(Al,Mg)₃La: a new phase in the Mg–Al–La system

During an investigation of the Mg-rich end of the Mg–Al–La system, a new ternary phase with the composition of (Al,Mg)₃La was identified. The crystal structure of this phase was determined by conventional X-ray powder diffraction and transmission electron microscopy analysis and refined using high-resolution X-ray powder diffraction. The (Al,Mg)₃La phase is found to have an orthorhombic structure with a space group of C222₁ and lattice parameters of a = 4.3365 (1) Å, b = 18.8674 (4) Å and c = 4.4242 (1) Å, which is distinctly different from the binary Al₃La phase (P6₃/mmc). The resolved structure of the (Al,Mg)₃La phase is further verified by high-angle annular dark-field scanning transmission electron microscopy.

Computing details

(I)

Crystal data

Orthorhombic, C2221	c = 4.42417 (3) Å
a = 4.33645 (4) Å	V = 361.98 (1) Å^3
b = 18.8674 (2) Å

Data collection

h = →	l = →
k = →

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Biso*/Beq
La1	0	0.10430 (5)	0.25	0.697 (15)
Al1	0	0.4666 (2)	0.25	0.90 (8)
Al2	0	0.33416 (19)	0.25	0.94 (8)
Al3	0	0.7493 (2)	0.25	0.69 (8)