Electronegativity calculation of bulk modulus and band gap of ternary ZnO-based alloys

The MgxZn1−xO alloy system may provide an optically tunable family of wide band gap materials that can be used in various UV luminescences, absorption, lighting, and display applications. A systematic investigation of the MgO-ZnO system using ab initio evolutionary simulations shows that MgxZn1−xO alloys exist in ordered ground-state structures at pressures above about 6.5 GPa. Detailed enthalpy calculations for the most stable structures allowed us to construct the pressure-composition phase diagram. In the entire composition, no phase transition from wurzite to rock-salt takes place with increasing Mg content. We also found two different slops occur at near x = 0.75 of Eg-x curves for different pressures, and the band gaps of high pressure ground-state MgxZn1−xO alloys at the Mg concentration of x > 0.75 increase more rapidly than x < 0.75.

Section: Resultssupporting

confidence: 92%

Miscibility and ordered structures of MgO-ZnO alloys under high pressure

Tian

Duan

et al. 2014

“…The difference in atomic radius influences the distribution of alloying elements and metallic bond energy. The electronegativity has an impact on the electron density of atoms and the larger value of electronegativity result in a higher Young’s modulus of metallic alloys 58 . Additionally, larger electronegativity differences ( ) and higher mixing enthalpy ( ) increases the probability of formation of intermetallic brittle phases, which have lower Young’s modulus.…”

Section: Resultsmentioning

confidence: 99%

Machine learning assisted prediction of the Young’s modulus of compositionally complex alloys

Khakurel

Taufique

Roy

et al. 2021

We identify compositionally complex alloys (CCAs) that offer exceptional mechanical properties for elevated temperature applications by employing machine learning (ML) in conjunction with rapid synthesis and testing of alloys for validation to accelerate alloy design. The advantages of this approach are scalability, rapidity, and reasonably accurate predictions. ML tools were implemented to predict Young’s modulus of refractory-based CCAs by employing different ML models. Our results, in conjunction with experimental validation, suggest that average valence electron concentration, the difference in atomic radius, a geometrical parameter λ and melting temperature of the alloys are the key features that determine the Young’s modulus of CCAs and refractory-based CCAs. The Gradient Boosting model provided the best predictive capabilities (mean absolute error of 6.15 GPa) among the models studied. Our approach integrates high-quality validation data from experiments, literature data for training machine-learning models, and feature selection based on physical insights. It opens a new avenue to optimize the desired materials property for different engineering applications.

“…Previous studies suggest that the symmetry of component structures is important in alloys of ZnO with other group-II metal oxides 6 18 26 27 34 . Most of these structures were created using the substitution method, where Zn was replaced with Ca in the wurtzite supercell or Ca was replaced with Zn in the rocksalt supercell.…”

Section: Resultsmentioning

confidence: 99%

“…Mixing ZnO-based semiconductor alloys with other materials which possess even wider band gaps, allows for the fabrication of quantum wells and superlattices 4 5 . Alloying is an effective approach to fine-tune the band gap in the range of blue-green and ultraviolet wavelengths, which greatly promotes the band-gap engineering and heterojunction design 6 7 . For different desired band gaps, there are several candidates, such as MgO, BeO, and CaO 8 9 10 .…”

mentioning

confidence: 99%

Ab initio investigation of CaO-ZnO alloys under high pressure

Sha

Tian

et al. 2015

CaxZn1–xO alloys are potential candidates to achieve wide band-gap, which might significantly promote the band gap engineering and heterojunction design. We performed a crystal structure search for CaO-ZnO system under pressure, using an ab initio evolutionary algorithm implemented in the USPEX code. Four stable ordered CaxZn1–xO structures are found in the pressure range of 8.7–60 GPa. We further constructed the pressure vs. composition phase diagram of CaO-ZnO alloys based on the detailed enthalpy calculations. With the increase in Ca concentration, the CaO-ZnO alloy first undergoes a hexagonal to monoclinic transition, and then transforms back to a hexagonal phase. At Above 9 GPa, there is no cubic structure in the alloys, in contrast to the insostructural components (B1-B1). The band gap of the CaxZn1–xO alloy shows an almost linear increase as a function of the Ca concentration. We also investigated the variation regularity of the band gap under pressure.