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Open AccessArticle

Comparative Study on AC Susceptibility of YBa2Cu3O7−δ Added with BaZrO3 Nanoparticles Prepared via Solid-State and Co-Precipitation Method

1
Department of Physics, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
2
School of Fundamental Science, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
3
Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
4
Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia
5
Shibaura Institute of Technology, 3 Chome-7-5 Toyosu, Koto, Tokyo 135-8548, Japan
*
Author to whom correspondence should be addressed.
Crystals 2019, 9(12), 655; https://doi.org/10.3390/cryst9120655
Received: 11 September 2019 / Revised: 4 November 2019 / Accepted: 6 November 2019 / Published: 9 December 2019
(This article belongs to the Special Issue Synthesis and Characterization of New Superconductors Materials)

Abstract

Polycrystalline samples of YBa2Cu3O7−δ (Y-123) added with x mol% of BaZrO3 (BZO) nanoparticles (x = 0.0, 2.0, 5.0, and 7.0) were synthesized using co-precipitation (COP) and solid-state (SS) method. X-ray diffraction (XRD) patterns showed the formation of Y-123 and Y-211 as the major and minor phases, respectively. The samples prepared using COP method showed higher weight percentage of Y-123 phase (≤98%) compared to the SS samples (≤93%). A peak corresponding to BZO was also found in the samples added with BZO nanoparticles. The increasing intensity of the BZO peak as the BZO amount increased showed the increasing amount of the unreacted nanoparticles in the samples. Refinement of unit cell lattice parameters indicated that all the samples have an orthorhombic crystal structure and there is no orthorhombic-tetragonal phase transformation. As observed using scanning electron microscopy (SEM), all the samples showed randomly distributed grains with irregular shape. The average grain size for the pure sample prepared using COP method is smaller (0.30 µm) compared with that of the pure SS sample (1.24 µm). Addition of 7.0 mol% BZO led to an increase of average grain size to 0.50 μm and 2.71 μm for the COP and SS samples, respectively, indicating grain growth. AC susceptibility (ACS) measurement showed a decrease in the onset critical temperature, Tc-onset with BZO addition. Comparatively, Tc-onset for the COP samples is higher than that of the SS samples. The value of Josephson’s current, Io increased up to 2.0 mol% BZO addition, above which the Io decreased more drastically for the SS samples. The value of Io is 53.95 μA and 32.08 μA for the 2.0 mol% BZO added SS and COP samples, respectively. The decrease of Io is attributed to the distribution of BZO particles at the grain boundaries as also reflected in the drastic decrease of phase lock-in temperature, Tcj. As a result of smaller average grain size, the presence of more grain boundaries containing insulating BZO particles led to lower Io in the COP samples.
Keywords: AC susceptibility; BaZrO3; co-precipitation; solid-state; YBa2Cu3O7−δ AC susceptibility; BaZrO3; co-precipitation; solid-state; YBa2Cu3O7−δ

1. Introduction

Yttrium-barium-copper-oxide, YBCO is the first type-II high temperature superconductor (HTS) that has been discovered to be superconducting above the boiling point of liquid nitrogen. Among the family members of YBCO, 123 phase (Y-123) shows the highest onset of superconductivity at around 90 K. In order for Y-123 to be more feasible for a wide range of applications, numerous studies have been undertaken to improve its critical temperature, Tc and critical current density, Jc [1,2,3]. In this regard, addition of chemical dopants is one of the most straight forward strategies. It was shown that the addition of BaZrO3 (BZO) nanoparticles into Y-123 improved Jc without affecting much the Tc value [4,5]. This is because BZO did not dope into the structure of Y-123. Instead, they either remained unreacted within the matrix or reacted with Y-123 to form nano-precipitates leading to enhanced flux pinning [6].
Intensive research on fabrication of BZO doped YBCO films was conducted in the past [7,8,9,10,11]. However, limited study of BZO doped YBCO bulks has been reported so far [5,12]. From the perspective of large scale applications, it is essential to investigate the effects of synthesis route and dopant additions on the superconducting properties of YBCO bulks. There are several methods used to synthesize the materials. For example, solid-state (SS) method [13,14] and wet method such as sol-gel [15], co-precipitation (COP) [16,17,18], and thermal treatment [19]. In particular, COP is a highly desirable chemical method used to prepare nanomaterials. The powders obtained by COP method show smaller grain size, higher purity, and better homogeneity compared to that obtained using SS method [20,21]. Moreover, multiple calcination and regrinding process is unnecessary to obtain a good superconducting phase for the COP method [17,22]. Previously, we successfully synthesized YBCO added with nano BZO using COP method [23]. Therefore, we are motivated to carry out a comparative study on structural and superconducting properties of BZO nanoparticles added Y-123 prepared via SS method and COP method. COP can be defined as the process of carrying down a precipitate of substances which are normally soluble under the suitable conditions [24] and the starting materials can be metal acetates or metal nitrates [14].

