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Open Access Research Article Issue
Enhanced electrical performance in CaBi4Ti4O15 ceramics through synergistic chemical doping and texture engineering
Journal of Materiomics 2024, 10 (2): 471-479
Published: 10 August 2023
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High-temperature piezoelectric materials with excellent piezoelectricity, low dielectric loss and large resistivity are highly desired for many industrial sectors such as aerospace, aircraft and nuclear power. Here a synergistic design strategy combining microstructural texture and chemical doping is employed to optimize CaBi4Ti4O15 (CBT) ceramics with bismuth layer structure. High textured microstructure with an orientation factor of 80%–82% has been successfully achieved by the spark plasma sintering technique. Furthermore, by doping MnO2, both advantages of hard doping and sintering aids are used to obtain the excellent electrical performance of d33 = 27.3 pC/N, tanδ~0.1%, Q31~2,307 and electrical resistivity ρ~6.5 × 1010 Ω·cm. Up to 600 ℃, the 0.2% (in mass) Mn doped CBT ceramics still exhibit high performance of d33 = 26.4 pC/N, ρ~1.5 × 106 Ω·cm and tanδ~15.8%, keeping at an applicable level, thus the upper-temperature limit for practical application of the CBT ceramics is greatly increased. This work paves a new way for developing and fabricating excellent high-temperature piezoelectric materials.

Open Access Research Article Issue
Achieving a high energy storage density in Ag(Nb,Ta)O3 antiferroelectric films via nanograin engineering
Journal of Advanced Ceramics 2023, 12 (1): 196-206
Published: 19 December 2022
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Due to its lead-free composition and a unique double polarization hysteresis loop with a large maximum polarization (Pmax) and a small remnant polarization (Pr), AgNbO3-based antiferroelectrics (AFEs) have attracted extensive research interest for electric energy storage applications. However, a low dielectric breakdown field (Eb) limits an energy density and its further development. In this work, a highly efficient method was proposed to fabricate high-energy-density Ag(Nb,Ta)O3 capacitor films on Si substrates, using a two-step process combining radio frequency (RF)-magnetron sputtering at 450 ℃ and post-deposition rapid thermal annealing (RTA). The RTA process at 700 ℃ led to sufficient crystallization of nanograins in the film, hindering their lateral growth by employing short annealing time of 5 min. The obtained Ag(Nb,Ta)O3 films showed an average grain size (D) of ~14 nm (obtained by Debye–Scherrer formula) and a slender room temperature (RT) polarization–electric field (P–E) loop (Pr ≈ 3.8 μC·cm−2 and Pmax ≈ 38 μC·cm−2 under an electric field of ~3.3 MV·cm−1), the P–E loop corresponding to a high recoverable energy density (Wrec) of ~46.4 J·cm−3 and an energy efficiency (η) of ~80.3%. Additionally, by analyzing temperature-dependent dielectric property of the film, a significant downshift of the diffused phase transition temperature (TM2–M3) was revealed, which indicated the existence of a stable relaxor-like AFE phase near the RT. The downshift of the TM2–M3 could be attributed to a nanograin size and residual tensile strain of the film, and it led to excellent temperature stability (20–240 ℃) of the energy storage performance of the film. Our results indicate that the Ag(Nb,Ta)O3 film is a promising candidate for electrical energy storage applications.

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