Elastic Anomalies in Single-Phase HgBa2Ca2Cu3O8+δ

X-ray diffraction measurements, vibrating-reed technique and tensile tests have been employed to investigate the elastic properties of single-phase HgBa2Cu3O8+δ. The discontinuities of both Young's sound velocity and linear thermal expansion coefficients for a and c directions have been observed near To (133K). Internal friction peaks are found in other two temperature ranges of 150K and 250K. Ferroelastic loops are also observed around 150K. A thermodynamics analysis of the experimental data is presented. The discontinuity in Young's sound velocity at To and Gruneisen parameter γ are estimated and in agreement with the experiments