Investigation of a high Tc piezoelectric system: (1−x)Bi(Mg1/2Ti1/2)O3–(x)PbTiO3

Abstract

(1−x) Bi(Mg 1/2 Ti 1/2 ) O 3 –x PbTiO 3 polycrystalline ceramics were investigated for potential as high-temperature piezoelectric materials. A morphotropic phase boundary (MPB) between tetragonal (T) and rhombohedral (R) ferroelectric (FE) phases, which exhibited enhanced piezoelectric activity and a ferroelectric–paraelectric phase transition at 478 °C was observed at x≈0.37. Electron diffraction patterns (x⩽0.37) contained discrete superlattice reflections at 12{hkl} positions arising from antiphase rotations of the O octahedra, consistent with R3c space group symmetry. These reflections were diffuse at the MPB (x=0.38) and absent in the T phase (x=0.5). In the unpoled state, FE R (x=0.35) ceramics revealed a polar microdomain structure whereas the T phase (x=0.5) contained classic {110} twin domain boundaries. However, poled R samples underwent a field-induced transformation to an aligned domain structure with {110} twin boundaries similar to those in the T phase. Correlations are made between structure and properties for these piezoelectric materials.

Temperature dependence of piezoelectric properties of high-TC Bi(Mg1/2Ti1/2)O3–PbTiO3

“…MgTiO 3 was first synthesized as a precur-sor at 1400°C for 4 h using reagent graded oxide precursors 13,15 and then mixed with PbO ͑99.9%, Alfa Aesar͒, TiO 2 ͑99.9%, Alfa Aesar͒, and Bi 2 O 3 ͑99.975%, Alfa Aesar͒ according to the stoichiometric formulas of each composition. These powder mixtures were ball milled in ethanol for 12 h. Calcination at 850°C for 5 h was then followed by renewed ball milling for another 12 h. Calcined powders were uniaxially pressed into pellets with a diameter of 10 mm and thickness of ϳ1 mm, and then hydrostatically compacted at 200 MPa.…”

“…[1][2][3] The operating temperature of piezoelectric ceramics is generally limited to one-half of the Curie point ͑T C ͒ due to loss of polarization, typically at temperatures lower than 200°C ͓e.g., 150°C for the conventional piezoelectric materials based on the Pb͑Zr 1−x Ti x ͒O 3 ͑PZT͔͒ with a Curie temperature, T C = 386°C. 4 After excellent piezoelectric properties for ͑1 − x͒BiScO 3 -xPbTiO 3 ͑BS-PT͒ near the morphotropic phase boundary ͑MPB͒ ͑x = 0.64͒ were reported ͑piezoelectric coefficient, d 33 = 460 pC/ N, planar coupling coefficient, k p = 0.56, and T C = 450°C͒ recently, 5,6 the discovery of several promising high temperature piezoelectric materials with high performance followed in the general BiMeO 3 -PbTiO 3 system, [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24] where Me can be a single cation of valency +3 ͑e.g., Sc 3+ and Fe 3+ ͒ or a mixture of cations with an average valence of +3 ͑e.g., Mg 1/2 Ti 1/2 and Ni 2/3 Nb 1/3 ͒. It has been proposed that the Bi substitution plays an unusual role of considerable enhancement of both Curie temperature ͑T C ͒ and tetragonality ͑c / a͒, which results from a strong coupling between Pb/Bi cations and B-site cations of strong ferroelectric activity, such as Ti, Zn, and Fe.…”

“…Hence, most recent studies have been focusing on nonscandium perovskites. [12][13][14][15][16][17][18][19][20][21][22][23][24] In fact, possible new compositions in BiMeO 3 -PbTiO 3 -based systems are plenty, because B-site Me of BiMeO 3 could be any combination, which gives an average valence of +3. According to the currently available literature, however, the design of BiMeO 3 -PbTiO 3 piezoelectrics faces a significant challenge in that only few systems form a MPB with PbTiO 3 .…”

Crossover from a nearly constant loss to a superlinear power-law behavior in Mn-doped Bi(Mg1/2Ti1/2)O3–PbTiO3 ferroelectrics

“…The measurement was taken over a temperature range of 175-450 K, which is far below its Curie temperature T C ͑ϳ694 K͒. 18 Two regions can be easily identified with the boundary located at around 273 K. The imaginary part of dielectric permittivity Љ in the low temperature region ͑below 273 K͒ is almost independent of frequency, reflecting a genuine NCL behavior. In the high temperature region ͑above 273 K͒ it becomes quite dispersed with frequency.…”

Growth of (111) One-Axis-Oriented Bi(Mg1/2Ti1/2)O3 Films on (100)Si Substrates

“…23) In the present study, we attempted to grow (111) one-axisoriented films of a high-pressure phase Bi(Mg 1=2 Ti 1=2 )O 3 on (100)Si substrates. Bi(Mg 1=2 Ti 1=2 )O 3 has been investigated as an end member of the piezoelectric materials, 24,25) and it showed good ferroelectricity in the case of (111)-oriented epitaxial films grown on (111) c SrRuO 3 /(111)SrTiO 3 substrates. 19) …”