Atomic Concentration Research Articles

Tailoring Optoelectronic Properties of ZnO Films Through Synergistic Mg and B Co-Doping for Unprecedented High-Performance Transparent Electrode Applications

The quest for indium-free transparent conductive electrodes with enhanced optical band gaps and superior electrical conductivity is imperative for the advancement of flexible electrochromic devices. This study presents a groundbreaking approach wherein composite ZnO films, incorporating Mg and/or B dopants through a facile sol–gel spin coating method, are meticulously crafted and systematically scrutinized for their optoelectrical properties. Our findings reveal that Mg doping primarily influences the optical band gap, while B doping facilitates the augmentation of free electrons by modulating morphology and electronic defect states. Optimal performance is achieved with pure Mg doping at an atomic molar concentration of 0.2, resulting in a ZnMgO film boasting an exceptional average transmittance of 98.79% and an impressively low electrical resistivity of 15.3 Ω·cm. Although pure B doping compromises the crystalline quality, it significantly reduces electrical resistivity. Intriguingly, co-doping with Mg at an atomic molar concentration of 0.2 introduces challenges to crystalline quality but enriches the composite film with additional charge carriers, leading to a reduction in bandgap and a remarkable drop in resistance to 6.2 Ω·cm. This innovative work not only sheds light on the delicate balance between Mg and B doping in ZnO films but also paves the way for unparalleled opportunities in the development of high-performance transparent conductive electrodes for flexible electrochromic devices.

Extracting mechanical and microstructural properties of Cu–Zr thin film alloys by MEMS, AFM and ellipsometer

The quantification of the atomic concentration ratios of thin-film metallic alloys having low atomic ordering is challenging, particularly if they are grown on similar metals and possess different surface chemistries. Micromechanical and optical methods have been used to correlate the elemental ratios with the mechanical and optical properties of the films. The room-temperature growth of Cu–Zn thin-film alloys with varying elemental ratios on cosputtered Si substrates was performed to obtain an amorphous film structure. X-ray diffraction patterns confirmed that the grown films exhibited a very short range ordering, suggesting an amorphous structure. The mechanical properties of the films evaluated using microelectromechanical system (MEMS) indicated that the alloy films with moderate Zr concentrations had lower surface stress compared to those with low and high Zr concentrations. Furthermore, spectroscopic ellipsometry was employed to qualitatively assess the relaxation times of free carriers. The results demonstrated a strong correlation between the relaxation times and surface roughness measurements, showing that the microstructure and resistivity characteristics of the alloys align with the Nordheim semiempirical model. The extinction coefficient of the binary alloy film linearly depends on the metallic bulk concentration ratio in a specific metallic ratio range, paving the way for realizing qualitative elemental percentage assessment in the field of metrology.

Silicon oxide film formation by spraying tetraethyl orthosilicate onto substrate with simultaneous low-energy SiO+ ion-beam irradiation

We attempted to deposit silicon oxide films by spraying tetraethyl orthosilicate (TEOS) onto a substrate while the substrate was also irradiated with a low-energy SiO+ ion beam. The energy of the SiO+ ions was 55 eV, and the substrate temperature was 300 °C. Following this process, we were able to deposit a film on the substrate. X-ray photoelectron spectroscopy (XPS) measurements of the film showed that it was composed of silicon oxide. XPS analysis also showed that the oxygen-to-silicon atomic concentration ratio (O/Si ratio) for the film was 1.57. For comparison, an SiO+ ion beam was used to irradiate a substrate at room temperature with simultaneous spraying of TEOS. XPS analysis of the deposited film showed that it was silicon oxide with an O/Si ratio of 1.45. In this case, however, a relatively large number of carbon atoms (7 at. %) were incorporated into the film. In both the 300 °C and room-temperature cases, we confirmed that the film deposition rate was substantially improved by supplying TEOS during SiO+ ion-beam irradiation.

