Indium Vacancies Research Articles

Indium vacancy modulated BiVO4/ZnIn2S4 for photoelectrochemical production of ammonia

BackgroundPhotoelectrochemical (PEC) reduction of nitrate to produce ammonia (NIRR) is a green strategy for converting waste NO3− into high-value chemicals. However, a lack of active sites and low selectivity still plague the single catalyst used to establish the PEC-NIRR system. MethodsHere, we construct a BiVO4/VIn-ZnIn2S4 (BVO/VIn-ZIS) heterostructure with indium vacancies. The introduction of indium vacancy significantly enhances the conversion of NO3− to NH3 by augmenting active sites and fostering carrier separation via the creation of a built-in electric field. Significant findingsNH3 yield of BVO/VIn-ZIS heterostructure with moderate indium vacancy (BVO/VIn-ZIS-m) has been promoted to 15.26 μg h−1 cm−2 (BVO/VIn-ZIS-m), and NH3 selectivity reaches 21.3 times that of NO2−. The results of cyclic experiments further demonstrate that NH3 yield of BVO/VIn-ZIS-m has remained 98.4% after five cycles, due to its excellent durability. Therefore, this work demonstrates that indium vacancy could significantly modulate the PEC performance of BiVO4 to achieve an efficient NH3 production.

Photocatalytic CO2 Reduction Using Zinc Indium Sulfide Aggregated Nanostructures Fabricated under Four Anionic Conditions.

Zinc indihuhium sulfide (ZIS), among various semiconductor materials, shows considerable potential due to its simplicity, low cost, and environmental compatibility. However, the influence of precursor anions on ZIS properties remains unclear. In this study, we synthesized ZIS via a hydrothermal method using four different anionic precursors (ZnCl2/InCl3, Zn(NO3)2/In(NO3)3, Zn(CH3CO2)2/In(CH3CO2)3, and Zn(CH3CO2)2/In2(SO4)3), resulting in distinct morphologies and crystal structures. Our findings reveal that ZIS produced from Zn(CH3CO2)2/In2(SO4)3 (ZIS-AceSO4) exhibited the highest photocatalytic CO2 reduction efficiency, achieving a CO production yield of 134 μmol g-1h-1. This enhanced performance is attributed to the formation of more zinc and indium vacancy defects, as confirmed by EDS analysis. Additionally, we determined the energy levels of the valence band maximum (VBM) and the conduction band minimum (CBM) via UPS and absorption spectra, providing insights into the band alignment essential for photocatalytic processes. These findings not only deepen our understanding of the anionic precursor's impact on ZIS properties but also offer new avenues for optimizing photocatalytic CO2 reduction, marking a significant advancement over previous studies.

Modulating charge centers and vacancies in P-CoNi loaded phosphorus-doped ZnIn2S4 nanosheets for H2 and H2O2 photosynthesis from pure water

Photocatalytic water splitting has recently attracted increasing interests for solar to chemical energy conversion. Nevertheless, the high-efficiency process for photocatalytic water splitting is driven by recombination of photogenerated electron-hole pairs and the resultant low H2 productivity. Herein, we demonstrate that P-doping induced positive charge centers (Pδ+) and indium vacancies (VIn) in ZnIn2S4 (ZIS) nanosheets can significantly promote photosplitting pure water to simultaneously produce H2 and H2O2. Microstructural and spectroscopic analysis suggest that Pδ+ and VIn can trap photogenerated electrons and holes, respectively, as a result of enhanced separation of electron-hole pairs. The optimal catalyst of P-CoNi/ZIS displays a stoichiometric H2 and H2O2 productivity of 1228.7 and 1105.5 μmol h−1 g−1, respectively, with an apparent quantum efficiency of 6.2% at 365 nm. Impressively, H2 productivity of P-CoNi/ZIS has surpassed most reported catalysts for photocatalytic pure water splitting. This work provides a unique strategy to create efficient photocatalyst for pure water splitting.

