| 1. |
- Thomas, HS, et al.
(author)
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- 2019
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swepub:Mat__t
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| 2. |
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| 3. |
- Dou, S.X., et al.
(author)
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Improvement of critical current density in the Bi-Pb-Sr-Ca-Cu-O system through hot isostatic pressing
- 1990
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In: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 167:5-6, s. 525-528
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Journal article (peer-reviewed)abstract
- The effects of hot isostatic pressing (HIPing) on densification and the superconducting properties of the Bi-Pb-Sr-Ca-O system were investigated. A relative density up to 95% and a critical current density greater than 1100 A/cm2 at 77 K were achieved through HIPing at 650°C for 2 h under 200 MPa argon. Under these conditions, the product gave a value of Jc four times that without HIPing. To was unaffected by HIPing for samples encapsulated with a combination of glass and silver tubes. However, To was suppressed from 103 K to 86 K for samples encapsulated with stainless steel and silver tubes while Jc increased from 260 A/ cm2 to 1086 A/cm2 during HIPing, indicating that the weak links were significantly improved. A new minor phase, having a composition of Bi/Pb/Sr/Ca/Cu=0.58/2.8/3.0/2.1/1.1, was observed in HIPed samples but its effect on Jc is not clear
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| 4. |
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| 5. |
- Andersson, Britt M., et al.
(author)
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Electrical transport properties of dense bulk YBa2Cu4O8 produced by hot isostatic pressing
- 1990
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In: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 170:5-6, s. 521-531
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Journal article (peer-reviewed)abstract
- Highly dense sintered YBa2Cu4O8 has been produced by hot isostatic pressing (HIP). The electrical resistivity varrho of this material has been measured as a function of temperature T and pressure varrho in the range 40–650 K and 0–0.7 GPa. Both the temperature dependence and the pressure dependence of varrho are found to be well described by a model based on the standard Bloch-Grüneisen theory. It is pointed out that varrho is liner in T only under isobaric conditions, while varrho is strongly nonlinear in all high-Tc superconductors under isochoric (constant volume) conditions. The critical current density of the material is 900 A/cm2 at 4 K, while the resistivity is 630 μΩ cm at 294 K.
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| 6. |
- Easterling, K.E., et al.
(author)
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The microstructure and properties of high Tc superconducting oxides
- 1990
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In: Science Progress. - 0036-8504 .- 2047-7163. ; 74:293, s. 69-90
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Journal article (peer-reviewed)abstract
- There has been considerable progress in producing and characterizing high Tc superconductors, but a number of materials science-related problems still exist, before their mechanical and electrical properties meet the requirements of many of the proposed applications. These materials are brittle, ceramic compounds with long unit cells that can be thought of as formed from layers of various oxides are an important common feature. The long unit cell structure leads to anisotropy in their electrical and mechanical properties, including the current carrying capacity or current density Jc. The crystallography and microstructure of the three major families of high Tc superconductors are reviewed and possible solutions to some of the materials problems are presented
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| 7. |
- Espenes, J., et al.
(author)
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Regression-based normative data for the Rey Auditory Verbal Learning Test in Norwegian and Swedish adults aged 49-79 and comparison with published norms
- 2023
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In: Clinical Neuropsychologist. - : Informa UK Limited. - 1385-4046 .- 1744-4144. ; 37:6, s. 1276-1301
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Journal article (peer-reviewed)abstract
- Objective: The Rey Auditory Verbal Learning Test (RAVLT) is a widely used measure of episodic verbal memory. To our knowledge, culturally adapted and demographically adjusted norms for the RAVLT are currently not available for Norwegian and Swedish adults, and imported North American norms are often used. We here develop regression-based norms for Norwegian and Swedish adults and compare our norms to North American norms in an independent sample of cognitively healthy adults. Method: Participants were 244 healthy adults from Norway and Sweden between the aged 49 and 79 years, with between 6 and 24 years of education. Using a multiple multivariate regression-based norming procedure, we estimated effects of age, sex, and years of education on basic and derived RAVLT test scores. The newly developed norms were assessed in an independent comparison group of cognitively healthy adults (n = 145) and compared to recently published North American regression-based norms. Results: Lower age, female sex and more years of education predicted higher performance on the RAVLT. The new norms adequately adjusted for age, education, and sex in the independent comparison group. The American norms corrected for demographics on all RAVLT trials except trials 4, 7, list B, and trials 1-5 total. Test-retest (M = 2.55 years) reliability varied from poor to good. Conclusion: We propose regression-based norms for the RAVLT adjusting for pertinent demographics. The norms may be used for assessment of Norwegian and Swedish adults between the aged of 49 and 79 years, with between 6 and 24 years of education.
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| 8. |
- Niska, John, et al.
(author)
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Effect of oxygen loss on densification when hot isostatic pressing YBa2Cu3O7-δ
- 1989
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In: Journal of The American Ceramic Society. - : Wiley. - 0002-7820 .- 1551-2916. ; 72:8, s. 1508-1510
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Journal article (peer-reviewed)abstract
- Hot isostatic pressing of the high-Tc superconductor YBa2Cu3O7-δ can lead to loss of oxygen and transformation of the material from the high-Tc orthorhombic phase to the nonsuperconducting tetragonal phase. It is shown that glass encapsulation helps retain the orthorhombic structure, whereas steel encapsulation resulted in formation of the tetragonal phase. Reasons for this phenomenon are discussed. The equilibrium oxygen gas pressure for the oxygen decomposition reaction in YBa2Cu3O7, however, prevents full densification of this material in glass when employing hot isostatic pressing conditions of 200 MPa and 845°C.
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| 9. |
- Niska, John, et al.
(author)
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Thermal expansivity of HIP synthesized YBa2Cu4O8
- 1991
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In: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 44:1, s. 93-94
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Journal article (peer-reviewed)abstract
- The thermal expansion coefficient of a sample of the YBa2Cu4O8 phase superconductor was measured using a low temperature X-ray diffractometer. The thermal expansivity was found to be highly anisotropic. The average coefficient of thermal expansion over the temperature range of 150 to 450 K was approximately equal for the a and b axes at 9×10-6/°C, vs a coefficient of about 15×10-6/°C for the c axis. This would indicate that the bonding is weaker along the c-axis than in the ab-plane and that the specific heat of single crystals of the high Tc superconductors can depend on their geometry. The low thermal expansivity in the ab-plane relative to typical metal conductors as copper and silver could lead to compressive stresses in the superconductor when cooling a composite metal-superconductor wire having good alignment of the ab-plane along the wire axis
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