Zinc-blende Phase Research Articles

A remarkable match of optical response in the amorphous-crystalline and zinc blende-rock salt phase pairs of GeTe.

Despite a large amount of theoretical and experimental work performed so far, the search of Phase Change Materials (PCM) is done with use of numerical modeling. However, it is not fully clear how and why the phase change translates into the optical contrast. In this work, we argue that a key prerequisite for a material to have a pronounced difference in optical properties between crystalline and glassy phases of PCM is the similar contrast between the observed crystalline and (may be experimentally inaccessible) parent crystalline polymorph of the glassy phase. To illustrate this claim, we report a comparison of dynamic dielectric function of zinc-blende (a-ZnS), CsCl, and rocksalt (NaCl) phases of the binary AIVBVI PCM exemplified by the well known GeTe prototype compound with experimental data and supply a theoretical explanation to the observed behavior based on topological properties of the Fermi surfaces appearing in the protoptypic "degenerate" crystals with A=B having the same local structure as the parent polymorphs and derived from simple analytical model. By this, we arrive to a qualitative rather than purely numeric guidance for possible search of the novel phase-change materials.&#xD.

Deciphering the influence of multi-component blends and their electronic band structure on the performance of All-Solid-State Batteries

The emergence of all-solid-state batteries (ASSBs) introduces a paradigm shift in energy storage technology, offering enhanced safety compared to conventional liquid-based metal-ion batteries. Significant effort is directed toward optimizing the solid-electrolyte blend composition to enhance the battery’s electrochemical performance. Despite some promising results, a lack of guidelines persists, particularly for optimizing multicomponent solid electrolytes given their large parameter window. This study aims to address this challenge by implementing a unified diffuse-interface approach to model and simulate the solid electrolyte morphologies and their corresponding electrochemical performance when incorporated in a battery. The electrolyte microstructures are simulated using the Cahn–Hilliard formulation while a diffuse-interface framework formulated in terms of electrochemical potential is utilized for exploring Li-ion transport across the battery. It is found that, while the variegated microstructures arising from various solid electrolyte blend compositions influence the power density of the battery, the electronic band structure of the blend phases is an important consideration. The proposed model is versatile and can be adapted for various battery technologies beyond ASSBs. This expands its potential impact and could lead to innovations in energy storage technology.

Fabrication of high performance polypropylene based blends from ethylene vinyl acetate-based sole waste via solid-state shear Co-milling

Ethylene vinyl acetate copolymer (EVA) foam products with cross-linked structure are now widely used in the fields of functional footwear. However, due to their cross-linked structure and complex composition, they are quite difficult to be recovered in large scale after disposal, causing serious environmental pollution. Based on our self-designed solid-state shear milling (S3M) equipment, a novel co-milling technology was established to recycle ethylene vinyl acetate-based sole waste (ESW) and reuse it to strengthen and toughen polypropylene (PP). The effects of co-milling on PP/ESW powders as well as blends were studied, and the results showed that the existence of PP promoted the solid pulverization of ESW, so formed the powders with smaller size and wider distribution. Ascribing to the partial de-crosslinking of ESW during co-milling process, the contact area and the molecular entanglements at their interfaces increased, effectively improving the compatibility between PP and ESW. In this way, the simultaneous enhancement and toughening of ESW on PP were achieved. After co-milling, ESW phase in blends significantly decreased and no visible phase interface was observed. With 20 co-milling cycles, the tensile strength and impact toughness of PP/20 wt% ESW blend respectively increased from 21.9 MPa to 3.79 kJ/m2 to 25.4 MPa and 5.83 kJ/m2, both higher than most other similar PP based materials. This work provides a new strategy for high-quality and efficient recycling of ESW in large scale, and fabrication of high-performance PP based materials.

Accelerated Crystallization and Preferred Formation of a Thermally Stable Crystal Phase in Enantiomeric Blends of Long-Spaced Chiral Polyesters

Accelerated Crystallization and Preferred Formation of a Thermally Stable Crystal Phase in Enantiomeric Blends of Long-Spaced Chiral Polyesters

Tailoring electronic structure and thermodynamic stability of (Al, In)-substituted GaAs: Ab-initio insights into bulk and (001) surfaces

