Thermal Expansion of Pb sub 2 Sr sub 2 Y sub (1-x) Ca sub x Cu sub 3 O sub (8+delta).

The thermal expansion of Pb sub 2 sr sub 2 Y sub (1-x) Ca sub x Cu sub 3 O sub (8+delta) has been measured between 25 and 700C for x = 0, .2 and .4. Measurements were made on ceramic samples with delta = 0 during heating at 4degrees/min in N sub 2 and O sub 2 atmospheres. In N sub 2 the CTE is ~13 ppm/C for all compositions. In O sub 2 the expansion varies greatly with temperature and composition as the samples undergo both oxidation and reduction. The expansion mimics previously reported gravimetric data as two maxima of ~1.4% are found near 550C and 700C. The lattice expansion of Pb sub 2 Sr sub 2 YCU sub 3 O sub 8 with oxidation contrasts to the shrinkage observed when Ba sub 2 YCU sub 3 O sub (6.2) is oxidized.