Effect of thermal cycling on normal state thermal properties of YBa2Cu3O7−x films

✍ Scribed by Shailendra Kumar; S.P. Pai; R. Pinto; Dhananjay Kumar

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 410 KB
• Volume: 215
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(93)90227-h

✦ Synopsis

The photopyroelectric (PPE) technique has been used to study the effect of thermal cycling on normal state thermal properties of YBa2Cu307_x thin films. For an optically opaque and thermally thin sample, the PPE voltage amplitude (V) is inversely proportional to the specific heat of the sample. Hysteresis in Vas a function of temperature is observed and annealing of films at T= 325 K enhances the magnitude of hysteresis. For annealed films, the magnitude of hysteresis reduces slowly as a function of time and in some films it disappears after a period of more than 24 h at 295 K. Two peaks in V-~ at T= 110 to 140 K and at T= 200 to 240 K have been observed. The peak at T= 200 to 240 K has been observed only during the heating path for samples cooled to a temperature less than 150 K. No hysteresis in the resistance as a function of temperature is observed, but annealing at 325 K reduces the magnitude of the resistance.