12/21/2023 0 Comments Ksp orbital supercolliderSuperconductivity in MFe 2 As 2 (M = Ba, Ca) compounds appears either at a critical doping level at ambient pressure or in the parent compound itself by application of pressure above a critical value. Tetragonal To Collapsed Tetragonal Phase Transition In BaFe2As2 and CaFe2As2 Some typical examples are reported in this present brief review. The H-insertion induces interesting magnetic transitions governed by two effects: the increase of the unit cell volume linked to the H-absorption and the occurrence of the RE-H chemical bonding. The hydrides RETXH (RE = rare earth, T = transition metal and X = Si, Ge) crystallizing in the tetragonal ZrSiCuAs-type are obtained by hydrogen absorption of the intermetallics adopting the tetragonal CeFeSi-type. Various magnetic behaviors of the hydrides deriving from the tetragonal CeFeSi-type compoundsĬhevalier, B. structure is quite distinct from that for a ternary DO 3 phase or any of the other possible bcc derivative structures (neglecting 2 possibilities with 128 or 432 atoms per unit cell(8) and interstitial ordering) They note that the site occupation for the Hsiung et al. The atomic coordinates for the latter, for a ternary composition Ti 2 AlNb, are also given. Though it is not the smallest possible unit cell for the structure, comparison with other bcc binary derivative structures is easily possible on this basis. Their unit cell is constituted by 8 bcc unit cells, and the atomic coordinates of their structure are given in Table 1 on this basis. ![]() They describe this new phase as a ''DO 3 like tetragonal structure'' with a composition Ti 5 Al 2 Nb, and lattice parameters, a = 0.65 nm and c/a ≅ 1.02. In a recent series of papers, describing aging transformations in plasma sprayed Ti-24Al-11Nb, Hsiung and co-workers proposed a new ordered tetragonal structure as the first metastable phase to form in a series of transformations from quenched-in B2 to the equilibrium phase. International Nuclear Information System (INIS) Is there an ordered tetragonal phase in the Ti3Al-Nb system?
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