Colossal permittivity and low losses in Ba1–Sr TiO3– reduced nanoceramics

Abstract

The oxalate route offers a controlled approach to synthesize pure Ba 1-x Sr x TiO 3 (BST) (0 ≤ x ≤ 1) nanoparticles (≈ 150 nm in diameter). Reduced BST dense nanoceramics were obtained by spark plasma sintering (SPS) and then annealed for a short time to reach colossal permittivity (′ r = 10 5) with low dielectric losses (tan ı = 0.03) at 1 kHz and 300 K. The effects of Ba-Sr substitution on structural, microstructural and electrical properties were analyzed. Comprehensive analysis of the electrical properties indicates that polaron hopping, mediated by Ti 3+ ions and oxygen vacancies is the main contributing mechanism to colossal permittivity in Ba-rich BST compounds. Substitution of Ba by Sr reduced the contribution of polaron hopping and led to a decrease of real and imaginary parts of permittivity, while preserving interfacial polarization and yielding better temperature stability. The lowest temperature coefficient of capacitance, or TCC (variation of capacitance between 310 K and 450 K) value, i.e., 44 ppm K −1 , is obtained for SrTiO 3 .

Internal barrier layer capacitor, nearest neighbor hopping, and variable range hopping conduction in Ba1−x Sr x TiO3−δ nanoceramics

“…Impedance measurements were recorded over the frequency range 10 Hz to 13 MHz and the temperature range 120-473 K using an Alpha-N Novocontrol impedance analyzer, with an ac voltage of 0.1 V. Impedance data were corrected for overall pellet geometry and for the blank cell capacitance (jig correction). For low-temperature impedance data measurements, the electroded samples were placed in a closed cycle cryogenic workstation (CTI 22, Cryo Industries of America, Manchester, NH) and measurements were performed as a function of frequency (40 Hz-100 kHz) from 300 to 40 K (20 K step size) using an Agilent 4284A LCR meter under an applied ac voltage of 1 V. Powders are homogeneous in shape and size as described in a previous paper [23]. Nanometer size of grains is preserved after SPS process and densities higher than 98 % of the theoretical densities are obtained.…”

“…To further expand on recent demonstrations of induced colossal effective permittivity in BaTiO 3 -based ceramics, the present work focuses on the dielectric properties of Ba 1-x Sr x TiO 3-d (BST 0 B x B 1) bulk ceramics for enhanced capacitive applications. In a previous paper, we have investigated the colossal effective permittivity and low losses in BST nanoceramics [23]. Polaron hopping mediated by Ti ?3 ions and oxygen vacancies is the main contributing mechanism to colossal permittivity in barium-rich BST.…”

The diffuse phase transition of Ti-rich (Ba0.75Sr0.25) Ti1+dO3+2d dielectric ceramics

“…Three common methods are employed: the addition of isovalent or aliovalent dopants such as Mg, 9 Na, 10 etc. ; process controlling especially the calcination/sintering progress; 11,12 and the usage of functionally graded materials (FGMs). 8 Among the dopants, rare-earth elements (e.g., La 3+ , Dy 3+ , Sm 3+ ) are found to be effective in controlling the temperature dependency of the dielectric properties in stoichiometric BST ceramics.…”

Enhanced properties of SPEEK with incorporating of PFSA and barium strontium titanate nanoparticles for application in DMFCs

“…It is well known that some perovskite‐type oxides show high proton conductivity under a hydrogen‐containing condition. Barium strontium titanate (Ba 0.9 Sr 0.1 TiO 3 ) (BST) is one of the best promising doped‐perovskite nanoparticles that have the various application such as gas sensors, capacitors, random access memories, infrared detectors, and fuel cells . The doped‐perovskite structure of BST nanoparticles act as hydrogen traps, and so increase the proton conductivity …”

“…Barium strontium titanate (Ba 0.9 Sr 0.1 TiO 3 ) (BST) is one of the best promising doped-perovskite nanoparticles that have the various application such as gas sensors, capacitors, random access memories, infrared detectors, and fuel cells. [37][38][39][40] The doped-perovskite structure of BST nanoparticles act as hydrogen traps, and so increase the proton conductivity. 41,42 In this work, for the first time, blend nanocomposite SPEEK/perfluorosulfonic acid (PFSA)/BST membranes were prepared and used as a suitable PEM in DMFC application.…”