The effect of Ba doping on Sr site on structural and superconducting properties of Bi2212 phase

Accepted Manuscript The Effect of Ba Doping on Sr site on Structural and Superconducting Properties of Bi2212 phase

C. Sam, M.-F. Mosbah, S. Attaf, N. Benbellat PII:

S0921-4526(18)30835-4

DOI:

10.1016/j.physb.2018.12.040

Reference:

PHYSB 311249

To appear in:

Physica B: Physics of Condensed Matter

Received Date:

21 October 2018

Accepted Date:

29 December 2018

Please cite this article as: C. Sam, M.-F. Mosbah, S. Attaf, N. Benbellat, The Effect of Ba Doping on Sr site on Structural and Superconducting Properties of Bi2212 phase, Physica B: Physics of Condensed Matter (2018), doi: 10.1016/j.physb.2018.12.040

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ACCEPTED MANUSCRIPT

The Effect of Ba Doping on Sr site on Structural and Superconducting Properties of Bi2212 phase C Sama,*, M-F Mosbaha,b, S Attafa, N Benbellat c aMaterial

Sciences and Applications Research Unit, Physics Department, Constantine1

University, B.P. 325 Route d’Ain El Bey, 25017 Constantine. Algeria. bNational

Polytecnic School of Constantine, Nouvelle Ville Universitaire Ali Mendjeli-BP 75° RP Ali Mendjeli-Constantine, Algeria.

cLaboratory

of Chemistry of Materials and Living: Activity, Reactivity (LCMVAR),Hadj Lakhdar University - Batna 1, Batna, 5000, Alegrie.

Abstract In this research, we investigate the effect of Ba substitution on Sr sites in the Bi-2212 system. X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometry (EDS), Raman spectroscopy and AC susceptibility measurements give structural and magnetic properties of the prepared samples. The results reveal the following. X-ray diffraction shows that the Bi-2212 phase is dominant and that the secondary Bi-2201 phase decreases as Ba content increases. Ba doping decreases the cell parameter of the samples. SEM reveals a structure of well-connected grains with a shape of plate. Raman spectroscopy shows the modes of vibration that are present in the superconducting material Bi2Sr(2x)BaxCaCu2O8+δ.

AC susceptibility shows that Ba substitution decreases the critical

temperature (Tc). *Corresponding author. Tel: +213 07 75 75 85 75 E-mail address: [email protected] (C. Sam).

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ACCEPTED MANUSCRIPT 1. Introduction The high temperature cuprates superconductors (HTCS) continue to stimulate considerable scientific literature and a number of research works explain their specific electrical and magnetic properties. Among these materials, the bismuth-based cuprates are the most used cuprates for practical applications in many areas, especially, in the terahertz equipment for security systems [1], superconducting fault current limiters [2], magnetic sensors [3] and magnetic resonance imagery systems [4]. The most studied cuprates have a general formula Bi2Sr2Can-1CunO2n+4 with three characteristic phases: the Bi-2201 phase, with Bi2Sr2CuO6 stoichiometric composition and Tc=24 K, the Bi-2212 phase, with Bi2Sr2Ca1Cu2O8 stoichiometric composition, a Tc ranging between 80 and 96 K, and the Bi-2223 phase, with Bi2Sr2Ca2Cu3O10 stoichiometric composition and Tc=110 K [5]. Because of its easier oxygenation, the Bi-2212 phase [6] is the subject of many preliminary studies, [7-10] which tried mostly to improve the Tc with different dopants in different sites. This is in order to improve the properties of superconductors. Rare earth elements have different ionic radii and

also

great

impact

as

substituent

on

the physical

properties

of

high Tc

superconductors as in the Bi2223 phase [11]. The use of barium (Ba) produces different effects on Tc and pinning properties of Bi-2223 phase, depending on its substitution on Ca or Sr site [12]. As far as the Barium belongs to the same group of rare earth metals such as Sr and Ca with a different ionic radius, its substitution effect in the Bi-2212 phase is very interesting to study. At very low rates, Ba doping on Ca site of the same phase has no effect on Tc, but influences the intergranular quality as deduced from AC susceptibility measurements [13]. With the Hg substituent on Bi site and Ba on Sr site, the two co-dopants have, at a low rate, an opposite effect on Tc of the Bi-2223 phase, by Hg enhancing Tc and Ba reducing it [14]. The addition of BaO2 to Bi-2212 has an effect on the phase formation and improves the Jc [15].

