Ga Substitution Research Articles

Doping-induced superconductivity in group-IV elements may enable quantum functionalities in material systems accessible with well-established semiconductor technologies. Non-equilibrium hyperdoping of group-III atoms into C, Si or Ge can yield superconductivity; however, its origin is obscured by structural disorder and dopant clustering. Here we report the epitaxial growth of hyperdoped Ga:Ge films and trilayer heterostructures by molecular-beam epitaxy with extreme hole concentrations (nh = 4.15 × 1021 cm-3, 17.9% Ga substitution) that yield superconductivity with a critical temperature of Tc = 3.5 K. Synchrotron-based X-ray absorption and scattering methods reveal that Ga dopants are substitutionally incorporated within the Ge lattice, introducing a tetragonal distortion to the crystal unit cell. Our findings, corroborated by first-principles calculations, suggest that the structural order of Ga dopants creates a narrow band for the emergence of superconductivity in Ge, establishing hyperdoped Ga:Ge as a low-disorder, epitaxial superconductor-semiconductor platform.

Magnetic 2D materials offer a compelling platform for next-generation electrocatalysis by enabling spin-dependent reaction pathways. Among them, layered ferromagnets such as Fe3GeTe2 (FGT) have garnered attention for combining intrinsic ferromagnetism with high predicted oxygen evolution activity. However, the stability of non-oxide ferromagnets in electrochemical environments remains an unresolved challenge, limiting their envisioned applications. In this study, we introduce a structural homolog approach to investigate the origin of FGT's catalytic behavior and the mechanisms underlying its degradation. By comparing FGT with its isostructural analog Fe3GaTe2 (FGaT), we demonstrate that the electrochemical activity of FGT arises primarily from Fe orbitals and is largely insensitive to changes in sublayer composition. Although both materials exhibit similar basal-plane hydrogen evolution performance, FGaT demonstrates significantly lower long-term stability. Density functional theory calculations reveal that this instability arises from weaker Te bonding introduced by Ga substitution. These findings establish structural homologs as a powerful strategy for decoupling catalytic activity from electrochemical deterioration and for guiding the rational design of stable magnetic electrocatalysts.

MotivationDNA damage patterns, such as increased frequencies of CT and GA substitutions at fragment ends, are widely used in ancient DNA studies to assess authenticity and detect contamination. In metagenomic studies, fragments can be mapped against multiple references or de novo assembled contigs to identify those likely to be ancient. Generating and comparing damage profiles, however, can be both tedious and time-consuming. Although tools exist for estimating damage in single reference genomes and metagenomic datasets, none efficiently cluster damage patterns.ResultsTo address this methodological gap, we developed AdDeam, a tool that combines rapid damage estimation with clustering for streamlined analyses and easy identification of potential contaminants or outliers. Our tool takes aligned ancient DNA (aDNA) fragments from various samples or contigs as input, computes damage patterns, clusters them, and outputs representative damage profiles per cluster, a probability of each sample pertaining to a cluster, as well as a Principal Component Analysis of the damage patterns for each sample for fast visualisation. We evaluated AdDeam on both simulated and empirical datasets. AdDeam effectively distinguishes different damage levels, such as uracil-DNA glycosylase-treated samples, sample-specific damages from specimens of different time periods, and can also distinguish between contigs containing modern or ancient fragments, providing a clear framework for aDNA authentication and facilitating large-scale analyses.Availability and ImplementationAdDeam is publicly available at https://github.com/LouisPwr/AdDeam and can also be installed via Bioconda. It is implemented in Python and C++. All analysis scripts and datasets are available at https://github.com/LouisPwr/AdDeamAnalysis and on Zenodo under: 10.5281/zenodo.15052427.