Ab-initio calculations are conducted to investigate the structural properties, electronic structure, and thermodynamic stabilities of bulk and (001) surface systems of the GaAs semiconductor in its zinc-blende crystal phase. For the bulk case, we focus on the impact of substituting gallium atoms with M atoms (M = Al, In) at various concentrations (5.55 %, 11 %, and 22 %). We present the resulting structural parameters, along with the formation and substitutional energies associated with these substitutions. For surface systems, we explore indium (In) or aluminum (Al) substitutions at coverages of 0.25, 0.50, and 1.0 monolayers. This includes investigating the effects of substituting M atoms within the first atomic layer of the slabs. Ab-initio thermodynamic calculations reveal that high Al substitutions, in both bulk and surface, result in more favorable formation and surface energies. In contrast, In substitutions exhibit the opposite behavior, with increasing In content leading to less favorable energetics. Moreover, density of states analysis reveals that bulk systems maintained a semiconducting character, while all studied surface configurations exhibited a metallic electronic behavior. This study provides valuable insights into the influence of Al and In substitutions on the structural, electronic, and thermodynamic properties of GaAs, both in bulk and on the (001) surface.

Chemical-bonding and lattice-deformation mechanisms unifying the stability and diffusion trends of hydrogen in TiN and AlN polymorphs

The continuous development of hydrogen-permeation barriers (HPB) based on metal nitrides highly desires a generic unification of the key thermodynamic and kinetic mechanisms therein. This work employs first-principles calculations to study the stability and diffusion trends of H impurity in the rock-salt, wurtzite, and sphalerite phases of the prototypical TiN and AlN. The formation energies (Ef) of H at various interstitial and vacant sites in these nitrides are calculated, and the underlying chemical-bonding and lattice-deformation mechanisms are self-consistently revealed by the systematic structual, energetic, and electronic-structure analyses. This leads to the discovery of a generic volcanic trend of Ef in terms of the electron number on H (QH), which well portrays how the covalent-ionic H–N and H–metal bondings determine its stability in different atomistic environments. Then, the kinetic properties (e.g., potential barriers, diffusion coefficients, and isotope effects) of interstitial H in these nitrides are calculated, where the volcanic Ef–QH relationship is applied to better understand the joint contributions of chemical bonding and lattice deformation. Finally, the revealed mechanisms and volcanic Ef–QH relationship are generalized to successfully describe the behaviors of H in some important grain boundaries of c-TiN and c-AlN, including the Σ3{112}〈110〉 twin frequently observed in c-TiN and the Σ5{210}〈001〉 twin prototypical to many rock-salt materials. The widely varying hydrogen permeabilities measured in experiment on many nitride coatings are successfully explained, inspiring more useful chemical principles to guide the design of HPB coatings facing harsh environments with long-term reliability.

Interplay of luminescence and magnetic phenomena in Mn-doped ZnS zinc blende nanocrystals: Influence of magnetic doping

This research comprehensively investigates the interplay between luminescence and magnetic phenomena in the zinc blende phase of manganese-doped and undoped zinc sulfide. The study involves the synthesis of zinc sulfide nanocrystals through a soft chemical method, followed by an in-depth experimental characterization. Theoretical studies were conducted using a 2 × 2 × 2 supercell model with 64 atoms to explore the impact of native defects and manganese doping on zinc sulfide's the electronic, magnetic, and optical properties. The research findings offer a detailed physical description of magnetic and optic phenomena observed, underpinned by a strong correlation between theoretical predictions and experimental results. An essential contribution of this work is developing a depiction that elucidates the relationship between optical transitions and spin-exchange in the context of these phenomena.

Structural electronic and thermodynamic properties of CdX(X: S, Se, and Te) cadmium chalcogenides compound

The structural and electronic properties of (CdS, CdSe, and CdTe) compounds in rock-salt, zinc-blend, and wurtzite crystal structures were calculated using ab initio calculation. In addition to these properties, the thermodynamic properties were added advantage to clarify their comportment as temperature variation. Under the context of density functional theory DFT, the calculations were carried out using the full potential linearized augmented plane wave FP-LAPW approach. The generalized gradient approximations GGA-PBE established by Perdew-Burke-Ernzerhof and the local density approximation LDA and modified Bucke Jhonson have both been employed for the exchange-correlation energy and related potential MBJ. The results show that the zinc-blend phases were the stable crystal structure for all compounds. The lowest direct band gap is found in the B3 phase for CdX, close to the experimental value. The values of band energies of CdS, CdSe, and CdTe were estimated to be 2,463 eV, 1,76 eV, and 1,532 eV, respectively. In general, this work fits well with other experimental and theoretical results. The quasiharmonic Debye theory is used to determine the impact of temperature and pressure on thermodynamic properties. This includes the calculation of pressure and temperature dependence, as well as the analysis of how heat capacity, thermal expansion, and the Debye temperature are affected by these variables.

