Critical TemperaturesTcof Ionic-Crystal Model for Infinite-Layer Compounds

Using several measured and calculated physical properties, we argue that the high-Tc metal-oxide superconductor Y1Ba2Cu3O7 is elastically soft compared with BaTiO3 or SrTiO3. We conclude that the bulk modulus equals approximately 107 GPa, despite several high-pressure x-ray diffraction studies that report values up to approximately 200 GPa. Part of the argument uses an ionic-crystal-model calculation of the bulk modulus.

Download Full-text

Elastic constants of polycrystalline Y1Ba2Cu3Ox

Journal of Materials Research ◽

10.1557/jmr.1992.2905 ◽

1992 ◽

Vol 7 (11) ◽

pp. 2905-2907 ◽

Cited By ~ 18

Author(s):

Hassel Ledbetter

Keyword(s):

Grain Boundary ◽

Bulk Modulus ◽

Debye Temperature ◽

Oxygen Content ◽

Elastic Constants ◽

Model Prediction ◽

Ionic Crystal ◽

Poisson Ratio ◽

Young’S Moduli ◽

Crystal Model

We measured the elastic constants of polycrystalline Y1Ba2Cu3Ox with eleven oxygen contents varying from 6.2 to 6.9. Reported properties include sound velocities; bulk, shear, Young's moduli; Poisson ratio; Debye temperature. After correction to the void-free state, the measurements fail to show a systematic dependence on oxygen content. Focusing on the bulk modulus, all measurements fall below an ionic-crystal model prediction, by 5–50%. We attribute this macroscopic softness to either microcracks or weak grain-boundary mechanical linkages. For the case x = 6.9, we suggest a set of intrinsic elastic constants.

Download Full-text

Relaxation times and ergodic properties in a realistic ionic-crystal model, and the modern form of the FPU problem

Physica A Statistical Mechanics and its Applications ◽

10.1016/j.physa.2019.121911 ◽

2019 ◽

Vol 532 ◽

pp. 121911 ◽

Cited By ~ 2

Author(s):

Andrea Carati ◽

Luigi Galgani ◽

Fabrizio Gangemi ◽

Roberto Gangemi

Keyword(s):

Ionic Crystal ◽

Relaxation Times ◽

Ergodic Properties ◽

Crystal Model ◽

Modern Form ◽

Fpu Problem

Download Full-text

The Nonempirical Calculation of the Cation Ordering and Lattice Dynamics in the Solid Solutions of PbSc1/2Nb1/2O3 and PbSc1/2Ta1/2O3

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.115.305 ◽

2006 ◽

Vol 115 ◽

pp. 305-310

Author(s):

V.I. Zinenko ◽

S.N. Sofronova

Keyword(s):

Solid Solutions ◽

Ionic Crystal ◽

Mean Field ◽

Nonempirical Calculation ◽

Cation Ordering ◽

Effective Hamiltonian ◽

The Monte Carlo Method ◽

Ordered Phases ◽

Phase Transition Temperatures ◽

Crystal Model

An effective Hamiltonian for the study of Sc–Nb(Ta) cation ordering in PbSc1/2Nb(Ta)1/2O3 solid solutions is worked out. To determine the parameters of the effective Hamiltonian, a nonempirical calculation is performed within an ionic-crystal model taking into account the deformation, dipole, and quadrupole polarizabilities of ions. The phase transition temperatures are calculated by the mean field, the cluster approximations, and the Monte-Carlo method. Within the same ionic-crystal model, we calculated the high-frequency permittivity, Born dynamic charges, and the phonon spectrum for completely disordered and ordered phases.

Download Full-text

Nano-probe x-ray analysis and high-resolution imaging on planar defects in high-pressure synthesized infinite-layer superconductor

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171377 ◽

1994 ◽

Vol 52 ◽

pp. 728-729

Author(s):

Y. Y. Wang ◽

H. Zhang ◽

V. P. Dravid ◽

H. Zhang ◽

L. D. Marks ◽

...

Keyword(s):

High Pressure ◽

High Resolution ◽

Atomic Structure ◽

Emission Spectra ◽

High Resolution Electron Microscopy ◽

Planar Defects ◽

X Ray ◽

Infinite Layer ◽

Resolution Electron ◽

Resolution Imaging

Azuma et al. observed planar defects in a high pressure synthesized infinitelayer compound (i.e. ACuO2 (A=cation)), which exhibits superconductivity at ~110 K. It was proposed that the defects are cation deficient and that the superconductivity in this material is related to the planar defects. In this report, we present quantitative analysis of the planar defects utilizing nanometer probe xray microanalysis, high resolution electron microscopy, and image simulation to determine the chemical composition and atomic structure of the planar defects. We propose an atomic structure model for the planar defects.Infinite-layer samples with the nominal chemical formula, (Sr1-xCax)yCuO2 (x=0.3; y=0.9,1.0,1.1), were prepared using solid state synthesized low pressure forms of (Sr1-xCax)CuO2 with additions of CuO or (Sr1-xCax)2CuO3, followed by a high pressure treatment.Quantitative x-ray microanalysis, with a 1 nm probe, was performed using a cold field emission gun TEM (Hitachi HF-2000) equipped with an Oxford Pentafet thin-window x-ray detector. The probe was positioned on the planar defects, which has a 0.74 nm width, and x-ray emission spectra from the defects were compared with those obtained from vicinity regions.

Download Full-text