2. Materials and Methods

Samples with nominal composition of YBa2Cu3O7−δ (Y-123) added with x mol% of BaZrO3 (BZO) nanoparticles (x = 2.0, 5.0, and 7.0) were prepared using solid state (SS) method and co-precipitation (COP) method, respectively.

2.1. Solid-State (SS) Method

To start with, Y2O3 (99.9%, Alfa Aesar, Ward Hill, Massachusetts, USA), BaCO3 (99.8%, Alfa Aesar, Ward Hill, Massachusetts, USA) and CuO (99.9%, Strem Chemical, Newburyport, Massachusetts, USA) with the stoichiometric ratio of Y:Ba:Cu (1:2:3) were mixed and hand-ground for 1 h using a mortar and pestle. Then, the grounded mixture was calcined in air at 940 °C for 12 h. After calcination, the powders were reground for 1 h before adding x mol% (x = 2.0, 5.0, and 7.0, respectively) of BaZrO3 nanoparticles (BZO, >50 nm, 98.5%, Sigma-Aldrich). The mixed powders were reground again and then pressed into circular pellets (~13-mm diameter and 2-mm thickness) by using a hydraulic press with an applied pressure load of five tons. Finally, the pellets were sintered at 950 °C for 12 h and slowly cooled to 450 °C for 12 h at the rate of 1 °C/min under oxygen flow before further cooling to room temperature. Pure samples (x = 0.0) were also prepared according to the same procedure to serve as reference for the purpose of comparison.

2.2. Co-Precipitation (COP) Method

For COP method, appropriate amounts of Y(CH3COO)3·4H2O (99.9% Alfa Aesar), Ba(CH3COO)2 (≥99% Alfa Aesar), and Cu(CH3COO)2.H2O (≥99% Sigma Aldrich) according to the stoichiometric ratio of Y:Ba:Cu (1:2:3) were dissolved in acetic acid to form solution A. To prepare solution B, oxalic acid was dissolved in a mixture of distilled water: 2-propanol (1:1.5). Both solutions A and B were stirred at 300 rpm for 2 h before being cooled in an ice bath. The mixed solution A and B was filtered and dried at 100 °C for 12 h. The obtained dried powders were ground and calcined in air at 900 °C for 24 h. After that, appropriate amount of x mol% (x = 2.0, 5.0, and 7.0, respectively) BaZrO3 nanoparticles (BZO, >50 nm, 98.5%, Sigma-Aldrich) was added to the calcined powders for mixing and grinding. Then, the mixture was pressed into circular pellets (~13-mm diameter and 2-mm thickness) by using a hydraulic press with an applied pressure load of 5 tons. Lastly, the pellets were sintered at 920 °C for 15 h and slowly cooled to 650 °C for 8 h (annealing process) before further cooling to room temperature. The sintering and annealing were done under a constant oxygen flow. Pure samples (x = 0.0) were also prepared according to the same procedure to serve as reference for the purpose of comparison.

2.3. Sample Characterization

Phase formation and crystal structure of the samples were examined by X-ray diffraction (XRD) method using the PW 3040/60 MPD X’Pert Pro Panalytical Philips DY 1861 X-ray diffractometer with Cu-Kα radiation source. Scanning was carried out in 2θ mode over the range of 20°–80° with the increment step size of 0.03°. The XRD data was analyzed using the X’pert HighScore Plus software. Surface morphology of the pellets was observed using a scanning electron microscope (SEM-LEO 1455 VPSEM). Superconducting properties of the samples were measured using the commercial AC Susceptometer of CryoBIND (cryogenic balanced inductive detector) SR830 at the frequency of 219 Hz and applied field of 0.5 Oe. Uncertainty of the AC Susceptometer is ±0.1 K.

