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The Polycrystalline samples of (Pb1− xGd x)(Sn0.45Ti0.55)1− x/4O3 (PGST) ( x = 0, 0.05, 0.07, 0.1) were prepared using a standard mixed-oxide method. The XRD and SEM studies of the samples reveal that PGST samples have tetragonal symmetry with uniform grain distribution. Measurements of dielectric constant, dielectric loss and ac electrical conductivity were made in a wide temperature (300–650 K) and frequency (100 Hz to 1 MHz) range. These materials undergo a ferroelectric–paraelectric phase transition at 569, 582, 598, and 603 K for x = 0, 0.05, 0.07, 0.1, respectively. The ferroelectric property of some samples at room temperature was confirmed through the study of hysteresis loops. The Cole–Cole plots (ε′′ vs. ε′) at 125 and 150 °C form semicircular arcs with the center lying underneath the abscissa, deviated from the ideal Debye relaxation model to some extent. In all the compounds, the slope of ln σac ~ 1/ T shows a distinct variation for temperature below 450, 450 K to Tc and for T > Tc. The room temperature ac conductivity at 10 kHz lies in the range of 10−5–10−6 (Ω−1 m−1). [ABSTRACT FROM AUTHOR]

The polycrystalline sample of Na1/2Nd1/2TiO3 was prepared by a high-temperature solid-state reaction technique. The formation of the compound was confirmed by both XRD and EDX studies. Preliminary structural analysis ofNa1/2Nd1/2TiO3 using X-ray diffraction data exhibits a tetragonal phase of the material at room temperature. The dielectric permittivity and the loss tangent of the pellet sample were obtained in a wide frequency range (1 kHz to 1 MHz) at different temperatures (30 °C to 425 °C). The dielectric anomaly at 114 °C, appearance of hysteresis loop and piezoelectric properties at room temperature confirmed the ferroelectric properties of the compound. Measurements of frequency and temperature dependence of impedance over a wide frequency range (100Hz–1MHz) were carried out by complex impedance spectroscopy as a non-destructive tool and indicate that the electrical properties of the material are strongly temperature dependent. Evidence of temperature dependence of electrical relaxation phenomenon as well as the negative temperature coefficient (NTC)-type of resistance behavior of the sample has also been observed. The dc conductivity graph follows the Arrhenius law. Studies of dielectric modulus suggest the non-Debye type of relaxation in the materials, which is supported by the impedance data. [ABSTRACT FROM AUTHOR]

Y-modified Pb(SnTi)O3 polycrystalline materials with a general formula (Pb $${_{1-x}\hbox{Y}_{x})}$$ (Sn $${_{0.45}\hbox{Ti}_{0.55})_{1-x/4}\hbox{O}_{3}}$$ (PYST) ( x = 0, 0.05, 0.07, 0.1) have been synthesized using the standard mixed oxide method. Crystallographic and surface morphology studies are carried out by the powder X-ray diffraction and scanning electron microscopy techniques. X-ray diffraction studies of the samples showed the tetragonal structure of the unit cell. Uniform grain distributions with porosity throughout the surface of the sample pellets are observed. The T C (transition temperature) increases with increase in the mole fraction of the substituent ( x). ɛ/ max is found to decrease with increase in x. The slope of lnσac∼ 1/ T shows distinct variations for temperature below 410 K, 410 K to T c and for T > T c. The room temperature ac conductivity at 10 kHz lies in the range of 10−5–10−6 (ohm−1 m−1). [ABSTRACT FROM AUTHOR]

We have synthesized $$Pb\left( {Sn_x Ti_{1 - x} } \right)O_3$$ (PST) with x=0.45, 0.55, 0.65 ferroelectric ceramics by a solid-state reaction technique and performed preliminary X-ray diffraction (XRD) analysis and the temperature and frequency dependence dielectric measurements on them. The a.c. and d.c. conductivities have been investigated over a wide range of temperature and the activation energy $$\left( {E_{a.c.} and E_{d.c.} } \right)$$ have also been calculated. It is observed that: (i) the relative dielectric permittivity (ε) and loss tangent (tan δ) are dependent on frequency, (ii) the temperature of dielectric permittivity maximum shifts toward lower temperature side, (iii) permittivity maximum decreases with the increase of Sn content in the (PST) compounds and (iv) no frequency dispersion of the dielectric permittivity reveals the no-relaxor behavior of the materials. [ABSTRACT FROM AUTHOR]