Normal-to-relaxor ferroelectric phase transition and electrical properties in Nb-modified 0.72BiFeO3-0.28BaTiO3 ceramics

BiFeO3-BaTiO3: A new generation of lead-free electroceramics

“…[68][69][70] In each case, oxygen vacancies (V O Þ are generated. To resolve these issues in BF-BT, excess Bi 2 O 3 is added to compensate for volatilisation [71][72][73] and/or dopants [74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90] are used to accommodate changes in local defect chemistry associated with the multiple valence state of Fe. Dopants in the field of piezoelectric materials are classified into three groups: donor (higher valence), acceptor (lower valence) and self-compensated (average valence number remains the same).…”

“…17). [74][75][76][77][78][79] And rare earth ions are reported to substitute on the A site of BiFeO 3 and improve d 33 but there are conflicting reports as to whether they improve the resistivity/d 33 of BF-BT ceramics. [80][81][82][83] However, a brief review of the literature suggests that the most successful dopants are stoichiometric or selfcompensated (e.g., Cr, Co, Al, Ga, Mg 1=2 Ti 1=2 , Zn 1=2 Ti 1=2 and Ni 1=2 Ti 1=2 Þ.…”

High Energy Storage Density and Large Strain in Bi(Zn2/3Nb1/3)O3-Doped BiFeO3–BaTiO3 Ceramics

“…22,23 In a recent study, Du et al showed a commensurate improvement in Wrec to ~ 4 J/cm 3 in KNN-ceramics due to an enhancement of BDS (300~400 kV/cm), which was achieved by a careful control of grain growth. 24,25 BiFeO3-BaTiO3 (BF-BT) ceramics are characterised by high values of Curie maximum (TC) and Pmax (> 40 C/cm 2 ) [26][27][28][29][30][31][32] , but because their dielectric tan and Pr are relatively large, their energy storage characteristics have been seldom studied. Recently, Nb2O5, La(Mg1/2Ti1/2)O3, Ba(Mg1/3Nb2/3)O3 and Nd2O3 have been used as either dopants in, or in solid solution with, BF-BT with Wrec of 0.71, 1.66, 1.56, and 1.82 J/cm 3 , respectively, reported [33][34][35][36] Nd doped BF-BT multilayers showed particular promise with both high Wrec ~ 6.74 J/cm 3 and ~ 77%, from RT to 125 °C.…”

“…Although there are commercial energy storage devices based on La-doped lead zirconate titanate, concerns over the toxicity of PbO have led to a large body of recent research on lead-free replacements such as BaTiO 3 (BT)-, (K 0.5 Na 0.5 )­NbO 3 (KNN)-, and (Bi 0.5 Na 0.5 )­TiO 3 (BNT)-based ceramics. − Oxide additives such as Al 2 O 3 , SiO 2 , and MgO enhanced both W rec and BDS in BT-based ceramics, − but BT-Bi­(M, N)­O 3 (M = Li, Mg, Zn; N = Nb, Ti, Zr) ceramics showed greater promise, with W rec up to 2.5 J/cm 3 . − In addition, Bi 0.5 Na 0.5 TiO 3 –Ba­TiO 3 –KNbO 3 (BNT-BT-KN) and Bi 0.5 Na 0.5 ­TiO 3 –BaTiO 3 –NaTaO 3 (BNT-BT-NT) also exhibited large W rec values of 1.72 and 1.2 J/cm 3 , respectively. , In a recent study, Du et al showed a commensurate improvement in W rec to ∼4 J/cm 3 in KNN-ceramics due to an enhancement of BDS (300–400 kV/cm), which was achieved by a careful control of grain growth. , BiFeO 3 –BaTiO 3 (BF-BT) ceramics are characterized by high values of Curie maximum ( T C ) and P max (>40 μC/cm 2 ), − but because their dielectric tan δ and P r are relatively large, their energy storage characteristics have been seldomly studied. Recently, Nb 2 O 5 , La­(Mg 1/2 ­Ti 1/2 )­O 3 , Ba­(Mg 1/3 ­Nb 2/3 )­O 3 , and Nd 2 O 3 have been used either as dopants in, or in solid solution with, BF-BT with W rec values of 0.71, 1.66, 1.56, and 1.82 J/cm 3 , respectively, reported. − Nd-doped BF-BT multilayers showed particular promise with both high W rec ∼ 6.74 J/cm 3 and η ∼ 77%, from room temperature (RT) to 125 °C …”

Optimisation of functional properties in lead-free BiFeO3–BaTiO3 ceramics through La3+ substitution strategy

“…We also questioned why some previous studies reported that donor doped BF-BT ceramics display significant reductions in remanent polarisation, which makes them promising candidates for energy storage dielectrics, 51 and/or high precision actuators due to reduced hysteresis. 52 The rationale of the present study was to employ both isovalent and aliovalent substitutions of La 3+ for Bi 3+ and Ba 2+ respectively, in the solid solution 0.75BiFeO 3 -0.25BaTiO 3 (75BFBT). This solid solution system was selected due to its proximity to the MPB and the existence of a major rhombohedral phase, which enables any possible structural distortions induced by La 3+ substitution to be identified.…”