characterization ceramic**

The *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> is a ferroelectric ceramic powder, and it is possible to characterized by x-ray and electric measures [8, 16]. The EPR measures were taking at Biophysics and Magnetic Measure National Polytechnic Institute Laboratory using an EPR JEOL JES-RE3X spectrometer, **Figure 7**.

**Figure 7.** *EPR JEOL spectrometer [23].*

#### **Figure 8.**

*General diagram for paramagnetic resonance spectrometer (EPR) that consist of magnetic system (electromagnet, modulation coils, magnet power supply and field scan drive), field modulation system (power amplifier, 100 kHz oscillator), cavity system (resonant cavity with sample, iris and the T-magic system), microwave source system (klystron power supply, automatic frequency control, etc.) and detection system (detector crystal, 100 kHz signal detector, 100 kHz signal amplifier, oscilloscope, computer and data bank; and display of the spectrum) [12].*

The temperature measures were at 300K and 77K. The power potency was varied from 1 mW until 40 mW [17–23], at 9.45GHz microwave frequency at X-band. The lead zirconate titanate was doped with five percentages of Cr of 0%, 1%, 2%, 4% and 5%, we called the samples 0, 1, 2, 4 and 5 respectively.

The spectrometer is connected to workstation ES-PRIT to HP-9000 computer with a converter analogic digital target (A/D). The programing package performs acquisition, procession and simulation data [23, 24]. The block diagram typical X-band EPR spectrometer employing 100KHz phase sensitive detection is shows in **Figure 8** [12, 23].

### **6. Results and discussions**

The X-rays and electric measured was published by F. Calderon, and Yañez, et al. [8], the x-rays spectra are show in **Figure 9** for samples 4 and 5. The X-rays program fixed the *Pb Zr* ð Þ <sup>0</sup>*:*44*Ti*0*:*<sup>56</sup> *O*<sup>3</sup> compound and this do not detect secondary phases. The quantity of chromium is not enough for be detected by X-rays measures, because the limit detection is 5% of the element. About electric measured, when the chromium concentration varies from sample 1 to 5, the Curie's temperature value increases. The Cr substitution causes a tetragonal distortion field to the tetrahedral symmetry structure causes energy splitting effect by zero splitting field [12]. Due to the *Cr*<sup>3</sup><sup>þ</sup> quantity is more than *Ti*<sup>4</sup><sup>þ</sup> or *Zr*<sup>4</sup><sup>þ</sup> quantities, the system tetragonality be modified and the grain size is increased [8]. The Curie's temperature varies slightly, and the energy activation is below and above to the transition.

#### **Figure 9.**

*X-rays for 4 and 5 samples that corresponds to perovskite structure or tetrahedral symmetry from Pb (Zr0.44Ti0.56)O3.*

The presence of chromium determined by EPR guaranteed an oxygen or hold vacancy mechanism, also this effect was confirmed by Yañez, et al. [8].