Effect of carboxyl group introduction and graft modification on the thermal properties and Fe wall adsorption performance of HNBR

Hydrogenated nitrile butadiene rubber (HNBR) has been widely used in petrochemical, aerospace, and other fields for its excellent properties. In this study, molecular dynamics methods were employed to construct molecular models of HNBR and hydrogenated carboxyl butadiene rubber (HXNBR). It was found that the introduction of carboxyl groups significantly enhanced the mechanical properties of the material, whereas the glass transition temperature of the material increased by 9.96% and the thermal conductivity decreased by 17.3%. Subsequently, the grafted hydrogenated carboxylated nitrile butadiene rubber (HXNBR-Rx) model and the HXNBR-Rx/Fe bilayer adsorption model, which incorporate grafting modifications with of C5H11OH, C10H21OH, C15H31OH, C20H41OH and C25H51OH, were constructed. In comparison between their thermal properties and the adsorption properties on the metal walls, we revealed that as the number of grafted side chain carbon atoms increased, both the mechanical properties and the glass transition temperature of the material showed a trend of first decreasing and then increasing, while the thermal conductivity of the material first increased and then decreased. Furthermore, the effect of grafting on the material properties was analyzed at the molecular level in terms of free volume fraction, interfacial interaction energy, and relative atomic concentration. The simulation results can provide some theoretical guidance for optimizing the thermal properties of HNBR materials and the adsorption capacity of the metal walls while maintaining their oil resistance and mechanical properties.

Improvement of charge carrier lifetime in heat exchange method multicrystalline silicon wafers by extended phosphorous gettering process

External phosphorous diffusion gettering were applied using homogenous and extended schemes on multicrystalline silicon (Mc-Si) wafers obtained from solar grade (SOG) silicon feedstock by the heat exchange method (HEM) growth technique. X-ray fluorescence (XRF) characterization shows the presence of transition metals like Chromium (Cr), manganese (Mn) and iron (Fe) in the analyzed as-cut Mc-Si substrates with a predominance of Mn and Fe elements. Before and after gettering process, we have observed that the Cr atoms concentration drop from 4.1015 at.cm-3 in the as-cut Mc-Si samples to 2.5 1015 at.cm-3 with homogeneous gettering and to 3.1014 at.cm-3 in the wafer undergoes extended gettering. The quasi-steady-state photo conductance (QSSPC) technique is used to characterize the minority charge carrier’s lifetime tn before and after gettering process. It was found that the response of Mc-Si wafers is better (form point of view of lifetime improvement) to the extended process but in some regions it is less effective and the homogenous process give the best amelioration due probably to the spatial distribution of crystalline defects and metallic precipitates densities. With tn initial values before gettering in the range of 2.5-8 usec we have measured lifetime values in the range of 15 to 37 usec with extended process and from 10 to 30 µsec with the homogenous one which ensure cell efficiencies in the range of 15 to 16%.

Evolution of the Bromate Electrolyte Composition in the Course of Its Electroreduction inside a Membrane-Electrode Assembly with a Proton-Exchange Membrane.

The passage of cathodic current through the acidized aqueous bromate solution (catholyte) leads to a negative shift of the average oxidation degree of Br atoms. It means a distribution of Br-containing species in various oxidation states between -1 and +5, which are mutually transformed via numerous protonation/deprotonation, chemical, and redox/electrochemical steps. This process is also accompanied by the change in the proton (H+) concentration, both due to the participation of H+ ions in these steps and due to the H+ flux through the cation-exchange membrane separating the cathodic and anodic compartments. Variations of the composition of the catholyte concentrations of all these components has been analyzed for various initial concentrations of sulfuric acid, cA0 (0.015-0.3 M), and two values of the total concentrations of Br atoms inside the system, ctot (0.1 or 1.0 M of Br atoms), as functions of the average Br-atom oxidation degree, x, under the condition of the thermodynamic equilibrium of the above transformations. It is shown that during the exhaustion of the redox capacity of the catholyte (x pass from 5 to -1), the pH value passes through a maximum. Its height and the corresponding average oxidation state of bromine atoms depend on the initial bromate/acid ratio. The constructed algorithm can be used to select the initial acid content in the bromate catholyte, which is optimal from the point of view of preventing the formation of liquid bromine at the maximum content of electroactive compounds.

Deposition of TiNi thin films on Ni(001) substrate using molecular dynamics simulation

