Tilt-wave dynamics of the oxygen octahedra inLa2CuO4from anelastic and139LaNQR relaxation

Anelastic Relaxation of Metallic Glasses

Anelastic spectroscopy studies of high-Tc superconductors

Two families of cuprates exhibiting high-Tc superconductivity, YBa2Cu3O6+x (YBCO) and La2xSrxCuO4+δ (LSCO), have been extensively studied by anelastic spectroscopy, by measuring the complex dynamic Young’s modulus E (ω, T ) = E′ + iE′′ of ceramic samples at frequencies of 0.5-20 kHz between 1 and 900 K. Results are also presented on oxygen vacancies in the ruthenocuprate RuSr2GdCu2O8−δ. The ela...

Anelastic relaxation processes due oxygen in Nb–3.1 at.% Ti alloys

In the last 50 years several studies have been made to understand the relaxation mechanisms of the heavy interstitial atoms present in transition metals and their alloys. Internal friction measurements have been carried out in a Nb–Ti alloy containing 3.1 at.% of Ti produced by the Materials Department of Chemical Engineering Faculty of Lorena (Brazil), with several quantities of oxygen in soli...

Anelastic Relaxation of Protonic Defects in M3+-Doped BaCeO3

When perovskite-structured BaCe03 is doped with M ~ + ions (e.g., ~ d ~ + , Gd3+,yb33 that substitute on ce4+ sites, oxygen-ion vacancies are created for charge compensation. However, when treated in water vapor, the vacancies are replaced by protons, which take the form of OH' ions. This treatment makes the materials a good protonic conductor. Questions about the defect structure of the proton...

Landau Theory of Tilting of Oxygen Octahedra in Perovskites

The list of possible commensurate phases obtained from the parent tetragonal phase of Ruddlesden-Popper (RP) systems, An+1BnC3n+1 for general n due to a single phase transition involving the reorienting of octahedra of C (oxygen) ions is reexamined using a Landau expansion. This expansion allows for the nonlinearity of the octahedral rotations and the rotation-strain coupling. It is found that ...