Nanostructural-property relations in complex lead perovskites
TL;DR: In this paper, a correlation between the nanoscale B-site order and relaxor on glassy ferroelectric behavior is found in these lead perovskites, and a hypothesis is suggested which relates 0-3 polar connectivity to order-disorder connectivity.
Abstract: From transmission electron microscopy studies on several complex lead perovskite compounds Pb(B'B'')O3, and their solid solutions a classification can be obtained based on B-cation order. This classification divides the complex lead perovskites into three subgroups; random occupation or disordered, nanoscale or short coherent long-range order and long coherent long-range order of B-site cations. A correlation between the nanoscale B-site order and relaxor on glassy ferroelectric behavior is found in these lead perovskites. An hypothesis is suggested which relates 0-3 polar connectivity to 0-3 order-disorder connectivity. This hypothesis is discussed with relation to present theories [G. A. Smolenskii: J. Phys. Soc. Jpn. (1970) Suppl., p. 26, L. E. Cross: Ferroelectrics 76 (1987) 241, T. L. Renieke and K. L. Ngai: Solid State Commun. 18 (1973) 1543] and reported experimental results of the perovskite relaxor ferroelectrics.
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TL;DR: In this paper, the perovskite structure is used to illustrate the relationship of structure to composition, and the history of the fundamental science of structure-to-composition is described.
Abstract: Starting with the history of the fundamental science of the relation of structure to composition delineated completely by Goldschmidt, we use the perovskite structure to illustrate the enormous pow...
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TL;DR: In this paper, a review deals with a variety of nanocomposites such as sol-gel, intercalation, entrapment, electroceramic and structural ceramic types, which exhibit superior properties when compared to the monophasic or microcomposite alternatives.
Abstract: The use of nanocomposites in materials processing can lead to monophasic or multiphasic ceramics, glasses or porous materials, with tailored and improved properties. This review deals with a variety of nanocomposites such as sol–gel, intercalation, entrapment, electroceramic and structural ceramic types, which exhibit superior properties when compared to the monophasic or microcomposite alternatives. The utilization of nanocomposites in materials processing is forecasted to have a major impact in catalytic, sensor, optical, electroceramic and structural ceramic materials.
462 citations
TL;DR: In this article, the authors present trends of enhanced mobility, connectivity, and reliability in consumer, industrial, and military electronics will continue to drive future innovations in ceramic capacitor technology, and power electronics applications are an emerging market in which ceramic capacitors will play an increasing role through improved breakdown strength, enhanced dielectric stability in harsh environments, and innovative packaging.
Abstract: A century of diligent R&D has resulted in a wide range of ceramic dielectrics and processing technologies. The technology used to manufacture an MLCC (multilayer ceramic capacitors) that costs pennies was unimaginable 30 years ago. The present trends of enhanced mobility, connectivity, and reliability in consumer, industrial, and military electronics will continue to drive future innovations in ceramic capacitor technology. In addition, power electronics applications are an emerging market in which ceramic capacitors will play an increasing role through improved breakdown strength, enhanced dielectric stability in harsh environments, and innovative packaging. The investment made by the US government to develop high energy density and high temperature capacitor technology will also contribute to the advancement of dielectric materials technology for pulse and power electronic capacitors.
364 citations
Cites background from "Nanostructural-property relations i..."
...First reported in 1954 [4], relaxor dielectrics are characterized by a very high dielectric constant and a diffuse phase transition [13], [14]....
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...This dielectric behavior is attributed to a microstructure of numerous polar nanoregions surrounded by a nonpolar matrix on the scale of nanometers [13]....
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TL;DR: In this article, a series of these phases with substitution levels ranging from 1% to 5% BaZrO 3 were examined using high-resolution TEM and it was shown that the low losses of the 1:2 ceramics are derived from the stabilization of the ordering-induced domain boundaries via the partial segregation of the Zr cations.
