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

Abstract

In the current study, we report on the dielectric behavior of colossal-dielectric-constant Na1/2La1/2Cu3Ti4O12 (NLCTO) ceramics prepared by mechanochemical synthesis and spark plasma sintering (SPS) at 850 °C, 900 °C, and 925 °C for 10 min. X-ray powder diffraction analysis showed that all the ceramics have a cubic phase. Scanning electron microscope observations revealed an increase in the average grain size from 175 to 300 nm with an increase in the sintering temperature. SPS NLCTO ceramics showed a room-temperature colossal dielectric constant (>103) and a comparatively high dielectric loss (>0.1) over most of the studied frequency range (1 Hz–40 MHz). Two relaxation peaks were observed in the spectra of the electrical modulus and attributed to the response of grain and grain boundary. According to the Nyquist plots of complex impedance, the SPS NLCTO ceramics have semiconductor grains surrounded by electrically resistive grain boundaries. The colossal dielectric constant of SPS NLCTO ceramics was attributed to the internal barrier layer capacitance (IBLC) effect. The high dielectric loss is thought to be due to the low resistivity of the grain boundary of SPS NLCTO.

Structural, Dielectric Properties and Conduction Mechanism of SrBi4Ti4O15 Ceramics

“…The SBT ceramic exhibits phonon modes around 118, 270, 560, and 866 cm -1 , which belong to the orthorhombic structure (space group of A2 1 am). The phonon modes observed in the spectra matched well with the previously reported literature data on SBT ceramics reported as the single-phase material (13) . The lower frequency phonon modes are due to the motion of Bi 3+ ions at the A-site, which was noticed in the ABi 4 Ti 4 O 15 (A = Sr, Ba, Ca, and Pb) layered structures.…”

Li1/2Y1/2Cu3Ti4O12 Ceramic: Structural, Dielectric, and Electrical Investigations

“…The ε′ values for LiY06 and LiY12 at 1 kHz and 20 °C are 5.00 × 10 3 and 4.70 × 10 3 , respectively. Additionally, our ε′ is greater than those of other perovskite ceramics, for instance, NSCTO (∼1.34 × 10 3 ) and NLCTO (∼2.00 × 10 3 ) . The comparable grain sizes of LiY06 and LiY12 are in accordance with the similar ε′ values of the two ceramics.…”

“…Additionally, our ε′ is greater than those of other perovskite ceramics, for instance, NSCTO (∼1.34 × 10 3 ) 27 and NLCTO (∼2.00 × 10 3 ). 25 The comparable grain sizes of LiY06 and LiY12 are in accordance with the similar ε′ values of the two ceramics. In the frequency range below 10 4 Hz, as seen in the inset, the tan δ of LiY06 is greater than that of LiY12.…”

Effects of multiple cations and sintering temperature on microstructure and dielectric properties in Na1/2Ln1/2Cu3Ti4O12 (Ln = Sm and Eu) ceramic materials

“…As displayed in the Table 1, the grain resistance (R g ) values of these Na 1/2 Ln 1/2 Cu 3 Ti 4 O 12 (Ln = Eu or Sm) ceramics evidently decreased with increasing sintering temperature. The variation of R g values for these ceramics was related to the appearance of low valent ions (Cu + and Ti 3+ ) at the grain during high-temperature sintering process 14,21,30 . Combined with XPS data, the Cu + and Ti 3+ ions were prone to occur in ceramics due to the occupation of multiple cations (Na + , Eu 3+ ) or (Na + , Sm 3+ ) in CCTO-related ceramics.…”

“…As a traditional dielectric material, CaCu 3 Ti 4 O 12 (CCTO) has been closely watched since its giant dielectric properties were found [8][9][10][11] . Two major aspects ways are used to optimize the dielectric properties of CCTO-like ceramics: (1) use of different preparation methods, for instance, solid-state reaction method 12 , sol-gel 13 , and spark plasma sintering 14 21 , etc. Simultaneously, internal barrier layer capacitors (IBLC), as a major polarization mechanism, is used to explain the origin of dielectric behaviors for CCTO-based family materials 22,23 .…”