Lead-free (Ag,K)NbO3 materials for high-performance explosive energy conversion

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Science Advances  20 May 2020:
Vol. 6, no. 21, eaba0367
DOI: 10.1126/sciadv.aba0367
  • Fig. 1 Macroscopic performance of (Ag0.935K0.065)NbO3 FE ceramics and devices.

    (A) The pressure-dependent polarization–electric field (P-E) loops of (Ag0.935K0.065)NbO3 FE ceramics measured at room temperature and 1 Hz. (B) The in situ depolarization curve of prepoled (Ag0.935K0.065)NbO3 FE ceramics under gradually increasing hydrostatic pressures at room temperature. The data were collected during the pressure-driven depolarization process and then integrated to obtain the pressure-dependent polarization. (C and D) The hydrostatic pressure–dependent dielectric constant and dielectric loss of poled (Ag0.935K0.065)NbO3 FE ceramics at room temperature. (E) Practical dynamic discharging response of assembled (Ag0.935K0.065)NbO3 FE ceramic devices collected under shock pressure of 6.9 GPa. (F) A comparison of the energy storage densities per unit of weight of the (Ag0.935K0.065)NbO3 ceramics and other FE materials.

  • Fig. 2 Structural analysis of (Ag0.935K0.065)NbO3 ceramics.

    Selected-area electron diffraction patterns (SAEDPs) of a crushed fragment of an (Ag0.935K0.065)NbO3 ceramic along (A) [001] = [0−11]p and (B) [0–13] = [0–21]p zone axis directions. The very weak, arrowed in white, reflections [in (B)] arise from a small amount of a second twin domain. (C) The Rietveld refinement of the NDP of (Ag0.935K0.065)NbO3 powders in terms of a two-phase model (Pmc21 + Pbcm). The refined Pmc21 phase structure viewed along (D) the a axis and (E) the b axis. (F) The refined Pbcm phase structure viewed along its a axis.

  • Fig. 3 In situ NDPs of (Ag0.935K0.065)NbO3 ceramics.

    (A) NDPs of an unpoled (fresh) (Ag0.935K0.065)NbO3 ceramic sample, a poled (Ag0.935K0.065)NbO3 ceramic sample, and a poled (Ag0.935K0.065)NbO3 ceramic after experiencing 600-MPa hydrostatic pressure. (B) In situ NDPs of poled (Ag0.935K0.065)NbO3 ceramics as a function of increasing hydrostatic pressure. (C) The integrated area values of the 1/2(321) and 1/2(341) peaks from NDP data for poled (Ag0.935K0.065)NbO3 samples as a function of hydrostatic pressure. (D) In situ NDPs of unpoled (Ag0.935K0.065)NbO3 ceramics with increasing hydrostatic pressure. For the in situ NDP measurements, lead shards, whose lattice parameter is already known as a relation of hydrostatic pressure, were used to calibrate the pressure applied onto the (Ag0.935K0.065)NbO3 ceramics. a.u., arbitrary units.

  • Fig. 4 Phenomenological modeling of the FE and AFE phases.

    (A) Pressure-composition phase diagram of the (Ag0.935K0.065)NbO3 system. (B) Energy contours as a function of p1 and p2 near the FE/AFE phase boundary. The value of p3 is zero, with polarization along the [110]p direction. (C) The energy profiles of AKN-0.065, i.e., (Ag0.935K0.065)NbO3, and AKN-0.08, i.e., (Ag0.92K0.08)NbO3 under different hydrostatic pressures. (D) The P-E loops of AKN-0.08 under different hydrostatic pressures.

Supplementary Materials

  • Supplementary Materials

    Lead-free (Ag,K)NbO3 materials for high-performance explosive energy conversion

    Zhen Liu, Teng Lu, Fei Xue, Hengchang Nie, Ray Withers, Andrew Studer, Felipe Kremer, Narendirakumar Narayanan, Xianlin Dong, Dehong Yu, Longqing Chen, Yun Liu, Genshui Wang

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    This PDF file includes:

    • Figs. S1 to S7
    • Tables S1 to S4
    • Bond valence sum calculation results

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