Enhanced energy storage properties of lead-free NaNbO3-based ceramics via A/B-site substitution

Energy storage performance of BiFeO3–SrTiO3–BaTiO3 relaxor ferroelectric ceramics

“…The temperature‐dependent P − E curves at 25 kV/mm and 10 Hz, and corresponding calculated W rec and η are plotted in Figure 7e,f. As the temperature rises from ambient temperature to high temperature, the slim P − E curves become more and more fat evidenced by obviously increased P max and P r because of the thermal‐generated large leakage current 38,39 . Consequently, the W rec and η increase from 3.1 J/cm 3 , 84.5% at 25°C to 2.8 J/cm 3 , 71.4% at 140°C, respectively.…”

Achieving ultrahigh energy storage density and efficiency in 0.90NaNbO3–0.10BaTiO3 ceramics via a composition modification strategy

“…Therefore, replacing Mg 2+ (CN = 6, r = 0.72 Å) with Nb 5+ (CN = 6, r = 0.64 Å) at the B site would increase the volume of the NN–BT lattice, causing the diffraction peak to move to a low angle. 31,32 The room temperature Raman spectra were measured to explore the local structural evolution of NNBT– x BLMT ceramics, as shown in Fig. 1(c)–(f).…”

“…Therefore, replacing Mg 2+ (CN = 6, r = 0.72 Å) with Nb 5+ (CN = 6, r = 0.64 Å) at the B site would increase the volume of the NN-BT lattice, causing the diffraction peak to move to a low angle. 31,32 The room tempera- 35 With the addition of BLMT, the Raman vibration at 590 cm −1 gradually broadens and red-shifts, showing the vibration softening of the BO 6 oxygen octahedron. 36 Briefly, the BO 6vibration softening is attributed to the generation of PNRs, while the increased disorder of the A-site ions leads to local random fields, both of which demonstrate that the ferroelectric long-range order is broken, and thus the energy storage properties are enhanced.…”

“…Accordingly, to reduce the P r value of the ceramic, La 3+ (CN = 12, r = 1.36 Å) replaces Na + (CN = 12, r = 1.39 Å) at the A site, while Nb 5+ (CN = 6, r = 0.64 Å) at the B site is replaced with Ta 5+ (CN = 6, r = 0.64 Å)/Mg 2+ (CN = 6, r = 0.72 Å). 26,31,32…”

“…Accordingly, to reduce the P r value of the ceramic, La 3+ (CN = 12, r = 1.36 Å) replaces Na + (CN = 12, r = 1.39 Å) at the A site, while Nb 5+ (CN = 6, r = 0.64 Å) at the B site is replaced with Ta 5+ (CN = 6, r = 0.64 Å)/Mg 2+ (CN = 6, r = 0.72 Å). 26,31,32 (III) However, the attenuation of P max and P r often accompanies the appearance of local random fields, so the energy storage density declines as a result. Fortunately, in perovskite ceramics, the 6p orbital of Bi 3+ can be strongly hybridized with the 2p orbital of O 2− , thereby maintaining large P max and ΔP.…”