3. Discussion

3.1. X-ray Diffraction (XRD) Analysis

Figure 1 shows the XRD patterns of the samples prepared via SS method and COP method, respectively. The XRD patterns were indexed to Y-123 phase with orthorhombic crystal structure and space group Pmmm (ICSD: 01-078-2143). Peaks with the highest intensity for both the SS and COP samples were indexed with the Miller indices of (0 1 3) and (1 0 3). Rietveld refinement was undertaken on the XRD data using the X’pert HighScore Plus software. Accordingly, the refined unit cell lattice parameters indicated that all the samples have an orthorhombic crystal structure. Hence, no structural transformation from orthorhombic to tetragonal phase was occurred as a result of BZO addition. By using the similar refinement method, fraction of different phases (in weight percentage) in the samples was obtained. Compared to SS method, the samples prepared using COP method have higher weight percentage of Y-123 phase in agreement with previous findings [20,21]. Table 1 indicates the weight percentage of Y-123 phase for the pure SS and COP samples is 93.2% and 97.5%, respectively. However, the weight percentage of Y-123 phase for the SS samples and COP samples started to decrease with the increasing of BZO additions. Some minor peaks of Y2BaCuO5 (Y-211) (ICSD: 01-079-0697) were also observed in the XRD patterns of all the samples. The presence of Y-211 phase may due to the synthesis condition such as the heat treatment process and the preparation of the material itself [25]. A peak corresponding to BaZrO3 (BZO) (ICSD: 01-074-1299) started to appear at 2.0 mol% BZO addition and became more intense with increasing of BZO addition. This observation confirmed the distribution of BZO in the samples [26]. The increased intensity of the peak with increasing BZO addition suggests the saturation of solid solubility of BZO in Y-123 [27].
Table 2 summarizes crystallite size calculated based on the (103) peak of Y-123 using the Scherrer equation [28]:
L = K λ B size COS θ
where L is the crystallite size, K is a dimensionless shape factor (0.9), Bsize is line broadening at half of the maximum intensity (FWHM) in radian, λ is the X-ray wavelength for Cu-Kα radiation (1.5406 Å) and θ is Bragg angle in degree. Table 2 shows that the crystallite size of the SS samples is larger than that of the COP samples. Crystallite size of the pure SS and COP samples is 101.61 nm and 63.66 nm, respectively. Upon addition of BZO, the crystallite size increased for the COP samples. The larger crystallite size may be due to the bridging of fine particles that formed the continuous grain boundary networks [29]. Conversely, crystallite size became smaller for the SS samples with addition of BZO. Previously, the crystalline size of CaTiO3 (CTO) was found to decrease possibly due to large difference in ionic radii between the dopant ion and host ion (Ti4+) [30]. The nanocrystalline CTO was synthesized using soft chemical method followed by annealing. For our work, however, the same BZO nanoparticles were used for addition into the samples prepared by SS method and COP method. Judging from the data given in Table 2, the decrease in crystalline size for the BZO added SS samples is believed to be due to larger difference of the crystalline size between the BZO and Y-123 compared to that between the BZO and Y-123 prepared using COP method.

3.2. Microstructure Analysis

Figure 2 shows the SEM images of the SS and COP samples. All the samples have irregular shape and randomly distributed grains. The SEM images also show the increment in number of pores with BZO addition suggesting more porous structure for both SS and COP samples added with BZO. For calculation of average grain size, 100 grains were selected randomly from each SEM image and measured using the Image-J software. Figure 3 shows the distribution of grain size of the SS and COP samples. The average grain size is 1.24 μm and 0.30 μm, for the pure samples prepared via the SS method and COP method, respectively (Table 2). Addition of BZO into Y-123 sample increased the average grain size of the samples especially for the SS samples. The average grain size increased to 2.71 μm and 0.50 μm for the 7.0 mol% BZO added SS and COP samples, respectively. The increasing grain size is probably due to dispersion of BZO nanoparticles between the grains of Y-123 which promoted grain growth [5,31]. According to Table 2, the powders obtained by the COP method have smaller size and narrower size range (0.30–0.50 μm) in comparison with that obtained via the SS method (1.24–2.71 μm). This may be partly associated with the higher sintering temperature used in the SS method (950 °C, compared with 920 °C used for the COP method) leading to larger grain growth [21].