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ACCEPTED MANUSCRIPT In this work, the effect of Ba substitution on Sr site on the superconducting and structural properties of Bi-2212 phase is presented. The effect of Ba substitution on Sr sites in the Bi-2212 on superconducting phase is investigated, using different types of characterization. For example, they are: X-ray diffraction, which shows the intensity and the angular position of the different percentages, the morphology and average grain size, which are characterized by the scanning electron microscope (SEM), and, subsequently, the Raman characterization is used to see the vibrations of the atoms in the Bi-2212 structure. Finally, AC susceptibility is used in order to determine the transition temperature. 2. Experiment The superconducting ceramics of Bi2Sr2CaCu2O8+δ were prepared via sol-gel route using Bi(NO3)3 5H2O, Sr(NO3)2, Ca(NO3)2 4H2O, Cu(NO3)2 3H2O and Ba(NO3)2 as precursors (purity 99.99%,Aldrich). The starting products, weighted in stoichiometric amount, were dissolved in a mixture of distilled water and nitric acid, beginning firstly by Bi (NO3)35H2O. While stirring at ambient temperature, At this point, the solution is dark blue, we add 3ml of 25% molar concentration of NH3 drop by drop until obtaining a PH between 6 and 9. And the solution becomes sky blue, without any evidence of precipitation, following the processes outlined in Figure-1-. The obtained solution is then, stirred and heated at 80 °C for two hours until it becomes complex. Afterwards, the obtained powder is calcined in an electric oven at 840°C during 10h. Subsequently, the powder is grounded and pressed in the form of pellets under a pressure of 5 Tons/cm2. The pellets are then sintered at 855°C during 27 h. The structural characterization of the samples was obtained on an X-ray diffractometer (XRD) Expert Powder Panalytical PW3040/60, using copper CuKα radiation (λCuKα = 1.5418 Å), and a Bragg-Brentano geometry with an angle 2θ varying from 5° to 70° with a step of 0.0130°. The use of JCPD-ICDD [16] data file allows the identification of the phase. The use of Dicvol04 software [17] allows the computing of cell parameters. Microstructure analysis 3

ACCEPTED MANUSCRIPT was conducted on a scanning electron microscope JEOL7200 (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). AC susceptibility measurements were carried out on SQUID Magnetometer (MPMS, Rennes 1 University, France) using an applied field of about 10Oe. Raman spectroscopy was performed on a Lab RAM HR Evolution (Raman Spectrometry) HORIBA. 3. Results and Discussions 3.1. DRX Figure-2- shows the X-ray diffraction spectra of the undoped and Ba doped samples. These spectra indicate that incorporation of barium promotes the formation of the Bi-2212 phase accompanied by the secondary phase Bi-2201 which increases with Ba and which is not detectable for Ba=0.03. The absence of Ba peaks indicates its probable complete incorporation. Assuming a tetragonal structure, the use of Dicvol04 software [17] allows calculating the cell parameters shown in Table-1-. Doping with Ba decreases c parameter, except for Ba = 0.03, and increases a parameter. Ba+2 replacing Sr+2, with lower radius, increases the Jahn Teller deformation of the CuO2 octahedron which at its turn changes the a and c parameters. The following formula [18] gives estimate of Bi-2212 phase volume fraction (the ratio of the volume of the Bi2212 phase on the volume of the sample): 𝐵𝑖 ― (2212)% =

∑𝐼(2212) ∑𝐼(2201) + ∑𝐼(2212)

∗ 100

I (2212) and I (2201) are the intensities of the XRD peaks identified for Bi-2212 and Bi-2201 respectively. Table-1- shows that, except for Ba = 0.01, volume fraction of the Bi-2212 phase is lowered by Ba doping. The minimum is Ba = 0.02, which is a sample presenting the higher peak intensity of Bi-2201 phase.

