Phase transitions in Sr 0.61 Ba 0.39 Nb 2 O 6 :Ce 3+ : II. Linear birefringence studies of spontaneous and precursor polarization

Lehnen, P.; Kleemann, W.; Woike, Th.; Pankrath, R.

doi:10.1007/pl00011055

Cited by 9 publications

(8 citation statements)

References 24 publications

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“…240 Simultaneously, the fractal dimension of domain boundaries increases, which indicates more pronounced "irregularity" of the polar structures in relaxor SBN. 238 Like in other relaxor systems, the relaxor behavior of SBN is attributed to the existence of PNRs, which is evidenced above T m by the measurements of the optical index of refraction, 242 birefringence, 243 and dynamic 244 and inelastic Brillouin 245 light scattering. The uniaxial character of the order parameter together with the existence of the quenched RFs due to the randomly distributed A-site vacancies allows considering SBN to be a member of the three-dimensional random-field Ising model (3D-RFIM) universality class.…”

Section: Local Tetragonal Symmetry 2 Rather Afe Than Ferroelectric Cmentioning

confidence: 82%

“…These are also sources of random electric fields. 238 Like in other relaxor systems, the relaxor behavior of SBN is attributed to the existence of PNRs, which is evidenced above T m by the measurements of the optical index of refraction, 242 birefringence, 243 and dynamic 244 and inelastic Brillouin 245 light scattering. From statistical considerations, the most ordered structure is expected in SBN20, where all A2-sites are occupied solely by Ba 2+ cations, while the Sr 2+ ions and vacancies are randomly distributed on the A1-sites.…”

Section: Lead-free Relaxor Systemsmentioning

confidence: 82%

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Lead‐Free Relaxor Ferroelectrics

2011

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Feature size is a natural determinant of material properties. Its design offers the technological perspectives for material improvement. Grain size, crystallite size, domain width, and structural defects of different nature constitute the classical design elements. Common ferroelectric ceramics contain micrometer grain sizes and submicrometer domain widths. Domain wall mobility is a major contribution to their macroscopic material properties providing approximately half of the macroscopic output in optimized materials. The extension into the dynamic nanoworld is provided by relaxor ferroelectrics. Ionic and nanoscale field disorders form the base to a state with natural nanometer‐size polar structures even in bulk materials. These polar structures are highly mobile and can dynamically change over several orders of magnitude in time and space being extremely sensitive to external stimuli. This yields among the largest dielectric and piezoelectric constants known. In this feature article, we want to outline how lead‐free relaxors will offer a route to an environmentally safer option in this outstanding material class. Properties of uniaxial, planar, and volumetric relaxor compositions will be discussed. They provide a broader and more interesting scope of physical properties and features than the classical lead‐containing relaxor compositions.

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Section: Local Tetragonal Symmetry 2 Rather Afe Than Ferroelectric Cmentioning

confidence: 82%

Section: Lead-free Relaxor Systemsmentioning

confidence: 82%

Lead‐Free Relaxor Ferroelectrics

2011

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“…For SBN doped with rare-earth ions, oxygen vacancy has been proposed as the compensation defect and as the source of the random field. [22][23][24][25][26][27][28][29][30][31] However, this viewpoint is incorrect, because the rare-earth ions have been assumed to substitute for the strontium ions, which act as donors. Oxygen vacancy is a charge compensation of an acceptor.…”

Section: March 2004mentioning

confidence: 99%

Charge‐Compensating Defect in Ceria‐Doped Strontium Barium Niobate by Electron Energy‐Loss Spectroscopy and X‐ray Photoelectron Spectroscopy

Shiue

Fang

2004

Journal of the American Ceramic Society

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Undoped and CeO2‐doped Sr0.5Ba0.5Nb2O6 (SBN) powders were synthesized using the solid‐state reaction method. The lattice parameters of undoped and CeO2‐doped SBN were evaluated using X‐ray diffractometry. The valence state of the cerium ion in Ce‐doped SBN was identified using X‐ray photoelectron spectroscopy (XPS), and the valence of 3+ was confirmed. The charge‐compensated defect of the cerium doping in SBN ceramics, i.e., excessive oxygen ions occupying the vacant O(4) or O(5) site, was further evidenced using electron energy‐loss spectroscopy (EELS) and XPS. The relationships of charge‐compensated defect, structure, binding energy, and temperature of the maximum of the relative permittivity (Tm) were discussed.

