Dielectric and Piezoelectric Properties of 10% KF-Doped BaTiO₃ Ceramics

Abstract

10% KF-doped barium titanate powders, Ba0.9K0.1TiO2.9F0.1, were synthesized through a sol–gel process. The powders, calcined at 650 °C, consist of cubic crystalline particles of ∼70 nm in length; the particle size increases to ∼200 nm as the firing temperature increases to ca. 800 °C, above which F2 begins to evaporate. Dense ceramics were fabricated by the spark plasma sintering (SPS) method; the average grain size is ∼2 µm in lengths. The ceramics, well annealed at 1,000 °C in an O2 gas flow, have good dielectric and piezoelectric properties; the piezoelectric d 33 value is 230 pC/N at room temperature. At the ferroelectric Curie temperature T C = 47 °C, the dielectric constant and loss tan δ are 10,000 and <5% at 10 kHz, respectively. The Curie–Weiss relation holds in the fully disordered cubic and ordered rhombohedral phases, showing the second order 1:2 relation. Below 10 kHz, large dielectric dispersion caused by a domain-wall motion appears at the temperature range of -50 to 107 °C. Some discussions are made for these dielectric properties of the ceramics.

Colossal Permittivity Materials as Superior Dielectrics for Diverse Applications

“…Noted that novel F substitution at the O site and co-doping at the Ba site with K have been reported. [138] A permittivity of 10 5 and a dielectric loss of less than 0.05 are obtained at 10 kHz, as shown in Figure 8d. These samples show a strong dependence on temperature.…”

“…Ion substitution can be divided into three types, donor, acceptor and isovalent doping based on the difference in the valences of impurities and host atoms. The dielectric properties of CP materials, including CCTO, [95,[109][110][111][112][113][114][115][116][117] TiO2, [3,[118][119][120][121][122][123][124][125][126][127] NiO [128][129][130][131][132][133][134] and BaTiO3, [135][136][137][138][139][140][141][142] with different dopants are summarized and demonstrated in Figure 8.…”

Radio-frequency actuated polymer-based phononic meta-materials for control of ultrasonic waves

“…BaTiO 3 ceramics doped with varying amounts of KF to produce KF-doped barium titanate (Ba x K 1 − x TiO x F 1 − x ) nanoparticles result in ceramics and powders that exhibit enhanced dielectric and piezoelectric properties in the RF frequency range. [39][40][41] The addition of KF to BaTiO 3 causes the compound to locate near the tri-critical point, which enhances the fluctuation of the crystal polarization. Additionally, 10% KF-doped BaTiO 3 (Ba 0.9 K 0.1 TiO 2.9 F 0.1 , KBT) is particularly interesting for its increased dielectric activity at room temperature, as shown in Figure 1b.…”

“…Additionally, 10% KF-doped BaTiO 3 (Ba 0.9 K 0.1 TiO 2.9 F 0.1 , KBT) is particularly interesting for its increased dielectric activity at room temperature, as shown in Figure 1b. 41 Adding high-k dielectric nanoparticles to the PNIPAm hydrogels enables the hydrogels to exhibit a stronger response to an applied RF field.…”

“…24 (b) The high dielectric constant (ε′) of 10% KF-Doped BaTiO 3 spark plasma sintered ceramics in the RF range near the PNIPAm phase transition temperature is utilized for increasing dielectric susceptibility. 41 Radio-frequency actuated polymer-based phononic meta-materials E Walker et al was experimentally determined to sufficiently prevent the precipitation of KBT nanoparticles while maintaining tunable elastic properties inherent to PNIPAm. For this work, we refer to the materials with adequate RF sensitivity and elastic tenability as acoustic materials.…”