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ACCEPTED MANUSCRIPT 3.2. SEM Figure-3- shows the characteristic SEM pictures of the samples, taken with the same magnification. All the samples contain long and plate shape grains characterizing the lamellar structure of the Bi-2212 system. A similar result is reported in Refs. [19, 20]. The non-doped sample reveals grains with compact and melted morphology, seeming to be well connected to each other, with a small apparent porosity. Although limited to a small area, the apparent texture can be estimated from the proportion of the grains showing their flat face versus the other showing their sharp-cutting edge. The increase of these last kinds of grains, i.e. those showing their sharp-cutting edge (indicated by white arrows in the picture of sample with Ba = 0.02), results in a lowering of the apparent texture. Using these criteria, SEM photos show that introducing Ba results in a lack of texture, which increases up to Ba = 0.02, and then reduces to Ba = 0.03. In fact, lowering the texture implies an increase in the porosity that affects the connectivity of grains. Doping with Ba results in an apparent lowering of the grain size and results in alimited increase of the apparent porosity. 3.3. EDS EDS gives the distribution of atomic elements in the doped samples and confirm the presence of dopant. In each sample, about twenty areas were analyzed. No parasitic element is detected showing an uncontaminated synthesis process. Table-2- provides, for the samples, the percent chemical weight composition deduced from EDS analysis. Figure-4- shows the mapping of the atomic elements belonging to the barium doped Bi2212 samples. The distribution of elements is the same in all the samples, except for Cu, which seems to be more concentrated where the others are absent. Barium is present in all the doped samples showing, as the other elements (except Cu), a homogenous distribution. For Ba = 0.03, the mapping of Cu and Ba shows the areas where low content of Cu corresponds to high content of Ba. This suggests a possible substitution of Cu by Ba.

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ACCEPTED MANUSCRIPT 3.4. Raman Figure-5- illustrates the room temperature Raman spectra of the samples. These spectra reveal the existence of four A1g lines located at 78.82, 111.83, 460.70 and 617.94 cm-1. The peak at 78.82 cm-1 corresponds to the A1g symmetry vibration of heavy Bi atom. The peak located at 111.83 cm-1 properly relates to A1g vibration of Sr. The peak at 460.70cm-1 can be assigned to A1g symmetry vibration of OSr (a-axis). The peak at 617.94 cm-1 corresponds to the A1gOsr (c-axis) [21]. The peak at 251.04 cm-1 may be assigned to B1g symmetry vibration of OCu [22]. This peak, which is absent in the undoped sample, appears when Ba is introduced. Doping with Ba (except for Ba = 0.02) shifts to the red, where all the peaks indicate the possible substitution of Sr by Ba and of Cu by Ba, which correspond to the enhancement of the B1g peak. 3.5. Susceptibility AC susceptibility is a powerful method for analyzing intergrain connections in the high-temperature superconductors. Figure-6- shows the temperature dependence curves of the real χ' and imaginary χ'' part of AC susceptibility measured, for all the samples, with an applied field of 10 Oe. These measurements show that the substitution of Sr by Ba causes a widening of the transition width. By decreasing the ambient temperature, the real curves show clearly two drops. The first drop corresponds to Tc where the superconducting transition occurs with the generation of superconducting screening currents in individual grains. The samples behave in a granular regime where the superconductivity is limited to the volume of grains. By decreasing more and more the temperature, an intergranular regime starts at the second drop at a temperature referred to as Tg. The superconducting current loops end to be limited to individual grains and go through the intergranular boundaries [23]. Below Tg, all the grains are coupled. That coupling occurs until the weak links, formed by the intergranular space, can carry a supercurrent. Thus, Tg and ΔT = Tc –Tg carry contain information on the characteristic of weak links, and consequently, on the granular quality of the samples. 6

