Metallic Phase Research Articles

Constructing partially spinel phase in Mn-rich cathode material

As a cathode with earth-abundant element, Mn-rich oxide has been explored to enable the scaling of the Li-ion battery. However, the irreversible transition metals migration and phase transformations in Mn-rich materials have been proven to be detrimental, which trigger capacity degradation, voltage decay, and poor kinetics. In this work, using Li2MnO3 as model, spinel-layered biphase was constructed via Ti doping and de-lithiation modification, which exhibits higher available capacity of 236.9 mAh/g (55.6 mAh/g for pristine material) and improved rate performance. Compared with pristine Mn-based cathodes, the new phase delivers neglectable voltage degradation during electrochemical cycling. Based on systematic characterization, the new phase exhibits higher oxygen redox reversibility and accelerated kinetics of lithium ions transformation. This work provides a new strategy for designing high-energy density Mn-rich cathodes.

Nanosecond Structural Dynamics during Electrical Melting of Charge Density Waves in 1T-TaS_{2}.

Electrical control of charge density waves has been of immense interest, as the strong underlying electron-lattice interactions potentially open new, efficient pathways for manipulating their ordering and, consequently, their electronic properties. However, the transition mechanisms are often unclear as electric field, current, carrier injection, heat, and strain can all contribute and play varying roles across length scales and timescales. Here, we provide insight on how electrical stimulation melts the room temperature charge density wave order in 1T-TaS_{2} by visualizing the atomic and mesoscopic structural dynamics from quasi-static to nanosecond pulsed melting. Using a newly developed ultrafast electron microscope setup with electrical stimulation, we reveal the order and strain dynamics during voltage pulses as short as 20ns. The order parameter dynamics across a range of pulse amplitudes and durations support a thermally driven mechanism even for fields as high as 19 kV cm^{-1}. In addition, time-resolved imaging reveals a heterogeneous, mesoscopic strain response across the flake, including MHz-scale acoustic resonances that emerge during sufficiently short pulsed excitation which may modulate the order. These results suggest that metallic charge density wave phases like studied here may be more robust to electronic switching pathways than insulating ones, motivating further investigations at higher fields and currents in this and other related systems.

Promotion of Probabilistic Bit Generation in Mott Devices by Embedded Metal Nanoparticles.

Considerable attention has been drawn to the use of volatile two-terminal devices relying on the Mott transition for the stochastic generation of probabilistic bits (p-bits) in emerging probabilistic computing. To improve randomness and endurance of bit streams provided by these devices, delicate control of the transient evolution of switchable domains is required to enhance stochastic p-bit generation. Herein, it is demonstrated that the randomness of p-bit streams generated via the consecutive pulse inputs of pump-probe protocols can be increased by the deliberate incorporation of metal nanoparticles (NPs), which influence the transient dynamics of the nanoscale metallic phase in VO2 Mott switches. Among the vertically stacked Pt-NP-containing VO2 threshold switches, those with higher Pt NP density show a considerably wider range of p-bit operation (e.g., up to ≈300% increase in ΔVprobe upon going from (Pt NP/VO2)0 to (Pt NP/VO2)11) and can therefore be operated under the conditions of high speed (400 kbit s-1), low power consumption (14 nJ per bit), and high stability (>105200 bits) for p-bit generation. Thus, the study presents a novel strategy that exploits nanoscale phase control to maximize the generation of nondeterministic information sources for energy-efficient probabilistic computing hardware.

Two distinct charge density waves in the quasi-one-dimensional metal Sr0.95NbO3.37 revealed by resonant soft X-ray scattering

The interplay of electron-electron and electron-lattice interactions plays an important role in determining exotic properties in strongly correlated electron systems. Of particular interest is quasi-one-dimensional SrNbOx metals, which are perovskite-related layered Carpy-Galy phases. Quasi-one-dimensional metals often exhibit a charge density wave (CDW) accompanied by lattice distortion; however, to date, the presence of a CDW in a quasi-one-dimensional metallic Carpy-Galy phase has not been detected. Here, we report the discovery of two distinct and simultaneous commensurate CDWs in Sr0.95NbO3.37 using resonant soft X-ray scattering (RSXS), namely, an electronic-(001) superlattice below ~ 200 K and an electronic-(002) Bragg peak. We also observe a non-electronic-(002) Bragg peak showing lattice distortion below ~ 150 K. Through the temperature dependence and resonance profile of these CDWs and the lattice distortion, as well as the relationship between the wavelength and charge density, these CDWs are determined to be Wigner crystals and Peierls-like instabilities, respectively. The electron‒electron interaction is strong and dominant even up to 350 K, and upon cooling, it drives the electron–lattice interaction. The correlation length of the electronic-(001) superlattice is surprisingly larger than that of the electronic-(002) Bragg peak, and the superlattice is highly anisotropic. Supported by theoretical calculations, the CDWs are determined by the charge anisotropy and redistribution between the O-2p and Nb-4d orbitals, and the strength of the electronic-(001) superlattice is within the strong coupling limit.

