Role of diffusion-annealing time on the superconducting, microstructural and mechanical properties of Cu-diffused bulk MgB2 superconductor

Doğruer, M.; Görür, O.; Zalaoğlu, Y.; Öztürk, O.; Varılcı, A.; Terzioğlu, C.

doi:10.1007/s10854-012-0755-0

Cited by 18 publications

(6 citation statements)

References 33 publications

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“…This region is referred to as the plateaued region and corresponds to independent (true) microhardness values of the samples. These plateaued zones are due to increased impurity phases, grain boundary weak connections, cracking/ porosity, disorder, and irregular grain orientation distribution in the crystal lattice [28,29].…”

Section: Vickers Microhardness Measurement Examinationmentioning

confidence: 99%

Improving Superconductivity, Microstructure, and Mechanical Properties by Substituting Different Ionic Pb Elements to Bi and Ca Elements in Bi-2223 Superconductors

Sarıtekin

Uzumcu

2022

J Supercond Nov Magn

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In this detailed study, the changes of microstructural, mechanical, and superconducting features of bulk Bi1.8Pb0.2Sr2.0Ca1.8Pb0.2Cu3Oy materials prepared at different milling time intervals (0.5 h ≤ x ≤ 8 h) were investigated in the most precise manner. The measurements of X-ray powder diffraction (XRD) and Vickers microhardness (Hv) were designed to scrutinize the bulk BSCCO samples. All the results of the measurements and calculations show that the characteristics responsible for the applications of the technology, industry, and engineering are significantly improved up to the 3 h milling time beyond that they tend to deteriorate. The enhancement of the characters is generally related to the transition from underdoped level of the (Bi, Pb)-2223 to the optimum level with the milling duration and this event approves that sufficient Pb nanoparticles penetrate the crystal structure. On the other hand, some of the reasons for the suppression in the superconducting properties are the presence of the porosity, disorder, defects, and the localization problem in the Cu-O2 consecutively stacked layers. In addition to those mentioned above, the other reasons are degradation in the crystallinity, reduction in the average crystallite size, and decrease in mobile hole concentration in the Cu-O2 layers. Similarly, the Pb inclusion rises the artificial random dislocations and grain boundary weak-links in the (Bi, Pb)-2223 superconducting system. Vickers microhardness measurements show that (Bi, Pb)-2223 bulk superconducting specimens exhibit typical indentation size behavior depending on the presence of both elastic and plastic deformations in the system. The results obtained from the hardness measurements have been analyzed by using Meyer law, PRS model, MPRS model, elastic–plastic deformation model, and Hays-Kendall approach. As a result, the Hays-Kendall approach was identified as the most successful model in describing the mechanical properties of the samples.

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Section: Vickers Microhardness Measurement Examinationmentioning

confidence: 99%

Improving Superconductivity, Microstructure, and Mechanical Properties by Substituting Different Ionic Pb Elements to Bi and Ca Elements in Bi-2223 Superconductors

Sarıtekin

Uzumcu

2022

J Supercond Nov Magn

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“…Numerically, the H v It is another probable result that the abrupt decrease in the independent microhardness values substitutes for the constant variation after the critical test load of about 2 N due to the presence of the saturation regions. The main reason of the plateau regions results from the increased impurity phases, grain boundary weak-connections, disorder, cracking/porosity and irregular grain orientation distribution in the crystal lattice [46,47]. Even, the similar results including the change of the elastic properties are verified from the X-ray crystal structures pertaining to the inorganic compounds.…”

Section: Vickers Micro Hardness Measurement Analysismentioning

confidence: 59%

Solubility limit of tetravalent Zr nanoparticles in Bi-2223 crystal lattice and evaluation of fundamental characteristic properties of new system