3.3. Superconducting Properties

Figure 4 shows the temperature dependence of the real (χ′) and imaginary (χ″) parts of AC susceptibility (ACS) for all the samples. The real part (χ′) shows two transitions labeled as onset critical temperature, Tc-onset and phase lock-in temperature, Tcj. Tc-onset is due to transition within the grains (intra-grain) while Tcj is due to superconducting coupling between grains (inter-grain) [32]. In the temperature range between Tc-onset and Tcj, the superconducting grains are decoupled and the sample as a whole becomes resistive even if all individual grains are still strongly superconducting. Below Tcj, the grains are coupled or phase-locked in which the phase difference across the intergranular junctions is zero. Consequently, the induced current from the externally applied ac magnetic field gives rise to shielding currents along the outermost surface of the sample. Tc-onset and Tcj were determined from the peaks of the derivative of normalized χ′, δχ′/δT against temperature, T plots (insets). It should also be noted that samples with approximately the same size (cross-section 0.3 × 0.5 cm) were used for measurements under the same conditions for the sake of consistency.
Table 3 shows that the values of Tc-onset and Tcj for the COP samples are close to that of the SS samples. The difference for Tc-onset and Tcj is ≤1.6 K and ≤1.2 K, respectively. With increasing of BZO addition from 0.0 mol% to 7.0 mol%, Tc-onset and Tcj for the COP samples decreased slightly (0.7 K and 0.8 K for Tc-onset and Tcj, respectively). Nevertheless, addition of 2 mol% BZO did not change the value of Tcj. The marginal decrease of Tc-onset is in good agreement with the previous finding [12,33,34] and could be associated with the reduced hole concentration [23]. However, the values of Tc-onset and Tcj for the SS samples showed a larger change compared to the COP samples. For the SS samples, Tc-onset decreased from 90.3 K for 0.0 mol% to 88.9 K for 7.0 mol% BZO addition (1.4 K). The lower Tc-onset of the 7.0 mol% BZO added SS sample compared to that of the COP sample may be attributed to inhomogeneity of the former. Meanwhile, the value of Tcj decreased from 87.8 K for 0.0 mol% to 85.5 K for 7.0 mol% BZO addition (2.3 K). The decrease of Tcj with the increasing of BZO addition for both COP and SS samples indicates weakening of intergranular coupling perhaps due to the increasing of impurities at the grain boundaries [35,36]. However, the larger decrease of Tcj in the SS samples implies more severe degradation of grain coupling caused by BZO addition compared to the COP samples.
Imaginary part (χ″) of ACS exhibits a broad peak known as coupling peak temperature, Tp that corresponds to the hysteretic energy dissipation as a result of AC losses at the inter-grain region [37]. The second peak near Tc (intra-granular peak) for all the samples is not apparent except for the pure sample prepared via the SS method. The absence of the second peak suggests that grain coupling is better for the pure sample prepared via COP method compared to the SS method [37,38]. For the COP samples, addition of 2.0 mol% of BZO did not change the Tp much compared to the pure sample. For the SS samples, Tp for the pure sample is 87.3 K compared to 85.8 K for the sample with 2.0 mol% of BZO addition. As shown in Figure 4 and Table 3, Tp of both the SS and COP samples shifted to lower temperature with the increasing of BZO addition due to the weakening of intergranular coupling between the grains [39]. Other factors that affect Tp also include the changes in microstructure and the amount of impurities at the grain boundaries [40]. It is noteworthy that both Tp and Tcj of the 5.0 and 7.0 mol% BZO added samples are quite close to each other for the COP and SS samples. Such a small variation could be related to the saturation of solid solubility of BZO in Y-123 as mentioned in the part of XRD analysis (Section 3.1).
The value of Josephson’s current, Io was calculated according to the Ambegaokar–Baratoff theory [41] using the following equation assuming that nearest-neighbor grains are coupled by identical Josephson junctions of maximum Io:
I o = 1.57 × 10 8 ( T c - onset 2 T c - onset T cj )
It should be noted that Equation (2) is only valid for s-wave superconductors at temperature near to the superconducting transition temperature, Tc. Nonetheless, the equation has been adapted for the estimation of maximum Josephson current in d-wave cuprate superconductor [42]. The values of Tc-onset and Tcj were estimated from Figure 4 as mentioned before. Due to the granular nature of HTS, grain boundaries of Y-123 act as Josephson junctions. In equation (2), Tcj represents the Josephson phase-locking temperature which is the crossover temperature between phase-locked and phase fluctuation dominated behavior, corresponding to coupling and decoupling of grains, respectively [41].
Table 3 shows that the Io increased for 2.0 mol% samples but decreased for 5.0 mol% and 7.0 mol% BZO addition for both methods. The Josephson current, Io = 53.95 μA for 2 mol% BZO added SS sample is the highest. Meanwhile, Io for 2.0 mol% BZO added COP sample is 32.08 μA. These values are higher than that Io ≈ 5 μA in Bi-Ca-Sr-Cu-O bulk prepared using solid state reaction method [42]. The increasing of Josephson’s current, Io up to 2.0 mol% indicated better coupling between the grains and thus, stronger Josephson junction. Consequently, the screening current circulated even at higher field causing the increasing tunneling of Josephson current across the grain boundaries [43]. However, further addition of 5.0 mol% and 7.0 mol% BZO in the SS samples, abruptly decreased the Io to 28.20 μA and 36.49 μA, respectively. For the COP samples, Io decreased to 30.56 μA and 30.54 μA with addition of 5.0 and 7.0 mol% BZO, respectively. Nevertheless, the variation in Io with increased BZO addition in the COP samples is smaller probably because of higher homogeneity over the SS samples. Such decrease in Io is reflected in the more drastic decrease of Tcj of the 5.0 and 7.0 mol% BZO added samples (Table 3). This is most probably related to the distribution of BZO particles which are insulating at the grain boundaries. The same reason is believed to be accounted for the lower Io of the COP samples compared to that of the SS samples. This can be understood by the presence of more grain boundaries in the COP samples due to smaller grain size (Table 2). Hence, tunneling of Josephine current is hindered due to the distribution of the insulating BZO particles at the grain boundaries.

4. Conclusions

In this work, structural properties of BZO doped Y-123 bulks prepared using COP and SS method, respectively, were studied and their AC susceptibility was compared. The polycrystalline samples with nominal composition of Y-123 added with x mol% of BZO nanoparticles (x = 0.0, 2.0, 5.0, and 7.0) were synthesized. The XRD patterns showed the formation of Y-123 as the major phase and Y-211 as the secondary phase. The COP samples showed higher weight percentage of Y-123 phase. Refinement of unit cell lattice parameters indicated that all the samples have an orthorhombic crystal structure. Estimation based on the SEM images showed that the COP samples have smaller average grain size than that of the SS samples probably because of lower sintering temperature used for the former. Tc-onset was found to decrease with addition of BZO as shown by the ACS measurement. The value of Josephson’s current, Io increased up 53.95 μA and 32.80 μA for 2.0 mol% BZO added SS and COP samples, respectively. The lower Io value of the COP samples compared with the SS samples is attributed to the presence of more grain boundaries. Hence, tunneling of Io is hindered due to the distribution of insulating BZO particles at the grain boundaries.