Synthesis and physical characterization of novel Ag2S-CdS /Ag /GNP ternary nanocomposite

A new type of Ag2S-CdS/Ag/GNP nanocomposite material was successfully synthesized in the presented work. The structural and physical properties of compounds were studied separately and together. Ag2S-CdS/Ag/GNP nanocomposite materials were studied by Xray diffraction (XRD), Ultraviolet-Visible (UV-Vis), Fourier Transform Infrared (FTIR), Raman spectroscopy and Scanning Electron Microscopy (SEM). Based on the results, Ag nanowires (NWs) were successfully synthesized, and then it was determined that during the hybridization process, two phases of acanthite Ag2S and the cubic crystal system of Ag2O were formed. Then, Ag2S-CdS NWs were formed from mixed monoclinic Ag2S and hexagonal CdS. In the absorption spectrum of Ag NWs, the main absorbance peaks were observed at 357.3 nm and 380.2 nm. The energy gap (Eg) values of the Ag sample are 3.8 eV. The band gap value of Ag2S (2.5, 3.8, 4.6 eV) and Ag2S-CdS (2.5, 3.8, 4.8 eV) have a triple value due to the formation of a hybrid structure. The Raman spectrum of Ag2S-CdS belongs to longitudinal-optical (LO) phonon modes of zinc-blende phase CdS and for the 1, 2, and 3 times spin-coated samples on the surface of GNP/PVA have observed all characteristic Raman peaks, which belong to NWs at 485.13 cm-1, and 960.22 cm-1.

Enhancing thermal energy storage properties of blend phase change materials using beeswax.

This study aims to use beeswax, a readily available and cost-effective organic material, as a novel phase change material (PCM) within blends of low-density polyethylene (LDPE) and styrene-b-(ethylene-co-butylene)-b-styrene (SEBS). LDPE and SEBS act as support materials to prevent beeswax leakage. The physicochemical properties of new blended phase change materials (B-PCM) were determined using an X-ray diffractometer and an infrared spectrometer, confirming the absence of a chemical reaction within the materials. A scanning electron microscope was used for microstructural analysis, indicating that the interconnection of the structure allowed better thermal conductivity. Thermal gravimetric analysis revealed enhanced thermal stability for the B-PCM when combined with SEBS, especially within its operating temperature range. Analysis of phase change temperature and latent heat with differential scanning calorimetry showed no major difference in the melting point of the various PCM blends created. During the melting/solidification process, the B-PCMs possess excellent performance as characterized by W70/P30 (112.45J.g-1) > W70/P20/S10 (94.28J.g-1) > W70/P10/S20 (96.21J.g-1) of latent heat storage. Additionally, the blends tend to reduce supercooling compared to pure beeswax. During heating and cooling cycles, the B-PCM exhibited minimal leakage and degradation, especially in blends containing SEBS. In comparison to the rapid temperature drop observed during the cooling process of W70/P30, the temperature decline of W70/P30 was slower and longer, as demonstrated by infrared thermography. The addition of LDPE to the PCM reduced melting time, indicating an improvement in the thermal energy storage reaction time to the demand. According to the obtained findings, increasing the SEBS concentration in the composite increased the thermal stability of the resulting PCM blends significantly. Despite the challenges mentioned earlier, SEBS proved to be an effective encapsulating material for beeswax, whereas LDPE served well as a supporting material. Leak tests were performed to find the ideal mass ratio, and weight loss was analyzed after multiple cycles of cooling and heating at 70°C. The morphology, thermal characteristics, and chemical composition of the beeswax/LDPE/SEBS composite were all examined. Beeswax proves to be a highly effective phase change material for storing thermal energy within LDPE/SEBS blends.

