Dole, B N

Shah, S S

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I n d ia n  J. Phys. 79 (1). 81 -84 (2005)^ ' < U P >Some properties of BSCCO-Ag lidded high temperature superconductorsB N I|oIe''' and S S Shah'J. E S Research Centre, Department o f  Physics. J E S C'oHege, Jalna- 431 203,M^harashtia, IndiaDepartment o f  F^hysics, Drl B A M University, Aurangabad-431 004,N^harashtra, IndiaE-mail bndnletn^mdiatimes comR eceived 29 A prd  2004. accep ted  17 N ovem ber 2004A bstract The samples o f  (B i-Pb),Sr,C a2C'u^O,,,^  ^ system were prepared by conventional solid state reaction method with silver addition from0% to 50% Some interesting results have been obtained It has been observed from the X-ray diffraction data that the enhancement in 2212 phase and reduction in 2223 phase may exhibit the suppression of T at certain concentration of Ag wt%- It is also view'cd from X-ray diffraction and intensity data that the addition o f silvei o f  30% to 40%>, docs not deteriorate the sample quality o f (2223) compounds But addition o f  silver beyond this, may lead to formation o f 2212 phase in increasing proportionK eyw ords • Superconductivity, enhancem ent in 2212 phase, volume fraction PACS N os. : 74 .25 .-q , 74 70.D d, 61 .72  F>dAfter the discovery o f high temperature oxide superconductors, major work, co n cen tra ted  on the ap p lica tio n  areas like transmission, high magnetic fields, superconducting magnets, superconducting wheels etc. Silver is very useful clement in preparing superconducting wires and tapes. Silver remains an additive material in the conventional YjBa^Cu^O.^ 5 and Bi-Sr- C?a-Cu-0 (BSCCO) compounds 11-3| and improves the properties of superconductors. The experimental work on superconductors shows improvement in current capacity of the materials. It acts as additive material and improves the mechanical strength and reduces porosity {4, 5]. Transition tem perature is found to decrease when percentage o f silver increases. Some interesting results were obtained when detailed study o f silver addition of the samples was done. The addition o f Pb to bismuth compound was found to stabilize the 2223 phase o f  the system. For the concentration of Ag studied in this paper, show the enhancement ot 2212 phase with Ag addition.The samples of Bi, 7PbQ3Sr2Ca2Cu3 0 , ^  system with Ag addition from 0% to 50% were prepared by ceramic route [6-9]. These samples were prepared by mixing stoichiometric amounts of oxide powders B i p , ,  Pb^O^, S1CO 3 , CaCOj and CuO withCorresponding Authorhigh purity t.e. 99.99% (Aldrich Make). The stoichiometry is taken with accurate form of the powders. Then pure silver is added with appropriate form from 0 wt% to 50 wt%. Initially, powders were ground for 3 hours; then the first calcination was done at 810°C for 24 hours. The black colour was observed for all the powders. Again these powders were ground for 3 hours, second calcination was done at 8 2 0 ^  for 48 hours, ccx^led slowly upto rot^m temperature. Subsequently, powders were pressed into pellets under the pressure o f 5 to 7 tonnes and sintered at 850°C for 120 hours followed by slow cooling in Carbolite tubular furnace upto room temperature.Electrical resistivity o f the system for all Ag-added samples were determined as a function of temperature. The values of r ,,,, T  and AT, are listed in Table 1. It is observed from Table 1 that the transition width for all samples is sharp. Figure 1 shows the resistivity graphs on the pure 