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Abstract This work had bee done in an attempt to prepare superconductor materials and study its hysico chemical properties. To achieve this goal, the Bi-Sr-Ca-Cu-O (BSCCO) system has been prepared by solidstate reaction using Bi J, srCoJ, CaC03 and CuO with different composition and differe t annealing time. PbO and BaC03 were used as doped materials to tudy their effects on the superconducting properties. Different te hniques have been utilized to study the properties of the prepar materials XRD, TG, surface morphology, density measurements, oisture effect, dc electrical conductivity measurements and de agnetic measurements. Also the La2CU04 system has been studied u ing the electrochemical technique. This thesis is pres ted in five main chapters: introduction, theories and method of c Iculation, experimental, characterization of samples, results and disc sion. The first chapter is th introduction, which includes some aspects of the origin of the superc nductivity. A literature survey was carried out to cover, almost, the ast decade related to the proposed subject. Also it is includes the aim fwork. The second chapte includes highlight on the theories and the calculation methods use in this work. The third chapter sows the preparation of the Bi-Sr-Ca-Cu-O system with different co position and different annealing time and the preparation of La2CuO compound. This chapter also includes the different techniques us in the investigation of the samples (XRDTO - surface morpholo - density measurements - moisture effect) and measuring the elect ical and magnetic properties. The preparation ofLa2Cu04 ring-disk ele trodes has been reported. The fourth chapter c ntains the samples characterization using the prior mentioned techniq es (XRJ), TO, surface morphology, density measurements and mois e effect). The fifth chapter divi ed into two parts: Part (A) includes e temperature dependence of the electrical resistance for all the PI’ pared samples. Also this part contains the results of magnetic me urements. The results were discussed and correlated with composi ion-of the samples, and the effect of the annealing time. Compar ng the obtained results from de electrical measurements and magn tic measurements with the XRD analysis to the supercondu ing properties. The effect of doping on the samples using Pb and Sa has been studied studying of the dissolution behavior of La2Cu04 by using electr chemical techniques in aqueous media under open circuit conditions a 298 K. Rotating ring-disk electrode (RRDE) techniques were emplo ed in collection (product detection) and shielding (reactant remo al) measure modes to monitor the surface chemistry, including a ew approach not involving separate disk electrode It” reduction measurements as required before. Also converted the La2CU04 emiconduetor material to a superconductor material (La2Cu04+x) at room temperature usi.ng a um.que electrochemical oxidatio method. The electrochemical efficiency of anodic formation of the uperconductor phase, ”La2CU04+xin, alkaline medium has been studied The main conclusions of is work are the following: 1- Thermal analysis sho s that all the samples are thermal stable lip to 1023 K. 2- The XRr> analysis or all the prepared samples indicates the presence of the two superconducting phases; 2212, 2223 and a semiconducting phase ; 220 I. 3- A <Jiffi’actionpeak at 5.90 which corresponds to the double Cu-O layers have been obs ed for all the samples, 2212, this explains the superconducting 4- The increase in the intensity of 4.80 peak corresponded to the increase of diamagnet c susceptibility of the high T< phase, which is clear in sample EMS, oped with Ba. 5- The surface morpho ogy of the samples indicates that all the samples have the s e type of surface and the addition of Pb2+ or Ba2+did not change type of crystal formed but causes a change in the size of crystals it means that they can be used as nucleation centers for supercond cting phases. 6- The de electrical mea urements showed a metallic behavior for all the samples from 300 to 120 K. 7- The change in the mposition or the annealing time plays an important role in the preparation and properties of the superconductor mate also 8- Using doping substan e as Pband Ba can be enhancement the value, 9- The addition of lead 00.3 atomic ratio increases the T. but more addition of lead in ces an insulator phase which causes an increase in the resis ce at temperature above To. This can be observed from the re istance values at 150 K for the samples containing lead. 10- All samples at 1123 K were superconducting, with bulk of their resistanc DROP between 120 and 135 K, however the Tc,ollv’ aried with the history. 11- The maximum To,o was 73 K in a sample EM2 heated at 1123 K FQr 10 days and slo ly cooled, and the minimum was 52 K in a sample EM3 heated at 1123 K for 3 days and slowly cooled. 12- The magnetic me urements showed a diamagnetic behavior for all the samples. 13- The dissolution re ion of La2CU04 with protons is limited by mass transport. 14- New simplified m thod for determining the number of protons in the dissolution reac ion can be made. 15- La2CU04 has che ical reaction properties in common with those QfBa2YCU3O, and is uch more reactive than CuO. 16- The rate of forma .on of superconductor phase is very slow, the maximum thickness f the superCQnductor formed was about 163 nm thick from short t e experiments. |