Author Contributions

Conceptualization: N.M.H., J.K.L., S.K.C., and O.J.L.; methodology: N.M.H., J.K.L., S.K.C., and O.J.L; validation: N.M.H., J.K.L., S.K.C., O.J.L., A.H.S., M.M.A.K., K.P.L., K.B.T., M.M., and M.M.; writing—original draft preparation: N.M.H.; writing—review and editing: J.K.L., S.K.C., and O.J.L; supervision: S.K.C., O.J.L., M.M.A.K., and K.B.T.; funding acquisition: S.K.C., O.J.L., A.H.S., M.M.A.K., K.P.L., M.M., and M.M.

Funding

This research was funded by Universiti Putra Malaysia through the Putra-Grant (vote no.: 9552300). N. M. Hapipi would like to acknowledge financial support from the Ministry of Education Malaysia through the MyMaster scholarship, Universiti Putra Malaysia under the Graduate Research Fellowship (GRF). The authors are also grateful to Japan Science and Technology Agency for their financial assistance through SAKURA Exchange Program in Science under Shibaura Institute of Technology.

Acknowledgments

We would like to thank Nik Afida Anis Azahari, Kamsiah Alias and Norhaslinda Noruddin for their technical support.

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Barnes, P.N.; Haugan, T.J.; Baca, F.J.; Varanasi, C.V.; Wheeler, R.; Meisenkothen, F.; Sathiraju, S. Inducing self-assembly of Y2BaCuO5 nanoparticles via Ca-doping for improved pinning in YBa2Cu3O7−x. Physica C 2009, 469, 2029–2032. [Google Scholar] [CrossRef]
  2. Horvath, D.; Harnois, C.; Noudem, J.G. Li and Ce doping of melt-textured YBCO: Improved Jc at medium fields. Mater. Sci. Eng. B 2008, 151, 36–39. [Google Scholar] [CrossRef]
  3. Klie, R.F.; Buban, J.P.; Varela, M.; Franceschetti, A.; Jooss, C.; Zhu, Y.; Browning, N.D.; Pantelides, S.T.; Pennycook, S.J. Enhanced current transport at grain boundaries in high-Tc superconductors. Nature 2005, 435, 475–478. [Google Scholar] [CrossRef]
  4. Jin, L.H.; Zhang, S.N.; Yu, Z.M.; Li, C.S.; Feng, J.Q.; Sulpice, A.; Wang, Y.; Zhang, P.X. Influences of BaZrO3 particles on the microstructure and flux pinning of YBCO film prepared by using modified TFA-MOD approach. Mater. Chem. Phys. 2015, 149–150, 188–192. [Google Scholar] [CrossRef]
  5. Awano, M.; Fujishiro, Y.; Moon, J.; Takagi, H.; Rybchenko, S.; Bredikhin, S. Microstructure control of an oxide superconductor on interaction of pinning centers and growing crystal surface. Physica C 2000, 341–348, 2017–2018. [Google Scholar] [CrossRef]
  6. Paulose, K.V.; Koshy, J.; Damodaran, A.D. Superconductivity in YBa2Cu3O7−δ-ZrO2 systems. Supercond. Sci. Technol. 1991, 4, 96–101. [Google Scholar] [CrossRef]
  7. Palonen, H.; Huhtinen, H.; Shakhov, M.A.; Paturi, P. Electron mass anisotropy of BaZrO3 doped YBCO thin films in pulsed magnetic fields up to 30 T. Supercond. Sci. Technol. 2013, 26, 045003. [Google Scholar] [CrossRef]
  8. Bretos, I.; Schneller, T.; Falter, M.; Backer, M.; Hollmann, E.; Wordenweber, R.; Molina-Luna, L.; Tendelooe, G.V.; Eibl, O. Solution-derived YBa2Cu3O7−δ (YBCO) superconducting films with BaZrO3 (BZO) nanodots based on reverse micelle stabilized nanoparticles. J. Mater. Chem. C 2015, 3, 3971–3979. [Google Scholar] [CrossRef]
  9. Peurla, M.; Paturi, P.; Stepanov, Y.P.; Huhtinen, H.; Tse, Y.Y.; Bodi, A.C.; Raittila, J.; Laiho, R. Optimization of the BaZrO3 concentration in YBCO films prepared by pulsed laser deposition. Supercond. Sci. Technol. 2006, 19, 767–771. [Google Scholar] [CrossRef]
  10. Malmivirta, M.; Rijckaert, H.; Paasonen, V.; Huhtinen, H.; Hynninen, T.; Jha, R.; Awana, V.S.; Driessche, I.V.; Paturi, P. Enhanced flux pinning in YBCO multilayer films with BCO nanodots and segmented BZO nanorods. Sci. Rep. 2017, 7, 14682. [Google Scholar] [CrossRef]
  11. Wang, F.; Tian, H. BaZrO3 (BZO) nanoparticles as effective pinning centers for -YBa2Cu3O7−δ (YBCO) superconducting thin films. J. Mater. Sci. Mater. Electron. 2019, 30, 4137–4143. [Google Scholar] [CrossRef]
