Enhanced energy storage properties of hafnium-modified (0.7Ba_0.55Sr_0.45–0.3Bi_0.5Na_0.5)TiO₃-based relaxor ferroelectric ceramics via regulating polarization nonlinearity and bandgap

Abstract

Achieving high energy storage density (ESD), energy storage efficiency (η) and exceptional stability is deemed as the foremost challenge for the application of lead-free dielectric energy storage materials. Relaxor ferroelectrics...

Ferroelectric Polarization Modulated Thermal Conductivity in Barium Titanate Ceramic

“…Raman spectroscopy is a measurement to catch part of the phonon modes by frequency shift. In the range of 0 to 900 cm –1 , four regions can be found in Raman spectra under room temperature, similar to those previously reported BaTiO 3 in solid solution. , 0–200 cm –1 and 200–400 cm –1 bands represent the short wave of ionic Ba–O and Ti–O bond vibration, while 400–600 cm –1 and >600 cm –1 are the vibration modes of [TiO 6 ] octahedron chains and long-range lattice, as shown in Figure (a). ,, By comparing major Raman peaks at the different bands in Figure (a), also demonstrated in Figure (b), it is found peak 3 obviously shifts to the higher frequency (wavenumber). By comparing the phonon (one mode of lattice vibration) to a spring motion, because they all share a similar sinusoidal harmonic motion, the enhanced vibration frequency corresponds to a resilience force in Ti–O ionic vibration; in other words, a tightened phonon (just a like tightened spring) emerges with the increased ferroelectric polarization P .…”

“…FORC measurement was also performed by the modified P – E loop at 2 V um –1 , which featured a repetitive triangle/sinusoidal input wave from negative maximum electric field. A two-dimensional density distribution function n R ( x , y ) was calculated by data points extracted from the FORC output P – E curve, − as shown in Figure S1, intending to illustrate the density of the minimum unit of reversible dipoles featuring coercive fields x and y . Depolarization Δ P was integrated by the discharged current in TSDC (temperature stimulus depolarization current) measurement in a heated chamber in the broadband dielectric impedance Alpha spectrometer (Novocontrol Technologies, Montabaur, Germany). , …”

“…BaTiO 3 ferroelectric ceramics were fabricated by solid state reaction, which frequently occurred in related works. − In this work, raw material was selected as BaCO 3 (99.38%) and TiO 2 (99.21%) were weighed accurately and mixed by ball-milling for 6 h. The solid-state synthesis was performed at 1273 K for 3 h, and the resulting blocks were crushed and further ball milled for 6 h. Then, the poly­(vinyl alcohol) (PVA) was chosen as binder and mixed with powders to granulate. After the debinding (873 K for 4 h) and forming process, ceramic sintering was performed at 1573 K for 2 h.…”

Giant comprehensive capacitive energy storage in lead-free quasi-linear relaxor ferroelectrics via local heterogeneous polarization configuration

“…Notably, the collected experimental data and calculated line perfectly matched, confirming the coexistence of the CT main-phase and NN secondary-phase in CT-0.4NN ceramic. To further gain insights into the dominant RFE feature, 63,64 FORC distribution is investigated, as given in Fig. 5(b) derived from a series of asymmetric P – E loops (Fig.…”

High discharge energy density in novel K1/2Bi1/2TiO3-BiFeO3 based relaxor ferroelectrics

“…Although it may seem counterintuitive that compositions with chemical inhomogeneity are electrically homogeneous, these observation are consistent with other BF-based ceramics [25,[27][28][29][30][31][32]34,35] that have been used to form high E pulse (1 MV cm − 1 ) prototype MLCCs. Apart from BF-based ceramics, achieving electrical homogeneity also enhances W dis in other lead-free systems, such as BT- [70] and NBT-based [23,71] bulk ceramics.…”