Si Phase Diagram Research Articles

Modeling of Physical-Chemical and Electronic Properties of Lithium-Containing 4H—SiC and Binary Phases of the Si—C–Li System

In the equilibrium model of the solid surface–adatom system, including a three-dimensional interfacial surface, changes in surface properties are considered, taking into account the chemical potential due to the action of surface tension. The relationship between chemical potential and electrochemical potential of the ith component in an electrochemical cell is analyzed. Using the density functional theory (DFT), the adsorption, electronic, and thermodynamic properties of 2 × 2 × 1 and 3 × 3 × 1 supercells of crystalline compounds AmBn, (, where n and m are stoichiometric coefficients) of the boundary binary systems of the ternary phase diagram of Si–C–Li are studied. The stability of phases AmBn and property calculations are carried out with the exchange-correlation functional within the framework of the generalized gradient approximation (GGA PBE). The parameters of the crystal structures of the compounds AmBn, the adsorption energy of the lithium adatom on a 4H–SiC substrate, the electronic structure, and the thermodynamic properties of supercells are calculated. The thermodynamically stable configurations of the 4H–SiC–Liads supercells having different locations Liads are determined. The DFT GGA PBE calculations of the enthalpy of formation of compounds AmBn are carried out in the ternary Si–C–Li system. Taking into account the changes in the Gibbs free energy in the solid-phase exchange reactions between binary compounds, equilibrium sections (connodes) in the concentration triangle of the Si–C–Li phase diagram are established. An isothermal section of the Si–C–Li phase diagram at 298 K is constructed. The patterns of diffusion processes that are related to the movement of particles on the surface layer of the 6H–SiC sample are analyzed. The activation energy of lithium diffusion in 6H–SiC is calculated from the Arrhenius type relation in two temperature ranges (769–973 K) and (1873–2673 K).

The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

The influence of Mo (10–40 at%) additions to Cr–8 at%Si is systematically studied by analyzing arc‐melted alloys in the as‐cast and annealed state. The oxidation resistance is tested by thermogravimetric analysis (TGA) at 1200 °C in air for up to 100 h. Samples are characterized by X‐ray diffraction, scanning electron microscopy, and wavelength‐dispersive X‐ray spectroscopy. The studied Cr–xMo–8Si alloy series shows a beneficial effect of Mo on the corrosion behavior. For all of the investigated Mo contents, no nitridation is observed and the oxide scale adhesion is improved. An increased amount of intermetallic A15 phase leads to the formation of a SiO2 scale beneath the Cr2O3 layer during high‐temperature exposure. The internal SiO2 layer inhibits further internal oxidation of the A15 phase. Uniform size and distribution of A15, benefits the formation of a duplex oxide scale. Cr–25Mo–8 at%Si, shows the most promising oxidation behavior. The TGA data follows the paralinear law, with both the growth rate, kp, and volatilization rate, kv, of Cr2O3 being reduced by adding 10–25 at% Mo. A binary Cr/Mo–Si phase diagram is generated in order to determine accurate annealing conditions and estimate the stability range of the metastable σ phase.

Sr–Si diagram at Si contents of 55–100 at% and crystal structure of SrSi2-x

Cubic SrSi2 has attracted attention as a thermoelectric material or Weyl semimetal candidate material. However, its physical properties have not been examined in detail. High-quality samples are required for this purpose. A previous study on the Sr–Si phase diagram reported that cubic SrSi2 is a low-temperature phase and tetragonal SrSi2 is a high-temperature phase based on little experimental evidence, highlighting the difficulty in synthesizing high-quality cubic SrSi2 samples. Therefore, a new investigation of the Sr–Si phase diagram is necessary. This study experimentally investigated the Sr–Si diagram at Si contents of 55–100 at% using arc-melted samples by performing inductively-coupled plasma optical emission spectroscopy, electron-probe microanalysis, powder X-ray diffraction analysis, and differential thermal analysis. Two intermetallic compounds (SrSi2-x and SrSi2) and two eutectic reactions existed in this Si content range. The eutectic points were approximately 57 at% and 1053.2 °C for Liquid⇔SrSi + SrSi2-x and approximately 75 at% and 1050.0 °C for Liquid ⇔SrSi2 + Si. SrSi2 had no high-temperature phase and melted congruently at 1121 °C. SrSi2-x existed at Si contents of 62.4–65.0 at%, and it is formed by the peritectic reaction Liquid + SrSi2⇔ SrSi2-x. SrSi2-x crystallized into a monoclinic variant of the √5 × √5 × 1 α-ThSi2-type superstructure with ordered Si defects at the body-center position of the cell (space group: I121, No. 5). SrSi2-x is the first example of the α-ThSi2-type superstructure.