Embedded high-quality ternary GaAs1−x Sb x quantum dots in GaAs nanowires by molecular-beam epitaxy

Semiconductor quantum dots are promising candidates for preparing high-performance single photon sources. A basic requirement for this application is realizing the controlled growth of high-quality semiconductor quantum dots. Here, we report the growth of embedded GaAs1−x Sb x quantum dots in GaAs nanowires by molecular-beam epitaxy. It is found that the size of the GaAs1−x Sb x quantum dot can be well-defined by the GaAs nanowire. Energy dispersive spectroscopy analyses show that the antimony content x can be up to 0.36 by tuning the growth temperature. All GaAs1−x Sb x quantum dots exhibit a pure zinc-blende phase. In addition, we have developed a new technology to grow GaAs passivation layers on the sidewalls of the GaAs1−x Sb x quantum dots. Different from the traditional growth process of the passivation layer, GaAs passivation layers can be grown simultaneously with the growth of the embedded GaAs1−x Sb x quantum dots. The spontaneous GaAs passivation layer shows a pure zinc-blende phase due to the strict epitaxial relationship between the quantum dot and the passivation layer. The successful fabrication of embedded high-quality GaAs1−x Sb x quantum dots lays the foundation for the realization of GaAs1−x Sb x -based single photon sources.

Novel green synthesis approach of eco-friendly magnetic/semiconductor nanocomposites as magnetically separable and reusable photocatalyst for organic dye degradation

Eco-friendly and effective separation of photocatalytic nanoparticles from the reaction mixture is crucial to facilitate their repeated use in photocatalysis. The development of magnetic/semiconductor nanocomposites with high catalytic performance and easy separation is an efficient strategy for wastewater treatments. In this study, we explore the potential of combination of magnetic (CoFe2O4) and semiconductor (ZnS) synthesized via a green approach using Moringa oleifera leaf extract as magnetically separable photocatalysts for dye degradation. X-ray diffraction analysis confirmed the presence of the cubic spinel ferrite phase of CoFe2O4 and the cubic zinc blend phase of ZnS within the nanocomposites. The micrographs illustrated nearly spherical nanoparticles with average particle sizes of 12 nm for CoFe2O4 and 26 nm for CoFe2O4/ZnS, respectively. The presence of SO suggested the incorporation of ZnS on the surface of CoFe2O4/ZnS nanocomposites. The UV–visible spectra revealed an increase in the band gap energy from 3.7 to 4.5 eV with increasing ZnS concentrations. Magnetic properties analysis signified that the CoFe2O4/ZnS nanocomposites exhibited ferromagnetic characteristics. The optimal degradation efficiency of photodegradation methylene blue was observed for CoFe2O4/ZnS 50 %, achieving 78.3 % degradation within 80 min with intervals 20 min. The magnetically separable capability allows for the recycling of nanocomposites after three consecutive cycles. Therefore, CoFe2O4/ZnS nanocomposites emerge as promising candidates as separable photocatalysts for the removal of organic pollutants in environments.

Properties of Chemically Stabilized Methanol–HVO Blends

Approximately 25% of global carbon emissions come from food production. Renewable fuels are crucial for curbing greenhouse gas (GHG) emissions from vehicles, non-road machines, and agricultural machinery. Tractors, key to modern farming, are central to these efforts. As agriculture strives for sustainability, alternative fuels like methanol and hydrotreated vegetable oil (HVO) are arousing interest because they are renewable and offer potential for blending for use in diesel engines. Methanol and HVO have limited solubility in direct mixing, so the addition of a co-solvent is essential. This study addresses the research gap regarding the properties of HVO and methanol blends with co-solvents. It investigated the impact of three co-solvents, 1-dodecanol, 1-octanol, and methyl butyrate, on the miscibility of HVO and methanol. The experimental measurements cross-varied the co-solvent type with different blending ratios (MeOH5 and MeOH10). Investigated parameters include fuel density, kinematic viscosity, distillation properties, and surface tension. The co-solvents enabled the formation of a singular, clear, and homogeneous phase in methanol-HVO blends. The co-solvent 1-dodecanol demonstrated the highest solubilizing capacity for MeOH5 and MeOH10 blends, followed by 1-octanol. Adding co-solvents led to increased fuel density, decreased kinematic viscosity, and small changes in surface tension. These findings contribute to the optimization of methanol–HVO fuel blends for efficient and environmentally friendly use in vehicles, non-road machinery, and agricultural machinery.

