A new method for measuring the degree of preferred orientation in bulk textured YBa2Cu3Ox

Leventouri, Th.

doi:10.1016/s0921-4534(97)00063-4

Cited by 12 publications

(9 citation statements)

References 6 publications

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“…During the refinement, the isotropic displacement parameters were kept at the values evaluated by single-crystal diffraction. In the final steps of the Rietveld refinement possible preferential orientation was modeled using an eighthorder spherical-harmonic description [39,40]. The average Cu-S bond length in the structure of the orthorhombic lowtemperature phase based on the Rietveld refinement is about 2.3(2)Å, which is in good agreement with the average bond length of 2.33(5) established by single-crystal diffraction.…”

Section: X-ray Diffractionsupporting

confidence: 67%

“…In accordance with published data for copper sulfides [38] isotropic thermal displacement parameters were fixed at 0.04Å 2 for copper and at 0.02Å 2 for sulfur during the refinement. In the final steps of the Rietveld refinement possible preferential orientation was modeled using an eighthorder spherical-harmonic description [39,40].…”

Section: A Characterizationmentioning

confidence: 99%

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Phase transition of tetragonal copper sulfide Cu2S at low temperatures

et al. 2017

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The low-temperature behavior of tetragonal copper sulfide, Cu 2 S, was investigated by powder and singlecrystal x-ray diffraction, calorimetry, electrical resistance measurements, and ambient temperature optical absorption spectroscopy. The experiments were complemented by density-functional-theory-based calculations. High-quality, polycrystalline samples and single crystals of tetragonal copper sulfide were synthesized at 5 GPa and 700 K in a large volume multianvil press. Tetragonal Cu 2 S undergoes a temperature-induced phase transition to an orthorhombic structure at around 202 K with a hysteresis of ±21 K, an enthalpy of reaction of 1.3(2) kJ mol −1 , and an entropy of reaction of 6.5(2) J mol −1 K −1. The temperature dependence of the heat capacity at the transition temperature indicates that the transition from the tetragonal to the low-temperature polymorph is not a single process. The structure of the low-temperature polymorph at 100 K was solved in space group P na2 1. The structure is based on a slightly distorted cubic close packing of sulfur with copper in threefold coordination similar to the structure of tetragonal copper sulfide. The electrical resistance changes several orders of magnitude at the transition following the temperature hysteresis. The activation energy of the conductivity for the tetragonal phase and the low-temperature polymorph are 0.15(2) and 0.22(1) eV, respectively. The direct band gap of the tetragonal polymorph is found to be 1.04(2) eV with the absorption spectrum following Urbach's law. The activation energies and the band gaps of both phases are discussed with respect to the results of the calculated electronic band structures.

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Section: X-ray Diffractionsupporting

confidence: 67%

Section: A Characterizationmentioning

confidence: 99%

Phase transition of tetragonal copper sulfide Cu2S at low temperatures

et al. 2017

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“…If the value is less than 1 the sample texture is said to be plate-like and if the value is greater than 1 the texture is acicular. This method has previously been applied by Leventouri [17], amongst others.…”

Section: Texture Measurementsmentioning

confidence: 99%

Does the preferred orientation of crystallites in tablets affect the intrinsic dissolution?

Tenho¹,

Heinänen²,

Tanninen³

et al. 2007

Journal of Pharmaceutical and Biomedical Analysis

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“…Using this pattern-fitting procedure also the preferred orientation of crystallites in solid dosage forms can be determined in the course of the quantitative analysis. Other studies concerning the evaluation of the degree of preferred orientation using the Rietveld method have been performed by von Dreele [9] and Leventouri [10], for example.…”

Section: Introductionmentioning

confidence: 99%