Abstract: Small substitutions of BaZrO 3 into Ba[(Zn,Ni) 1/3 Ta 2/3 ]O 3 are utilized in the commercial preparation of low-loss perovskite microwave dielectrics. The structures of a series of these phases with substitution levels ranging from 1% to 5% BaZrO 3 were examined using high-resolution TEM. For < 2.15% BaZrO 3 the solid solutions retain the ordered 1:2 structure of the Ba[(Zn,Ni) 1/3 Ta 2/3 ]O 3 end-member but are comprised of small ordered domains whose size decreases as the Zr content is raised. The decrease in the size of the domains parallels a decrease in the processing time required to access a low-loss state. Although for pure Ba[(Zn,Ni) 1/3 Ta 2/3 ]O 3 reductions in the degree of cation order produce a large increase in the dielectric loss, the Zr-substituted ceramics retain a very low loss. We believe the low losses of the 1:2 ceramics are derived from the stabilization of the ordering-induced domain boundaries via the partial segregation of the Zr cations. For substitutions between 3% and 5% BaZrO 3 the size of the ordered domains continues to decrease but the system undergoes an abrupt transformation to a cubic 1:1 ordered structure with a doubled perovskite repeat. The structures of these phases have been interpreted using a random layer model in which one site is occupied by Ta and the other by a random distribution of Zn, Zr, and the remaining Ta cations, i.e., Ba{[Zn (2-y)/3 Ta (1-2y)/3 Zr y ] 1/2 [Ta 1/2 ]}O 3 . Although the ordering is confined to nano-sized domains, these ceramics also exhibit low losses, again reflecting the relative stability of the domain boundaries. In this case we believe the low losses reflect the effectiveness of the random layer in stabilizing the anti-phase boundaries.
297 citations
TL;DR: In this paper, it is proposed that the strain gradient might change the Gibbs free energy of the relaxor system and easily reorient the already existing polar microregions, leading to the greatly enhanced flexoelectric effect.
Abstract: Flexoelectric coefficient μ12 is greatly enhanced in the relaxor ferroelectric lead magnesium niobate ceramic. Phenomenological analysis suggests the high dielectric permittivity is inadequate to explain the great enhancement. Temperature dependent measurement reveals a close relation between the flexoelectric polarization and the preexisting polar microregions in this relaxor ferroelectrics. It is proposed that the strain gradient might change the Gibbs free energy of the relaxor system and easily reorient the already existing polar microregions, leading to the greatly enhanced flexoelectric effect.
244 citations
References
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01 Sep 1969
590 citations
TL;DR: Evidence for an incommensurate phase within the antiferroelectric and ferroelectric phase, respectively is revealed and a possible ``lock-in'' transition is found in Pb (${\mathrm{Sc}}_{1/2}$) and Pb (£3), but the incommonsurate to commensurate transition seems to be dependent on the degree of B-site order.
Abstract: A transmission electron microscopy study of two B-site order perovskites Pb(${\mathrm{Co}}_{1/2}$${\mathrm{W}}_{1/2}$)${\mathrm{O}}_{3}$ and Pb(${\mathrm{Sc}}_{1/2}$${\mathrm{Ta}}_{1/2}$)${\mathrm{O}}_{3}$ has revealed evidence for an incommensurate phase within the antiferroelectric and ferroelectric phase, respectively. Direct observations by dark field techniques have revealed discommensurate structures in both Pb(${\mathrm{Sc}}_{1/2}$${\mathrm{Ta}}_{1/2}$)${\mathrm{O}}_{3}$ and Pb(${\mathrm{Co}}_{1/2}$${\mathrm{W}}_{1/2}$)${\mathrm{O}}_{3}$. A possible ``lock-in'' transition is found in Pb(${\mathrm{Sc}}_{1/2}$${\mathrm{Ta}}_{1/2}$)${\mathrm{O}}_{3}$, but the incommensurate to commensurate transition seems to be dependent on the degree of B-site order.
89 citations