Vickers hardness measurements and some physical properties of Pr2O3 doped Bi-2212 superconductors

Asikuzun, E.; Öztürk, O.; Çetinkara, H.A.; Yıldırım, G.; Varılcı, A.; Yilmazlar, Mustafa; Terzioğlu, C.

doi:10.1007/s10854-011-0537-0

Cited by 47 publications

(18 citation statements)

References 46 publications

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“…The results obtained are listed in Table 3. As seen from the table, the value of a is positive for the Lu0.1, Lu0.3, Lu0.5 and Lu0.7 samples showing the ISE behavior whereas it is negative for the virgin sample exhibiting RISE behavior, verifying that both the elastic and plastic deformations are produced in the Lu-doped samples [31][32][33]. In other words, there is no elastic (reversible) deformation for sample obeying RISE behavior.…”

Section: Analysis According To Psr Modelmentioning

confidence: 74%

Experimental and theoretical approaches on mechanical evaluation of Y123 system by Lu addition

Turkoz

Nezir

Öztürk

et al. 2013

J Mater Sci: Mater Electron

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This work is the continuation of a systematic study on the characterization of the Lu-added Y123 bulk superconducting materials prepared by the nitrate compounds and derivatives at 970°C for 20 h. In this part, the effect of Lu inclusions on the physical and mechanical properties of the Y123 superconductors is examined with the aid of microhardness measurements performed at various applied loads in the range of 0.245-2.940 N. The microhardness measurement results allow us to determine the important mechanical characteristics such as Vickers microhardness, elastic (Young's) modulus, yield strength and fracture toughness values being responsible for the potential industrial applications. It is found that all the properties given above are strongly dependent upon the Lu concentration in the Y123 matrix. Especially, Vickers microhardness (H v ) values of the samples studied in this work are found to suppressed considerably with the enhancement of the Lu addition in the system due to the degradation in the connectivity between superconducting grains. Moreover, the H v values of the pure Y123 sample are observed to increase with increasing the applied load whereas those of the Lu-doped superconducting materials are obtained to decrease with the load. In other words, the pure sample exhibits the reverse indentation size effect (RISE) behavior while the others obey the indentation size effect (ISE) feature, confirming the degradation in the mechanical properties with the Lu inclusions in the Y123 matrix. In addition, the microhardness measurement results are estimated using the 5 different models such as Meyer's law, proportional sample resistance model, elastic/plastic deformation model, Hays-Kendall (HK) approach and indentation-induced cracking (IIC) model. According to the results obtained from the simulations, of the mechanical analysis models, the Hays-Kendall (HK) approach is determined as the most successful model for the description of the mechanical properties of the Lu-doped superconducting materials (exhibiting the ISE behavior) where both the both the reversible (elastic) and irreversible (plastic) deformations are produced. On the other hand, the IIC model is found to be superior to other approaches for the pure sample (presenting the RISE feature) where the irreversible deformation becomes more and more dominant compared to the reversible deformation.

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Section: Analysis According To Psr Modelmentioning

confidence: 74%

Experimental and theoretical approaches on mechanical evaluation of Y123 system by Lu addition

Turkoz

Nezir

Öztürk

et al. 2013

J Mater Sci: Mater Electron

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“…It is obtained from the Table 2 that the microhardness values enhance with ascending the Gd content and the Gd4 sample, among the samples studied, has the highest microhardness values for all the applied loads. In fact, the microhardness value of 3.577 GPa is found to be the maximum for the Gd4 sample whereas the minimum value (2.705 GPa) is obtained for the Gd0 sample in the applied load of 2.940 N. The increase of microhardness value with the increment of the Gd doping can be explained by the formation of impurities, porosities and irregularities as observed in the SEM investigations [40,41]. The H v (in GPa unit) value computed reduces rapidly with ascending F(N) up to 2 N and remains approximately constant hereafter.…”