Steel–Aluminum Hybrid Die Casting: Microstructures related to the applied Al–Si bond coating

The microstructure of a successfully applied Al–Si bond coating for the interconnection of cast aluminum alloy with a conventional steel substrate is analyzed in detail. The bond coating formed a 10–20 μm columnar Al layer which is attached to the steel substrate with an intermetallic layer (2–3 μm) during physical vapor deposition at approx. 853 K. Silicon grains precipitated in between the columnar Al layer and the intermetallic phases, giving rise to the ternary compounds on top of the IMC layer, whereas binary intermetallics were found in vicinity to the steel. Peculiarities of the crystallographic structural models of the observed intermetallics are discussed in light of the existing literature and are evaluated integrally using X-ray diffraction and locally by electron backscatter diffraction. The sequence of the phases of the bond coating and a resulting diffusion path is discussed on basis of the isothermal section of the ternary Fe–Al–Si phase diagram. After mechanical shear tests it was found that the applied bond coating did not detach from the steel substrate and instead failure was observed at the interface between columnar Al and cast Al or even within the microstructure the cast Al, proving the successful connection of the bond coating with the steel substrate.

Is Thermal Analysis Able to Provide Carbon and Silicon Contents of Cast Irons?

The determination of silicon and carbon contents by thermal analysis is based on the recording of a cooling curve of a melt whose eutectic solidification takes place in the metastable system. The temperatures of the austenite and eutectic arrests are evaluated and then related to the carbon and silicon contents by linear relationships that would be defined by the phase diagram if there were no undercoolings. However, published experimental values of austenite liquidus arrest and metastable eutectic arrest both show significant undercoolings when compared to the equilibrium metastable Fe–C–Si phase diagram. The undercooling of the austenite observed in hypo-eutectic alloys can be explained by tip undercooling during dendritic growth. On the other hand, it is pointed out that alloys with a composition close to the stable eutectic—either slightly hypo- or slightly hypereutectic—can show much higher undercoolings than expected if some stable eutectic precipitates. For such compositions, the thermal analysis could hardly be reproducible enough if the alloy does not solidify completely in the metastable system. Furthermore, the published experimental information on the temperature of the metastable eutectic is here supplemented by new results for silicon contents up to nearly 4 wt%. Both previous and new results show a similar undercooling of 5 to 15 °C compared to the calculated equilibrium metastable eutectic. Each foundry wishing to use thermal analysis for carbon and silicon evaluation must determine its own relationships for austenite liquidus and metastable eutectic to account for the specificity of its melting process and casting system. Care should be taken to avoid any graphite precipitation in the thermal cup, and testing should be performed to improve reproducibility as this defines the accuracy of the composition determination.

Isothermal section of the Dy‒Ge‒Si system at 600 C

The interaction of the components in the ternary Dy–Ge–Si system was investigated by means of X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The isothermal section of the Dy–Ge–Si phase diagram was constructed at 600 °C for the first time. The alloys for the investigation were synthesized by arc melting the metals (purity of the elements higher than 99.9 wt.%) in an arc furnace under argon atmosphere. The alloys were annealed at 600 °C in evacuated quartz tubes for 720 h, and subsequently quenched in ice water, and examined by X-ray powder diffraction (DRON-4.07 diffractometer, Fe K α-radiation). The crystal structures of the phases were refined using the program DBWS-9807. The chemical and phase compositions of the samples were examined by Scanning Electron Microscopy (SEM) (REMMA-102-02 electron microscope). The existence of continuous solid solutions between the isostructural binary germanides and silicides delimiting the Dy 5 Si 3-x Ge x (Mn 5 Si 3 -type structure), Dy 5 Ge 4-x Si x (Sm 5 Ge 4 -type structure), DyGe 1-x Si x (CrB-type structure), and DyGe 1.5-x Si x (AlB 2 -type structure) ranges was established. Limited solid solutions were observed based on the binary germanides DySi 1.67 (α-GdSi 2 -type structure) and Dy 11 Ge 10 (Ho 11 Ge 10 -type structure). The solubility of Ge in the compound DySi 1.67 is 0.20 at. part, the solubility of Si in the compound Dy 11 Ge 10 is ~0.07 аt. part. The ternary compound DyGeSi 0.75 was found: α-ThSi 2 -type structure, Pearson symbol tI 12, space group I 4 1 / amd , a = 4.052(3), c = 13.6207(10) Å, V = 221.78(3) Å 3 , R B = 0.1011, R p = 0.0318, R wp = 0.0437. Keywords : rare-earth metal, germanide, silicide, phase diagram, solid solution, crystal structure.