ACCEPTED MANUSCRIPT Moreover, ΔT provides the transition width in the same way as done by transport measurements; the R= 0 point corresponds to Tg. The arrow in Figure-6- shows, for a sample of Ba = 0.01, how Tg is determined. Similarly, in the insert, the arrow shows how Tc is determined for the same sample. Table-3- reports the values of Tg, Tc and ΔT for all the samples. Table-3- shows that doping with Ba reduces Tc and ΔT, but except for Ba = 0.02, it enhances Tg. The imaginary part [24], out of phase of the magnetic response resulting from inhomogeneity and geometrical shape of the grains, gives information on structural defects in the samples. The temperature of its peak correlates with Tg with slightly lower values. The dephasing of the magnetic response begins at a very low temperature, caused firstly by intrinsic defects (anisotropy, oxygen vacancies) and then, the dephasing at higher temperatures caused by structural defects (secondary phases, grain boundaries, etc…). Figure-6- shows that (except for Ba = 0.02) the temperature of the peak in the imaginary part increases with x indicating an improvement of the quality of the samples. This fact confirms SEM observations where the corresponding samples show better quality and lower apparent porosity. Previous works have tried to obtain an improvement of the Bi2212 phase properties by addition of BaO2 particles [15, 25]. It was shown that addition of BaO2 influence significantly the melting and solidification behavior of the Bi2212 phase. Moreover, the critical current density is improved only when the content of the BaO2 added is around 2.38 wt. %. On the other hand, adding low content of BaCO3 to the Bi2Sr2Ca2Cu5Oy system gives a predominantly formation of 0the Bi2212 phase [26]. For higher contents of BaCO3 the Bi2223 phase is predominantly formed. This result explains why doping or co-doping the Bi2223 phase with Ba is the subject of various works [11-14]. Another study [27], confirms the effect of lowering the content of the Bi2212 phase by doping with Ba on Sr site. All these

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ACCEPTED MANUSCRIPT studies show an improvement of the superconducting properties when the content of Ba is low as it is the situation in our samples. 4. Conclusion In conclusion, the doping by Ba in Bi2Sr1-xBaxCaCu2O8+. Ba=0, 0.01, 0.02 and 0.03. prepared by sol-gel route has a remarkable effect on structural and superconductive properties. The structural study has shown that the addition of Ba improves the formation of the Bi-2212 phase; no Ba peaks have been detected, which means that there is a total incorporation of Ba into the Bi-2212 phase. The substitution of Sr by Ba changes the cell parameters. The SEM images show an improvement in the connection between the grains with a small size with the exception of the 0.02 Ba Doped Sample. The increase of the B1g peak means that there is a substitution of Sr by Ba. Therefore, Ba has reduced the critical temperature (Tc).On the other hand, the peak temperature increases with the increase in doping by Ba, indicating an improvement in the structural quality of the samples (i.e. a better connection between the grains).