ABSTRACT LiFe6Ge4, with a theoretically predicted saturation magnetization of 1 T, a magnetocrystalline anisotropy energy of 1.78 MJ/m3 and a Curie temperature of 620 K was suggested to be a promising permanent magnet as an outcome of a data-mining search. Magnetic measurements of the synthesized sample are reported here. Unfortunately, experiments revealed a weak ferromagnetic behaviour with magnetization values much below that predicted by theory. This discrepancy is analyzed in detail, and is attributed to the trigonal crystal symmetry that was missed in the previous characterisation of the material. The correct crystal structure is R 3 ‾ mH (space group 166) and it is found here to have an antiferromagnetic ground state, as opposed to a theoretically predicted ferromagnetic state of the previously reported monoclinic crystal structure. Theoretical calculations show that element substitution can stabilize a ferromagnetic state of the trigonal crystal structure, with high values of saturation magnetization and magnetocrystalline anisotropy. The best results are seen for the Al or Ga substitution for Ge of the LiFe6 X 4 compound.

Abstract In this work, Ga-doped CeRhIn5 single crystals are grown by In/Ga flux method. Single-crystal X-ray diffraction, magnetic susceptibility, specific heat, and neutron diffraction measurements are utilized to characterize the sample quality and the antiferromagnetic transition temperature T N. By substituting In with Ga, T N is slightly decreased, but the antiferromagnetic transition peaks in magnetic susceptibility and specific heat measurements are obviously broadened by external field along c-axis. By comparing with Zn-doped CeRhIn5, it can be concluded that T N is dominated by electron density, and the stiffness of antiferromagnetic transition is obviously reduced by Ga substitution. The substitution effects of Ga are possibly caused by forming heterogeneous local structures, which avoids quantum critical point, superconductivity, and non-Fermi liquid states. Investigations on Ga-doped CeRhIn5 help to comprehend the chemical substitution effects in CeRhIn5, and the interaction between heterogeneous structure and long-range antiferromagnetic states.

Obtaining versatile Cr3+-activated phosphors with improved far-red emissions via host composition modulation

Together with EuGa4 and EuAl4, EuAl2Ga2 belongs to the BaAl4 structure type with space group I4/. EuAl2Ga2 develops an incommensurate charge density wave (CDW) at temperatures below TCDW=51K. On the basis of temperature-dependent single-crystal x-ray diffraction data, the incommensurately modulated CDW crystal structure of EuAl2Ga2 is determined to possess orthorhombic symmetry (0000)s0000. This symmetry is different from the orthorhombic -based symmetry of the CDW state of EuAl4. Nevertheless, both symmetries, (00)s00 and (00)s00, lead to the same conclusion, that the CDW is supported by the layers of Al1 type atoms, while the Eu and Al2 or Ga atoms are not directly involved in CDW formation. The different symmetries of the CDW states of EuAl4 and EuAl2Ga2, as well as the observation of negative thermal expansion in the CDW state of EuAl2Ga2, might be explained by the effects of Ga substitution in the latter compound. Published by the American Physical Society 2025

The undoped K2ZnV2O7 material has a melilite-like structure, with the K+ ions distributed orderly on two distinguishable crystallographic sites, which is the main difference with the case in a typical A2B3O7 melilite material where the A site cations occupy only one crystallographic position. Herein, we report that substitution of Ga for Zn in K2ZnV2O7 would induce the K+ ions' order-to-disorder transition and transform the K2ZnV2O7 from the melilite-like structure to a typical melilite phase, coupled with significantly enhanced oxide ion conductivity, e.g. ∼1.01 × 10-1 S/cm at 600 °C for the K2Zn0.7Ga0.3V2O7.15 sample, which is about 2 orders of magnitude higher than the parent material. The powder neutron diffraction data analysis results revealed two sites for the interstitial oxygen defects that are introduced by the donor-doping. The introduction of interstitial oxygen into the K layer strongly correlated with the K ions' order-to-disorder transition, while the interstitial oxygens within the 5-fold (Zn/Ga/V)O4 tetrahedral rings are responsible for the enhanced oxide ion conductivity. These findings provided a comprehensive understanding of the melilite-like and typical melilite materials for the mechanism of the stabilization and migration of interstitial oxygen defects.