Microstructural characteristics and mechanical properties of the Al–Si coating on press hardened 22MnB5 steel

The microstructural characteristics and mechanical properties of the phases in the substrate-coating interdiffusion layer of an Al–10%Si coated 22MnB5 press hardened steel (PHS) were studied by means of electron diffraction, chemical analysis, and nano-indentation. The interdiffusion layer of the Al–Si coated PHS, austenitized at 900 °C for 6.5 min, consisted of α-Fe(Al), Fe3Al, FeAl, Fe2Al5, and an Fe–Al–Si ternary intermetallic phase. The chemical analysis results indicated that the Fe3Al and Fe2Al5 phases were non-stoichiometric, and their composition ranges were not fully consistent with existing Fe–Al and Fe–Al–Si phase diagrams. These results partly explain the significant discrepancies between research groups in phase analysis of the interdiffusion layer. The observed Fe–Al or Fe–Al–Si phases were harder and more brittle compared to the martensitic matrix. With increasing austenitizing temperature and hold time, the thickness of the interdiffusion layer increased and the major constituent in the coating changed from Fe2Al5 to a multi-layered structure of FeAl, Fe3Al, and Fe(Al), leading to significant softening of the interdiffusion layer. Free bend testing was employed to investigate cracking and fracture behavior of the interdiffusion layer. The cracks formed in the thicker coating associated with the highest austenitizing temperature propagated deeper into the substrate material than in the case of lower austenitizing temperatures. Fracture of the interdiffusion layer involved transgranular cleavage and intergranular fracture features. The fracture surface appearance depended on both the phases present and the Al distribution in the coating. FeAl phase, known to be relatively “ductile”, was more susceptible to intergranular fracture than other phases (Fe2Al5, Fe3Al, and α-Fe(Al)).

Phase stability of U5Si4, USi, and U2Si3 in the uranium–silicon system

The intermetallic compound U3Si2 has received interest in recent years for use as accident tolerant fuels in light water reactors due to its combination of high thermal conductivity, reasonably high melting point, and high uranium density compared to UO2. Although U3Si2 is well characterized there are ucertainties about the remaining phases in the U–Si system which could be potential fission products of the silicide fuel. In an effort to better detail the U–Si binary phase diagram, the 44–60 at.% Si region of the U–Si phase diagram was investigated experimentally by analyzing samples with nominal compositions U/Si = 5/4, U/Si = 1/1 and U/Si = 2/3 using SEM-EDS, XRD, and high temperature time-of-flight neutron diffraction, supported by DFT calculations. Both the U/Si = 5/4 and the U/Si = 2/3 samples were composed of two phases, U3Si2 + USi and USi + U3Si5 for U/Si = 5/4 and U/Si = 2/3, respectively. Both U5Si4 and U2Si3 were found from DFT calculations to have imaginary phonon frequencies and an enthalpy of formation above the U–Si convex hull, and thus likely to be thermodynamically unstable compared to the other phases, consistent with the experimental results.In the literature there are three different structures that are proposed for the USi phase, and for the first time, high temperature neutron diffraction measurements were collected on the compound synthesized with the U/Si = 1/1 composition to verify the correct structure. The structure of the USi phase was confirmed to be tetragonal with the I4/mmm space group from room temperature to 1100 °C. The USin crystal structure has 6 U atom sites and 8 Si atoms sites of which two are partially occupied.

