Pawar, S H

Shinde, V N

IACS Institutional Repository

Indian J. Phys. 71A (2), 219-223 (1997)IJP A- an international journalStudies cm electrolytic deposition of Mg films and their oxidationV N  Sh inde  and S H Pawar*Department of Physics. Shivaji University Centre for PG Studies. Solapur-413 001. Maharashtra, IndiaEnergy Studies Laboiatory, Department of Physics, Shivup University. Kolhapur-416 (X)4, Maharashtra. IndiaReceived 5 August 1996, aa epted H August 1996Abstract : Preparation, characterisation and feasibility of polycryslalline MgO film substrates lor superconducting films have been studied. The clectrodeposition of magnesium subsequently followed by oxidation were earned out onto stainless steel substrates Effect o( heat treatment and other conditions have been discussed White coloured MgO films arc obtained which are compact, dense, umfonn and adhesive to the substrates. On these MgO film substrate, wc have screen primed the Bi-Sr-Ca-Cu-0 ceramic and then tested for their feasibility in high-Tc superconductivity.Keywords : Magnesium, electrodeposition, superconductivityFACS No. : 74 76 B/.D eposition  o f  h igh  quality  film s o f  the h igh-T c su p erco n d u c to rs  on to  d ifferen t substra tes has s ig n ifican t ap p lica tio n  in m odern  sc ience  and techno logy  [1,2]. A m ong the d ifferen t classes o f  p o ss ib le  substra te  m ate ria ls 13-5], the m alleab le  and duc tile  substra tes  form  an in teresting  c la ss  |6 ,7 ] s ince  they o ffer hope  fo r d ev e lo p em en t o f  rep lacem en t for w ires, sheets and tapes, w hich  have been d ifficu lt to realize due  to b rittle  ceram ic  characte r o f  new  high-Tc superconduc to rs.U p till now , several research  g roups have prepared  superconducting  film s on to  single  crystal su b s tra te s  su ch  as M gO , S r T i0 3, Y S Z  (Y ltria  s ta b ilize d  L irc o n ia )  etc |8 -1 ( ) |.  H ow ever, for ad ap tab ility  to  large  sca le  p rocess, som e inexpensive  and easily  av a ilab le  su b s tra tes  a re  re q u ire d . S o m e  in v e s tig a to rs  p re p a re d  the  su p e rc o n d u c tin g  film s on po lycrysla lline  M gO , Y S Z  p e lle ts  and sta in less steel substra tes [1 1 -1 3 ], S u p erco n d u ctin g  hi ms have  a lso  been  p rep ared  by using  S i 0 2, Z rO 2 and  ind ium -tin  o x id e  as a bu ffer layer onto p o ly cry sla llin e  substra tes [14—17].©  1997 l A CS220 V  N  Shinde and S  H  Paw arIn Lhc present investigation, we have carried out the electrodeposition of Mg onto stainless steel, copper, brass and fluorine doped tin-oxide (FTO) coated glass substrates The different preparative parameters of the deposition were studied and optimised. These as-deposited films were heat treated in order to obtain oxide film. White coloured MgO films are obtained which arc compact, uniform and adhesive to the substrates. On the MgO film substrate, the Bi-Sr-Ca-CuO ceramic was screen printed and tested for temperature dependence of the resistivity at liquid nitrogen temperature.Electrolytic bath was prepared by using reagent grade chloride of magnesium in double distilled water. Concentration of Mg-chloride was of 100 mM. The electrodeposition was carried out polentiostatically onto stainless steel, copper, brass and FTO coated glass substrates. The sheet resistance of conducting glass substrate was 20 to 30 ohm/cm. The back sides of the substrates were covered with insulating tape. The cathode area was one cm2. The anode was a high purity graphite plate and distance between the anode and cathode was 0.6 cm. All depositions were carried out in an unstirred condition and at ambient temperature (300 K).The cathodic polarization curves for solution of Mg chloride were Recorded with the Scanning Potentiostat/galvanostat model 362 (EG & G) and X-Y recorden Microstructural properties of the films were carried out with an Mctzer optical microscope. Resistance of MgO film substrate was measured with eight and half digit 7^ 081 precision voltmeter.A