Aluminium substitution induced superstructures in Mg1-xAlxB2 (x = 0.0 to 0.50): An X-ray diffraction study
arXiv:0708.3882 · doi:10.1016/j.physc.2007.08.005
Abstract
The physical property characterization of Al doped Mg1-xAlxB2 system with x = 0.0 to 0.50 is reported. The results related to phase formation, structural transition, resistivity R(T) and magnetization M(T) measurements are discussed in detail. It is shown that the addition of electrons to MgB2 through Al results in loss of superconductivity. Also seen is a structural transition associated with the collapse of boron layers reflected by the continuous decrease in the c parameter. The main emphasis in this paper is on slow scan X-ray diffraction (XRD) results, which confirm the existence of a superstructure along the c-direction for the x = 0.50 sample. The appearance of some additional peaks, viz. [103], [004], [104] and [112], results in doubling of the lattice parameter along the c-axis. This possibly indicates the alternative ordering of Al and Mg in MgAlB4 separated by hexagonal boron layers but still maintaining the same hexagonal AlB2 type structure.
17 Pages Text + Figs. To appear in Physica C
References in corpus (9)
- Band filling and interband scattering effects in MgB: C vs Al doping
- Effects of Al doping on the structural and electronic properties of Mg(1-x)Al(x)B2
- Critical Field of Al-Doped MgB2 Samples: Correlation with the Suppression of Sigma-Band Gap
- Crystal structure of the MgAlB superconductors near x=0.5
- Inversion of two-band superconductivity at the critical electron doping of (Mg,Al)B
- Multiband and impurity effects in infrared and optical spectra of MgB2
- Physical property characterization of Fe-tube encapsulated and vacuum annealed bulk MgB2
- Thermoelectric power of MgBBe
- Comment on ``BCS to Bose-Einstein crossover phase diagram at zero temperature for a d_{x^2-y^2} order parameter superconductor: Dependence on the tight-binding structure''