“Perturbed Angular Correlation Study of the PbTixHf1-xO3 family of Compounds”

R.E. ALONSO; A. LÓPEZ GARCÍA; M. A. DE LA RUBIA; J. DE FRUTOS

PHYSICA B - CONDENSED MATTER

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2011 p. 1 - 7

0921-4526

In this work,the hyperfine quadrupole interaction at Ta-doped PbTi1xHfxO3 polycrystalline samples is studied for the firsttime.Powders with x¼0.25, 0.50and0.75 were prepared and characterized by X-ray diffraction analysis. Perturbed Angular Correlation(PAC)analyses were done as a function of temperature,using low concentration 181Ta nuclei as probes.In the ferroelectric and paraelectric phases of these compounds two sites were occupied by the probes.For each site the quadrupole frequency,asymmetry and relative distribution width parameters were obtained as a function of temperature above and below the Curie temperature(TC).One of these site swas assigned to the regular Ti–Hf site,while the other one was assigned to some kind of defect.The behavior of the hyperfine parameters as a function of temperature was analyzed interms of a recent published phase diagram and the presence of disorder below and above TC. For the three compositions measured,the obtained hyperfine parameters present discontinuities which correspond to the ferroelectric–paraelectric phase transition. In both phases it was found broad frequency distributed interactions. The disorder in the electronic distribution would be responsible for the broad line width of the hyperfineinteraction.