Controlled growth of MPA-capped ZnS quantum dots through concentration-modulated single injection hydrothermal method

This study presents the controlled growth of 3-Mercaptopropionic acid (MPA)-capped ZnS quantum dots (QDs) using a concentration-modulated single injection hydrothermal method. Employing the Concentration optimization by optical spectra (COOS) method, we optimized the MPA:Zn:S ratios to investigate the influence of the capping agent, cation, and anion for exceptional properties suitable for optoelectronic and sensor applications. CMSIH operates as a single-step synthesis process, reducing processing time and complexity. This streamlined approach not only enhances efficiency but also minimizes the risk of contamination and ensures batch-to-batch consistency in QD production. Its moderate operating conditions, compared to other high-energy methods, also contribute to reduced energy consumption and environmental impact, aligning with sustainable manufacturing practices. Further, X-ray diffraction (XRD) confirmed the Zinc blend (cubic) phase of ZnS, and Fourier-transform infrared spectroscopy (FTIR) validated MPA capping. The QDs exhibited strong quantum confinement, causing a blue shift in absorption peaks compared to bulk ZnS. Higher MPA concentrations ranging from 0.02 M to 0.1 M induced a red shift in the absorption edge due to prolonged reaction times and strong cation binding by MPA. Variations in cation Zn and anion S ratios from 0.02 M to 0.1 M caused blue and red shifts in the absorption edge, respectively. For instance, Zn:S = 0.04:0.01 M increased cation concentrations, reducing QD size up to 0.67 nm, while enhanced anion concentrations Zn:S = 0.04:0.04 M enlarged the QDs size up to 2.35 nm. Remarkably, calculated QD sizes using Brus’ equation were smaller than the Bohr radius, even at an elevated temperature of 95 °C, indicating significant quantum confinement. Luminescence studies revealed reduced luminescence with higher MPA concentrations, increased luminescence intensity with higher cation Zn+ concentrations, and a red shift in the luminescence peak with higher anion S concentrations. As the temperature rises, there is an observable decrease in luminescence intensity. Furthermore, the investigation into the relationship between chemical composition and optical properties of MPA-capped ZnS QDs at elevated temperatures expands understanding of quantum confinement effects. The synthesised unique ultra small ZnS QDs can be used in advanced quantum sensors mainly as radiation detectors.

Fabrication and Characterization of PLA/PBAT Blends, Blend-Based Nanocomposites, and Their Supercritical Carbon Dioxide-Induced Foams.

In this study, a twin-screw extruder was used to fabricate poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends and blend-based nanocomposites with carbon nanotube (CNT) or nanocarbon black (CB) as nanofillers. The fabricated samples were subsequently treated with supercritical carbon dioxide (scCO2) to fabricate the corresponding foams. Bi-phasic morphology and selective distribution of CNTs or CBs in the PBAT phase were observed in the blends/composites through scanning electron microscopy. After the scCO2 treatment, the selective foaming of the PBAT phase in the prepared blends/composites was confirmed. The cellular structure of PBAT phase in scCO2-treated blends is similar to the size/shape of PBAT domains in untreated blends or treated neat PBAT foam. The addition of CNTs or CBs in the blends led to a slight reduction in cell size of the foamed PBAT phase, demonstrating CNT/CB-induced cell nucleation. Differential scanning calorimetry (DSC) results showed that CNTs and CBs played as nucleating agents and increased the initial crystallization temperature up to 14 °C compared with neat PBAT for PBAT in different composites during cooling. The scCO2 treatment induced the bimodal stability of PBAT crystals in different samples, which melted mainly in two temperature regions in DSC studies. Thermogravimetric analyses revealed that compared with parent blends, the addition of CNTs or CBs increased the temperature at 80 wt.% loss (degradation of PBAT portion) up to 6 °C. The electrical resistivity decreased by more than six orders of magnitude for certain CNT- or CB-added composites compared with the parent blends. The hardness of the blends slightly increased after forming the corresponding composites and then declined after the scCO2 treatment.

Photocatalytic and persulfate-facilitated tetracycline degradation using NiFe2O4/carbon/polymer membranes: Activity and stability during flow-through

We synthesized NiFe2O4/carbon composite nanoparticles through a straightforward co-precipitation method, and incorporated these particles into porous polyethersulfone (PES) membranes via casting solution blending and film casting cum phase separation. The resulting photocatalytic membranes were used for the oxidative degradation of tetracycline (TC) in flow–through. We could demonstrate a higher catalytic activity in acidic conditions, a photocatalytic enhancement under visible light irradiation, and a 3x higher TC removal by persulfate (PS) in comparison to H2O2. Moreover, we observed the leaching of all Ni from the incorporated NiFe2O4 after using a membrane for 30 h in the flow-through degradation of 5 ppm TC with PS. This was accompanied by a loss of the total organic carbon removal activity, suggesting that Ni plays an important role as mineralization promoter. However, no Fe leaching occurred and the in situ formed FexOy retained the high TC conversion activity of NiFe2O4 after 30 h contact to acidic conditions, highlighting an exceptional long-term stability. We further identified that substrate desorption, catalyst complexation, and metal leaching can be facilitated by the presence of radical scavengers. This significantly contributed to their inhibitory effects, illustrating that an altered substrate-catalyst interaction may frequently be overlooked during the detection of radical species.