Effect of Post-thermal Annealing on the Structural, Morphological, and Optical Properties of RF-sputtered In2S3 Thin Films

Indium sulfide films were deposited by radio frequency magnetron sputtering technique on soda lime glass substrate. The deposition was conducted at the temperature of 150 °C and prepared films were then thermally annealed under argon atmosphere at 350 °C and 450 °C for 30 min. The impact of post-thermal annealing treatment on the properties of the films was investigated. From X-ray diffraction analysis, the formation of the stable tetragonal β-In2S3 crystal structure was substantiated and revealed that the thermal annealing treatment at 450 °C improved the crystallization of the films. The change in surface topographies and morphologies of the films depending on the post-thermal annealing process were examined by atomic force microscopy and scanning electron microscopy techniques, respectively. The stoichiometric ratio of constituent elements in the films was obtained by elemental analysis and it was seen that the films had slightly sulfur (S) deficit composition. It was found that the concentration of S slightly increased with the thermal annealing process. The room temperature photoluminescence spectra revealed that the films included vacancies of sulfur (VS: donor) and indium (In) (VIn: acceptor), indium interstitial (Ini: donor) and oxygen (O) in vacancy of sulfur (OVs: acceptor) defects with strong and broad emission bands at around 1.70, 2.20, and 2.71 eV.

Simulation of Supercell Defect Structure and Transfer Phenomena in TlInTe2

The local environment of atoms in a semiconductor compound TlInTe2 with tetragonal syngony is studied by the density functional theory (DFT). The introduction of a point defect (indium vacancies) into the TlInTe2 lattice is modeled using supercells. The DFT electronic properties (total and local partial densities of states (PDOS) of electrons) are modeled for the primitive TlInTe2 cell (16 atoms per unit cell) and for the defective TlInTe2 cell (where is the vacancy In) consisting of 32 atoms. The DFT-GGA calculations of the TlInTe2 band structure show that the band gap ( ) is = 1.21 eV. This value is significantly dif-ferent from the experimental value. The Hubbard model is used to correct the interaction of particles in the lattice. The DFT-GGA + U (U is the Hubbard potential) calculated by the TlInTe2 band gap is 0.97 eV. For the TlInTe2 supercell, the energies of the formation of a vacancy, the chemical potential of indium, and the standard enthalpy of the formation of TlInTe2 are calculated. When explaining the effect of various factors on the transport phenomena in TlInTe2, their thermal and electrical conductivity, both the DFT-calculated data and experimental data, are used. Taking into account the experimental data for the p-TlInTe2 crystals, the mechanism of conduction in the direction of structural chains (c axis of the crystal) is established. From the experimental data in the temperature range = 148–430 K, the band gap = 0.94 eV and the activation energy of impurity conduction = 0.1 eV (at 210–300 K) are estimated. At temperatures of ≤ 210 K, DC hopping conduction takes place in the p-TlInTe2 crystals. With this in mind, the following physical parameters are calculated for p-TlInTe2: the density of states localized near the Fermi level, their energy spread, and the average hopping distance.

Photogalvanic effects in Janus monolayer In2SSe with vacancy defects

Linear photogalvanic effects (PGEs) in Janus monolayer In 2 SSe with five different central regions, which are pure, S-vacancy, In-vacancy, SSe-vacancy and InIn-vacancy are investigated by non-equilibrium Green's function technique combined with density functional theory. Janus monolayer In 2 SSe is a kind of new two-dimensional (2D) indirect bandgap semiconductor that generates photoresponse in the absence of external bias voltage, showing potential applications in low power consumption photoelectronic devices. It is found that the photoresponse is related to the polarization angle in the form of cosine function. All the introduction of defects has enhanced the photocurrent, but the degree is different. The concentration and the position of vacancy defects also affect the photoresponse. Compared with other vacancy types, single In vacancy has the best performance because it has the highest photocurrent (29.80) and the largest ER (183.33) simultaneously. Our results indicate that appropriate vacancy defects can significantly enhance the photoresponse and ER. Janus monolayer In 2 SSe is promising in photoelectric detection. • The photoresponse is related to the polarization angle in the form of cosine function. • Indium vacancy defects can significantly enhance the photoresponse and ER. • The concentration of vacancy defects also affects the photoresponse.

