Electrical and dielectric properties of Na _1/2 La _1/2 Cu ₃ Ti ₄ O ₁₂ ceramics prepared by high energy ball-milling and conventional sintering

Abstract

We report on the measurements of the electrical and dielectric properties of Na 1/2 La 1/2 Cu 3 Ti 4 O 12 (NLCTO) ceramics prepared by high energy ball-milling and conventional sintering without any calcination steps. The x-ray powder diffraction analysis shows that pure perovskite-like CCTO phase is obtained after sintering at 1025 • C-1075 • C. Higher sintering temperatures result in multi-phase ceramics due to thermal decomposition. Scanning electron microscope observations reveal that the grain size is in a range of ∼ 3 µm-5 µm for these ceramics. Impedance spectroscopy measurements performed in a wide frequency range (1 Hz-10 MHz) and at various temperatures (120 K-470 K) are used to study the dielectric and electrical properties of NLCTO ceramics. A good compromise between high ε (5.7 × 10 3 and 4.1 × 10 3 at 1.1 kHz and 96 kHz, respectively) and low tan δ (0.161 and 0.126 at 1.1 kHz and 96 kHz, respectively) is obtained for the ceramic sintered at 1050 • C. The observed high dielectric constant behavior is explained in terms of the internal barrier layer capacitance effect.

Dielectric Properties of Colossal-Dielectric-Constant Na1/2La1/2Cu3Ti4O12 Ceramics Prepared by Spark Plasma Sintering

“…Moreover, the sample S-900 showed the best compromise between the minimum tan δ (~0.39) and colossal ε′ (~1420) at 200 kHz. The dielectric constant of SPS NLCTO ceramics is comparable with the literature values [ 22 , 23 ]. Meanwhile, their dielectric losses are noticeably high compared to literature values.…”

“…As a result, ε′ decreases due to the reduced polarizability. Moreover, the values of resistivity of the grain boundary for SPS NLCTO ceramics is less than the reported values for NLCTO ceramics prepared by other techniques [ 22 , 23 ]. This result explains the comparatively higher dielectric loss of the SPS NLCTO.…”

“…NLCTO is a promising CP material that exhibited ε′~6.1–8.7 × 10 3 when prepared by the SSR process that included two calcinations steps, at 950 °C for 15 h and at 1000 °C for 10 h, and conventional sintering at 1080–1090 °C for 5 h. In another study, the powder of NLCTO was first prepared by sol–gel and then conventionally sintered at 1060–1100 °C for 5–15 h. The resulting ceramics exhibited ε′~1.1–1.8 × 10 4 [ 21 ]. Previously, we reported on the colossal dielectric properties of NLCTO ceramics prepared by the mechanomechanical synthesis of the powder and reactive sintering inside a conventional tubular furnace at 1025–1100 °C for 10 h [ 22 ]. The obtained ceramics showed ε′~3.8–9.6 × 10 3 at 1.1 KHz.…”

Improved dielectric properties of Na1/2Y1/2Cu3Ti4O12 ceramics synthesized by ball-milling and reactive sintering

“…According to this model, the apparent giant dielectric constant arises due to the Maxwell-Wagner polarization effects at internal resistive boundaries such as grain-boundaries and/or domain-boundaries. Recently, a great deal of studies on the effects of doping, powder synthesis and sintering techniques on the dielectric properties of CCTO has been carried out [2][3][4][10][11][12][13][14][15][16]. Most of these studies used the solid state reaction (SSR) technique for the fabrication of ceramics.…”

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi)

“…Therefore, research continues for better understanding and improving the dielectric response of CCTO, and to suggest alternative colossal permittivity dielectric materials. In this regard, several strategies are being implemented, such as doping, substitution, and controlling synthesis conditions [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. In particular, cosubstitution for Ti 4+ with heterovalent elements was reported as a promising technique to reduce tanδ without degrading the ε’ of TiO 2 and CCTO ceramics [ 12 , 18 , 19 , 20 , 21 ].…”