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Tl-2212 superconducting thin films were fabricated on LaAlO3 (00l) substrates by sol-gel method. In the process, the precursor films were annealed in various gas atmospheres. XRD and EDX testing results showed that the precursors annealed in O2 converted into pure Tl-2212 superconducting phase, and the nominally stoichiometric cation ratio of TlBaCaCu was close to 2:2:1:2. The Tl-2212 film had a layered morphology and medium-quality superconductive parameters, which included the critical temperature T c of 105.5 K, and the critical current density J c of 0.8 MA/cm2 (self-field, 77K).

The stress–strain relationships for four different shear processes of L1 0 TiAl have been investigated from first-principles calculations, and the peak shear stresses in these slip systems were obtained. By analysing the structural unit cell, bond length and charge density, the deformation modes under shear were elaborately discussed. Both of the peak shear stresses and the charge density indicate that the ideal shear strength of L1 0 TiAl occurs in the $\boldsymbol {\langle \! 11\bar {2} ]\{111\}}$ direction. It is shown that some bonds are enormously stretched accompanying with depletion of charge density as the strain increase. The density of states was studied in detail. It is indicated that strong hybridization exists between Ti 3 d and Al 2 p, and the structural stability would be lowered with increase of the strain.

A theoretical formalism to investigate the elastic anisotropy and phonon focusing for tetragonal crystals is described in detail in this paper. This is applied for γ-TiAl and both of the numerical indicators and the three dimensional images of elastic anisotropy are derived. The percentage of bulk and shear anisotropies indicate γ-TiAl exhibits relatively high degree of anisotropy in shear but small anisotropy in compressibility. Anisotropy indexes A ∗ and A U demonstrate γ-TiAl possesses high degree of anisotropy, and this feature is also reflected in the three dimensional Young’s modulus, shear modulus and Poisson’s ratio. Three slowness surfaces are constructed for γ-TiAl to investigate the phonon focusing patterns, and the group velocity surfaces are also obtained to gain more insight into the elastic anisotropy. Due to elastic anisotropy, both of the slowness surfaces and the group velocity surfaces are nonspherical. The anisotropy is highest for slow transverse mode, and then followed by fast transverse mode and longitudinal mode. Interestingly, only transverse phonons cause caustics for γ-TiAl. Furthermore, the phase velocity and group velocity are not collinear for transverse mode in some directions, resulting in cuspidal edges along these directions in the group velocity surfaces.

First-principles calculations have been performed to systematically investigate the uniaxial loading response of seven one dimensional long period structures Al3Ti. The stress–strain relations under [1 0 0] and [0 0 1] uniaxial tensile deformation reveal that the distinction of Ea and Ec increases as increase of antiphase boundary period parameter M′. Both of the Young modulus and the lattice parameters variation indicate that the inter-atomic interactions along [0 0 1] direction is much stronger for all of these structures. The peak tensile stresses show that, except for 〈3 2〉, the [1 0 0] direction uniaxial tensile deformation is much easier. Furthermore, it is interesting to find that the critical tensile strains under [1 0 0] direction decrease with increase of M′, meaning the existence of antiphase boundary reduces the symmetry of the crystal and leads to poor ductility. Electronic structures development indicate that with increase of the strain the electron density exhibits gradual depletion together with stretch of bonds and the structure gradually becomes unstable.