Effect of indium vacancy point defect on the structural, electronic and optical properties of double perovskite halide Cs2InSbCl6

Efforts to replace the lead-based perovskite have gain significant improvements in the last decade. Lead free double halide perovskite are being considered to replace the toxic lead-based perovskite materials for solar cell applications. Density functional theory (DFT) and linear response time-dependent density functional theory (TDDFT) are used in this study to simulate and investigate the effect of vacancy in the Indium (In) site of leadfree double halide perovskite A2BB′X6 (A = Cs; B = In, B′ = Sb; X = Cl) on the structural, electronic, and optical properties for possible solar cell application. On the structural properties, the total bond length of the material Cs2InSbCl6 was found to be 30.3848 Å and the creation of the indium vacancy raises the value to 30.594 Å. The bulk modulus of Cs2InSbCl6 was calculated to be 28.44 Gpa and 26.22 Gpa for Cs2In-xSbCl6. The calculated band structure for Cs2InSbCl6 reveals semiconducting behavior with a direct energy band gap of 0.99 eV along 𝛤 point symmetry while the created indium vacancy band structure reveals metallic behavior with an overlap of electronic states along the Γ - W – Γ symmetry. The result of the optical properties calculations shows that the material Cs2InSbCl6 has higher absorption coefficient, low refractive index, low reflectivity and higher conductivity when compared to the created indium vacancy material.

Theoretical investigation on defect induced changes in electronic structure and magnetism of Eu-doped In2S3

Using density functional theory calculations, the effects of various point defects, including indium vacancy (VIn) and europium doping (EuIn), on the crystal structure, electronic structure and magnetic properties of Eu-doped In2S3 have been investigated. The magnetic origin of the system, especially the contribution of each atomic orbit, is analyzed through the state density of spin polarization. The total magnetic moment of EuIn, VIn and EuIn + VIn systems are 0.267, 1.900 and 2.063 μB, respectively. Our results show that the introduction of Eu doping and In vacancy defects induce impurity energy levels. This impurity band is mainly formed by Eu-4f orbitals, which are also spin polarised and hybridised with S-3p orbitals. The calculated defect formation energies of EuIn, VIn and EuIn + VIn systems are −12.30, 1.67 and −4.05 eV, respectively. This work provides theoretical guidance for designing unique spintronic materials, which can promote the development of spintronic applications.

Rich Indium-Vacancies In2 S3 with Atomic p-n Homojunction for Boosting Photocatalytic Multifunctional Properties.

Design and development of highly efficient photocatalytic materials are key to employ photocatalytic technology as a sound solution to energy and environment related challenges. This work aims to significantly boost photocatalytic activity through rich indium vacancies (VIn ) In2 S3 with atomic p-n homojunction through a one-pot preparation strategy. Positron annihilation spectroscopy and electron paramagnetic resonance reveal existence of VIn in the prepared photocatalysts. Mott-Schottky plots and surface photovoltage spectra prove rich VIn In2 S3 can form atomic p-n homojunction. It is validated that p-n homojunction can effectively separate carriers combined with photoelectrochemical tests. VIn decreases carrier transport activation energy (CTAE) from 0.64eV of VIn -poor In2 S3 to 0.44eV of VIn -rich In2 S3 . The special structure endows defective In2 S3 with multifunctional photocatalysis properties, i.e., hydrogen production (872.7µmol g-1 h-1 ), degradation of methyl orange (20min, 97%), and reduction in heavy metal ions Cr(VI) (30min, 98%) under simulated sunlight, which outperforms a variety of existing In2 S3 composite catalysts. Therefore, such a compositional strategy and mechanistic study are expected to offer new insights for designing highly efficient photocatalysts through defect engineering.

Quantitative Evaluation of Carrier Dynamics in Full-Spectrum Responsive Metallic ZnIn2S4 with Indium Vacancies for Boosting Photocatalytic CO2 Reduction.

