Low temperature sintered giant dielectric permittivity CaCu₃Ti₄O12 sol-gel synthesized nanoparticle capacitors

Abstract

This paper reports on synthesis of polycrystalline complex perovskite CaCu 3 Ti 4 O 12 (as CCTO) ceramic powders prepared by a solgel auto combustion method at different sintering temperatures and sintering times, respectively. The effect of sintering time on the structure, morphology, dielectric and electrical properties of CCTO ceramics is investigated. Tuning the electrical properties via different sintering times is demonstrated for ceramic samples. X-ray diffraction (XRD) studies confirm perovskite-like structure at room temperature. Abnormal grain growth is observed for ceramic samples. Giant dielectric permittivity was realized for CCTO ceramics. High dielectric permittivity was attributed to the internal barrier layer capacitance (IBLC) model associated with the Maxwell-Wagner (MW) polarization mechanism.

Grain boundary engineering that induces ultrahigh permittivity and decreased dielectric loss in CdCu3Ti4O12 ceramics

“…Raman scattering spectra were determined to further clarify the phase structure of the obtained ceramics (Figure B). As is known, perovskite‐structured CdCTO belongs to the centrosymmetric Im –3 ( T h ) space group; therefore, the characteristic Raman vibration modes of CdCTO materials should be 4F g + 2E g +2A g . It is easy to identify the five characteristic Raman vibration peaks in the plot as F 1g (265‐272 cm −1 ), E 1g (320‐322 cm −1 ), A 1g (440‐442 cm −1 ), A 2g (509‐510 cm −1 ), and F 3g (574 cm −1 ).…”

“…The details of the results are provided in Table . The unknown phases in the grain boundaries of the CdCTO‐04Zn ceramics are Cu/Zn‐enriched phases, while that in the CdCTO ceramics is a Cu‐enriched phase …”

“…As is known, perovskite-structured CdCTO belongs to the centrosymmetric Im-3 (T h ) space group; therefore, the characteristic Raman vibration modes of CdCTO materials should be 4F g + 2E g +2A g . 13,31 It is easy to identify the five characteristic Raman vibration peaks in the plot as F 1g (265-272 cm −1 ), E 1g (320-322 cm −1 ), A 1g (440-442 cm −1 ), A 2g (509-510 cm −1 ), and F 3g (574 cm −1 ). The F 3g (574 cm −1 ) mode was due to the Ti-O-Ti anti-symmetric stretching vibrations, while the other four Raman modes at low wavenumbers were closely related to the symmetric rotational modes of the TiO 6 octahedron.…”

“…The unknown phases in the grain boundaries of the CdCTO-04Zn ceramics are Cu/Zn-enriched phases, while that in the CdCTO ceramics is a Cu-enriched phase. [26][27][28][29][30][31][32][33][34] The frequency-dependent dielectric behavior of the CdCu 3−x Zn x Ti 4 O 12 ceramics is shown in Figure 4A; the inset shows an enlarged view of the frequency-dependent (40-10 4 Hz) dielectric loss tangent. The dielectric permittivity maintains a high value above 2.0 × 10 4 and seems to be frequency independent when the measured frequency is below 10 5 Hz, while a sharp decrease to ~100 occurs when the frequency reaches 10 7~1 0 8 Hz.…”

Synthesis of CaCu3Ti4O12 utilizing eggshell waste as a calcium source: Structure, morphology, and dielectric properties

“…CCTO is well known as a dielectric material with high relative permittivity or dielectric constant and low dielectric loss, which is called giant dielectrics material [1][2][3][4]. Dielectric properties of CCTO are a characteristic that is most studied and investigated to explore its potential applications in electronics technology, including in energy storage devices [5], capacitors [6], gas sensors [7], random access memory [8], and microwave devices [9]. CCTO is also used as a photoanode for photocatalysis and photoelectrocatalysis in solar energy conversion [10].…”