Silicon-Rich Corner of the Yb–Pt–Si Ternary System at 850°C

We have studied phase equilibria in the silicon-rich part of the Yb–Pt–Si system. To this end, 22 alloys were prepared by a standard arc-melting process in an argon atmosphere and annealed at a temperature of 850°C. Physicochemical characterization of the samples included electron microscopy, X-ray microanalysis, X-ray diffraction, and differential thermal analysis. We have confirmed the existence of four previously known intermetallic compounds: YbPtSi, YbPt2Si2, Yb3Pt4Si6, and Yb2Pt3Si5. In addition, three new phases have been identified: YbPtSi2, Yb33Pt17Si50, and Yb11Pt33Si56. The structure type of the YbPtSi2 compound has been determined. We present statistical crystallographic data for the ternary phases and describe phase equilibria in the region studied in the 850°C isothermal section of the Yb–Pt–Si phase diagram.

Silicon Liquid Structure and Crystal Nucleation from AbInitio Deep Metadynamics.

Studying the crystallization process of silicon is a challenging task since empirical potentials are not able to reproduce well the properties of both a semiconducting solid and metallic liquid. On the other hand, nucleation is a rare event that occurs in much longer timescales than those achievable by abinitio molecular dynamics. To address this problem, we train a deep neural network potential based on a set of data generated by metadynamics simulations using a classical potential. We show how this is an effective way to collect all the relevant data for the process of interest. In order to efficiently drive the crystallization process, we introduce a new collective variable based on the Debye structure factor. We are able to encode the long-range order information in a local variable which is better suited to describe the nucleation dynamics. The reference energies are then calculated using the strongly constrained and appropriately normed (SCAN) exchange-correlation functional, which is able to get a better description of the bonding complexity of the Si phase diagram. Finally, we recover the free energy surface with a density functional theory accuracy, and we compute the thermodynamics properties near the melting point, obtaining a good agreement with experimental data. In addition, we study the early stages of the crystallization process, unveiling features of the nucleation mechanism.

Extended View on the Vapor–Liquid–Solid Mechanism for Oxide Compound Nanowires: The Role of Oxygen, Solubility, and Carbothermal Reaction

The Si nanowire growth can be well explained by the classical vapor–liquid–solid (VLS) process taking into account the respective Au–Si phase diagram. For oxide-based compound materials, no phase d...

Nanosecond Melting and Recrystallization in Shock-Compressed Silicon.

Insitu, time-resolved, x-ray diffraction and simultaneous continuum measurements were used to examine structural changes in Si shock compressed to 54GPa. Shock melting was unambiguously established above ∼31-33 GPa, through the vanishing of all sharp crystalline diffraction peaks and the emergence of a single broad diffraction ring. Reshock from the melt boundary results in rapid (nanosecond) recrystallization to the hexagonal-close-packed Si phase and further supports melting. Our results also provide new constraints on the high-temperature, high-pressure Si phase diagram.

The ternary Fe–Sb–Si system: Experimental phase diagram study and thermodynamic calculation

Isothermal sections of the Fe–Sb–Si system at 973 K and 1173 K were investigated using equilibrated alloys by means of scanning electron microscopy equipped with energy dispersive X–ray spectrometry and X–ray diffraction. No ternary compound was found at those two temperatures. A thermodynamic extrapolation of the Fe–Sb–Si system was carried out by considering the reliable experimental data from the literature and the present work. Calculated phase relationship agreed well with experimental results. It is worth noting that an isolated ternary miscibility gap generating from monotectic four–phase reactions exists in the calculated Fe–Sb–Si phase diagram.

A comprehensive study of the high-pressure–temperature phase diagram of silicon

A high-pressure–temperature (P–T) phase diagram of silicon (Si) has been constructed in a range of temperatures covering from 0 to 2000 K and pressures up to 80 GPa. In this system, there is a potential for the following phases to occur: cubic diamond, β-tin, simple hexagonal, double-hexagonal close-packed, hexagonal close-packed and face-centered cubic. Besides, the lattice vibrational energy and thermodynamic quantities of each phase were calculated, in combination with quasi-harmonic approximation using the first-principles phonon density of state. The calculated temperature dependencies of thermodynamic quantities are in good agreement with experimental and theoretical observations. Thereinto, the Gibbs free energy differences of these six phases, as a function of pressure and temperature, were used to define the phase boundaries of the P–T phase diagram of Si. The results in this work not only integrate previous experimental and theoretical investigations, but also successfully predict the phase relationships of the stable phases of Si under conditions of high temperature and pressure for the first time.