Static and dynamic conductivity of amorphous nanogranular composites (CoTaNb)x(MgO)1-x

The paper presents the results of study of amorphous nanogranular composite films CoTaNbxMgO1−x, (21.73≤ x ≤73.27 at%) with a thickness of 311–1040 nm on a lavsan substrate with a thickness of about 20 μm. The results of experimental studies of microstructure, static conductivity (at direct current), dynamic conductivity (50 kHz – 15 MHz), determined from measurements of the total impedance and phase angle, and dynamic microwave conductivity (8–12 GHz), calculated from measurements microwave reflectance, were presented. The spectra of dynamic conductivity as a function of frequency, the dependence of static conductivity and the ratio of dynamic to static conductivity on the content of the metal phase and on the ratio of the sizes of granules to the spaces between granules were obtained. Using the mechanisms of closed and open circuit models of intragranular currents and an algorithm for calculating structural and conductive characteristics from measured values of microwave reflectance, the conductivity of granules was calculated and its contribution to the dynamic microwave conductivity of composites was assessed.

Effect of nanoparticles on morphological parameters of wheat

ABSTRACT This work is devoted to studying the features of the generation of metal nanoparticles (NPs) by underwater discharges and their use in the technology of growing grain crops. The purpose of the study is to use the latest nano-containing preparations based on NPs of biofunctional metals, which will allow the introduction of modern technologies and technological processes for environmentally friendly crop production while simultaneously increasing the quality indicators of the final wheat harvest. To obtain NPs, metals of the biogenic group were chosen, the content of which in known agrochemical preparations is at least 0.01%. Metal NPs were obtained in discharge chambers filled with deionized water. As a result of underwater electric spark discharges, metal colloids were obtained as a preparative form of nanomaterials for further use and processing of wheat crops. To carry out the certification of NPs by the methods of electron microscopy (SEM and TEM) and X-ray structural analysis, the metal phase of the colloidal solutions was separated from the dispersion medium by drying. We determined the composition, structure, and average size of the target NPs. A complex preparation was studied, the composition of which included metal NPs, in particular Fe − 1800 ppm; Cu − 400 ppm; Zn − 1000 ppm; Mn − 800 ppm. Testing of the drug was carried out in field conditions during the cultivation of winter wheat at various stages of organogenesis. The application rate of the drug was 1–1.5 L/ha, accordingly, 1.0–1.5 L of the drug was diluted in 250 L of water. Foliar treatment of wheat plants was carried out. The analysis of grain quality indicators showed a 30% increase in the total protein content and a more than two-fold increase in gluten, which indicates the extraordinary prospects of using the obtained preparations.

Raman scattering of TixV1‐xO2 thin films on (110) rutile TiO2 in the low and high temperature phase adjacent to the metal–insulator transition

AbstractVanadium dioxide (VO2) undergoes a reversible first‐order metal‐to‐insulator transition (MIT) from a high‐temperature metallic phase to a low‐temperature insulating phase at a critical temperature Tc of 68°C. The MIT is accompanied by a structural phase transition. In addition to the metallic high‐temperature rutile phase, several insulating phases may be involved depending on doping, interfacial stress, or external stimuli. Unambiguously identifying the crystal phases involved in the phase transition is of key interest from the point of view of application as well as fundamental science. We study the impact of Ti doping of VO2 thin films on (110) rutile TiO2 substrates. We conduct a careful analysis of structural properties by combining results of x‐ray diffraction, Raman spectroscopy, and transmission electron microscopy. The transition temperature Tc of the deposited thin films decreases with increasing Ti‐content. All our thin film samples undergo a structural phase transition from the monoclinic M1‐phase to the rutile R‐phase with increasing temperature without passing the intermediate monoclinic M2‐phase. A careful analysis of polarization and angle‐dependent Raman data reveals that, above Tc, the unit cell of the high‐temperature rutile TixV1‐xO2 phase is aligned with that of the rutile TiO2 substrate whereas, below Tc, 180°‐domains of the M1‐phase of TixV1‐xO2 are observed. The structural relationship between TiO2 substrate and the high respective low‐temperature phase of the TixV1‐xO2 determined by Raman spectroscopy is in excellent agreement with TEM results on these samples. Raman spectroscopy is a powerful tool for studying structural changes of VO2‐based samples in the vicinity of MIT.