This paper investigates the effect of incident energy and substrate temperature on the morphological and microstructural properties of TiNi thin films deposited on Ni substrate. The detailed analysis of surface morphology, the interface intermixing, density, and the voids in TiNi thin films was performed by molecular dynamics simulation combined with the second nearest-neighbor modified embedded-atom method interatomic potential (2 NN MEAM). The results indicate that higher incident energy and substrate temperature affect morphological properties of TiNi thin film. When the incident energy ranges from 0.1 to 10 eV, the surface roughness initially increases before eventually decreasing. Regarding the substrate temperature, the roughness decreases initially from 300 K to 700 K, but beyond 700 K, it begins to increase again. In addition, the interface mixing analysis was also affected by incident energy. It is found that, the thickness of the mixing interface was increased as the incident energy increase. This suggests that the growth mode changes from epitaxial to mixing. When the incident energy is higher than 10 eV, the diffusion rate of Ti atoms in the substrate layers is higher than that of Ni atoms. Conversely, at the surface of thin film, the concentration of Ni atoms is higher than that of Ti atoms. However, the substrate temperature has no significant effect on the change in interface thickness. The density of the TiNi thin films shows a significant dependence on the incident energy, but not affected by the substrate temperature. In addition, the result reveal that the increasing both the incident energy and the thickness of thin films reduces the concentration of voids and vacancies.

Production of nickel and cobalt metal powders under autoclave conditions

This paper presents the results of studies on the reduction of dispersed cobalt and nickel metal powders from their salts in ammonia-alkaline aqueous solutions under hydrothermal autoclave conditions. A unified and environmentally friendly method for producing these powders has been developed. Hydrazine hydrate, with a 25–50 % excess of the stoichiometric ratio, was used as a reducing agent. This choice allows for obtaining metal phases that are chemically uncontaminated by decomposition products. The experiments determined the conditions for the quantitative reduction of cobalt (II) and nickel (II) ions from ammonia-alkaline aqueous solutions. The synthesis temperature for the dispersed phases ranged from 110 to 155 °C. It has been demonstrated that under the conditions used, the process is completed quantitatively within 60 min. Metal concentrations in the solutions were determined using atomic absorption spectroscopy. The results of the X-ray phase analysis confirm that cobalt forms in the HCP lattice, while nickel forms in the FCC lattice. No other phases, including X-ray amorphous phases, were observed. It was found that with an increase in the hydrothermal synthesis temperature from 110 to 155 °C, the specific surface area of cobalt increased by more than 1.5 times, and that of nickel black powders increased by approximately 2 times. Scanning electron microscopy revealed that cobalt is formed in the shape of lamellar particles with a lateral size of about 500 nm and a thickness of 50 nm, which aggregate into fractal structures. Nickel is represented by spherical particles arranged in chain-like structures. Using X-ray photoelectron spectroscopy, it was determined that the surface of the materials is covered with oxidized forms. The surface atomic concentration of cobalt (0) was approximately 2 %, while that of nickel (0) was about 25 %.

New insight into dissociation of molecular oxygen at temperatures below 5000 K

The data available in the literature on measurements of the rate coefficient of molecular oxygen dissociation were considered and structured. Modern models of hydrocarbons combustion were analyzed considering values of the O2 dissociation rate constant. Precision measurements of the rate of O2 dissociation behind shock waves at temperatures of 2500–5000 ± 50 K and pressures of 1.2–2.5 bar were carried out using atomic resonance absorption spectrometry on O atom (O-ARAS). The ARAS measurements of the absolute concentration of oxygen atoms were calibrated in the conditions of complete dissociation of N2O and O2, considering the temperature splitting of the calibration curves. Using kinetic modeling, a detailed analysis of experimental uncertainties was carried out with an assessment of the influence of impurities of various origin at the dissociation of O2. An updated expression for the rate constant of the reaction O2 + Ar = 2O + Ar was obtained in the form kdiss(±15%)=1.30·1014·exp(−108.95[kcalmol]/RT) cm3 mol−1 s−1. A significant influence of the O2 dissociation rate constant on the predictive ability of modern models of hydrocarbons (on the example of biofuels) combustion at high temperatures was shown. Recommendations were formulated on the use of the corresponding oxygen dissociation rate constant in the development and/or refinement of combustion kinetic models.

On the role of vacancy-hydrogen complexes on dislocation nucleation and propagation in metals

