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Wicks, Jeffrey D.; Börjesson, Lars; Bushnell‐Wye, G.; Howells, W.S.; McGreevy, R.L.

doi:10.1103/physrevlett.74.726

Cited by 162 publications

(75 citation statements)

References 27 publications

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“…AgI additive serves to decouple the network of chains by steadily inserting itself between chains at low x, and converting long chains to closed rings at high x. These observations are broadly consistent with the earlier MD simulations 69 and molar volume results. 70 In the MD simulations, a conductivity percolation transition was predicted near x ¾ 0.3, which is consistent with the conductivity increase observed in these glasses.…”

Section: Intermediate Phases In Solid Electrolyte Glassessupporting

confidence: 89%

Raman scattering as a probe of intermediate phases in glassy networks

Boolchand

Jin

Novita

et al. 2007

J Raman Spectroscopy

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Bulk glass formation occurs over a very small part of phase space, and 'good' glasses (which form even at low quench rates ∼10 K/sec) select an even smaller part of that accessible phase space. An axiomatic theory provides the physical basis of glass formation, and identifies these sweet spots of glass formation with existence of rigid but stress-free networks for which experimental evidence is rapidly emerging. Recently, theory and experiment have come together to show that these sweet spots of glass formation occur over a range of chemical compositions identified as 'intermediate phases' (IPs). These ranges appear to be controlled by elements of local and medium-range molecular structures that form isostatically rigid networks. IP glasses possess nonhysteretic glass transitions (T g 's) that do not age much. Raman scattering has played a pivotal role in elucidating the molecular structure of glasses in general, and in identifying domains of IPs. Experiments reveal that these phases possess sharp phase boundaries and are characterized by an optical elasticity that varies with network mean coordination number, r, as power law. In this review, we provide examples in chalcogenide and oxide glass systems in which these phases along with optical elasticity power laws have been established. IP glasses represent self-organized nanostructured functional materials optimized by nature.

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Section: Intermediate Phases In Solid Electrolyte Glassessupporting

confidence: 89%

Raman scattering as a probe of intermediate phases in glassy networks

Boolchand

Jin

Novita

et al. 2007

J Raman Spectroscopy

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show abstract

“…In (K 2 O) x (GeO 2 ) 1−x glasses, Jain et al 40 estimate E c to be ≃ 0.5 eV, typically 30% of E A (≃ 1.5 eV) at x < 0.10. Reverse Monte Carlo Models of (AgPO 3 ) x (AgI) 1−x glasses by Wicks et al have also emphasized E c to be small 42 , and E s to be the major contributor to E A . A similar conclusion is reached by Adams and Swenson 43 , who explicitly reveal that strain energy dominates ionic conductivity.…”

Section: Coulomb Energy Ec and Ag + Ion Mobilitiesmentioning

confidence: 99%

Fast-ion conduction and flexibility and rigidity of solid electrolyte glasses

et al. 2009

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Electrical conductivity of dry, slow cooled (AgPO3)1−x(AgI)x glasses is examined as a function of temperature , frequency and glass composition. From these data compositional trends in activation energy for conductivity EA(x), Coulomb energy Ec(x) for Ag + ion creation, Kohlrausch stretched exponent β(x), low frequency (εs(x)) and high-frequency (ε∞(x)) permittivity are deduced. All parameters except Ec(x) display two compositional thresholds, one near the stress transition, x = xc(1)= 9%, and the other near the rigidity transition, x = xc(2)= 38% of the alloyed glass network. These elastic phase transitions were identified in modulated-DSC, IR reflectance and Raman scattering experiments earlier. A self-organized ion hopping model (SIHM) of a parent electrolyte system is developed that self-consistently incorporates mechanical constraints due to chemical bonding with carrier concentrations and mobility. The model predicts the observed compositional variation of σ(x), including the observation of a step-like jump when glasses enter the Intermediate Phase at x>xc(1), and an exponential increase when glasses become flexible at x>xc(2). Since Ec is found to be small compared to network strain energy (Es), we conclude that free carrier concentrations are close to nominal AgI concentrations, and that fast-ion conduction is driven largely by changes in carrier mobility induced by an elastic softening of network structure. Variation of the stretched exponent β(x) is square-well like with walls localized near xc(1) and xc(2) that essentially coincide with those of the Intermediate Phase (IP) (xc(1)