Process for incineration and in can vitrification: Glass melt/liquid metal interactions and the multiphasic package

A process for incineration and in can vitrification was studied as a potential conditioning solution for nuclear fuel cycle wastes consisting of various mixtures (organics, minerals, and metals including Al) contaminated with actinides (mainly U, Pu). The organic matter was first incinerated, followed by melting of the metallic phase and ashes together with an aluminosilicate glass as a vitrification additive. This resulted in the formation of a multiphasic glass/metal package containing the actinides without organic material. During the process, interactions between liquid metal and the glass melt led to redox reactions (aluminum oxidation, silica reduction…) and the reductive environment induced sodium volatilization. Characterization of the upper layer of glass–ceramic material with 53 wt% Al2O3 showed crystallizations and metallic inclusions. The lower metallic part of the package showed demixing of the Cu-rich liquid phase and the formation of three metallic phases (stainless steel-rich, copper-rich, and Cr-Fe). Based on the results acquired, a waste package description consistent with the proposed glass/metal interaction mechanisms was obtained.

New insight into tuning magnetic phases of RMn6Sn6 kagome metals

Predicting magnetic ordering in kagome compounds offers the possibility of harnessing topological or flat-band physical properties through tuning of the magnetism. Here, we examine the magnetic interactions and phases of ErMn6Sn6 which belongs to a family of RMn6Sn6, R = Sc, Y, Gd–Lu, compounds with magnetic kagome Mn layers, triangular R layers, and signatures of topological properties. Using results from single-crystal neutron diffraction and mean-field analysis, we find that ErMn6Sn6 sits close to the critical boundary separating the spiral-magnetic and ferrimagnetic ordered states typical for non-magnetic versus magnetic R layers, respectively. Finding interlayer magnetic interactions and easy-plane Mn magnetic anisotropy consistent with other members of the family, we predict the existence of a number of temperature and field dependent collinear, noncollinear, and noncoplanar magnetic phases. We show that thermal fluctuations of the Er magnetic moment, which act to weaken the Mn-Er interlayer magnetic interaction and quench the Er magnetic anisotropy, dictate magnetic phase stability. Our results provide a starting point and outline a multitude of possibilities for studying the behavior of Dirac fermions in RMn6Sn6 compounds with control of the Mn spin orientation and real-space spin chirality.

Sulfur vacancy-induced 1T-MoS2 co-catalyst loaded on Zn3In2S6 for simultaneous promoting photocatalytic hydrogen evolution and pollutant degradation

In the field of photocatalytic hydrogen evolution, Zn3In2S6 has caught tremendous attention because of its suitable band gap and outstanding stability. However, the lower number of active sites as well as lower efficiency of photoproduced carrier separation restricted its further application. Introducing co-catalysts and structural defects are effective methods to solve the above problems. In this paper, Zn3In2S6 loaded metal phase MoS2 to construct flower-shaped spherical catalysts 1T-MoS2/Zn3In2S6 (M/ZIS6) with abundant sulfur vacancies. The visible-light-driven photocatalytic hydrogen evolution rate of 2.4 % M/ZIS6 was 8.71 mmol∙g−1·h−1, which far exceeded those of pure Zn3In2S6 (0.80 mmol∙g−1·h−1) and 2.4 % Pt/Zn3In2S6 (3.86 mmol∙g−1·h−1). Moreover, 2.4 % M/ZIS6 simultaneously displayed the excellent photocatalytic degradation performance toward acid orange 7 (AO7) in the hydrogen evolution reaction process. Co-catalyst metal phase 1T -MoS2, abundant sulfur defects, and a large and dense contact interface between 1T -MoS2 and Zn3In2S6 mainly contributed to the enhanced photocatalytic performance of 2.4 % M/ZIS6. This work provided a potential concept to construct efficient photocatalysts with noble metal-free co-catalyst for bifunctional applications.

