Enhancement of dielectric properties by optimization of sintering condition in tungsten–bronze structured Ba5SmTi3Nb7O30 ferroelectric ceramics

Abstract

In this work, polycrystalline Ba 5 SmTi 3 Nb 7 O 30 tungsten-bronze structured ferroelectric ceramics were synthesized by solid-state reaction technique at different sintering temperatures and durations. The X-ray diffractograms reveal the formation of the compounds in orthorhombic crystal system. The density of the compound is observed to increase with increase in sintering temperature and duration. Scanning electron microscopy (SEM) has been used for the microstructural investigation. Detailed dielectric properties of the compounds have been studied as a function of frequency and temperature. The variations of dielectric constant " 0 r À Á with temperature show that the compounds undergo a diffuse type ferro-paraelectric phase transition. The dielectric constant is found to increase with the increasing sintering temperature and duration. In all the samples, the variation of dielectric loss (tan δ) with temperature is observed to be almost constant initially but it increases as temperature is increased and a peak is observed only when the material is sintered at higher temperature for longer duration. The frequency dependence of dielectric constant and loss shows a decreasing trend up to nearly 10 kHz and beyond this frequency there is almost no variation. Also, the diffusivities of the samples have been calculated and it is found to increase with increasing sintering temperature and duration.

Investigations of dielectric, pyroelectric and electrical properties of Ba5SmTi3Nb7O30 ferroelectric ceramic

“…The mixture was then admixed with 5 wt.% polyvinyl alcohol (M/s Aldrich, USA) as a binder and pressed at ∼300 MPa into disk shaped pellets of 15 mm diameter and 1.2 mm thickness. These pellets were then sintered at 1300 • C for 10 h. This is the optimized sintering condition found from the extensive studies reported elsewhere [24]. Also, this process yields a homogeneous specimen and the detail is reported elsewhere [23].…”

Structural and electrical properties of Ba5−xCaxSmTi3Nb7O30 (x=0–5) ferroelectric ceramics

“…Hence these differences in result may be due to the difference in sintering temperature used in both the studies. Moreover, it is known that concentration of oxygen vacancies increases with increase in sintering temperature in this compound [13] and the relaxor behaviour diminishes due to defects such as oxygen vacancy as polar clusters formed by oxygen vacancies never freezes [18]. So, in the present work, a higher sintering tem- Table 1 Different parameters of (Ba1−xCax)5SmTi3Nb7O30 (x = 0-5) compounds.…”

“…The mixture was then admixed with 5 wt.% polyvinyl alcohol (M/s Aldrich, USA) as a binder and then pressed at ∼300 MPa into disk shaped pellets. These pellets were then sintered at 1300 • C for 10 h. This sintering condition is the optimized sintering condition and the details are reported elsewhere [13].…”

Effect of the Sintering Temperature on Nanocrystalline Non-stoichiometric Sr0.8Bi2.2Ta2O9Ferroelectric Ceramics

“…Also, it is known that these BLSF compounds exhibits oxygen loss during high sintering temperature [27] which can be represented by Kröger and Vink notation [28] as: formed. These oxygen vacancies, V •• o , act as a space charge which play an important role in the electrical behaviour of these materials [29]. This oxygen vacancy induced polarization becomes dominant at higher temperature [30].…”