Characterization of Mn-modified Pb(Mg1∕3Nb2∕3)O3–PbZrO3–PbTiO3 single crystals for high power broad bandwidth transducers

Abstract

The effect of MnO 2 addition on the dielectric and piezoelectric properties of 0.4Pb͑Mg 1/3 Nb 2/3 ͒O 3 -0.25PbZrO 3 -0.35PbTiO 3 single crystals was investigated. Analogous to acceptor doping in "hard" Pb͑Zr, Ti͒O 3 based polycrystalline materials, the Mn doped crystals exhibited enhanced mechanical Q ͑ϳ1050͒ with low dielectric loss ͑ϳ0.2% ͒, while maintaining ultrahigh electromechanical coupling k 33 Ͼ 90%, inherent in domain engineered single crystals. The effect of acceptor doping was also evident in the build-up of an internal bias ͑E i ϳ 1.6 kV/ cm͒, shown by a horizontal offset in the polarization-field behavior. Together with the relatively high usage temperature ͑T R-T ϳ 140°C͒, the Mn doped crystals are promising candidates for high power and broad bandwidth transducers. © 2008 American Institute of Physics. ͓DOI: 10.1063/1.2992081͔High power ultrasonic transducers generally use "hard" piezoelectric ceramics Pb͑Zr, Ti͒O 3 ͑PZT͒, including PZT4 and PZT8 ͑DOD types I and III͒ 1 . These materials are characterized by low dielectric ͑tan ␦͒ and mechanical losses ͑high mechanical quality factor Q͒. In general, to achieve the "hardening" effect, these materials are acceptor doped, e.g., Fe 3+,2+ , Mn 3+,2+ substitution for Zr 4+ / Ti 4+ , resulting in the development of acceptor-oxygen vacancy defect dipoles. These dipoles align parallel to the polarization direction, leading to an internal bias, as evident in a horizontal offset in the polarization-electric field ͑P-E͒ behavior. This offset effectively increases the coercive field ͑E C ͒ and reduces or clamps domain wall motion/mobility. 2,3 A consequence of these dopants, however, is a reduction in electromechanical coupling and piezoelectric activity, with k 33 values less than 70% and piezoelectric strain coefficients d 33 's on the order of 200-350 pC/ N, 4 so limits the bandwidth of transducer since the power and bandwidth capabilities of the transducer are functions of the mechanical quality and electromechanical coupling factors 5,6 . Recently, domain engineered ͗001͘ oriented single crystal perovskites have been demonstrated to possess ultrahigh electromechanical couplings k 33 Ͼ 90% and high piezoelectric coefficients d 33 Ͼ 1500 pC/ N. However, the relaxor-PbTiO 3 ͑PT͒ crystals exhibit low mechanical quality Q's ͑Ͻ100͒ and coercive fields ͑E C ϳ 2-3 kV/ cm͒, typical of "soft" piezoelectric behavior. 7-9 Numerous efforts have been made to piezoelectrically harden the crystals through the addition of acceptor dopants. To date, only moderate mechanical Q values in the range of 200-300 have been achieved in flux grown Pb͑Zn 1/3 Nb 2/3 ͒O 3 -PbTiO 3 crystals. [10][11][12] In this work, the effect of acceptor doping with MnO 2 in solid state crystal grown ͑SSCG͒ 0.4Pb͑Mg 1/3 Nb 2/3 ͒O 3 -0.25PbZrO 3 -0.35PbTiO 3 ͑PMN-PZT͒ crystals was investigated. The SSCG method was selected owing to its inherent benefit of maintaining dopant uniformity in a solid solution, unlike the melt Bridgman process. The PMN-PZT composition was selected owing to its relatively...

Complete set of elastic, dielectric, and piezoelectric constants of [011]C poled rhombohedral Pb(In0.5Nb0.5)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3:Mn single crystals

“…11,12 Recently, manganese modified relaxor-PT crystals have been reported to exhibit enhanced mechanical quality factors Q m and increased field stability. 13,14 To date, however, the full matrix of electromechanical properties for rhombohedral PIN-PMN-PT:Mn single crystals has not been measured and the effect of Mn 2þ,3þ on relaxor-PT crystals is still not fully understood.…”

Multiscale simulations of defect dipole–enhanced electromechanical coupling at dilute defect concentrations

“…Experimentally, aging ferroelectrics to align defect dipoles could achieve improved electromechanical responses. 19,29 Our simulations suggest that poling the sample during the aging process is critical in controllably aligning the defect dipoles and applying an electric field perpendicular to the poling direction to realize optimal electro-strain coupling during device operation.The magnitude of the built-in electric field arising from dipole impurities depends on the concentration and magnitude of defect dipoles. For a collection of dipoles (q = 0.1 e) aligned along −y, the shape of the P x -E x loop evolves from square (n = 0.6%) to slim, pinched (n = 0.8%), and eventually becomes double loops (n = 1.2 %) as the concentration increases ( Figure 2a).…”

“…Experimentally, aging ferroelectrics to align defect dipoles could achieve improved electromechanical responses. 19,29 Our simulations suggest that poling the sample during the aging process is critical in controllably aligning the defect dipoles and applying an electric field perpendicular to the poling direction to realize optimal electro-strain coupling during device operation.…”

PMN-PT based quaternary piezoceramics with enhanced piezoelectricity and temperature stability

“…Therefore, over the past few years, tremendous efforts have been made to improve the temperature stability of the properties, two potential approaches have been adopted so far: shifting T c /T rt to higher temperature by composition tuning, and taking advantage of the engineered domain configuration in single crystals. 3 In the first method, through elements substituting and/or adding of other end-members, numerous new higher T c /T rt binary and ternary material systems were developed, including Pb(In 1/2 Nb 1/2 )-PbTiO 3 (PIN-PT), 6,7 Pb(Yb 1/2 Nb 1/2 )-PbTiO 3 (PYN-PT), 8,9 Pb(Sc 1/2 Nb 1/2 )-PbTiO 3 (PSN-PT), 10 Pb(In 1/2 Nb 1/2 )-Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PIN-PMN-PT), [11][12][13][14][15] Pb(Mg 1/3 Nb 2/3 )O 3 -PbZrO 3 -PbTiO 3 (PMN-PZ-PT), [16][17][18][19] and Pb(Sc 1/2 Nb 1/2 )-Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PSN-PMN-PT), 20 etc. However, it was found that the temperature stability remained unsolved despite of the high T c /T rt .…”

“…[11][12][13][14][15][16][17][18][19][20]30 The PMN-PZ-PT ternary system, which can be regarded as the combination of PMN-PT and PZT, was reported to possess high ferroelectric phase transition temperatures and high coercive fields, the as-grown PMN-PZ-PT single crystals were considered to be the second generation relaxor-PT crystals. 3 (PMN-PFN-PZ-PT) was reported with high d 33 > 600 pC/N and enhanced ferroelectric phase transition temperature.…”