Elastic and nonlinear acoustic properties of YBa2Cu3O7-x ceramics with different oxygen contents.

摘要: The effects of temperature and hydrostatic pressure on the velocities longitudinal shear ultrasonic waves propagated in ceramic samples ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.3}$, ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.6}$, ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.94}$ have been measured, to examine oxygen content ordering elastic nonlinear acoustic properties ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{x}}$. Corrections made by several methods for sample porosity microcracking properties. Temperature dependence characteristics are compared. moduli ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.3}$ show normal behavior with accord a phenomenological model vibrational anharmonicity down 40 100 K, respectively. Particularly marked stiffening has found ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{6.6}$ decreasing from 270 200 K. It is suggested that origin this distinctive feature relaxation process oxygen-atom hopping formation localized orthorhombic I phase within II compound.The derivatives natural bulk modulus tend decrease increasing content. Using results obtained work some data published previously, we shown derivative (\ensuremath{\partial}${\mathit{B}}^{\mathit{s}}$/\ensuremath{\partial}P${)}_{\mathit{P}=0}$ adiabatic ${\mathrm{YBa}}_{2}$${\mathrm{Cu}}_{3}$${\mathrm{O}}_{7\mathrm{\ensuremath{-}}\mathit{x}}$ correlated strongly decreases approximately linearly n/${\mathit{P}}_{\mathit{m}}$, ratio n maximum applied ${\mathit{P}}_{\mathit{m}}$. We also values mean mode Gr\"uneisen parameter ${\ensuremath{\gamma}}^{\mathrm{el}}$ superconducting compounds, determined measurements, linear relationship n. contents (\ensuremath{\partial}${\mathit{B}}^{\mathit{S}}$/\ensuremath{\partial}P${)}_{\mathit{P}=0}$ discussed.