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“…Meanwhile, we propose a new mean-field of pseudospin-strings to solve this kinetic model.The main facts of relaxor-ferroelectricity, i.e. the novel phase-transition phenomenon of RFEs, are: (i) As a function of temperature, (a) the frequency-dependent peak of permittivity, with a broad distribution of relaxation time and the average relaxation time varying as the Vogel-Fulcher-law 31-33 , (b) the diffuse change of spontaneous-polarization (order-parameter) [34][35][36][37][38] , and particularly, the quasi-fractal characteristic of the local-spontaneous-polarization (local-order-parameter) as well as its variation 17,18 , (c) the small broad peak of www.nature.com/scientificreports www.nature.com/scientificreports/ specific-heat [39][40][41]43 and the corresponding polar-nano-regions (PNRs) appearing far above the DPT 44-47 ; and (ii) With varying components, the evolutions between normal-ferroelectrics ↔ RFEs ↔ paraelectrics 48-51 . Our theory can account for these facts, and in addition gives a good quantitative agreement with the experimental results of the order-parameter, specific-heat, high-frequency permittivity, and Burns-transformation of PMN, the generally viewed canonical RFE 52,53 , which is convincing evidence that the theory is essentially correct.…”

mentioning

confidence: 99%

“…As shown in the Sec. Local-order-parameter, it is just these PS clusters that lead to the appearance of the PNRs 15,16,[44][45][46][47] first proposed by Burns et al 42,43 , although its definition is quite unclear now as pointed out by Cowley et al 16 .…”

mentioning

confidence: 99%

Theory of relaxor-ferroelectricity

Zhang

Huang

2020

Sci Rep

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Relaxor-ferroelectrics are fascinating and useful materials, but the mechanism of relaxor-ferroelectricity has been puzzling the scientific community for more than 65 years. Here, a theory of relaxorferroelectricity is presented based on 3-dimensional-extended-random-site-Ising-model along with Glauber-dynamics of pseudospins. We propose a new mean-field of pseudospin-strings to solve this kinetic model. The theoretical results show that, with decreasing pseudospin concentration, there are evolutions from normal-ferroelectrics to relaxor-ferroelectrics to paraelectrics, especially indicating by the crossovers from, (a) the sharp to diffuse change at the phase-transition temperature to disappearance in the whole temperature range of order-parameter, and (b) the power-law to Vogel-Fulcher-law to Arrheniusrelation of the average relaxation time. Particularly, the calculated local-order-parameter of the relaxorferroelectrics gives the polar-nano-regions appearing far above the diffuse-phase-transition and shows the quasi-fractal characteristic near and below the transition temperature. We also provide a new mechanism of Burns-transformation which stems from not only the polar-nano-regions but also the correlationfunction between pseudospins, and put forward a definition of the canonical relaxor-ferroelectrics. The theory accounts for the main facts of relaxor-ferroelectricity, and in addition gives a good quantitative agreement with the experimental results of the order-parameter, specific-heat, high-frequency permittivity, and Burns-transformation of lead magnesium niobate, the canonical relaxor-ferroelectric. 65 years after the discovery of so-called relaxor-ferroelectrics (RFEs) 1 , this manuscript promises to deliver the still missing theory of relaxor-ferroelectricity [Supplementary Information (SI) 1] 2-10 . For the existing phase-transition theories of normal-ferroelectrics are based on both structure and component homogeneity [11][12][13] , theoretically, the main difficulty in describing relaxor-ferroelectricity originates from RFEs being component-disordered although structure-ordered, i.e. disordered components on crystal lattices [14][15][16][17][18][19] . In fact, understanding how the component disorder on lattices leads to novel properties is an outstanding scientific challenge for a broad class of materials that include not only RFEs, but also spin glasses 20 , superelastic strain glasses (shape-memory alloys) 21 , colossal magnetoresistance manganites, and some superconductors 22 .The best-known member of the RFE family is the disordered perovskite crystal PbMg 1/3 Nb 2/3 O 3 (PMN), for which 27 years ago a plausible interpretation of its diffuse-phase-transition (DPT) was proposed by Westphal et al. 3 . Fluctuations of random-internal-electric-field (RIEF) emerging from the quenched charge disorder of the RFE are stabilizing the typical disordered polar nanodomain state. This disordering mechanism convinced sceptical experts at the latest thanks to a favorable review of Cowley et al. 16 . The subseq...

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Phase transitions in Sr 0.61 Ba 0.39 Nb 2 O 6 :Ce 3+ : II. Linear birefringence studies of spontaneous and precursor polarization

Cited by 9 publications

References 24 publications

Lead‐Free Relaxor Ferroelectrics

Lead‐Free Relaxor Ferroelectrics

Charge‐Compensating Defect in Ceria‐Doped Strontium Barium Niobate by Electron Energy‐Loss Spectroscopy and X‐ray Photoelectron Spectroscopy

Theory of relaxor-ferroelectricity

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