Insights into hardening and strengthening in ultrafine Ti(C, N)-based cermets

Ultrafine Ti(C, N)-based cermets are vacuum-sintered by refining the particle size of raw materials and tailoring the WC/TaC ratio to achieve the improvements in comprehensive mechanical properties and cutting performance. The hardness, flexural strength and tool lifespan of ultrafine Ti(C, N)-based cermets are substantially higher than those of submicron Ti(C, N)-based cermets with the same composition because of the refined grains and the improved distributions of both metal phases and residual stress. The hardness attenuation behavior and strengthening mechanism in Ti(C, N)-based cermets at different test temperatures have been proposed. At 400 ℃, the hardness attenuation of Ti(C, N)-based cermets depends mainly upon the softening of metal phases. However, at 800 ℃, the hardness attenuation of Ti(C, N)-based cermets is mainly related to the reduced bearing capacity of hard ceramic phases and interfacial sliding. The addition of refractory TaC is beneficial for the improvement of high-temperature mechanical properties and the tool lifespan, attributed to the strengthening of the ceramic framework by tantalum atoms.

The re-entrant transition from the molecular to atomic phases of dense fluids: The case of hydrogen.

A simple phenomenological thermodynamic model is developed to describe the chemical bonding and unbonding in homonuclear diatomic systems. This model describes the entire phase diagram of dimer-forming systems and shows a transition from monomers to dimers, with monomers favored at both very low and very high pressures, as well as at high temperatures. In the context of hydrogen, the former region corresponds to hydrogen present in most interstellar gas clouds, while the latter is associated with the long sought-after fluid metallic phase. The model predicts a molecular to atomic fluid transition in dense deuterium, which is in agreement with recently reported experimental measurements.

Phase Evolution of Multi-Metal Dichalcogenides With Conversion-Alloying Hybrid Mechanism for Superior Lithium Storage.

Traditional lithium-ion battery (LIB) anodes, whether intercalation-type like graphite or alloying-type like silicon, employing a single lithium storage mechanism, are often limited by modest capacity or substantial volume changes. Here, the kesterite multi-metal dichalcogenide (CZTSSe) is introduced as an anode material that harnesses a conversion-alloying hybrid lithium storage mechanism. Results unveil that during the charge-discharge processes, the CZTSSe undergoes a comprehensive phase evolution, transitioning from kesterite structure to multiple dominant phases of sulfides, selenides, metals, and alloys. The involvement of multi-components facilitates electron transport and mitigates swelling stress; meanwhile, it results in formation of abundant defects and heterojunctions, allowing for increased lithium storage active sites and reduced lithium diffusion barrier. The CZTSSe delivers a high specific capacity of up to 2266mA h g-1 at 0.1 A g-1; while, maintaining a stable output of 116mA h g-1 after 10000 cycles at 20 A g-1. It also demonstrates remarkable low-temperature performance, retaining 987mA h g-1 even after 600 cycles at -40°C. When employed in full cells, a high specific energy of 562Wh kg-1 is achieved, rivalling many state-of-the-art LIBs. This research offers valuable insights into the design of LIB electrodes leveraging multiple lithium storage mechanisms.

Multiscale structural understanding of plasma spraying anti-ablation coating: an example of Ta-Hf-W-C ultrahigh temperature ceramics

The coating formation and structural design of ultra-high temperature ceramics (UHTCs) for aerospace vehicle anti-ablation coatings through plasma spraying remain uncertain despite extensive engineering applications. In this study, (Ta,Hf,W)C/HfC micro-composite, (Ta,Hf,W)C single-phase, and (Ta,Hf,C)/W nanocomposite coatings were successfully prepared using induction plasma spheroidization (IPS), vacuum plasma spraying (VPS), and spark plasma sintering (SPS). Density functional theory (DFT) was employed to capture the electronic structure of (Ta,Hf,W)Cy (y = 1, 0.875, 0.75, 0.5), confirming the influence of carbon vacancies and ceramic metallicity on the plastic forming behavior of sprayed coatings. Additionally, the contribution of HfC to structural stability and WC to the metallicity of carbon-based rock salt-structured UHTCs was elucidated. The pivotal role of carbon vacancies in inducing metastable phase formation and metal phase precipitation for (Ta,Hf,W)C was identified. Ablation behavior variations resulted from differences in multi-scale coating structures, where transverse cracks exhibited more detrimental effects than vertical cracks. Notably, a scale effect of oxidation related to the uniformity of metal elements in the multicomponent ceramic coating was uncovered. It was determined that components capable of forming high melting point oxides should not be uniformly dissolved in the matrix.