Sarıtekin

Terzioğlu

Pakdil

et al. 2015

J Mater Sci: Mater Electron

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In this comprehensive work, we focus sensitively on the changes of microstructural, electrical, superconducting and mechanical properties belonging to the bulk Bi 1.7 Pb 0.4 Sr 2.0 Ca 2.0 Zr x Cu 3.1 O y materials with the different Zr nanoparticles (0 B x B 1.0) inserted in the superconducting matrix. The characterizations of the materials prepared are experimentally performed by bulk density, dc resistivity (q-T), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-ray (EDX) and Vickers microhardness (H v ) investigations. It is found that all the characteristics given above (especially superconducting properties) degrade considerably with the increment in the Zr addition level, and in fact they reach to the global minimum points in case of the maximum dopant level. The main reason of the rapid decrement in the electrical and superconducting properties stems from the presence of the localization problem in the Cu-O 2 consecutively stacked layers. Likewise, the Zr foreign addition increases the artificial random defects, dislocations and grain boundary weak-links in the superconducting system, even being favored by the SEM examinations. At the same time, the EDX surveys indicate that the Zr nanoparticles in the tetravalent state prefer to substitute for the divalent states of the Cu inclusions through the crystal structure as a result of their close ionic radius values (86 pm for Zr 4? ion and 87 pm for Cu 2? ion). Thus, the differentiation of the electronegativity reduces the mobile hole concentration in the Cu-O 2 slabs. Additionally, the XRD experimental findings show that there is a systematic decrement in the Bi-2223 (high) phase up to the Zr concentration level of x = 0.70 beyond which new characteristics peaks of ZrO 2 appear immediately. This is in relation to the fact that the solubility limit corresponding to the Zr foreign impurity in the Bi-2223 system is about x = 0.70. Similarly, the regular decrement in both the c-axis length and crystallite size with the dopant confirms the deterioration of the superconducting properties. Furthermore, the dramatic reduction of the H v values stems from the suppression of the crystallinity and connection quality in the intergrain coupling of the superconducting samples exhibiting typical Indentation Size Effect behavior due to the existence of both elastic and plastic deformations in the system.

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“…This behavior is known as indentation size effect (ISE) [43][44][45]. Dogruer et al obtained the similar results for the Cu-diffused bulk MgB 2 superconductor samples [33,46].…”

Section: Microhardness and Modelingmentioning

confidence: 76%

Investigation of microstructural, Vickers microhardness and superconducting properties of YBa2Cu3−xGdxO7−δ (0 ≤ x ≤ 0.150) superconducting ceramics via experimental and theoretical approaches

Doğruer

Öztürk

Varılcı

et al. 2012

J Mater Sci: Mater Electron

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This study manifests the change of pinning mechanism, electrical, structural, physical, mechanical and superconducting properties of YBa 2 Cu 3-x Gd x O 7-d superconductors samples prepared by the conventional solidstate reaction method (x = 0, 0.025, 0.050, 0.100 and 0.150) by use of dc resistivity, X-ray analysis (XRD), scanning electron microscopy (SEM) and Vickers microhardness measurements. Zero resistivity transition temperatures (T c offset ) of the samples are deduced from the dc resistivity measurements. Additionally, the lattice parameters are determined from XRD measurements when the microstructure, surface morphology and microhardness of the samples studied are examined by SEM and mechanical measurements, respectively. The results obtained demonstrate that T c offset values of the samples decrease slowly with the increase in the Gd content. The maximum T c offset (92.0 K) is obtained for the pure sample prepared at 940°C for 20 h in air atmosphere while the minimum value of 83.3 K is found for the sample doped with 0.150 Gd content. Moreover, it is obtained that J c values reduce from 132 to 34 A/cm 2 with the enhancement of the Gd level in the crystalline structure. Further, the peak intensities belonging to Y123 (major) phase are obtained to decrease whereas the peak intensities of the minor phases such as BaCuO 2 and Y211 are found to enhance systematically with the increment in the Gd content in the system, illustrating that partial substitution of Cu 2? ions by Gd 3? ions are carried out successfully. Moreover, SEM images display that the undoped sample obtains the best crystallinity and connectivity between superconducting grains and largest grain size whereas the worst surface morphology is observed for the maximum doped sample (x = 0.150). At the same time, Vickers microhardness, elastic modulus, load independent hardness, yield strength, fracture toughness and brittleness index values, playing important roles on the mechanical properties, are computed for all the samples. The experimental results of the microhardness measurements are examined using the Meyer's law, PSR (proportional specimen resistance), modified PRS, ElasticPlastic deformation model (EPD) and Hays-Kendall (HK) approach. The microhardness values obtained increase with the enhancement of the Gd content in the samples. Besides, it is noted that the Hays-Kendall approach is the most successful model explaining the mechanical properties of the samples studied in this work.

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Role of diffusion-annealing time on the superconducting, microstructural and mechanical properties of Cu-diffused bulk MgB2 superconductor

Cited by 18 publications

References 33 publications

Improving Superconductivity, Microstructure, and Mechanical Properties by Substituting Different Ionic Pb Elements to Bi and Ca Elements in Bi-2223 Superconductors

Improving Superconductivity, Microstructure, and Mechanical Properties by Substituting Different Ionic Pb Elements to Bi and Ca Elements in Bi-2223 Superconductors

Solubility limit of tetravalent Zr nanoparticles in Bi-2223 crystal lattice and evaluation of fundamental characteristic properties of new system

Investigation of microstructural, Vickers microhardness and superconducting properties of YBa2Cu3−xGdxO7−δ (0 ≤ x ≤ 0.150) superconducting ceramics via experimental and theoretical approaches

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