2223-Ag samples with Ag% varying from 10% to 50%. From resistivity graph, we see that there is a single step transition for a sample without Ag. With addition of silver, we see a double-step effect. This may be due to one or two layers of 2212 phase which remain preferentially at the common (001) twist boundaries [ 10] and produce a double- step in the T^ . transition. We feel upto 30-40% o f Ag addition©2005 lACS82 B N Dole and S S Shah'liable 1. Resistiviiy data for Bi, ^Pb^3S i2Ca2Cu^OjQ^g (Bi-2223) Ag-addcd systemAg% ~ n^onsien001020304 050I 10 1 10 I 10 1 10 85 80120 1 15 I 15 1 13 9 0  851005050 30505that the superconductivity is sustained through 2223 grains. From Table 1 we see that there is no change in T. upto 30% Ag- addition, then deformation of lattice starts. Either oxygen- content is reducing or the low T phase is increasing. It is difficult to prepare pure Bi-2223 compound- As we start adding Ag, we see that reflections corresponding to Bi-2212 phase become more prominent which can be seen by comparing A gl0%  wt addition and Ag50% wt addition samples [11-12]. The peak intensity of A gl0%  wt sample is higher than that of Ag50%> wtCritical Temperature 2223 with Pb Ag0%50 100 150 200 250 300Critical Temperature2223 with Pb + Ag30%Critical Temperature 2223 with Pb Ag20%50 100 150 200 250 300Critical Temperature2223 with Pb + Aq40%51.2ISO 100 150 200 250 300 Critical Temperature 2223 with Pb ^  Ag20%sample. On addition o f Ag% wt, the pieak intensity gets reduced. Also it is wellknown that Ag goes along grain boundaries and Ag peaks become more prominent as Ag% increases [13]. The SEM photographs also confirm  this fact [13]. The X-ray diffraction patterns o f Bi-2223-Ag-added samples are shown m Figure 2. The lattice parameters for high T phase (2223) and low  T phase (2212) are calculated from X- ray diffraction data and listed in Table 2 and 3 respiectively. From Table 2, we see that a, b and c values of lattice parameters are constant up to 30% ot silver addition and then there is deformation. From X-ra> diffraction and intensity data, we have calculated the volume fractions for (2223) and (2212) phases and listed in Table 4. The volume fractions for both the phases versus Ag% is plotted and shown in Figure 3. It is clear that from these results, the addition of more silver tends to increase the low T. phase /.<?. 2212 phase in the samples beyond 40 wt% of Ag.Tabic 2. Variation o f  lattice parameters o f  Bi, jSrjCa^Cu^O,^^^^  ^ (Hi 2223) Ag-added system.Ag% a ( A f r (A r Volume cell (A")^50 100 150 200 250 300CrHioal Temperature2223wfthPb4^Ag50% j ("K) of Bi-2223 Ag-addedsystem .00 5 .4 0 3 6 .9 9 6 1078 .8 0 310 5 .4 0 3 6 .9 9 6 1078 80320 5 .4 2 3 6 .9 9 6 1986 8093 0 5 42 36 9 9 6 1 0 8 6 .8 0 94 0 5.41 37 104 1085 9635 0 5 41 37 6 5 0 I I 0 1 .9 4 4T able 3 . Variation o f  lattice parameters o f  B i, 7Pb„3Sr,C a2C u ,0 ,y , (B i-2212) Ag-added systemAg% « (A)« c (A)*> Volume cell (A®)^00 3 .8 1 6 3 0 .6 9 6 4 4 6 ,9 9 110 3 .8 1 6 3 0 .7 3 2 447  51520 3 .8 1 6 30  7 32 4 4 7 .5 1 53 0 3 .8 1 6 3 0 .8 5 5 4 5 4 .0 2 84 0 3 .8 1 2 3 0 .7 6 7 4 4 7 .0 8 55 0 3 .7 7 6 3 1 .0 0 0 4 4 2 .0 0 3Table 4 . The relative intensity and volum e fraction o f  2212 and 2223 phases o f  (B i-2223) Ag-added system.Ag% R elative  intensity o f  2212 phaseR elative  intensity o f  2223 phaseVolume Volume fraction o f  fraction o f  2212 phase (%) 2223 phase (%)00 6 4 6 9 4 8 .1 2 5 1 .8 7JO 6 4 6 9 4 8 .1 2 51-8720 5 0 6 9 4 2 .0 2 5 7 .9 