  12. Jha, A.K.; Khare, N. Investigation of flux pinning properties of YBCO: BaZrO3 composite superconductor from temperature dependent magnetization studies. J. Magn. Magn. Mater. 2010, 322, 2653–2657. [Google Scholar] [CrossRef]
  13. Arlina, A.; Halim, S.A.; Awang Kechik, M.M.; Chen, S.K. Superconductivity in Bi-Pb-Sr-Ca-Cu-O ceramics with YBCO as additive. J. Alloys Compd. 2015, 645, 269–273. [Google Scholar] [CrossRef]
  14. Paz-Pujalt, G.R.; Mehrotra, A.K.; Ferranti, S.A.; Agostinelli, J.A. Solid state reactions in the formation of YBa2Cu3O7−δ high Tc superconductor powders. Solid State Ionics 1989, 32–33, 1179–1182. [Google Scholar] [CrossRef]
  15. Fujihara, S.; Kozuka, H.; Yoko, T.; Sakka, S. Mechanism of formation of YBa2Cu4O8 superconductor in the sol-gel synthesis. J. Sol-Gel Sci. Technol. 1994, 1, 133–140. [Google Scholar] [CrossRef]
  16. Ramli, A.; Halim, S.A.; Chen, S.K.; Awang Kechik, M.M. The effect of Gd2O3 nanoparticles addition on microstructural and electrical properties of YBCO superconductor. ARPN J. Eng. Appl. Sci. 2016, 11, 13708–13715. [Google Scholar]
  17. Hamadneh, I.; Rosli, A.M.; Abd-Shukor, R.; Suib, N.R.M.; Yahya, S.Y. Superconductivity of REBa2Cu3O7−δ (RE = Y, Dy, Er) ceramic synthesized via coprecipitation method. J. Phys. Conf. Ser. 2008, 97, 012063. [Google Scholar] [CrossRef]
  18. Bhargava, A.; Mackinnon, I.D.R.; Yamashita, T.; Page, D. Bulk manufacture of YBCO powders by coprecipitation. Physica C 1995, 241, 53–62. [Google Scholar] [CrossRef]
  19. Mousa Dihom, M.; Shaari, A.H.; Baqiah, H.; Al-Hada, N.M.; Talib, Z.A.; Chen, S.K.; Aziz, R.S.; Awang Kechik, M.M.; Lim, K.P.; Shukor, R.A. Structural and superconducting properties of Y(Ba1-xKx)2Cu3O7−δ ceramics. Ceram. Int. 2017, 43, 11339–11344. [Google Scholar] [CrossRef]
  20. Wahid, M.H.; Zainal, Z.; Hamadneh, I.; Tan, K.B.; Halim, S.A.; Rosli, A.M.; Alaghbari, E.S.; Nazarudin, M.F.; Kadri, E.F. Phase formation of REBa2Cu3O7−δ (RE: Y0.5Gd0.5, Y0.5Nd0.5, Nd0.5Gd0.5) superconductors from nanopowders synthesised via co-precipitation. Ceram. Int. 2012, 38, 1187–1193. [Google Scholar] [CrossRef]
  21. Ochsenkuhn-Petropoulou, M.; Argyropoulou, R.; Tarantilis, P.; Kokkinos, E.; Ochsenkuhn, K.M.; Parissakis, G. Comparison of the oxalate co-precipitation and the solid state reaction methods for the production of high temperature superconducting powders and coating. J. Mater. Process. Technol. 2002, 127, 122–128. [Google Scholar] [CrossRef]
  22. Mohd Hapipi, N.; Chen, S.K.; Shaari, A.H.; Awang Kechik, M.M.; Tan, K.B.; Lim, K.P. Superconductivity of Y2O3 and BaZrO3 nanoparticles co-added YBa2Cu3O7−δ bulks prepared using co-precipitation method. J. Mater. Sci. Mater. Electron. 2018, 29, 18684–18692. [Google Scholar] [CrossRef]
  23. Mohd Hapipi, N.; Chen, S.K.; Shaari, A.H.; Awang Kechik, M.M.; Tan, K.B.; Lim, K.P.; Lee, O.J. AC susceptibility of BaZrO3 nanoparticles added YBa2Cu3O7−δ superconductor prepared via coprecipitation method. J. Supercond. Novel Magn. 2018, 32, 1191–1198. [Google Scholar] [CrossRef]
  24. Patnaik, P. Dean’s Analytical Chemistry Handbook, 2nd ed.; McGraw Hill Professional: New York, NY, USA, 2004. [Google Scholar]
  25. Zhang, C.J.; Oyanagi, H. The synthesis condition and its influence on Tc in Mn doped La1.85Sr0.15CuO4. Physica C 2008, 468, 1155–1158. [Google Scholar] [CrossRef]
  26. Pomar, A.; Vlad, V.R.; Llordes, A.; Palau, A.; Gutiérrez, J.; Ricart, S.; Puig, T.; Obradors, X.; Usoskin, A. Enhanced vortex pinning in YBCO coated conductors with BZO nanoparticles from chemical solution deposition. IEEE Trans. Appl. Supercond. 2009, 19, 3258–3261. [Google Scholar] [CrossRef]
  27. Cracolice, M.S.; Peters, E.I. Introductory Chemistry: An Active Learning Approach; Brooks Cole: Belmont, CA, USA, 2012. [Google Scholar]