New insights are provided into the role of vacancy-hydrogen (VaH) complexes, compared to the hydrogen atoms alone, on hydrogen embrittlement of nickel. The effect of the concentration of hydrogen atoms and VaH complexes is investigated in different crystal orientations on dislocation emission and propagation in single crystal of nickel using atomistic simulations. At first, embrittlement is studied on the basis of unstable and stable stacking fault energies as well as fracture energy to quantify the embrittlement ratio (unstable stacking fault energy/fracture energy). It is found that VaH complexes lead to high embrittlement compared to H atoms alone. Next, dislocation emission and propagation at pre-cracked single crystal crack-tip are investigated under Mode-I loading. Depending upon the elastic interaction energy and misfit volume, high local concentrations at the crack front lead to the formation of nickel-hydride and nickel-hydride with vacancies phases. These phases are shown to cause softening due to earlier and increased dislocation emission from the interface region. On the other hand, dislocation propagation under the random distribution of hydrogen atoms and VaH complexes at the crack front or along the slip plane shows that VaH complexes lead to hardening that corroborates well with the increased shear stresses observed along the slip plane. Further, VaH complexes lead to the disintegration of partial dislocation and a decrease in dislocation travel distance with respect to time. The softening during emission and hardening during propagation and disintegration of partial dislocation loops due to VaH complexes fit the experimental observations of various dislocation structures on fractured surfaces in the presence of hydrogen, as reported in literature.

Dynamic Homogenization of Internal Strain in Multi-Principal Element Alloy via High-Concentration Doping of Oxygen with Large Mobility.

Internal strain and its distribution within the crystal lattice play crucial roles in modulating dislocation activities, thereby affecting mechanical properties of materials. Through the synergistic application of integrated differential phase contrast, in situ transmission electron microscopy characterizations, and computational simulations, a method is unveiled for homogenizing dislocation pinning in NiCoCr multi-principal element alloy (MPEA) through the introduction of a high concentration of oxygen atoms with high diffusion mobility. The doping of massive oxygen atoms creates a high density of strong local pinning points for dislocation motion. Notably, oxygen interstitials exhibit remarkable diffusion and mobility across different octahedral and tetrahedral sites within the distorted crystal lattice of NiCoCrO alloy, even at room temperature. The capability allows for the release of severe stress concentrations arising from dislocation entanglement and the establishment of new strong local pinning points at alternative locations in a uniform way, enabling the material with high strength and outstanding deformability. These findings suggest that interstitial atoms can exhibit significant mobility, even at ambient temperature, in complex MPEAs with spreading lattice distortion, opening new possibilities for dislocation engineering.

Hybrid photonic device based on Graphene Oxide (GO) doped P3HT-PCBM/p-Silicon for photonic applications

Graphene oxide (GO) doped poly(3-hexylthiophene):[6,6]-phenyl C61 butyric acid methyl ester (P3HT:PCBM) interlayered Al/p-Si Schottky barrier diodes (SBDs) were manufactured by spin coating technique and investigated for the effects of GO concentration on electrical and photodiode parameters. The current–voltage (I-V), measurements for the different mass ratios of GO:P3HT:PCBM (0:1:1(S1), 0.5:1:1(S2) and 2:1:1(S3)) used diodes allowed the determination of key electrical parameters, including ideality factor (n), barrier height (Φ B ), series resistance (R s ), shunt resistance (R sh ), interface states density (N ss ) and optical sensing behaviors in dark and different illumination levels (10, 30, 60, 80 and 100 mW cm−2). The rectification ratio (RR) was found to be in the order of 104. The trends obtained for the n, Φ B , R s /R sh and N ss show that these are influenced by the contribution of the GO. Observed increasing behavior of reverse current with increasing illumination shows that this SBDs can be use as photo-diodes/sensors/detectors. On the other hand, it was observed that the linear dynamic range (LDR), which is important parameter for image sensors, increased (6.86, 16.95 and 26.98 for S1, S2 and S3, respectively) with increasing GO contribution. In addition, to investigate and compare in more detail, capacitance–voltage (C-V) and conductance-voltage (G-V) measurements used for the determination of diffusion potential (V D ), concentration of dopant acceptor atoms (N A ), Fermi energy level (E F ), depletion layer width (W D ) for low frequency (1 kHz) and high frequency (1 MHz). The measured capacitance values showed a high value at the low frequency in comparison with the high frequency. This behavior explained on the basis of N ss . The findings suggest that the prepared diodes has the potential to serve as a photo-diodes/sensors/detectors for optical sensing applications.