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ACCEPTED MANUSCRIPT References [1] Z. Güven Özdemir, Ö. Aslan Çataltepe and Ü. Onbaşlı, “Some Contemporary and Prospective Applications of High Temperature Superconductors” in “APPLICATIONS OF HIGH-TC SUPERCONDUCTIVITY” Chapter 2, pp 15-44, Ed by Adir Moysés Luiz, InTech Croatia, 2011, ISBN 978-953-307-308-8 [2] K Suzuki, J Baba and T Nitta. “Conceptual design of an SFCL by use of BSCCO wire”. Journal of Physics: Conference Series 97 (2008) 012293 [3] B A Albiss. “Thick films of superconducting YBCO as magnetic sensors.”Supercond. Sci. Technol. 18 (2005) pp1222–1226 [4] MC Cheng, B P Yan, K H Lee, QYMa and E S Yang. “A high temperature superconductor tape RF receiver coil for a low field magneticresonance imaging system.”Supercond. Sci. Technol. 18 (2005) pp1100–1105 [5] A. Nilsson, “BSCCO Superconductors Processed by the Glass–Ceramic Route”,PhD Thesis, Dresden, RFA 2009. [6] M. Mimouni, M.-F. Mosbah, A. Amira, F. Kezzoula, A. Haouam ,A. Bouabellou. “Structural and transport properties of superconducting ceramics Bi2Sr2CaCu2O8+d”. Physica B 321 (2002) pp287–291. [7] Abderrezak Amira, Y. Boudjadja, A. Saoudel, A. Varilci, M. Akdogan, C.Terzioglu, M.F. Mosbah. “Effect of doping by low content of yttrium at Ca and Sr sites of Bi(Pb)-2212 superconducting ceramics”, Physica B 406 (2011) 1022–1027. [8] S. Vinu, P.M. Sarun, R. Shabna, P.M. Aswathy, J.B. Anooja, U. Syamaprasad. “Suppression of flux-creep in (Bi,Pb)-2212 superconductor byholmium doping”, Physica B 405 (2010) 4355–4359. [9] M. Gürsul, A. Ekicibil, B. Özçelik, M. A. Madre, A. Sotelo. “Sintering Effects in NaSubstituted Bi-(2212) Superconductor Prepared by a Polymer Method”, J Supercond Nov Magn (2015). DOI 10.1007/s10948-015-2977-x. 9

ACCEPTED MANUSCRIPT [10] M. Ebru Kir, Berdan Özkurt, M. Ersin Aytekin. “The effect of K-na co-doping on the formation and particle size of bi-2212 phase”, Physica B 309403 (2016). [11] M. Anis-ur-Rehman, M. Mubeen , “Synthesis and enhancement of current density in cerium doped Bi(Pb)Sr(Ba)-2 2 2 3 high Tc superconductor” . Synthetic Metals 162 (2012) 1769– 1774. [12] H.Salamati, P.Kameli, T.Morshedloo, I.Abdolhosseini, H.Ahmadvand, M.Baghi, H.Koohani, H.Beirami, ”The Effect of Barium Doping on the Selective Structure of Bi2223 Phase”, J Supercond Nov Magn 24(2011)pp1267–1272 [13] S.A. Halim, S.B. Mohamed, H. Azhan, S.A. Khawaldeh, H.A.A. Sidek, “Effect of barium doping in Bi–Pb–Sr–Ca–Cu–O ceramicssuperconductors”, Physica C 312 (1999)pp78–84 [14] A. R. Jabur, “Bi2-xHgxSr2-yBayCa2Cu2O10/Ag Sheath HTSC Wires, (Hg, Ba)Substitution Effect on The Critical Temperature”, Energy Procedia 36 ( 2013 ) pp985 –994 [15] U. P. Trociewitz, P. R. Sahm, R. E. Koritala, L.Brandao, C.Bacaltchuk, J. Schwartz, “Microstructural Development and Superconducting Properties of BaO2-added Bi2Sr2CaCu2O8+x”, IEEE Trans. Appl. Supercond.11(2001) pp3054-3057 [16] PDF-2 DATABASE 47 6A JUN 97 JCPD-ICDD (1997), USA. [17] A. Boultif and D. Louër,“Powder pattern indexing with the dichotomy method”, J. Appl. Cryst. 37, 724 (2004). [18] I. Hamadneh , A. Agil, A.K. Yahya , S.A. Halim. “Superconducting properties of bulk B1.6Pb0.4Sr2Ca2-xCdxCu3O10 system prepared via conventional solid state and coprecipitation methods”, Physica C 463–465 (2007) 207–210. [19] A. AitKaki, F. Benmaamar, M.F. Mosbah, A. Amira, “Effect of co-doping by Pb and La on structural and magnetic properties of Bi2212 superconducting ceramics”, Int. J.Mater.Res. 9 (2009) 1226. 10

