Evidence of a novel intermetallic Mg₇Ag₃ phase in Mg–Ag binary alloy system

A novel intermetallic Mg₇Ag₃ phase in the Mg–Ag binary alloy system at 573 and 623 K was discovered by the diffusion couple technique combined with the equilibrated alloy method. The composition and crystal structure of the Mg₇Ag₃ phase were identified via scanning electron microscopy/energy dispersive spectrometry, X-ray diffractometry (XRD), electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The refinement of the XRD patterns was performed by Rietveld analysis. The XRD data have shown that Mg₇Ag₃ crystallizes in a body-centered crystal structure with Immm/orthorhombic symmetry (space group No. 71) and lattice parameters a = 14.2172, b = 14.6184, c = 14.177 Å and α = 90°. The well indexed selected area electron diffraction patterns and Kikuchi pattern obtained from TEM and EBSD confirmed the crystallographic structure obtained by XRD.

Computing details

(I)

Crystal data

Orthorhombic, Immm	c = 14.1770 (1) Å
a = 14.2172 (1) Å	Cu Kα radiation
b = 14.6184 (1) Å	Specimen preparation: Prepared at 608 K

Data collection

Rigaku SmartLab diffractometer

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

	x	y	z	Biso*/Beq	Occ. (<1)
Ag1	0.0000	0.0000	0.0000
Ag2	0.0000	0.1729	0.5000
Ag3	0.5000	0.0000	0.8051
Ag4	0.0000	0.3389	0.2066
Ag5	0.0000	0.3355	0.4002		0.4600
Ag6	0.0000	0.1698	0.1096		0.2400
Ag7	0.2055	0.0000	0.3323
Ag8	0.6621	0.7869	0.0000
Mg1	0.6148	0.0000	0.0000
Mg2	0.0000	0.3521	0.0000
Mg3	0.0000	0.0000	0.3848
Mg4	0.0000	0.3463	0.4011		0.5200
Mg5	0.0000	0.1687	0.1095		0.7400
Mg6	0.1068	0.0000	0.1731
Mg7	0.6097	0.0000	0.6193
Mg8	0.1803	0.1029	0.0000
Mg9	0.6830	0.5975	0.0000
Mg10	0.1116	0.1812	0.3065
Mg11	0.1815	0.2846	0.1177
Mg12	0.1926	0.3914	0.3114