  28. Langford, J.I.; Wilson, A.J.C. Scherrer after sixty years: A survey and some new results in the determination of crystallite size. J. Appl. Crystallogr. 1978, 11, 102–113. [Google Scholar] [CrossRef]
  29. Hassanzadeh-Tabrizi, S.A.; Mazaheri, M.; Aminzare, M.; Sadrnezhaad, S.K. Reverse precipitation synthesis and characterization of CeO2 nanopowder. J. Alloys Compd. 2010, 491, 499–502. [Google Scholar] [CrossRef]
  30. Mondal, O.; Pal, M.; Singh, R.; Sen, D.; Mazumder, S.; Pal, M. Influence of doping on crystal growth, structure and optical properties of nanocrystalline CaTiO3: A case study using small-angle neutron scattering. J. Appl. Crystallogr. 2015, 48, 836–843. [Google Scholar] [CrossRef]
  31. Luo, Y.Y.; Wu, Y.C.; Xiong, X.M.; Li, Q.Y.; Gawalek, W.; He, Z.H. Effects of precursors with fine BaZrO3 inclusions on the growth and microstructure of textured YBCO. J. Supercond. 2000, 13, 575–581. [Google Scholar] [CrossRef]
  32. Nikolo, M. Superconductivity: A guide to alternating current susceptibility measurements and alternating current susceptometer design. Am. J. Phys. 1995, 63, 57–65. [Google Scholar] [CrossRef]
  33. Ciontea, L.; Celentano, G.; Augieri, A.; Ristoiu, T.; Suciu, R.; Gabor, M.S.; Rufoloni, A.; Vannozzi, A.; Galluzi, V.; Petrisor, T. Chemically processed BaZrO3 nanopowders as artificial pinning centres. J. Phys. Conf. Ser. 2008, 97, 012289. [Google Scholar] [CrossRef]
  34. MacManus-Driscoll, J.L.; Foltyn, S.R.; Jia, Q.X.; Wang, H.; Serquis, A.; Civale, L.; Maiorov, B.; Hawley, M.E.; Maley, M.P.; Peterson, D.E. Strongly enhanced current densities in superconducting coated conductors of YBa2Cu3O7−x + BaZrO3. Nat. Mater. 2004, 3, 439–443. [Google Scholar] [CrossRef] [PubMed]
  35. Kameli, P.; Salamati, H.; Eslami, M. The effect of sintering temperature on the intergranular properties of Bi2223 superconductors. Solid State Commun. 2006, 137, 30–35. [Google Scholar] [CrossRef]
  36. Nedkov, I.; Veneva, A. Grain boundaries contribution to the complex susceptibility of KCu-doped YBCO high-temperature superconductors. J. Low Temp. Phys. 1997, 107, 497–502. [Google Scholar] [CrossRef]
  37. Deac, I.G.; Burzo, E.; Pop, A.V.; Pop, V.; Tetean, R.; Kovacs, D.; Borodi, G. Intergranular properties of (Y1−x−yZrxCay)Ba2Cu3O7−δ compounds. Int. J. Mod. Phys. B 1999, 13, 1645–1654. [Google Scholar] [CrossRef]
  38. Sbarciog, C.; Redac, R.T.; Deac, I.G.; Pop, I. Intergranular properties of Zr-substituted Y123 compounds. Mod. Phys. Lett. B 2006, 20, 1191–1198. [Google Scholar] [CrossRef]
  39. Rani, P.; Jha, R.; Awana, V.P.S. AC susceptibility study of superconducting YBa2Cu3O7: Agx bulk composites (x = 0.0–0.20): The role of intra and intergranular coupling. J. Supercond. Novel Magn. 2013, 26, 2347–2352. [Google Scholar] [CrossRef]
  40. Nur-Akasyah, J.; Nur-Shamimie, N.H.; Abd-Shukor, R. Effect of CdTe addition on the electrical properties and AC susceptibility of YBa2Cu3O7−δ superconductor. J. Supercond. Novel Magn. 2017, 30, 3361–3365. [Google Scholar] [CrossRef]
  41. Clem, J.R. Granular and superconducting-glass properties of the high-temperature superconductors. Physica C 1988, 153–155, 50–55. [Google Scholar] [CrossRef]
  42. Emmen, J.H.P.M.; Brabers, V.A.M.; De Jonge, W.J.M.; Steen, C.V.D.; Dalderop, J.H.J.; Geppaart, P.M.A.; Kopinga, K. Microstructure and properties of Bi-Ca-Sr-Cu-O superconductors. J. Less-Common Met. 1989, 151, 63–69. [Google Scholar] [CrossRef]
  43. Narlikar, A.V. Field Penetration and Magnetization of High Temperature Superconductors; Nova Science Publisher, Inc.: New York, NY, USA, 1995. [Google Scholar]
Figure 1. X-ray diffraction patterns of Y-123 + x mol% of BZO samples prepared via (a) SS method and (b) COP method. The Y-211 and BZO are marked with (♦) and (◊), respectively.