Prediction of Oxide Phases Formed upon Internal Oxidation of Advanced High-Strength Steels

The effect of Cr on the oxidation of Fe–Mn-based steels during isothermal annealing at different dew points was investigated. The Fe–Mn–Cr–(Si) phase diagrams for oxidizing environments were computed to predict the oxide phases. Various Fe–Mn steels with different concentrations of Cr and Si were annealed at 950 °C in a gas mixture of Ar or N2 with 5 vol% H2 and dew points ranging from − 45 to 10 °C. The identified oxide species after annealing match with those predicted based on the phase diagrams. (Mn,Fe)O is the only oxide phase formed during annealing of Fe–Mn binary steel alloys. Adding Cr leads to the formation of (Mn,Cr,Fe)3O4 spinel. The dissociation oxygen partial pressure of (Mn,Cr,Fe)3O4 in the Fe–Mn–Cr steels is lower than that of (Mn,Fe)O. The Si in the steels results in the formation (Mn,Fe)2SiO4, and increasing the Si concentration suppresses the formation of (Mn,Cr,Fe)3O4 and (Mn,Fe)O during annealing.

The 500 °C isothermal section of the Tb–Al–Si system and thermal behavior of selected Al-rich alloys

Phase relationships in the Tb–Al–Si system have been established and experimentally studied at 500 °C. The main experimental techniques used were scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. Some samples have been analyzed by differential thermal analysis. Six ternary compounds form in the system: the five ternary structures τ1-TbAl2Si2, τ2-Tb2Al3Si2, τ3-TbAlSi, τ5-TbAl0.15Si0.85 and τ6-Tb6Al3Si have been confirmed, while the compound τ4 (Tb2AlSi2, crystal structure oI10-W2CoB2) was not previously known in the literature for the Tb–Al–Si system, but its formation was known in other R–Al–Si (R: Dy,Ho,Er,Tm) systems. The two ternary phases τ4-Tb2AlSi2 and τ5-TbAl0.15Si0.85 show a homogeneity range, at constant Tb content. A number of boundary binary phases dissolve the third element, at 500 °C, forming ternary solid solutions extending into the ternary field: Tb(Al1−xSix)3 (0 ≤ x ≤ 0.13), Tb(Al1−xSix)2 (0 ≤ x ≤ 0.02), Tb5(AlxSi1−x)3 (0 ≤ x ≤ 0.08), Tb5(AlxSi1−x)4 (0 ≤ x ≤ 0.10), Tb(AlxSi1−x) (0 ≤ x ≤ 0.10), Tb(AlxSi1−x)2-b (0 ≤ x ≤ 0.24) and Tb(AlxSi1−x)2−a (0 ≤ x ≤ 0.15). The Al and Si richest part of the system is characterized by the coexistence of three phases (Al), (Si) and TbAl2Si2 (τ1); this behavior is common to all the known R–Al–Si phase diagrams. The phases are involved in the ternary eutectic equilibrium L ⇄ (Al) + (Si) + TbAl2Si2 close to the binary eutectic point of the Al–Si binary system. Experimental measurements confirm the ternary eutectic reaction at a temperature of 565 °C.

Inherently consistent temperature function for interaction parameters demonstrated for the Mg–Si assessment

A new inherently consistent temperature function for interaction parameters, L, is proposed. It is designed for the unconstrained application of any optimization software, such as PanOptimizer or PARROT, to avoid artifacts, for example inverted liquid miscibility gaps or re-stabilization of liquid well below solidus. Without introducing additional system-dependent adjustable parameters, the new function automatically excludes both the exaggerated negative values of L at low temperature and the exaggerated positive values of L at high temperature. The viability of the new function is demonstrated by a complete Calphad re-assessment of the Mg–Si system, which is the prime example of the most challenging systems pertinent to both artifacts. For the first time the calculated Mg–Si phase diagram from 0K to very high temperature is presented. The new assessment also includes the quantitative solidus data of (Si) and other previously not considered original experimental data.

