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Herein, (Na0.5Bi0.5)0.94Ba0.06Ti1‐x(Al0.5Nb0.5)xO3 (NBBT‐xAN) ceramics are fabricated through a solid reaction method. X‐ray diffraction reveals the structure of NBBT‐xAN ceramics transforms from coexistence of rhombohedral and tetragonal structures to a pseudocubic structure with increasing AN content. Raman spectroscopy indicates the long‐range ferroelectric order of NBBT ceramics is broken by AN and the polar nanoregions (PNRs) with weak polarization are formed. The relaxor behavior of NBBT ceramics is enhanced by the enhanced random electric fields (REFs) through the heterovalent cations Al3+/Nb5+. Therefore, a slim and pinched P–E loop is obtained for NBBT ceramics by doping AN and the energy‐storage properties (ESPs) can be improved dramatically under a low electric field. The maximum recoverable energy density (Wrec) of 1.2 J cm−3 is obtained at x = 0.04 under a low electric field of 100 kV cm−1. However, a relatively high Wrec of 1.0 J cm−3 and efficiency (η) of 77% are simultaneously obtained at x = 0.05 under the same electric field strength. Moreover, NBBT‐0.05AN ceramics also exhibit excellent temperature (30–180 °C), fatigue (104) and frequency (1–40 Hz) stabilities. Most important, the study provides a strategy to design high energy‐storage capacitors under a low electric field. [ABSTRACT FROM AUTHOR]

Herein, (Na0.5Bi0.5)0.94Ba0.06Ti1‐x(Al0.5Nb0.5)xO3 (NBBT‐xAN) ceramics are fabricated through a solid reaction method. X‐ray diffraction reveals the structure of NBBT‐xAN ceramics transforms from coexistence of rhombohedral and tetragonal structures to a pseudocubic structure with increasing AN content. Raman spectroscopy indicates the long‐range ferroelectric order of NBBT ceramics is broken by AN and the polar nanoregions (PNRs) with weak polarization are formed. The relaxor behavior of NBBT ceramics is enhanced by the enhanced random electric fields (REFs) through the heterovalent cations Al3+/Nb5+. Therefore, a slim and pinched P–E loop is obtained for NBBT ceramics by doping AN and the energy‐storage properties (ESPs) can be improved dramatically under a low electric field. The maximum recoverable energy density (Wrec) of 1.2 J cm−3 is obtained at x = 0.04 under a low electric field of 100 kV cm−1. However, a relatively high Wrec of 1.0 J cm−3 and efficiency (η) of 77% are simultaneously obtained at x = 0.05 under the same electric field strength. Moreover, NBBT‐0.05AN ceramics also exhibit excellent temperature (30–180 °C), fatigue (104) and frequency (1–40 Hz) stabilities. Most important, the study provides a strategy to design high energy‐storage capacitors under a low electric field. [ABSTRACT FROM AUTHOR]

Lead‐free Ba0.8Ca0.2TiO3–xmol%Ba(Mg1/3Nb2/3)O3 (abbreviated as BCT20–xBMN, x = 0–8) ceramics are fabricated by a conventional solid‐state reaction method. All BCT20–xBMN ceramics have pure perovskite phases which gradually change from tetragonal phase to cubic phase. The average grain size decreases significantly from ≈23 to ≈1.2 μm with the increase in BMN content. The Tm corresponding to the dielectric maximum of BCT20–xBMN decreases with the increase in x, and the room temperature dielectric constant increases significantly. The recoverable energy storage density Wrec and efficiency η% are enhanced to 0.17 J cm−3 and 81.3% for BCT20–6BMN due to the reduced remanent polarization by BMN doping. The Wrec increases with increasing temperature and shows peak values near the Tm. The η% of BCT20–6BMN and BCT20–7BMN has good temperature stability due to enhanced relaxor behavior. [ABSTRACT FROM AUTHOR]

Lead‐free Ba0.8Ca0.2TiO3–xmol%Ba(Mg1/3Nb2/3)O3 (abbreviated as BCT20–xBMN, x = 0–8) ceramics are fabricated by a conventional solid‐state reaction method. All BCT20–xBMN ceramics have pure perovskite phases which gradually change from tetragonal phase to cubic phase. The average grain size decreases significantly from ≈23 to ≈1.2 μm with the increase in BMN content. The Tm corresponding to the dielectric maximum of BCT20–xBMN decreases with the increase in x, and the room temperature dielectric constant increases significantly. The recoverable energy storage density Wrec and efficiency η% are enhanced to 0.17 J cm−3 and 81.3% for BCT20–6BMN due to the reduced remanent polarization by BMN doping. The Wrec increases with increasing temperature and shows peak values near the Tm. The η% of BCT20–6BMN and BCT20–7BMN has good temperature stability due to enhanced relaxor behavior. [ABSTRACT FROM AUTHOR]

Two calcium-doped α-SiAION compositions (Ca[sub 0.6]Si[sub 10.2]Al[sub 1.8]O[sub 0.6]N[sub 15.4] and Ca[sub 1.8]Si[sub 6.6]AI[sub 5.4]O[sub 1.8]N[sub 14.2]) were prepared by hot pressing at 1600° and 1500°C, respectively, for complete phase transformation from α-Si[sub 3]N[sub 4] to α-SiAION. Both samples were subsequently fired at different temperatures for different periods of time to study the grain growth of α-SiAION. Elongated α-SiAION grains were developed in both samples at high temperatures. The kinetics of grain growth was investigated based on the variations in length and width of the α-SiAION grains under different sintering conditions. Different growth rates were found between the length and width directions of the α-SiAION crystals, resulting in anisotropic grain growth in the microstructural development. [ABSTRACT FROM AUTHOR]

Thick translucent and luminescent Gd–α-sialon ceramic disks (0.7–1.06 mm in thickness) were prepared by hot pressing. The effect of carbon atmosphere on their optical properties during sintering was explored by change packing methods. The results show that the sample with a lower carbon contamination has a higher translucence in the visible band and IR band (450–3500 nm), increasing transmission around 10% even if it is thicker. When excited at 350 nm, Gd–α-sialon with the lower carbon contamination can produce a visible light at 450–500 nm bands, but the luminescence is very weak in the sample containing more carbon contamination. These indicate that carbon contamination causes a severe degradation of the optical properties of α-sialon ceramics, and reduction of carbon contamination of α-sialon ceramics is very important for the optical property improvement. [ABSTRACT FROM AUTHOR]

Dy-α-sialon and β-Si3N4 materials containing Dy-oxynitride glass were hot pressed at 1800°C for 1 h. The luminescence spectra of Dy3+ in these samples were compared when excited at 350 nm. The results showed that two strong emission bands in the region 470–500 nm and 570-600 nm, associated with the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions of Dy3+ ions, were observed in Dy-α-sialon. However, no emission peak was detected from the β-Si3N4 sample, despite it containing the same amount of Dy3+ cations. This proved that only the Dy3+ cations in the α-sialon structure, not those in the oxynitride glass, produce the luminescence spectrum. [ABSTRACT FROM AUTHOR]