Figure 1. X-ray diffraction patterns of Y-123 + x mol% of BZO samples prepared via (a) SS method and (b) COP method. The Y-211 and BZO are marked with (♦) and (◊), respectively.
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Figure 2. SEM images of Y-123 added with (a) 0.0 mol%, (b) 2.0 mol%, (c) 5.0 mol%, and (d) 7.0 mol% of BZO at 5000× magnification prepared via SS method. Bottom: SEM images of Y-123 added with (e) 0.0 mol%, (f) 2.0 mol%, (g) 5.0 mol%, and (h) 7.0 mol% of BZO at 5000× magnification prepared via COP method.
Figure 2. SEM images of Y-123 added with (a) 0.0 mol%, (b) 2.0 mol%, (c) 5.0 mol%, and (d) 7.0 mol% of BZO at 5000× magnification prepared via SS method. Bottom: SEM images of Y-123 added with (e) 0.0 mol%, (f) 2.0 mol%, (g) 5.0 mol%, and (h) 7.0 mol% of BZO at 5000× magnification prepared via COP method.
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Figure 3. Distribution of average grain size for Y-123 added with (a) 0.0 mol%, (b) 2.0 mol%, (c) 5.0 mol%, and (d) 7.0 mol% of BZO prepared via SS method and Y-123 added with (e) 0.0 mol%, (f) 2.0 mol%, (g) 5.0 mol%, and (h) 7.0 mol% of BZO prepared via COP method.
Figure 3. Distribution of average grain size for Y-123 added with (a) 0.0 mol%, (b) 2.0 mol%, (c) 5.0 mol%, and (d) 7.0 mol% of BZO prepared via SS method and Y-123 added with (e) 0.0 mol%, (f) 2.0 mol%, (g) 5.0 mol%, and (h) 7.0 mol% of BZO prepared via COP method.
Crystals 09 00655 g003aCrystals 09 00655 g003b
Figure 4. Temperature dependence of ACS for Y-123 + x mol% of BZO samples prepared via (a) SS method (b) COP method. Insets show the derivative of normalized χ′, δχ′/δT against temperature, T.
Figure 4. Temperature dependence of ACS for Y-123 + x mol% of BZO samples prepared via (a) SS method (b) COP method. Insets show the derivative of normalized χ′, δχ′/δT against temperature, T.
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Table 1. Percentages of Y-123, Y-211, and BZO phases for Y-123 + x mol% of BZO samples prepared via SS method and COP method.
Table 1. Percentages of Y-123, Y-211, and BZO phases for Y-123 + x mol% of BZO samples prepared via SS method and COP method.
BZO x (mol%)Weight Percentage of Phases (%)
SS MethodCOP Method
Y-123Y-211BZOY-123Y-211BZO
0.093.26.80.097.52.50.0
2.092.96.60.596.63.10.3
5.092.85.71.594.84.12.7
7.092.83.83.494.33.02.7
Table 2. FWHM of (103) peak, crystallite size and average grain size for Y-123 + x mol% of BZO samples calculated using Scherrer method. The average grain size of the samples was calculated from the randomly selected 100 grains of the SEM image.
Table 2. FWHM of (103) peak, crystallite size and average grain size for Y-123 + x mol% of BZO samples calculated using Scherrer method. The average grain size of the samples was calculated from the randomly selected 100 grains of the SEM image.
BZO x (mol%)SS MethodCOP Method
FWHM of (103) Peak (º)Crystallite Size (nm)Average Grain Size, D (μm)FWHM of (103) Peak (º)Crystallite Size (nm)Average Grain Size, D (μm)
0.00.1315101.611.24 ± 0.140.180163.660.30 ± 0.01
2.00.142489.621.77 ± 0.060.173766.940.39 ± 0.02
5.00.151581.562.29 ± 0.010.179364.030.45 ± 0.02
7.00.143688.442.71 ± 0.110.172967.36 0.02
Table 3. Coupling peak temperature, Tp, onset critical temperature, Tc-onset, phase lock-in temperature, Tcj, and Josephson current, Io for Y-123 + x mol% of BZO samples in applied AC field of 0.5 Oe.
Table 3. Coupling peak temperature, Tp, onset critical temperature, Tc-onset, phase lock-in temperature, Tcj, and Josephson current, Io for Y-123 + x mol% of BZO samples in applied AC field of 0.5 Oe.
BZO x (mol%)SS MethodCOP Method
Tp (K)Tc-onset (K)Tcj (K)Io (μA)Tp (K)Tc-onset (K)Tcj (K)Io (μA)
0.087.390.387.851.2184.890.686.631.69
2.085.888.986.653.9584.590.586.532.08
5.084.189.985.428.2082.989.885.630.56
7.084.588.985.536.4983.689.985.830.54
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