Low temperature magnetic and structural properties of Sr-doped La2CoMnO6 (La2-xSrxCoMnO6: 0 ≤ x ≤ 0.08) double perovskite nanoparticles

A study on crystal structure and physical properties has been performed on nanoparticles of lead-free double perovskites, La2CoMnO6 (LCMO) and Sr-doped La2-xSrxCoMnO6 (LSMO:0 ≤ x ≤ 0.08) prepared by the sol–gel synthesis method. In preparation for the LSMO nanoparticle, the La site of the LCMO double perovskite was replaced with an increasing concentration of Sr atom. Structural investigation done by employing the X-ray Diffraction technique indicates that the crystallite size decreases as the doping concentration increases. The Rietveld refinement on the XRD pattern shows the formation of the rhombohedral phase of LCMO (S.G. no. 161). Strain in the prepared samples estimated from Williamson Hall (W-H) analysis shows that the strain decreases as crystallite size decreases. The presence of compressive strain is also evident from the blue shift obtained in the Raman spectrum of the nanoparticles. The UV–Vis spectra reveal the maximum absorption in the near UV region of the electromagnetic spectrum. The Bandgap analysis from Tauc’s plot shows an increase in band gap with Sr doping in the LCMO host lattice (from 1.81 eV to 1.92 eV). This is attributed to the decrease in crystallite size and octahedral tilting with Sr doping. Resistivity versus temperature plots reveal the semiconducting nature of the compound. A linear nature graph between lnρ and T-14 indicates that the electric transport mechanism is governed by the variable range Hopping (VRH) model. The M−H curves show that the maximum magnetization decreases as a result of Sr doping due to the anti-site disorder introduced. dM/dT vs T curve shows two magnetic transitions at ∼ 215 K and at ∼ 173 K which are due to Co2+–O2--Mn4+ and Co3+–O2--Mn4+ ferromagnetic superexchange interactions, respectively.

Investigation into the Adsorption Mechanism of a Novel Collector Cetyl Trimethyl Ammonium Chloride on the Surface of Hematite and Quartz

In this research, a novel collector cetyl trimethyl ammonium chloride (CTAC) was used to separate hematite from quartz via reverse flotation for the first time. Micro-flotation tests showed that CTAC had a strong ability to selectively collect quartz and that a separation of hematite from quartz could be accomplished with a concentration of 0.00263 mmol/L CTAC. Zeta-potential measurements indicated that the positive CTAC+ species could selectively increase the surface potential of quartz, but that it had rather a weak effect on the hematite. X-ray photoelectron spectroscopy (XPS) detection indicated that CTAC had a stronger binding affinity to oxygen sites on the surface of quartz than on hematite, resulting in a large amount of CTAC being predominantly adsorbed onto quartz. This was supported by the atomic concentration of C1s and N1s of quartz after CTAC treatments were 4.25 and 2.84 times higher than hematite, respectively.

Corrosion Resistance of Fe-Cr-Si Alloy Powders Prepared by Mechanical Alloying

Powders with nanometric crystallites of two ternary alloys Fe0.90Cr0.05Si0.05 and Fe0.85Cr0.10Si0.05 were prepared by mechanical alloying (MA) in a planetary high-energy ball mill at various milling times followed by annealing in a vacuum at 900 K to induce an oxygen-induced surface segregation of Cr and Si atoms. The prepared powders were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The obtained results show that all prepared powders crystallize in the body-centered cubic structure and are composed of micrometric particles, which are polycrystalline and consist of many nanometric crystallites. The mean size of the particles as well as the crystallites decreases progressively with milling time. In order to study the anti-corrosion properties of the obtained materials, the powders were exposed to atmospheric gases at 870 K. After each oxidation step, the formation of iron oxides was investigated using 57Fe transmission Mössbauer spectroscopy (TMS). It was found that the powders of Fe0.90Cr0.05Si0.05 and Fe0.85Cr0.10Si0.05 obtained after 10 and 20 h of MA are extremely resistant to oxidation. This result can be connected with the fact that XPS measurements reveal a high concentration of Cr and Si atoms on the surface of powder particles.

Investigation on wear-resistance of nanocrystalline Pt-Au by molecular dynamics simulations

In this study, molecular dynamics simulation was used to investigate the wear-resistance behavior in nanocrystalline Pt-Au under a hard grinding ball. A comprehensive analysis was performed regarding the variation of wear volume and rate with sliding distance, frictional forces, and defect evolution at different temperatures. The effect of adding atomic concentrations of Au as solute segregation at GBs has also been investigated subsequently. It was found that the segregation of Au to the GBs of nanocrystalline Pt demonstrates improvement in the slab's anti-wear behavior compared to the pure Pt samples across all the temperatures, and it was concluded that the underlying wear-mechanism is adhesion-dominated across all the samples, and that diffusion-driven phenomenon might be an influencing factor at homologous temperature.