Abstract We elucidate the role of gallium (Ga) in the structural and electronic properties of amorphous indium gallium oxide (a-IGO) for different Ga concentrations with oxygen interstitial defects using hybrid density functional methods. Ab initio molecular dynamic simulations reveal that Ga substitution significantly affects the structural characteristics, and that Ga–O coordination is particularly sensitive to changes in oxygen stoichiometry. The electronic structure indicates the formation of an O–O dimer in the neutral state. The stability of this dimer upon capturing electrons is influenced by the local atomic structure around the dimer. When the bond breaks, the dimer’s antibonding defect level is significantly lowered from the conduction band, approaching the valence band. This makes it more energetically advantageous for the dimer to capture two electrons. We statistically studied the Ga concentration dependence on the impact of O2 dimer generation in a-IGO. Formation transition energy indicates that O–O bond is broken easily with more Ga, which acts as an electron trap identifying the origin of positive bias stress observed in the transistor behavior.

ABSTRACTLanthanum based alloys are used in this current work to store the low temperature (less than 120°C) thermal energy, as they absorb and desorb hydrogen gas reversibly. LaNi5−xMx (M = Al, Fe, Ga, and Zn) alloys are compared at constant energy storage and recovery temperatures based on their absorption characteristics. A comparison is made between a Simple Absorption System (SAS), a Compressor Operated Absorption system (CAS), and a Cascade Resorption System (CRS) to store thermal energy at low temperatures. van't Hoff relation is used to estimate the lowest temperature to store energy and the maximum temperature to extract it. The energy was successfully upgraded by CAS and CRS. For various La‐based alloys, the three systems' performances were thermodynamically examined and compared. A maximum COP of 0.86 and 0.74 is obtained in a simple absorption and compressor operated absorption system, respectively, using LaNi4.75Fe0.25 due to low hysteresis. Maximum heat upgradation with the Al, Fe, Ga, and Zn substitution is reported as 50°C, 20°C, 48°C, and 60°C, respectively, at a compressor ratio of 5 with CAS. The CRS with same substitution gives the highest heat upgradation of 66°C, 43°C, 88°C, and 107°C at regeneration temperature of 120°C respectively.

All-solid-state lithium-ion batteries (ASSLBs) are the next advancement in battery technology which is expected to power the next generation of electronics, particularly electric vehicles due to their high energy density and superior safety. ASSLBs require solid electrolytes with high ionic conductivity to serve as a Li-ion battery, driving extensive research efforts to enhance the ionic conductivity of the existing solid electrolytes. Keeping this in view, the B-site of Li0.33La0.56TiO3 (LLTO) solid electrolyte has been partially substituted with Ga and novel Ga-doped LLTO (Li0.33+x La0.56Ti1-x Ga x O3) solid-electrolytes are fabricated using the solid-state reaction method, followed by sintering at 1100 °C for 2 h. The effects of Ga substitution on the structural changes, chemical states, ionic conductivity, and electrochemical stability of LLTO are systematically analyzed. The XRD analysis of the LLTO samples confirms the formation of a tetragonal perovskite structure and increasing bottleneck size up to 3% Ga-doped samples. XPS results have further confirmed the successful substitution of Ti4+ by Ga3+. The Ga3+ substitution has successfully enhanced the conductivity of LLTO solid electrolytes and the highest conductivity of 4.15 × 10-3 S cm-1 is found in Li0.36La0.56Ti0.97Ga0.03O3 (x = 0.03), which is an order of magnitude higher than that of pristine LLTO. This increase in ionic conductivity is a synergistic effect of B-O bond stretching resulting from the size difference between Ga3+ and Ti4+ and the increase in grain size. Moreover, the synthesized solid electrolytes are stable within the range of 2.28 to 3.78 V against Li/Li+, making them potential candidates for all-solid-state lithium-ion batteries.

