Phase stability of three-dimensional bulk and two-dimensional monolayer As_1-x Sb _x solid solutions from first...

Area of Science:

• Computational Materials Science
• Thermodynamics of Alloys
• Semiconductor Materials

Background:

• Understanding the mixing thermodynamics of arsenic-antimonide (As_1-x Sb _x) alloys is crucial for their application in advanced electronic and optoelectronic devices.
• Previous studies on bulk As_1-x Sb _x have reported conflicting alloying behaviors, necessitating a comprehensive thermodynamic investigation.
• The influence of dimensionality on the alloying behavior of materials is a key area of research in condensed matter physics.

Purpose of the Study:

• To investigate the mixing thermodynamics of three-dimensional bulk and two-dimensional monolayer As_1-x Sb _x alloys.
• To elucidate the effects of alloy composition and temperature on the phase stability and ordering of As_1-x Sb _x.
• To explain existing discrepancies in the literature regarding the alloying behavior of bulk As_1-x Sb _x.

Main Methods:

• Employed a first-principles cluster-expansion method to model the alloy system.
• Utilized canonical Monte Carlo simulations to explore thermodynamic properties as a function of composition and temperature.
• Compared theoretical predictions with existing experimental observations for validation.

Main Results:

• Bulk As_1-x Sb _x exhibits chemical ordering at x=0.5, forming a stable AsSb compound up to high temperatures.
• A miscibility gap exists in bulk alloys between 475 K and 550 K, leading to the coexistence of two disordered solid solutions.
• Monolayer As_1-x Sb _x demonstrates significantly altered alloying behavior, with a stable single-phase solid solution predicted above 250 K across all compositions.

Conclusions:

• The study clarifies the complex alloying behavior of bulk As_1-x Sb _x, resolving previous experimental uncertainties.
• Reduced dimensionality from 3D bulk to 2D monolayer profoundly influences the thermodynamic stability and phase behavior of As_1-x Sb _x alloys.
• Findings provide critical insights for the rational design and synthesis of novel As-Sb based materials with tailored properties.