Phase transition, piezoelectric, and multiferroic properties of La(Co_0.5Mn_0.5)O₃-modified BiFeO₃-BaTiO₃lead-free ceramics

Abstract

(0.75–x)BiFeO3−0.25BaTiO3−xLa(Co0.5Mn0.5)O3 + 1 mol% MnO2 lead‐free ceramics (x = 0–0.10) were synthesized by a conventional solid‐state reaction route and the effects of La(Co0.5Mn0.5)O3 on phase transition, piezoelectric, ferroelectric, and multiferroic properties of the ceramics were investigated. The ceramics can be well sintered at 960 °C for 2 h. After the addition of La(Co0.5Mn0.5)O3, the crystal structure of the ceramics is transformed from rhombohedral (space group R3c) to orthorhombic symmetry (space group Amm2), and the morphotropic phase boundary (MPB) of rhombohedral and orthorhombic phases is formed at x = 0.01–0.03. The dielectric peak of the ceramics was found to become diffusive with increasing x. The ceramics with x = 0–0.03 possess strong piezoelectricity with d33 of 95–108 pC N−1, strong ferroelectricity with Pr of 2.2–18.1 μC cm−2, considerable magnetoelectric coefficient of 372–672 mV/cmOe, and high Curie temperature of 523–659 °C, showing potential applications in multiferroic devices.

High strain (0.4%) Bi(Mg2/3Nb1/3)O3‐BaTiO3‐BiFeO3 lead‐free piezoelectric ceramics and multilayers

“…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). All the above‐mentioned dopant strategies improve the resistivity of BT‐BF ceramics as reported in the literature . Wang et al reported that Nb (donor) improves the resistivity of BT‐BF while it gives rise to a decrease in the grain size.…”

“…For instance, as Yao et al reported, Mn increases the resistivity and decreases the dielectric loss of 0.8BF‐0.2BT ceramics. However, the most successful dopants are stoichiometric or self‐compensated (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 ) which improve not only the resistivity of furnace cooled ceramics but also their piezoelectric properties . Nonetheless, the d 33 of furnace‐cooled doped BF‐BT compositions is typically much smaller (163 pC/N) than that of quenched samples …”

“…All the above-mentioned dopant strategies improve the resistivity of BT-BF ceramics as reported in the literature. 11,19,20,[30][31][32][33][34][35][36][37][38][39][40][41][42] Wang et al 30 reported that Nb (donor) improves the resistivity of BT-BF while it gives rise to a decrease in the grain size. Curiously, acceptor dopants also improve the resistivity of BT-BF.…”

“…However, the most successful dopants are stoichiometric or self-compensated (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 ) which improve not only the resistivity of furnace cooled ceramics but also their piezoelectric properties. 18,[35][36][37][38][39][40][41][42] Nonetheless, the d 33 of furnace-cooled doped BF-BT compositions is typically much smaller (163 pC/N) than that of quenched samples. 16,39 Given that all dopant strategies appear empirically to improve resistivity and stoichiometric/self-compensated dopants improve d 33 , it is logical to design doped compositions which not only act locally as aliovalent dopants but which also maintain macroscopic stoichiometry.…”

Phase Evolution and Local Piezoelectric Response of Sn‐Doped BaTiO3 Ceramics

“…[1][2][3][4][5][6][7][8] Among the numerous lead-free piezoelectric ceramics, BaTiO 3 (BT) has gained many attentions on account of its low cost, easy processing, and good temperature stability.Whether for the lead-free or lead-based piezoelectric ceramics, an effective method to acquire high piezoelectric properties is to adjust the composition of the material to the vicinity of the phase transition boundaries. [9][10][11][12][13][14] Paraelectric to ferroelectric phase transition or two ferroelectric phase transition could be induced by the compositions, resulting in the instablility of the polarization state. Therefore, the polarization direction could be easily rotated under external stress or electric field, so that high piezoelectric properties could be achieved.…”