| Abstract [eng] |
In this work, samples of lead magnesium niobate, lead titanate system (1-x)Pb1-ySmy(Mg1/3Nb2/3)O3-xPb1-ySmyTiO3 (ySm-PMN-xPT system, where x and y are expressed in mole % respectively) were investigated. Five different concentrations of modifying samarium (y = 0, 0.01, 0.02, 0.025, 0.03) were used in the preparation of the samples, the Ti concentration was fixed (x = 0.29) - ySm-PMN-29PT. The samples were investigated in terms of their dielectric, piezoelectric properties. Dielectric permittivity measurements were carried out in the frequency range of 20 Hz to 300 MHz from approximately 100 K to 500 K. Hysteresis loop measurements were made using a sawtooth signal at 10 Hz and a maximum electric field of approximately 27 kV/cm. The measurements were done from room temperature at 10 K intervals, over a temperature range between - 60 °C and 180 °C. The investigated samples have been found to exhibit the characteristics of relaxors. It has been found that their dielectric permittivity at high temperatures can be described by a modified Curie-Weiss law. The Vogel-Fulcher law can also be applied to them. The dielectric permittivity dependencies have shown that the dielectric anomaly shifts towards lower temperatures as the samarium concentration increases. It is assumed that the increase in the piezoelectric coefficients is related to the proximity of this anomaly to room temperature. The piezoelectric investigations have revealed that the electrostriction coefficients of all samples show little dependence on the samarium concentration. The observed increase of the piezoelectric coefficient with increasing samarium concentration strongly suggests that samarium ions completely replace lead ions in the A - region of the perovskite. |