Synthesized nanosphere ZnSe and reduced graphene oxide as anode materials for sodium-ion batteries: Analysis on phase transition and storage mechanism

Zinc selenide (ZnSe), a metal chalcogenide, is an attractive anode material for sodium-ion batteries, exhibiting high theoretical capacity (371.4 mAhg−1) and numerous redox sites. However, volume expansion and low stability during the charge/discharge processes present challenges. This study aimed to solve these inherent problems and synthesize a high-performance anode material by growing nano sized ZnSe on surface of reduced graphene oxide (rGO). ZnSe has two crystal structures, namely zinc-blende and wurtzite, and undergoes a transformation from wurtzite to the zinc-blende phase during sodium ion storage. This study conducted X-ray diffraction analysis of the electrode after the galvanostatic charge/discharge test and performed cyclic voltammetry analysis to investigate the transformation process. In addition, real-time monitoring of Nyquist plot and phase transition was performed to investigate the mechanisms of sodium ion storage. The ZnSe-rGO, exhibiting conversion reactions, shows cycle performance of 316.14 mAhg−1 at a current density of 0.5 Ag−1 after 1000 cycles. The evaluation of anode materials and analysis of their storage mechanism can facilitate sodium-ion batteries research.

Structural, optical and morphological characterization of Zinc Selenide Nanoparticles synthesized by Solvothermal method

Zinc Selenide nanoparticles were synthesized via solvothermal method using zinc chloride and selenium powder. X-ray diffraction (XRD), Scanning Electron Microscope (SEM), Ultraviolet – Visible spectroscopy and Photoluminescence Spectroscopy were used to analyze the sample. XRD confirmed the cubic zinc blende phase and the mean size of the particle was determined using Scherrer formula was 65nm. SEM image revealed the spherical shape of the particles. Photoluminescence spectra with excitation wavelength (325nm) show a weak emission peak at 555nm. Key Words: ZnSe ,SEM, UV – Vis, XRD

Unveiling Variations in Electronic and Atomic Structures Due to Nanoscale Wurtzite and Zinc Blende Phase Separation in GaAs Nanowires.

Phase separation is an intriguing phenomenon often found in III-V nanostructures, but its effect on the atomic and electronic structures of III-V nanomaterials is still not fully understood. Here we study the variations in atomic arrangement and band structure due to the coexistence of wurtzite (WZ) and zinc blende (ZB) phases in single GaAs nanowires by using scanning transmission electron microscopy and monochromated electron energy loss spectroscopy. The WZ lattice distances are found to be larger (by ∼1%), along both the nanowire length direction and the perpendicular direction, than the ZB lattice. The band gap of the WZ phase is ∼20 meV smaller than that of the ZB phase. A shift of ∼70 meV in the conduction band edge between the two phases is also found. The direct and local measurements in single GaAs nanowires reveal important effects of phase separation on the properties of individual III-V nanostructures.

ScN/GaN(11̅00): A New Platform for the Epitaxy of Twin-Free Metal-Semiconductor Heterostructures.

We study the molecular beam epitaxy of rock-salt ScN on the wurtzite GaN(11̅00) surface. To this end, ScN is grown on freestanding GaN(11̅00) substrates and self-assembled GaN nanowires exhibiting (11̅00) sidewalls. On both substrates, ScN crystallizes twin-free thanks to a specific epitaxial relationship, namely ScN(110)[001]∥GaN(11̅00)[0001], providing a congruent, low-symmetry interface. The 13.1% uniaxial lattice mismatch occurring in this orientation mostly relaxes within the first few monolayers of growth by forming a near-coincidence site lattice, where 7 GaN planes coincide with 8 ScN planes, leaving the ScN surface nearly free of extended defects. Overgrowth of the ScN with GaN leads to a kinetic stabilization of the zinc blende phase, that rapidly develops wurtzite inclusions nucleating on {111} nanofacets, commonly observed during zinc blende GaN growth. Our ScN/GaN(11̅00) platform opens a new route for the epitaxy of twin-free metal-semiconductor heterostructures including closely lattice-matched GaN, ScN, HfN, and ZrN compounds.