Structural, optical and dielectric relaxor properties of neodymium doped cubic perovskite (Ba_(1-x)Nd_(2x/3))(Zr_(0.3)Ti_(0.7))O_3

摘要

Neodymium doped Barium Zirconate Titanate (Ba_(1-x)Nd_(2x/3))(Zr_(0.3)Ti_(0.7))O_3 (x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10) ceramics were prepared using the solid state reaction route. Structural characterizations of the materials were done by using X-ray diffraction and Raman spectroscopy. XRD study suggested that all the compositions were of single phase cubic perovskite structure with space group Pm-3m while Raman spectra revealed that the replacement of the Ba~(2+) ions by Nd~(3+) ions significantly reduced the intensity of the Raman active modes and shifted them towards higher energy side. Room temperature optical property was analyzed by photoluminescence spectroscopy, which confirmed formation of shallow defects in the band gap. Photoluminescence property was attributed to the presence of polar [TiO_6] distorted clusters in the globally cubic matrix. As a result PL emission spectra of these materials were found to belong to violet-blue regions. Microstructural study of sintered pellets revealed that the grain sizes increase with increase in doping concentration. The temperature dependence of the dielectric properties was investigated in the frequency range 1 kHz to 1 MHz. The broadening in the dielectric constant peak around the phase transition temperature and shifting of the temperature maximum towards higher temperatures with increase in frequency indicated a relaxor type of behavior.