Dielectric, Pyroelectric and Thermally Stimulated Depolarization Current Investigations on (Ba, Sr)TiO₃Ceramics with Bi₂O₃Additive

Abstract

The Ba 1−x Sr x TiO 3 materials have received increased attention as one of the most important materials for electroceramic components, such as high dielectric ceramic capacitors, tunable phase shifters and PTCR. In this paper the effect of 0.5; 1; 1.5; and 2 mole% of Bi 2 O 3 addition on microstructure, structure, dielectric properties (i.e., dielectric constant ε , and dielectric loss factor tan δ), as well as pyroelectric and thermally stimulated depolarization currents (TSDC) of (Ba 0.8 Sr 0.2 )TiO 3 ceramics have been investigated. The distinct correlation between Bi 2 O 3 content, wide maxima in TSDC, anomalies in ε (T ) and tan δ(T ) characteristics occurring within the range of the paraelectric phase was confirmed. Changes of electric conductivity and Seebeck's coefficient, caused by Bi 2 O 3 -additives, were also studied.

Structural, Dielectric and Ferroelectric Studies of Tungsten Substituted Barium Strontium Titanate

“…In récent years, materials with a high dielectric constant and lead free compositions have attracted renewed interest as environment friendly materials for applications such as capacitors, sensors and actuators, DRAM memories, etc. [3,4]. In addition, the strong dependence of permittivity on electric field with low dielectric loss makes them attractive for application in tunable microwave devices such as filters, delay lines and phase shifters, which are essentials elements in communication and radar systems [5,6].…”

Impedance Spectroscopy Structural Analysis: Ca-Dopant Segregation in (Pb0.75Ba0.25)(Zr0.70Ti0.30)O3

“…The latter makes it possible to detect impurities within a grain boundary. 15) Although, IS has already been successfully used for the characterization of ferroelectric materials, 16,17) we show for the first time that the subtle structural changes in PBZT significantly affect its electrical conductivity. However, one should keep in mind that in materials such as PBZT, the charge flow depends on dipole reorientation.…”

“…4). An interesting result of this research is the detection of a transition from ion p-type conductivity to electron n-type conductivity 16) at a Ca-content of 2 at. %.…”

Molecular Ferroelectric Crystals with Superior Pyroelectricity, Plasticity, and Recyclability

“…The pyroelectric effect, i.e., the change of spontaneous polarization in polar materials induced by the variation of temperature, is used in a wide range of applications such as infrared (IR) sensing and thermal energy harvesting. − Pyroelectricity has been extensively investigated in inorganic ferroelectrics (such as single crystals and ceramics) and organic polymers. − High pyroelectric effect was first explored in triglycine sulfate (TGS) for IR sensors, a typical order–disorder ferroelectric single crystal whose spontaneous polarization originates from the ordering of the positively charged NH 3 groups of G1 glycine molecules. − Nowadays, displacive ferroelectrics such as lithium tantalite (LT), lead zirconate titanate (PZT), lead niobium magnesium–lead titanate (PMN–PT), barium strontium titanate (BST) single crystals, and ceramics have been extensively equipped in IR detectors and thermal energy harvesters, in which the pyroelectric response is generated by the change of ion displacement (electric dipole moment) caused by the variation of temperature. − Besides, poly­(vinylidene fluoride) (PVDF)-based ferroelectric polymers showing an order–disorder phase transition at around the Curie temperature have also been widely used for flexible pyroelectric devices. , Over the last few decades, strenuous efforts have been made to increase the pyroelectric coefficient of the materials for high-sensitivity IR detectors and high-efficiency thermal energy harvesters. − However, high figures of merit (FOMs) are essential for high-performance pyroelectric devices, in which not only high pyroelectric coefficient but also other complementary parameters, e.g., low dielectric constant, are all indispensable. − , Taking IR sensors for instance, F V = p /(ε 0 ε r C v ) ( p , ε 0 , ε r , and C v are the pyroelectric coefficient, vacuum permittivity, relative dielectric constant, and volumetric specific heat, respectively) denotes the maximum pyroelectric voltage that can input into the circuit of the devices, determining the sensitivity of the detectors. Analogously, for thermal energy harvesters, F E = p 2 /(ε 0 ε r ) represents the amount of electric power converted by the pyroelectrics with a given thermal energy.…”