ACCEPTED MANUSCRIPT [20] A. Amira, F. Bouaîcha, N. Boussouf, M.F. Mosbah, “Substitution of Sr2+ by Eu3+ in Bi-2201 ceramics, effects on structure and physical properties”, Solid State Sci. 12 (2010) 699. [21] R. Liu, M.V. Klein, P.D. Han and D.A. Payne,“Raman scattering from Ag and B1g phonons in Bi2Sr2Can-1CunO2n+4 (n =1, 2)”, Phys. Rev.B, 45, 7392 (1992). [22] X. Wang, L. X. You, X. M. Xie, C. T. Lin and M. H. Jiang, “Micro-Raman study of exfoliatedBi2Sr2CaCu2O8+d single crystals with differentthicknesses”, J. Raman Spectrosc.43 (2012), pp 949–953 [23] S. Zhang, C. Li, Q.Hao, X. Ma, T. Lu and P.Zhang,“Optimization of Bi-2212 high temperature superconductors by potassium substitution.”Supercond. Sci. Technol. 28 (2015) 045014 [24] K.-H. Müller, “AC susceptibility of high temperature superconductors in a criticalstate model”, Physica C 159 (1989), pp 717-726. [25] U.P. Trociewitz, P.R. Sahm, R.E. Koritala, L. Brandao, C. Bacaltchuk, J. Schwartz, “The influence of BaO2 additions on microstructure and superconducting properties of Bi2Sr2CaCu2O8+δ. “Physica C: Vol. 366, N° 2 (2002), pp 80-92. [26] S. M. Khalil, “Role of rare-earth Ba2+ doping in governing the superconducting and mechanical characteristics of Bi–Sr–Ca–Cu–O.” Smart Mater. Struct. Vol. 14, N° 4 (2005) pp. 804-810. [27] S. Durrani, A. Qureshi, S. Qayyum, M. Arif, “Development of superconducting phases in BSCCO and Ba-BSCCO by sol spray process.” J. Therm. Anal. and Cal. Vol. 95, N° 1(2009) pp. 87-91.

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Figure-1-: Outline of the prepared samples.

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Figure -2-: XRD patterns of the Bi-2212 samples undoped and doped with Ba (Ba = 0, 0.01, 0.02 and 0.03).

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Figure -3-: SEM micrographs of Bi2212 obtained in the surfaces of Ba = 0, 0.01, 0.02 and 0.03 samples.

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Figure-4-: Results of EDS measurements of Ba = 0, 0.01, 0.02 and 0.03 samples.

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Figure -5-: Room temperature Raman spectra for Bi-2212 samples doped with Ba (Ba = 0, 0.01, 0.02 and 0.03)

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Figure -6-: AC susceptibility measurements of the Bi-2212 samples: Real (χ’) and imaginary (χ’’) parts of the AC susceptibility versus temperature.

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Figures captions: Figure-1-: Outline of the prepared samples. Figure -2-: XRD patterns of the Bi-2212 samples undoped and doped with Ba (Ba = 0, 0.01, 0.02 and 0.03). Figure -3-: SEM micrographs of Bi2212 obtained in the surfaces of Ba = 0, 0.01, 0.02 and 0.03 samples. Figure-4-: Results of EDS measurements of Ba = 0, 0.01, 0.02 and 0.03 samples. Figure -5-: Room temperature Raman spectra for Bi-2212 samples doped with Ba (Ba = 0, 0.01, 0.02 and 0.03) Figure -6-: AC susceptibility measurements of the Bi-2212 samples: Real (χ’) and imaginary (χ’’) parts of the AC susceptibility versus temperature.

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Table-1-: Lattice parameters (a, c) and volume fraction of Bi2212 phase.

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Table 2: Results of EDS analysis in (wt.%) of Bi 2212 phase doped Ba (Ba = 0, 0.01, 0.02 and 0.03).

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Table-3-: reports the values of Tg, Tc and ΔT for all the samples.