microcomputer-controlled Philips PW 1710 X-ray diffractometer equipped with a copper target with CuKu radiation was used to obtain the X-ray diffraction patterns of MgO film substrates.Figure I shows the cathodic polarization curves of magnesium onto stainless steel, copper brass and FTO coated glass substrates. From these polarisation curves, it is observedFigure 1 . The cathodic polarisation curves for Figure 2. The variation of cathodic current density withM g onto different substrates. deposition timeStudies on electrolytic deposition o f Mg films and their oxidation 221that nature o f  c u r v e s  f o r  M g  o n  c o p p e r  a n d  b ra s s  a re  s im ila r  a n d  d e p o s i t io n  o c c u r s  in  th e  lower p o te n t ia l  r e g io n .  W h ile  th e  n a tu r e  o f  c u rv e s  f o r  M g  o n  s ta in le s s  s te e l  a n d  F T O  c o a te d  ^ lass s u b s tr a te s  a r e  v e ry  b ro a d  a n d  d i f f u s e  in  n a tu re  a n d  d e p o s i t io n  o f  m a g n e s iu m  o c c u r s  in  die larger p o te n t ia l  r e g io n .  T h e  v a lu e s  o f  se t d e p o s i t io n  p o te n t ia l s  a re  o p t im is e d  fo r  a ll  th e  substrates a n d  a re  l is te d  in  T a b le  1.Table 1. Electrodeposilion potentials of magnesium from chloride solution onto different substratesSubstrateStainless steelCopperBrassFTO coaled glassElectrodeposition potential V vs SC E- 1.20 - 0  80 -0  90 -1.85F ro m  T a b le  1, it is  s e e n  th a t  s e t  d e p o s i t io n  p o te n t ia l  o f  m a g n e s iu m  is  s m a l le s t  f o r  copper a n d  b ra s s  s u b s tr a te s ,  w h i le  fo r  s ta in le s s  s te e l  a n d  F T O  c o a te d  g la s s  s u b s tr a te s ,  la rg e  d e p o s itio n  p o te n t i a l s  a re  r e q u ire d .T h e  f i lm s  w e re  d e p o s i te d  a t c o n s ta n t  p o te n t ia l  a n d  th e  v a r ia t io n  o f  c a th o d ic  c u r r e n t  d e n s ity  w a s  r e c o r d e d  a s  a f u n c t io n  o f  d e p o s i t io n  t im e . F o r  a  g iv e n  b a th ,  th e  c a th o d ic  d e p o s itio n  c u r r e n t  d e n s i ty  w a s  fo u n d  to  v a ry  w ith  d e p o s i t io n  lim e . It is  fo u n d  th a t  c u r re n t  d e n sity  g r a d u a l ly  d e c r e a s e s  u p to  th e  d e p o s i t io n  p e r io d  o f  2 5  m in u te s  a n d  th e n  p r a c t ic a l ly  ic m u in c d  c o n s t a n t  w ith  d e p o s i t io n  t im e . T h e  c u r r e n t  d e n s i t i e s  w e re  fo u n d  to  lie  b e tw e e n  2 to 4 m A /c m 2. S im ila r  v a r ia t io n s  o f  c u r r e n t  d e n s i ty  w ith  l im e  w a s  o b s e r v e d  fo r  a ll o th e r  su b s tia tc s  A  ty p ic a l  c u rv e  is d e p ic te d  in F ig u re  2.T h e  v a r ia t i o n  o f  t h ic k n e s s  o f  th e  f i lm  w a s  m e a s u r e d  w ith  d e p o s i t i o n  t im e  fo r  all s u b s tra te s .  A ty p ic a l  c u rv e  is s h o w n  in F ig u re  3. It w a s  fo u n d  in g e n e ra l ,  th a t  th e  f ilmfigure 3. The vanation of film thickness with deposition lime.Figure 4 . A typical X-ray diffraction pattern of M gO  onto stainless steel substrate, oxidised at 400°C for five minutes222 V N Shinde and S H Pawarthickness gradually increases with deposition time and attains a certain value and then saturates for longer deposition times. The thickness of the film was found to lie between 2 to 4 microns for the deposition period of 50 minutes for different substrates.These films are oxidised at 200°C to 400°C for five minutes, in order t,o obtain the complete oxidation of the films. Resistance measurements of as-deposited and oxidised films were carried out at room temperature by the precision 7081 voltmeter. From the resistance measurements, it is found that the resistance of as-deposited film is in the range of 4 to 6 megaohms, the resistance of the film increased on oxidation to around 20 megaohms.From X-ray diffraction patterns, it is found that both as-deposited and oxidised Mg films arc