Thermal stability of YBa↓(2)CU↓(3)O↓(7-x) single crystal surfaces investigated by the ion channeling technique

摘要

We have performed ion channeling characterizations on the (001) and (100) surfaces of YB↓(a2)Cu↓(3)O↓(7-x) single crystals, using 950 keV He↑(+) ions at temperatures ranging from 20 to 780℃. In oxygen pressures below 5×10↑(-5) Torr, we directly observed the surface changes as the sample temperature was increased, and found that the compositional and structural changes occurred from around 400℃. At higher oxygen pressures, we heated the crystals and performed channeling analysis before and after the heating. We found that the YB↓(a2)Cu↓(3)O↓(7-x) crystal surfaces were stable at temperatures up to 780℃ in the oxygen pressure range of I mTorr-1 Torr. Beyond this range, the surfaces deteriorated at high temperatures. # 1997 American Institute of Physics. S0003-6951(97)04432-X