Performance of Mg target for neutron generator under deuterium ion irradiation

Compared with Ti, Mg has large hydrogen storage capacity, high hydrogen release temperature and weak ion stopping power. The neutron yield can be improved if Mg is used in tritium targets of the neutron generator. In this paper, numerical calculations are applied to prove that Tritium-Mg targets can effectively improve the neutron yield. Magnetron sputtering was used to prepare the MgD2 targets with smooth surfaces free from apparent microcracks. The MgD2 crystals mainly had stable tetragonal structure α-MgD2. The atomic concentration of deuterium in the samples was comparable to that in other types of targets. The thermal stability of the samples and neutron yield provided by them were better than respective characteristics of Ti targets. However, the neutron yield with MgD2 targets was substantially attenuated due to the irradiation damage.

Influence of focusing intensity on optically pumped metastable rare gas based on laser-induced ionization

When traditional optically pumped metastable rare gas laser (OPRGL) operating in high power output, a potential issue may arise: electromagnetic interference (EMI) caused by large volume atmospheric pressure discharge. This EMI problem imposes limitations on the application of OPRGL. We propose a new idea of preparing metastable atoms by 532 nm laser-induced preionization, which has the potential to circumvent the EMI problem. An 811.5 nm laser was used to excite the metastable (4s[3/2]2) Ar atoms in Ar-He mixture, resulting in the generation of a prominent amplified spontaneous emission (ASE) signal at 912.3 nm (4p[1/2]1→4s[3/2]2). By investigating intensities of the 912.3 nm fluorescence and ASE as a function of the delay time between 811.5 nm and 532 nm lasers, the influence of the 532 nm laser's focusing intensity on the evolution of prepared metastable atomic concentration was unveiled, as well as the amplification mechanism of 912.3 nm signal. Furthermore, the competition mechanism between ASE and the fluorescence channels originating from the 4p[1/2]1 level was studied. Considering the influence of plasma expansion on metastable atomic concentration, as well as the influences of threshold, gain and gain length on ASE, at the “photoexcitation + radiation + collisional relaxation” stage, we obtained a reliable effective lifetime of the metastable 4s[3/2]2 level through analysis of the decay curve of the 912.3 nm ASE intensity. Similarly, in the “ion-electron recombination” stage, a reliable effective lifetime of the metastable 4s[3/2]2 level was obtained by analyzing the decay curve of the 912.3 nm fluorescence intensity. Additionally, the 912.3 nm ASE pulse width was influenced by various factors, including the effective lifetime of the 4p[1/2]1 level, the concentration of metastable Ar, the plasma expansion rate, and the gain length, etc. This work demonstrates that OPRGL based on laser-induced preionization offers a promising alternative for the future advancement of OPRGL.

Molecular dynamics modeling of hydrogen-induced plastic deformation and cracking of ɑ-iron

In this work, molecular dynamics modeling was conducted to study hydrogen (H)-induced plastic deformation and cracking of polycrystal α-Fe. Under cyclic loading, the number of vacancies and the stress intensity increase with H atom concentration and the number of loading cycles. However, the effect of cyclic loading on cracking is not as significant as the increment of H concentration. As the H concentration increases, the dislocation generation and emission are enhanced in the {110}<111> slip system, but are inhibited in other slip systems. There is a critical H atom concentration, below which the plastic deformation of α-Fe is facilitated by H atoms. When the critical H concentration is exceeded, the dislocation emission is inhibited by H atoms at grain boundaries, where the H atoms can pin dislocations, causing piling-up of the dislocations to generate a stress concentration.

Unexpected doping effects on phonon transport in quasi-one-dimensional van der Waals crystal TiS3 nanoribbons

Doping usually reduces lattice thermal conductivity because of enhanced phonon-impurity scattering. Here, we report unexpected doping effects on the lattice thermal conductivity of quasi-one-dimensional (quasi-1D) van der Waals (vdW) TiS3 nanoribbons. As the nanoribbon thickness reduces from ~80 to ~19 nm, the concentration of oxygen atoms has a monotonic increase along with a 7.4-fold enhancement in the thermal conductivity at room temperature. Through material characterizations and atomistic modellings, we find oxygen atoms diffuse more readily into thinner nanoribbons and more sulfur atoms are substituted. The doped oxygen atoms induce significant lattice contraction and coupling strength enhancement along the molecular chain direction while have little effect on vdW interactions, different from that doping atoms induce potential and structural distortions along all three-dimensional directions in 3D materials. With the enhancement of coupling strength, Young’s modulus is enhanced while phonon-impurity scattering strength is suppressed, significantly improving the phonon thermal transport.