polycrystalline in nature; however, crystallinity improved after oxidation of the films. A typical X-ray diffraction pattern of MgO film onto stainless steel substrate, which was oxidised at 400°C for five minutes is shown in Figure 4.Surface morphology of the as-deposited and oxidised Mg filpis were studied Figures 5(a, b) show the typical microphotographs of as-deposited land oxidised Mg films with magnification 500 X. White coloured deposits are obtained\which are dense, uniform and adhesive to the substrates. The as-deposited film consists of packed arrangement of grains, while grain size of the oxidised films was increased, with increase in oxidation temperature.The Bir Sr-Ca-CuO ceramics were screen-printed onto MgO film substrates and then heated in oxygen atmosphere at 1100 K for 10 minutes. The films turned into dark black'in appearance, adhesive to substrate and stable towards atmospheric conditions. These substrates are as good as single crystal substrates. Figure 6 shows the resistivity dependence of temperature of screen printed BSCCO film. ,Figure 6 . Resistivity dependence of tcmperatuic of screen printed B S C C O  filmThe resistivity measurement was done using a four probe method with it silver paint contacts on the film surface. It is found that the resistivity of the film was in the rangeStudies on ,electrolytic deposition of Mg films and their oxidationPlate /(b)Figure 5. Micrbphotographs of MgO films with magnification 500 X (a) as deposited, (b) oxidised at 400°C.of 15 to 20 ohm/cm at room temperature and found to decrease drastically at liquid nitrogentemperature.In this work, electrodeposition of Mg films are carried out onto stainless steel, copper, brass and PTO coated conducting glass substrates. Oxidation of the film is necessary in order to obtain the pure oxidised film of MgO. X-ray diffraction patterns show the MgO films are polycrystalline in nature. The MgO films onto stainless steel substrate are used as a barrier layer for obtaining high-Tc superconducting films.AcknowledgmentThe authors wish to thank Dr. A V Narlikar for his constant encouragement.References[1] S G Lee, G Koren, A Gupta, A Segmuller and C C Chi A ppl. P h ys. Lett. 55 1261 (1989)[2] K Char, D K Fork, T H Geballe, S S Laderman. R C Taber, R D Jacowitz, F Bridges, G A N  Connel and J B Boyce A p p l. P h ys. L ett. 56 785 (1990)[3] S Hatta, H Higashino, K Hirdchi, H Adachi and K Wasa A ppl. P h ys. L ett. 53 148 (1988)14 ] T Asano, K Tran, A S Byrne, M M Rehman, C Y Hnag and J D Reardon A p p l. P h ys . L ett. 54 1275(1989)[5] S B Ogale, R D Vispute and R R Rao A pp l. P h ys. L ett. 57 1805 (1990)[6 ] T Yamaguchi, S Aoki, N Sadkaia, O Korto and H Osanai A ppl. P h ys. Lett. 55 1581 (1989)[7] Ashok Kumar, L Ganapathi, S M Kanetkar and J Naiayan A p p l. P h ys. L ett. 57 2594 (1990)[8 ] E Fogarassy, C Fuchs, P Siffert, J Penierc, X Z Wang and F Rocket S o lid  S ta te  C om m u n . 67 975 (1988)[9] K Shinohara, F Manukta and M Yamanoka Jpn. J. A pp l. P h ys. 27 1683 (1988)[10] T Akune and N Sakamoto Jpn. J. A pp l. P h ys. 27 2078 (1988)[11] S H Pawar, B M Toddar, H A Mujawar and M H Pendse M a te r  R es. Bull. 25 503 (1990)[12] S H Pawar and H A Mujawar M ater . R es . Bull. 25 1443 (1990)[13] S B  Ogale. V N Koinkar, R Viswanathan, S D Roy and S M Kanetkar A p p l. P h ys . L e tt. 59 1908 (1991)[14] B J Kellett, i  H James, A Gauzzi, B Dwir, D Pavuna and F K Reinhart A p p l. P h ys  L e tt. 57 1140(1990)[15] L S Hung. J A Agostanelli, G R Paz-Pujalt and J M Mir A pp l. Phys. Lett. 53 2450 (1988)[16] LW  Sinke, G P A Frijilink and F W Saris A p p l. P h ys. Lett. 47 4 7 1 ( 1985)[17] K Moroishi, Y Ogawa and A J Ikushima Jpn. J. A pp l. Ph ys. 27 2330 (1988)Studies on electrolytic deposition of Mg films and their oxidation 22371A(2M8

Studies on Electrolytic Deposition of Mg Films and their Oxidation

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Studies on Electrolytic Deposition of Mg Films and their Oxidation

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