| Автор | M Cankurtaran |
| Автор | G A Saunders |
| Дата выпуска | 1992-09-01 |
| dc.description | The velocities of longitudinal and shear ultrasonic waves propagated in dense (96% of theoretical density) ceramic YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> have been measured as functions of temperature and hydrostatic pressure. The temperature dependences of the elastic stiffnesses and bulk modulus, which have been determined from the velocity data between 10 K and 300 K, show the previously recognized step-like increase at about 200 K on cooling and a similar decrease at about 225 K during warming, with a pronounced hysteresis in the range 190-235 K. The pressure dependences of the velocities of both longitudinal and shear ultrasonic waves show a substantial reduction in slope at a pressure P<sub>c</sub> and are practically linear on either side of P<sub>c</sub>. The pressure P<sub>c</sub> at which the kink occurs decreases linearly on decreasing the temperature from 297 K to 247 K and extrapolates to atmospheric pressure at 220 K, which is within the temperature range where the steep changes in the temperature dependences of the elastic moduli occur. Hence the kink in the elastic properties under pressure at P<sub>c</sub> correlates with the steep change observed in the range 190-235 K at atmospheric pressure, which has been attributed previously to a phase transition involving oxygen ordering. The measured pressure and temperature dependences of the anomalies in the ultrasonic wave velocities have been used to locate the ortho-I to mixed (ortho-I and ortho-III) phase boundary in the P-T plane of the phase diagram. |
| Формат | application.pdf |
| Издатель | Institute of Physics Publishing |
| Название | Correlation between anomalous elastic behaviour under pressure and with temperature near 220 K in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7-x</sub> |
| Тип | paper |
| DOI | 10.1088/0953-2048/5/9/001 |
| Electronic ISSN | 1361-6668 |
| Print ISSN | 0953-2048 |
| Журнал | Superconductor Science and Technology |
| Том | 5 |
| Первая страница | 529 |
| Последняя страница | 533 |
| Аффилиация | M Cankurtaran; Sch. of Phys., Bath Univ., UK |
| Аффилиация | G A Saunders; Sch. of Phys., Bath Univ., UK |
| Выпуск | 9 |