A New Approach of the Synthesis of SiO2 Nanowires By Using Bulk Copper Foils As Catalyst

Silica nanowires (SiO2NWs) have attracted considerable attention over the last decades due to their diverse properties and broad range of applications. Among them, it is well-known the capacity of SiO2NWs to emit strong blue light. It is also widely recognized the versatility of this material as biosensor, since it can be easily functionalized in order to respond to several targets. Other applications include their potential use as anode electrode for lithium-ion batteries, or as protective layer against corrosion by exposure to the environment. In this regard, the use of a metal substrate is of paramount relevance; therefore, an adequate contact between the substrate and the nanostructures is required. Especially numerous and varied are the procedures for the growth of SiO2NWs, being one of the most employed the so-called vapor-liquid-solid (VLS) method. By this mechanism, the nanowires grow from a metal nanoparticle when the adequate gaseous precursor is added. However, the main drawback of this mechanism resides in the need of a Si substrate for the synthesis of the SiO2NWs. Apart from the original Au-Si system, a broad variety of other metals such as Fe, Co, Ni or Cu may act as catalysts for the growth. Particularly, of special interest is the case of copper, which is present in a large majority of electronic devices. Furthermore, the Cu–Si phase diagram shows a eutectic point at 802 ⁰C (16 wt% of silicon) promoting the formation of a liquid alloy at an accessible temperature for a relatively low concentration of silicon in copper. This work presents a novel procedure for the growth of SiO2 nanowires directly from polycrystalline copper foils. The single-step synthesis procedure consists of a thermal treatment at 900 ◦C without the need for additional catalysts. As a result, nanowires with an average diameter of 100 nm are synthesized. A systematic study undertaken at different stages of the SiO2NWs growth confirmed the generation of nucleation centers on the Cu surface as well as revealed the existence of an intermediate gaseous SiO species at the synthesis temperature, which promotes the growth of the SiO2NWs via a VLS mechanism. Figure 1 shows the dark field scanning transmission electron microscopy (DF-STEM) image of the as-synthesized SiO2NWs. As can be seen there, SiO2NWs growth is generated from substrate protrusions of around 200 nm in diameter, exceling from the Cu substrate. These protuberances produced during the thermal treatment could be the evidence of the formation of Cu-Si alloys required as initial step for generating the SiO2NWs. Figure 2a shows the detail of a protrusion of the Cu substrate (in bright contrast) just under the nanowire (in dark contrast). EDX elemental maps performed on the inset area confirms the presence of Cu at the bottom of the nanowire (Fig 2b). Meanwhile, Figs 2c and 2d show a homogeneous distribution of Si and O across the whole nanowire. This process with bulk Cu foils as catalytic agent allows the growth of SiO2NWs over metallic substrates, granting an adequate interconnection between both surfaces. Figure 1

Calorimetric measurements and assessment of the binary Cu–Si and ternary Al–Cu–Si phase diagrams

Using dynamic scanning calorimetry the temperature, composition and reaction enthalpy of a number of invariant reactions in the Cu–Si and Al–Cu–Si systems were determined. The temperatures and compositions are in good agreement with previous experimental data. Reaction enthalpies have not been previously measured. The Cu–Si system was thermodynamically modelled in detail using all available data. Experimental data are well reproduced, including the presently measured reaction enthalpies. Compared to the best previous thermodynamic description some improvements could be achieved. The Al–Cu–Si system was tentatively modelled using a new model for the γ-Al4Cu9 phases and without using large ternary interactions with large temperature dependencies. The Cu-rich part is very complex and the complete system could be reasonably described. Though it was not possible to present a detailed assessment in this work there are important improvements compared to previous thermodynamic descriptions.

Investigation of new phases in the Ba-Si phase diagram under high pressure using ab initio structural search.

Barium silicides are versatile materials that have attracted attention for a variety of applications in electronics and optoelectronics. Using an unbiased structural search based on a particle-swarm optimization algorithm combined with density functional theory calculations, we investigate systematically the ground-state phase stability and the structural diversity of Ba-Si binaries under high pressure. The phase diagram turns out to be quite intricate, with several compositions stabilizing/destabilizing as a function of pressure. In particular, we identify novel phases of BaSi, BaSi2, BaSi3, and BaSi5 that might be synthesizable experimentally over a wide range of pressures. Our results not only clarify and complete the previously known structural phase diagram, but also provide new insights for understanding the Ba-Si binary system.