Superconductivity behaviour of screen-printed LnBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> (Ln=Eu,Y)films

Thick films of the high Tc superconducting oxides, LnBa2Cu3O7, Ln=Eu, Y, have been fabricated by screen printing on alumina and SrTiO3 substrates. Conditions for optimum superconductivity behaviour of the films have been established. Tconset varies from 90-94 K for all the films but zero resistance was observed only in a few cases

Effect of oxide additives on the properties of high temperature superconductor, YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB>

The effect of oxide additives-CuO, SiO<SUB>2</SUB>, Y<SUB>2</SUB>O<SUB>3</SUB>, Bi<SUB>2</SUB>O<SUB>3</SUB> and ZnO in 1-10 mol% on the sintering and superconducting properties of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> was studied. SEM studies indicated improvement of grain size and interconnectivity due to the additives, the best results being obtained with Bi<SUB>2</SUB>O<SUB>3</SUB>, SiO<SUB>2</SUB> and Y<SUB>2</SUB>O<SUB>3</SUB>. The superconducting transition temperature is unaffected (92&#177;2 K) even with 10 mol % of the additives. ZnO, however, decreases the T<SUB>c</SUB> as expected

Superconductivity behaviour in screen-printed YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7</SUB> films

We have fabricated films of the high Tc superconducting oxide YBa2Cu3O7 by screen printing on alumina, calcia-stabilized zirconia, yttria-stabilized zirconia, SrTiO3 and La2CuO4 substrates. Alumina was found to be a suitable substrate for screen printing. La2CuO4 and SrTiO3 substrates can be used with shorter annealing times. Superconducting transition temperatures in the vicinity of 85 K have been established in some of the films

Oxygen-enrichment of YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>7-&#948;</SUB> using the fluidization technique

The oxygen-deficient phase of the high Tc superconductor, YBa2Cu3O7, was oxygen-enriched using the fluidization technique to give good superconducting properties. The normal method of oxygen treatment at 900&#176;C for 24 h and at 600&#176;C for 24 h has been reduced to just one treatment at 600&#176;C for 12 h by the fluidization technique to achieve almost the same strength of superconducting signal for the YBa2Cu3O7 powder, which establishes the attractiveness of the latter route for the large-scale preparation of superconducting material. The particle sizes were in the range 0-90, 90-180 and 180-420 &#956;m. The fluidized particles were crystalline with orthorhombic distortion. Tconset, estimated using the a.c. magnetic susceptibility method, was 91&#183;3 K. The volume fraction of superconducting material in the product was 83&#183;7-85&#183;3%, one of the highest values reported so far for YBa2Cu3O7