Ga has an ionic radius fitting the radius of Zn much better than Al, which makes it an interesting candidate for doping of ZnO, which is relevant in context with Cu/ZnO-catalysts and with transparent conductive oxides. Here, the structural changes of Ga-doping of nano-scale ZnO, which is obtained via thermal decomposition of hydrozincite, are studied by a combination of X-ray diffraction, 71Ga/1H MAS NMR, quantum-chemical calculations and electron microscopy techniques. By quantum chemical calculations the NMR fingerprint of different Ga point defects is predicted, the calculations are validated against experimental data for different crystalline compounds. The relevant point defect in ZnO could be identified by the point symmetry of the isolated defect and comparison to the calculated values. The kinetic solubility limit for Ga in ZnO is determined by X-ray diffraction and NMR. It is shifted to higher values as compared to the Al variant. Finally, the distribution of Ga and H atoms within the nano-scale material is studied by "paramagnetically assisted surface peak assignment" (PASPA) NMR, REDOR and electron microscopy which shows that for Ga substitution ratios above the solubility limit the excess of Ga is incorporated into a heavily disordered or amorphous, hydrogen-rich surface-layer.

The mineral, Burckhardtite, Pb2TeFe[AlSi3O8]O6, is synthesized and characterized. A new analogue, Pb2TeGa[AlSi3O8]O6, is successfully prepared for the first time under laboratory conditions. The substitution of Ga3+ by Ti0.5M0.5 (M=Co2+, Ni2+) results in new compounds with the Burckhardtite mineral structure. The transition metal-containing compounds exhibit interesting new colors, partly resulting from d-d transitions and metal-to-metal charge transfer (MMCT) transition. The Ga compound shows a deep UV cut-off (~86 %), which is one of the better known values of deep UV cut-off compounds. The compounds exhibit good dielectric behavior with low dielectric loss. The Eu3+ - substituted samples show deep red emission with a long lifetime of ~0.89 ms. The magnetic behavior of the transition metal containing compounds indicates anti-ferromagnetic interactions. The successful synthesis of the naturally occurring mineral along with newer analogues with interesting properties suggests that it is profitable to investigate compounds of mineral origin.

Near-infrared (NIR) spectroscopy has diverse applications across various fields, such as the detection of food components and pesticide residues, early diagnosis, and treatment of cancer. In this work, a series of optimized LiAl5-xGaxO8:0.1Ni2+ (x = 0-5) ultrabroadband NIR-II luminescent systems are developed. The density functional theory (DFT) calculations, time-resolved photoluminescence (TRPL) spectroscopy, and 77 K PL spectra demonstrate that the substitution of Ga3+ for Al3+ creates more favorable sites for Ni2+ luminescence and enhances structural orderliness while reducing the number of luminescent centers. This leads to a red shift in the emission peak from 1177 to 1252 nm with a 14-fold increase in luminescence intensity. At 375 K, thermal stability increases from 81% (x = 0) to 90% (x = 5) compared to 300 K. Subsequent co-doping with Cr3+ results in an excitation peak with a red shift into the blue-violet region (420 nm), accompanied by a notable enhancement in absorption efficiency (AE) and an increase in external quantum efficiency (EQE) from 4% to 62%. Finally, the potential application of the prepared phosphors in both qualitative and quantitative analysis of organic compounds is demonstrated, which will offer new insights for the design and synthesis of ultrabroadband NIR-II light sources.

