Structural and electrical properties of Ba5SmTi3V7O30 ceramics
Polycrystalline sample of Ba5SmTi3V7O30 was prepared by a high-temperature solid-state reaction technique. Structural and microstructural characterizations were performed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). X-ray preliminary structural studies reveal that the material has orthorhombic structure at room temperature. Detailed electrical (dielectric and impedance) properties of the material studied by using a complex impedance spectroscopy (CIS) technique in a wide temperature range (33–450°C) at different frequencies (102–106Hz) reveal that the relative dielectric constant of the material increases with rise in temperature and thus bulk has a major contribution to its dielectric and electrical properties. The bulk resistance of the material decreases with rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior. The nature of the temperature variation of conductivity and value of activation energy, suggest that the conduction process is of mixed-type (ionic–polaronic and space charge). The existence of ferroelectricity in the compound was confirmed from polarization study.
[Show abstract] [Hide abstract] ABSTRACT: This paper presents the effect of water vapor on the electrical response of antimony sulfoiodide (SbSI) nanowires obtained sonochemically to explore its application as a humidity sensor. For the first time this material has been studied using impedance spectroscopy. The measurements have been made in nitrogen for various humidities and temperatures. The real part of the total complex impedance is found to decrease by three orders of magnitude with the increase of humidity from 10% to 85%. Influence of temperature and humidity on relaxation time of SbSI is reported. The least square fitting of the Nyquist characteristics of the investigated gel allowed one to distinguish between different equivalent electric models of the SbSI gel. The changes of the parameters of the model with increasing temperature and humidity are presented. The polarization of water molecules is shown to be a major contributor to the capacitance–temperature characteristics of SbSI gel.0Comments 1Citation
- "It agrees with the decreasing (Fig. S4b) of Z MAX peak heights (proportional to resistance) with increasing temperature. The coincidence of Z at higher frequencies for all temperatures (Fig. S4a) indicates a possible release of space charge . The peaks in the frequency dependence of Z (Figs. 4b and S4b) indicate relaxation in the system. "
- [Show abstract] [Hide abstract] ABSTRACT: The polycrystalline sample of K2Pb2Dy2W2Ti4Nb4O30 was synthesized by high—temperature solid—state reaction method (calcinations temperature *1,050 �C and sintering temperature *1,075 �C). The phase formation of the desired compound was confirmed by preliminary X-ray structural analysis. The scanning electron micrograph shows uniform plate and rod like grain distribution throughout the surface of the sample without much pores. Detailed studies of the nature of (1) variation of dielectric parameters with temperature (27–480 �C) and frequency (1 kHz–5 MHz) and (2) polarization (at three different temperatures) confirmed the existence of ferroelectricity in the material, with phase transition occurring at 316 �C. The temperature dependence of electrical parameters (impedance, modulus, conductivity, etc.) of the material exhibits a strong correlation between its micro-structure (i.e., bulk, grain boundary, etc.) and electrical properties. The nature of temperature dependent dc conductivity follows the Arrhenius equation, and reveals the negative temperature coefficient of resistance (NTCR) behaviour of the material. The material obeys Jonscher’s universal power law which is evident from the graphs of frequency dependence of ac conductivity.0Comments 23Citations
- [Show abstract] [Hide abstract] ABSTRACT: The ferroelectric ceramic Ba5LaTi3V7O30 has been synthesized by solid-state reaction technique. Preliminary X-ray structural analysis confirmed a single-phase formation (orthorhombic crystal system) of the compound. Surface morphology of the compound was studied by scanning electron microscopy (SEM). Detailed studies of electrical properties (i.e., dielectric constant, loss tangent, ac and dc conductivity) as a function of temperature (RT - 773 K) at four different frequencies, 1 kHz, 10 kHz, 100 kHz and 1 MHz show ferroelectric—paraelectric phase transition of the compound. The impedance spectra show two distinctly separated regions in wide temperature range corresponding to grain boundary and grain interior contributions. The activation energy has been evaluated from ac conductivity and dc conductivity following Arrhenius equation is 0.15 eV at 1 MHz and 0.28 eV, respectively. The temperature dependence of electrical conductivity shows that the conductivity increases with increase in temperature suggesting that the compounds have a negative temperature coefficient of resistance (NTCR) behaviour. The conductivity pattern shows that it is strongly frequency dependent and obeys Jonscher’s power relation.0Comments 0Citations