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“…Its corresponding amplitude and phase were calculated by the program FEFF. 26 We performed RMC simulation [27][28][29][30] simultaneously for three experimental data ͑one S͑Q͒ and two EXAFS Zr and Ni K-edge ͓ ͑k͔͒ spectra͒ to get the atomic configuration of Zr 70 Ni 30 MG as reliable as possible. Before the simulation, a box, containing 5000 atoms following its composition and hard sphere dense-packed ͑HSDP͒ model, was built.…”

Section: Methodsmentioning

confidence: 99%

“…5 Stability of MG is linked with its atomic structure, 6,7 which correlates with atomic structure of the corresponding crystalline phase by annealing. 8,9 For example, icosahedral clusters are found to be dominant atomic structure in Zr 70 Cu 29 Pd 1 MG, 10,11 which leads to primary phase transition by forming icosahedral quasicrystal 12,13 after annealing, while Zr 70 Ni 30−x Pd x ͑x Ͻ 10 at. % ͒ MGs do not exhibit such primary precipitation.…”

Section: Introductionmentioning

confidence: 99%

Atomic structure in Zr70Ni30 metallic glass

Yang

Yin

Wang

et al. 2007

Journal of Applied Physics

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Atomic structure of Zr 70 Ni 30 metallic glass ͑MG͒ was investigated by reverse Monte Carlo simulation combining with x-ray diffraction and Ni and Zr K-edge extended x-ray absorption of fine structure measurements. Distributions of coordination number ͑CN͒ and Voronoi clusters were analyzed by Voronoi tessellation method. The average CN of atoms was obtained to be 11.4 together with the average CN of Zr and Ni atoms of about 11.8 and 10.6, respectively. It is found that Z11 Kasper polyhedron and distorted icosahedra are mainly favored structural units in INTRODUCTIONAtomic structure of metallic glasses ͑MGs͒ has been studied experimentally and theoretically 1-4 because their extraordinary mechanical and magnetic properties strongly depend on their atomic structures. Gaskell proposed that atomic structure of MG is similar with that of corresponding crystalline phases. 5 Stability of MG is linked with its atomic structure, 6,7 which correlates with atomic structure of the corresponding crystalline phase by annealing. 8,9 For example, icosahedral clusters are found to be dominant atomic structure in Zr 70 Cu 29 Pd 1 MG, 10,11 which leads to primary phase transition by forming icosahedral quasicrystal 12,13 after annealing, while Zr 70 Ni 30−x Pd x ͑x Ͻ 10 at. % ͒ MGs do not exhibit such primary precipitation. 8 Furthermore, Zr-Cu binary MGs exhibit a glass transition event, whereas Zr-Ni binary MGs do not, 14 which might be due to their different atomic structures. 8 Thus, studies of atomic structure in such simple MGs are strongly demanded, which will promote our understanding to multicomponent bulk metallic glasses. However, structure of Zr-Ni MGs is still not completely understood [15][16][17][18] in spite of its wide amorphous-forming compositional range. 19 In the present work, we report the atomic structure of a Zr 70 Ni 30 MG by reverse Monte Carlo ͑RMC͒ simulation combining with x-ray diffraction ͑XRD͒ and extended x-ray absorption of fine structure ͑EXAFS͒ as well as Voronoi tessellation method. EXPERIMENTZr 70 Ni 30 ingot was prepared by arc melting high-purity metals ͑99.8% Zr and 99.9% Ni͒. Amorphous ribbons with a cross section of 0.03ϫ 2 mm 2 were obtained from these alloys by single-roller melt spinning at a wheel surface velocity of 30 m / s in purified Ar atmosphere. The oxygen content of the as-prepared ribbon samples was analyzed to be less than 800 mass ppm by inductively coupled plasma spectroscopy. The influence of oxygen on the transformation behavior can thus be disregarded. 20,21 Room-temperature high resolution XRD measurements were carried out for as-prepared Zr 70 Ni 30 sample with high energy x-ray ͑100 keV͒ at beamline BW5, Hasylab in Germany. Diffraction patterns were recorded by a Mar2300 image plate. Beamstop was located away from the center to record data with larger Q ͑wave vector transfer͒ range, resulting in high resolution in real-space reduced pair distribution function G͑r͒. XRD patterns were integrated to Q-space data file after subtracting its background by the program FIT...

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Structure and Ionic Conduction in(AgI)x(AgPO3

Cited by 162 publications

References 27 publications

Raman scattering as a probe of intermediate phases in glassy networks

Raman scattering as a probe of intermediate phases in glassy networks

Fast-ion conduction and flexibility and rigidity of solid electrolyte glasses

Atomic structure in Zr70Ni30 metallic glass

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