Segregation effects of doped VN and ZrN on magnetic and microstructural characteristics of FePt-based films

Segregants are essential materials for forming the complexation or granular microstructure in thin films for magnetic recording media. One such film, FePt-BN, has a metallic L10 FePt main phase as its matrix, in addition to having BN and C segregants at the grain boundaries. Amorphous BN has sufficient mechanical strength to support the columnar growth of FePt grains, however, it has a lower deposition rate resulting in columnar grains with a nonuniform aspect ratio. Moreover, some B diffuses in the interstitial site of FePt lattices. To overcome these limitations, this study added the transition nitride VN and ZrN with equal volume percentages to replace some BN segregants in FePt(BN, Ag, C) films: substantially different segregation behaviors were observed. Microstructural imaging mapping revealed that although VN segregated the FePt grains boundary, ZrN was diffused in the lattice. The FePt-BN-ZrN film thus had more disordered grains contributing to a higher in-plane magnetization and wider hard axis magnetic hysteresis loops than did FePt-BN-VN. The FePt-BN-VN film has the highest perpendicular magnetic anisotropy constant (Ku= 2.17 × 106 J/m3) and coercivity (Hc= 4 T); moreover, parallel remanence magnetization was minimal with a linear in-plane magnetization loop. The FePt-BN-VN film was sputtered directly on MgO(100) but depositing the FePt-BN-ZrN film required a 2-nm-thick FePt nucleation layer. The high atomic number of Zr and high sputter yield ratio (YN/Ymetal) of ZrN may increase the sites occupied by N, potentially affecting ZrN segregation.

Catalytic oxidation of carbon monoxide at low temperature using AuRh/TiO2 bimetallic catalysts: Effect of the synthesis method

AuRh nanoparticles supported on TiO2 P25 were synthesized by two sequential deposition methods: sequential deposition-precipitation with urea (DPU) and impregnation (IMP)-DPU. Segregated nanoparticles (RhcoreAushell ball-cup-type, and Janus-type arrangements) were observed in gold-rhodium bimetallic catalysts, but mainly ball-cup-type and Janus-type nanoparticles were found on catalysts prepared by IMP-DPU. XPS analysis of gold-rhodium bimetallic catalysts, before and after reaction allowed concluding that gold-rhodium interaction on metallic state was an important factor to avoid the oxidation of rhodium during CO oxidation. However, this effect of stabilization of the rhodium metallic phase by gold does not fully explain the promoting effect observed for some bimetallic catalysts on CO oxidation. Some structural aspects such as the atomic arrangement of the bimetallic nanoparticles and the type of active sites, determined by DRIFTS-CO, were also considered. TPR and UV–visible DR spectroscopy characterizations also showed differences in the gold-rhodium interactions.

Secondary phases characterization by SANS and XAS of an ODS ferritic steel after thermal aging at 873 K

An ODS steel with nominal composition Fe–14Cr–2W–0.4Ti-0.3Y2O3 (wt.%) was produced by mechanical alloying and compacted by hot isostatic pressing (HIP) followed by hot cross rolling (HCR). To check the effects of thermal aging at relevant temperatures of operation in fusion power plants, the alloy was thermally aged at 873 K for 2000 h. In this work, small-angle neutron scattering (SANS) and X-ray absorption spectroscopy (XAS) techniques are used for the advanced characterization of secondary phases and the oxide nanoparticle dispersion. SANS results show that the oxide nanoparticles remain stable after the thermal aging treatment. Composition of the oxide nanoparticles was identified as Y2TiO5 or Y2Ti2O7 by SANS, while non-stoichiometry was found by XAS analysis. Laves phase precipitation after the thermal aging treatment is further confirmed by SANS, from the magnetic anisotropic contribution to the scattering intensity associated to this metallic phase, and by XANES.