Yttrium iron garnet (YIG) has minimum damping factor and low ferromagnetic resonance (FMR) linewidth, making it a preferred material for low loss microwave and spintronic devices. The saturation magnetization of YIG is 1750 Gauss, and for low-frequency devices, a lower saturation magnetization is more suitable. Ga3+ and Al3+ are with smaller radii and non-magnetic moment, so the substitution of Ga3+ and Al3+ can decrease saturation magnetization. Here, 4.8–193.7 nm ultra-thin Y3(GaAlFe)5O12 garnet (GaAl-YIG) monocrystalline films are prepared on gadolinium gallium garnet (GGG) substrates by using the liquid-phase epitaxy (LPE) method. As expected, these films exhibit a low saturation magnetization of almost less than 100 Gauss, while their FMR linewidth remains at levels close to that of YIG. The films show a (111) orientation and in a state of tension, and the diffraction intensity of the films get stronger as films thickness increases. The free energy and density of states are calculated for different Ga/Al substitution position by density functional theory simulations. The elements show a different diffusion distance in the GaAl-YIG/GGG interface, and the variation of magnetization properties with interface width are analyzed. The surface roughness of the films is only a few angstroms. The damping factor of these ultra-thin films are on an order of 10−4 except the 4.8 nm film, which suggests that the minimum thickness of the garnet film with good performance by using the LPE method is about 10 nm. According to the analysis of structure and magnetization properties, it demonstrates that the LPE method has potential to provide nanoscale garnet films for low loss microwave and spintronic devices.

Abstract While ∼30% of materials are reported to be topological, topological insulators are rare. Magnetic topological insulators (MTI) are even harder to find. Identifying crystallographic features that can host the coexistence of a topological insulating phase with magnetic order is vital for finding intrinsic MTI materials. Thus far, most materials that are investigated for the determination of an MTI are some combination of known topological insulators with a magnetic ion such as MnBi2Te4. Motivated by the recent success of EuIn2As2, the role of chemical pressure on topologically trivial insulator is investigated, Eu5In2Sb6 via Ga substitution. Eu5Ga2Sb6 is predicted to be topological but is synthetically difficult to stabilize. The intermediate compositions between Eu5In2Sb6 and Eu5Ga2Sb6 are observed through theoretical works to explore a topological phase transition and band inversion mechanism. The band inversion mechanism is attributed to changes in Eu–Sb hybridization as Ga is substituted for In due to chemical pressure. Eu5In4/3Ga2/3Sb6 is also synthesized, the highest Ga concentration in Eu5In2‐xGaxSb6, and report the thermodynamic, magnetic, transport, and Hall properties. Overall, the work paints a picture of a possible MTI via band engineering and explains why Eu‐based Zintl compounds are suitable for the co‐existence of magnetism and topology.

Impact of Hf alloying on the functional properties of Ni-Mn-Ga high temperature shape memory alloys

Infections caused by the airborne fungal pathogen, Aspergillus fumigatus, are increasing in severity due to growing numbers of immunocompromised individuals and the increasing incidence of antifungal drug resistance, exacerbating treatment challenges. Gallium has proven to be a strong candidate in the fight against microbial pathogens due to its iron-mimicking capability and substitution of Ga(III) in place of Fe(III), disrupting iron-dependent pathways. Since the antimicrobial properties of 2,2'-bipyridine and derivatives have been previously reported, we assessed the in vitro activity and proteomic effects of a recently reported heteroleptic Ga(III) polypyridyl catecholate compound against A. fumigatus. This compound has demonstrated promising growth-inhibition and impact on the A. fumigatus proteome compared to untreated controls. Proteins associated with DNA replication and repair mechanisms along with lipid metabolism and the oxidative stress responses were elevated in abundance compared to control. Crucially, a large number of mitochondrial proteins were reduced in abundance. Respiration is an important source of energy to fuel metabolic processes required for growth, survival and virulence, the disruption of which may be a viable strategy for the treatment of microbial infections.

Tailoring monoclinic Na3V2(PO4)3-based cathode via bimetallic substitution for high-energy and long-lifespan Na-ion batteries

Multifaceted investigation into the impact of Ga substitution for Al in V[formula omitted]MnAl inverse Heusler alloys