Section: Microhardness and Modelingmentioning

confidence: 84%

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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“…Therefore, the researchers have attempted to improve the superconducting, mechanical, structural and flux pinning properties of the superconductors to make them suitable for high temperature and magnetic field applications [1][2][3][4]. The Bi-Sr-Ca-Cu-O (BSSCO) materials, one of the cuprate high-temperature superconductor families, have widely been investigated because of their higher critical temperature, remarkable smaller power losses, higher current and magnetic field carrying capacity, optical and electronic properties [5][6][7][8][9][10][11][12][13]. Moreover, in the literature there have been several reports relating to BSCCO films for high frequency applications including filters, antennas and magnetic shield devices [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…In order to overcome these problems appeared, the flux pinning mechanism in the film should be investigated in detail. In the recent works [12][13][14][15][16][17][18][19][20][21][22][23][24], the researchers have extensively analyzed the flux pinning mechanism in the superconducting state to introduce the effective pinning centers such as planar defects, stacking faults, and microdefects, resulting in thermally activated jumps; or hopping of flux lines; or flux bundles over an energy barrier [25,26]. Over the pinning energy barrier of a structure, the flux line might be thermally activated although the Lorentz force exerted on the flux bundle by the current is smaller than the pinning force [27][28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Effect of Magnetic Field Direction on Magnetoresistivity, Activation Energy, Irreversibility and Upper Critical Field of Bi-2212 Thin Film Fabricated by DC Sputtering Method

Bal

Varılcı

2012

J Supercond Nov Magn

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This study aims to investigate the effect of magnetic field direction on superconducting properties of Bi-2212 thin film fabricated on MgO (100) substrate using the direct current (DC) magnetron reactive sputtering technique at 100 watt with the aid of magnetoresistivity measurements. The zero resistivity transition temperatures (T c ), irreversibility fields (μ 0 H irr ) and upper critical fields (μ 0 H c2 ) are deduced from the magnetoresistivity versus temperature curves under DC magnetic fields (parallel and perpendicular to c-axis) up to 5 T. Moreover, thermally activated flux flow (TAFF) model is studied for activation energy (U 0 ) values of the sample. It is found that the T c value decreases from 76.4 K to 39.1 K for the applied magnetic field perpendicular to c-axis (μ 0 H ⊥c-axis); likewise, the T c reduces towards 28.8 K with the increase in the applied field parallel to c-axis (μ 0 H c-axis). Furthermore, the U 0 values are found to decrease considerably with increasing applied magnetic field. In fact, the U 0 of 134.5 K is obtained to be smallest at 5 T field parallel to the c-axis. Additionally, both the μ 0 H irr and μ 0 H c2 values determined are also observed to reduce with the increase of the applied magnetic field. At absolute zero temperature (T = 0 K), the extrapolation of the μ 0 H irr (T ) and μ 0 H c2 (T ) curves is used to obtain the μ 0 H irr (0) and μ 0 H c2 (0) values of the film, respectively. The inner is found to be about 22.216 T (19.046 T) for the applied field perpendicular (parallel) to c-axis whereas the latter is determined to be about 54.095 T (126.522 T) for the applied field parallel (perpendicular) to c-axis, respectively, as a result of anisotropic behavior of the film prepared. On the other hand, penetration depths (λ) and coherence lengths (ξ ) inferred from μ 0 H irr (0) and μ 0 H c2 (0) values are obtained to be about 38.519 Å (41.601 Å) and 16.147 Å (24.685 Å) in the case of applied field perpendicular (parallel) to c-axis, respectively. Based on all the results, the change of the superconducting properties as a function of the magnetic field direction presents the anisotropy of the sample produced. X-ray diffraction (XRD) and scanning electron microscopy (SEM) examinations are also conducted for microstructural and phase analyses of the film.

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Vickers hardness measurements and some physical properties of Pr2O3 doped Bi-2212 superconductors

Cited by 47 publications

References 46 publications

Experimental and theoretical approaches on mechanical evaluation of Y123 system by Lu addition

Experimental and theoretical approaches on mechanical evaluation of Y123 system by Lu addition

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

Effect of Magnetic Field Direction on Magnetoresistivity, Activation Energy, Irreversibility and Upper Critical Field of Bi-2212 Thin Film Fabricated by DC Sputtering Method

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