Ferric sludge derived pyrolyzed-hydrochar supported iron catalysts for catalytic cracking of toluene

Effective treatment of ferric sludge in an eco-friendly method is key to the feasibility of Fenton technology in pollution treatment, contributing to the realization of the “dual-carbon” strategic objectives. In this study, Fe-loaded pyrolyzed-hydrochar catalysts were prepared using simple one-pot hydrothermal carbonization (HTC) method with ferric sludge as the precursor, which greatly reduced the energy and time consumption on the preparation of the sludge derived catalyst. At 800 °C with a reaction time of 20 min, all catalysts showed high toluene removal performance (>60 %) and produced H2-rich syngas (H2 > 90 %). In particular, the catalyst prepared by HNO3-assisted HTC (HNC) presented the highest toluene removal efficiency and H2 yield, 77.52 ± 3.36 % and 11.12 ± 0.66 mol%, respectively. Additionally, the sources of carbon deposits and the interaction between the active site and carbon deposits were analyzed in detail by DFT to reveal the catalytic activity and deactivation mechanism of catalyst. The results showed that the adsorption energy of C generated from methyl on different Fe phases was lowest (the adsorption energy of C was −8.79 eV for Fe, −5.28 eV for Fe2O3, and −4.70 eV for Fe3O4), suggesting that the adsorption of C on catalyst was the main reason for the formation of carbon deposits. The lowest adsorption energy of the metallic Fe phase for C indicated that Fe0 was coated by carbon deposits during toluene catalytic cracking, which hampered catalytic activity. These results are of great significance for optimizing the preparation of Fe-loaded carbonaceous catalysts and the regulation of Fe active phase.

Revealing 1T-MoS2 with 76 % purity induced by various saccharides for supercapacitor performance

The preparation of metallic phase molybdenum disulfide (1T-MoS2) through an implementable method has become a top priority in research due to its excellent electrochemical performance. In this study, 1T-MoS2 using a facile one-pot hydrothermal method is successfully synthesized by incorporating saccharides. Moreover, a comprehensive understanding of the synthesis mechanism is induced by various saccharides. Glucose, a monosaccharide, not only possesses reducibility but also plays a crucial role in preparation of sulfur vacancies. Maltose is a disaccharide that can hydrolyze into glucose and fructose, both of which exhibit reducibility. On the contrary, dextrin is difficult to break down into fructose or glucose, and faces certain challenges in promoting the formation of 1T-MoS2. Importantly, 1T-MoS2 with 76 % purity obtained in our study exhibits exceptional electrochemical performance, demonstrating a high specific capacitance of 228.4 F g−1 at 2 A g−1 and maintaining a cycling stability of 97 % after 10,000 cycles. Furthermore, an asymmetric flexible supercapacitor device is assembled by 1T-MoS2 and active carbon on carbon cloths, which shows superior flexibility, high power density, and energy density. Notably, this work not only unveils the mechanism by which saccharides influence the synthesis of 1T-MoS2 but also provides support for the preparation of other metallic members in the transition metal dichalcogenides (TMDs) family.

Contrasting irradiation behavior of dual phases in Ti-6Al-4V alloy at low-temperature due to ω-phase precursors in β-phase matrix

Aiming to simulate the radiation damage effect on a dual α+β phase Ti-6Al-4V alloy utilized as high-intensity accelerator beam window material, a series of irradiation experiments were conducted with a 2.8 MeV-Fe2+ ion beam in several dpa regions at room temperature. The nano-indentation hardness increased steeply at 1 dpa and unchanged up to 10 dpa, due to the saturation of defect clusters and tangled dislocations in the dominant α-phase matrix with a size of 2–3 nm and a density of about 1×1023 m−3. In contrast in the intergranular β-phase, larger loops of 20–30 nm diameter were observed with much less density of about 5×1020 m−3. The diffraction pattern showed rectilinear diffuse streaks between the β-phase reflections, corresponding to the ω-phase precursor, without dose dependency in its intensity. FFT/I-FFT analysis of the HREM revealed a sub-nanometer-sized lattice disorder with local fluctuations, not discrete but continuous, and homogeneously distributed within the matrix β-phase stably against the irradiation. The significantly low dislocation density and the absence of phase transformation in the β-phase matrix could be attributed either to the strong sink effect expected for this distinctive sub-nanometer-sized homogeneous lattice disorder or to the anomalous point defect recombination induced by the high mobility of vacancies, both of which are originated from the metastable ω-phase precursors specifically formed in the β(BCC) phase of group-4 transition metals.