STUDY THE STABIUZATION OF MERCURY CUPRATE COMPOSITES (H6-1228)USIN6 THALUUM AND YTTRIUM

Abstract

The synthesis of Hg-cuprates at standard pressure is a difficult problem. This difficulty comes from the fact that an excess oxygen "o" with respect to the ideal formula HgBa2Can-l Cun02n+2 is necessary to stabilize the structure. An interesting way to stabilize such structure deals with partial substitution of mercury (divalent) by foreign elements with a higher valance such a Bi (trivalent) or Tl (trivalent) and Pb (tetravalent). In this work, the substitution of thallium for mercury and yttrium for calcium has been studied. A series of samples type Hg1-xTlxBa2CaL8Yo2Cu30s+8 for x=0.3, 0.5, 0.7, 0.9 and 1 have been synthesized at standard pressure, using the solid state reaction technique. The structure of these samples is determined using X-ray

diffraction. the data revealed that this structure is tetragonal unit cell with space group P4/mmrn. The lattice parameters "a" and "c" are calculated. The lattice parameter "a" does not change by changing Tl content, whereas "c" is decreased with increasing of Tl content. The scmming electron microscope (SEM) and micro probe analysis were done for some samples. The data of micro probe analysis shows that the thallium ions were successfully doped into this structure.