83 0 4 9 8 4 3 6 .8 4 6 3 .1 54 0 4 0 75 3 4 .7 8 65 .2 15 0 82 7 7 5 1 .5 7 4 8 .4 2S a m e p r o p e r tie s  o f  B SC O O -A ^ acled tem p era tu re  su p erco n d u c to rs 83400 '300200'100400-10 15 20  25  30  35 40  45  50 55 60Degrees 2-Theta200100600-O p t i m m | H i m »n | i i i m n q iTn i i n r f r r m i n t p M r rr r» i | iT n r r m | i t i i n i'n | t i iT in n | i M H m ? f10 15 20  26  30  35  40  45  50 55 60Dearees 2-Theta400200nil rt|<rs 5(0200-0* j i im iinn-iim rn n i i i im n |i-MMnrn i « im TTn *in i ■nip n m »i| W i i i i iip n m m | r10 15 20  25 30 35  40  46  60 65Dearees 2-Theta15 20  25  30  35 40  45  50 56Dearees 2-Theta300-20020 (Degree)f ig u r e  2 X-ray diffraction patterns o f Bi-2223 Ag wt% samples prepared by conventional solid state reaction mute. It is observed that the B i-« 2 3  fhase gets reduced and B i-22I2 phase is enhanced on addition o f A gw t*. If we compare Ag0% sample w .thA g50%  sample, extra peaks have been Observed in Ag30wt% sample, which are absent in Ag0wt% sample. From this, one may conclude that the number o f peaks goes on increasing while peak ntensity goes on decreasing.84 B N Dole and S S ShahStudies o f addition o f silver in BSCCO (2223) compounds have becom e very important from the point o f  view  o f  technological applications 114-17). We note that addition of sil ver10 20 30Ag pcrccmagc40 50F igure  3. Volume fraction {% ) o f bolh phases v e rsu s  Ag% is plotted The volume fraction of 2212 phase is increased beyond 40wt%  of Ag while the volume fraction of 2223 phase decreases beyond 40wi% of Ag From this, one can conclude that the T of the system may decrease due to increase in volume fraction o f 2212.upto 30% of weight will not alter T , this will give mechanical strength and reduce porosity from Table 4, o f volume fraction, we see that high T (2223) phase is stabilized by silver. Beyond 40%, we see the increase in lattice parameter c and cell volume, which reflects deformity in the structure. However, the volume fraction should show that beyond 40wt% o f Ag, the high T phase decreases and low T phase increases. It may be possible cause for the reduction in T . Hence, addition o f silver beyond 40wt% is not advisable.AcknowledgementAuthor would like to thank National Physical Laboratory, NewDelhi, for availing resistivity measurement and X-ray diffractui facilities.References[ IJ F Deslands, B Raveau, P Dulx)ts and D Legal S o lid  S ta te  Conwitm 71 407 (1989)[2] G P Meissner and C A Taylor J. A p p l. P liys. 69 5370 (1991)13] A S  Nash, K C Gorclta. Philip Nash, R B Poeppcl and Donglii sin M a te r ia l  R e s e a r c h  S o c . S y m p , P ro c . 169 1287 (1990)[ 4 1 R J Topare, K Ganesh, N K Sahuji, S S Shah and P Venugupj Reddy P h y s ic a  C 253 89 (1995)15] R J Toapare, N K Sahuji and S S Shah A llo y s  arid C om pounds 23(1 23 (1995)[6] W Meissner and Ochscnfcld N a tu r e w is s  21 1175 (1933)[7] J G Bednorz and K A Muller Z  P h y s ik  H C o n d en s. M a tte r  H64 189 (1986)18] M K Wu, J R Asshbur, C J Torng, P H Hor, R L Meng. L Gan /  J Huang, Y Q Wang and C W Chu P hys, Rev. 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N K Sahuji. A Chinchure and S S Shah In d ia n  J. C r y o g e n ic s  18 68 (1993)

Some Properties of BSCCO-Ag Added High Temperature Superconductors

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Some Properties of BSCCO-Ag Added High Temperature Superconductors

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