Dielectric and pyroelectric properties of BaTiO₃–PVC composites

Abstract

Dielectric relaxation and pyroelectric response of the barium titanate–poly (vinyl chloride) BaTiO3–PVC composites of 0–3 connectivity and volume fraction of ceramics ϕ from 0.0 to 0.4 were investigated. Dielectric properties of the composites were found to be a combination of those of pure PVC polymer and BaTiO3 ceramics: the value of dielectric permittivity increases with increasing volume fraction of the ceramics but the temperature dependence is determined by two relaxation processes in the polymer (at ∼270 K – the local motion of the small groups in the chain and at ∼350 K – the segmental molecular motion) and in the ceramics (dielectric anomaly at the phase transitions). The value of the pyroelectric coefficient p of poled composites increases with ϕ and depends on the light modulation frequency fm as p ∼ f–nm with n ≈ 0.9 to 1.1, dependently on ϕ. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Dielectric response of PVC polymer loaded with Ba0.3Na0.7Ti0.3Nb0.7O3ceramic powder

“…Previous works performed on the BNTN ceramics obtained by conventional methods showed their high permittivity [1][2][3][4], pyroelectric [3,4] and piezoelectric properties [4]. The poly(vinyl chloride), (PVC), polymer shows two anomalies occurring above 350 K and at $270 K [5], corresponding to and relaxation processes, respectively. The more intense peak is associated with glass transition (T g $ 350 K) of the polymer.…”

Dielectric properties of BST/polymer composite

“…The feasibility of these composites for use in piezoelectric and pyroelectric applications, flexible sensors, transducers, thick film dielectrics, embedded capacitors, tunable antennas and other multilayer RF devices has been studied. [2][3][4] The research has mainly concentrated on epoxy-ceramic composites, [5][6][7][8] but also other polymers, such as PVDF, 9 P(VDF-TrFE), 10 silicon-rubber, 11 polyimide, 12 polyvinylchloride (PVC), 13 cyanoethylated cellulose polymer (CR-S), 14 polystyrene, 15 and polyurethane, 16 have been used. However, only a few composites that use thermoplastic polymers have been reported.…”

Intrinsic pyroelectric properties of thick, coarse grained Ba 1−x Sr x TiO 3 ceramics

“…In any case, the values obtained for the intrinsic pyroelectric coefficient, without applied electric field, are comparable if not slightly better than previous studies reporting room temperature values (with or without applied electric field) of: about 10 -3 C/m 2 K for BST with 30 % or 33 % Sr content [4,16,22,52], with the mention that 33 % Sr means a lower transition temperature, leading to better pyroelectric properties; total value of (1-4)u10 -3 C/m 2 K for BST with 30 % Sr content, with an applied field of 700 Vmm -1 , including thus the induced part of the pyroelectric coefficient [17]; up to 4u10 -4 C/m 2 K for BST with 30 % Sr, doped with Mn or Y, with an applied field of 400 Vmm -1 [19]; up to 2u10 -4 C/m 2 K for undoped BaTiO 3 thick films and ceramics [67,68]. The values in Table 3 can be further enhanced by doping and by applying an external electric field on the active pyroelectric element in order to increase the contribution of the induced pyroelectric coefficient to the total pyroelectric coefficient defined by equation (1).…”