Synthesis of Intermetallic (Mg_1-x,Al_x)₂Ca by Combinatorial Sputtering

Area of Science:

• Materials Science
• Thin Film Deposition
• Computational Materials Science

Background:

• Understanding the synthesis-composition-structure relationship is crucial for designing new materials.
• The Mg-Ca-Al system presents opportunities for novel intermetallic compound development.

Purpose of the Study:

• To investigate the synthesis-composition-structure relationship in the Mg-Ca-Al system.
• To explore the role of deposition temperature and Mg desorption on thin film formation.
• To synthesize novel (Mg,Al)2Ca thin films with controlled stoichiometry.

Main Methods:

• Combinatorial magnetron sputtering for thin film synthesis.
• Density functional theory (DFT) calculations for desorption energy analysis.
• X-ray diffraction (XRD) for structural characterization.
• Correlative structural and chemical analysis.

Main Results:

• Mg concentration in Mg-Ca-Al films decreases significantly with increasing deposition temperature due to Mg desorption.
• Hexagonal Mg2Ca (C14 Laves phase) forms over an expanded Mg/Ca ratio range (1.7–2.2).
• Stoichiometric (Mg1-x,Alx)2Ca thin films were synthesized by exploiting Mg desorption and preferential Al incorporation, forming C14 phase up to 23 at.% Al.

Conclusions:

• Thermally-induced desorption of weakly bonded Mg is a key factor in Mg-Ca-Al thin film synthesis.
• A novel synthesis strategy based on controlled desorption and preferential incorporation enables the creation of tunable intermetallic compounds.
• This approach is applicable for solubility studies and the synthesis of other intermetallics.