The influence of defects on quantitative carrier dynamics is still unclear. Therefore, full-spectrum responsive metallic ZnIn2S4 (VIn-rich-ZIS) rich in indium vacancies and exhibiting high CO2 photoreduction efficiency was synthesized for the first time. The influence of the defects on the carrier dynamic parameters was studied quantitatively; the results showed that the minority carrier diffusion length (LD) is closely related to the catalytic performance. In situ infrared spectroscopy and theoretical calculations revealed that the presence of indium vacancies lowers the energy barrier for CO2 to CO conversion via the COOH* intermediate. Hence, the high rate of CO evolution reaches 298.0 μmol g-1 h-1, a nearly 28-fold enhancement over that with ZnIn2S4 (VIn-poor-ZIS), which is not rich in indium vacancies. This work fills the gaps between the catalytic performance of defective photocatalysts and their carrier dynamics and may offer valuable insight for understanding the mechanism of photocatalysis and designing more efficient defective photocatalysts.

Effect of heat treatment in sulfur on structural, optical and electrical properties of thermally evaporated In2S3 thin films

Crystallinity, optical band gap, resistivity and photoresponse of thermally evaporated In2S3 thin films deposited at a temperature of 350 °C and further annealed in sulfur vapour at different temperature range of 200–300 °C is investigated. It is observed that with an increase of annealing temperature, predominantly β-In2S3 phase is formed and the optical band gap for indirect allowed transitions increases from 1.6 eV to 2.0 eV and for direct allowed transitions from 2.3 eV to 2.7 eV. The electrophysical properties indicate that the activation mechanism of conductivity with an activation energy in the range of 0.5–0.73 eV, which is typical for the presence of indium vacancies in the β-In2S3 crystal structure and for the replacement of sulfur by oxygen atoms. It is also noted that sulfur annealing at temperatures of 250–300 °C leads to an increase in the conductivity and photosensitivity of films, which is suitable for photovoltaic applications.

Thermodynamic stability of defects in hybrid MoS2/InAs heterostructures

Vertical van der Waals heterostructures created from two chemically different two-dimensional (2D) materials have made significant headway in the current electronic manufacturing landscape since they demonstrate enhanced attributes. Recently, among the wide variety of possible van der Waals heterostructures, a 2D molybdenum disulfide (MoS2) thin film deposited on a 3D indium arsenide (InAs) semiconductor substrate has demonstrated promising properties. To realize the true potential of these hybrid heterostructures, it is imperative to understand their structural stability, as well as the thermodynamic stabilities of various defects at the heterointerface. We report first principles-based electronic structure calculations to study MoS2(100)/InAs(111) heterostructures with two different terminations of the substrate. We present relative stabilities of arsenic-terminated and indium-terminated heterostructures, and shed light on the thermodynamic stabilities of arsenic, indium, and sulfur vacancy defects at the heterointerface. Atomic-scale structure and electronic structure of defects is detailed along with changes in band gaps due to inclusion of vacancy defects. In general, defects are found to be energetically favorable to occur at the interface as compared to the bulk. We offer new insights into the fundamental role of interfaces in hybrid van der Waals heterostructures and their influence on defects, with potential implications for future design of next-generation semiconductors.

Study on the effect of thermal annealing process on ohmic contact performance of AuGeNi/n-AlGaInP

In this paper, Ni/Au/Ge/Ni/Au laminated metals were deposited on the n-(Al<sub>0.27</sub>Ga<sub>0.73</sub>)<sub>0.5</sub>In<sub>0.5</sub>P by electron beam evaporation, the ohmic contact with low contact resistance was successfully prepared by optimized annealing process. The specific contact resistance reached 1.4 × 10<sup>–4</sup> Ω·cm<sup>2</sup> when annealed at 445 ℃ for 600 s. The result of the secondary ion mass spectrometer shows that the solid-state reaction takes place at the interface between the laminated metal Ni/Au/Ge/Ni/Au and n-AlGaInP, then the germanium atoms and indium atoms diffuse outwards due to thermal decomposition and leave vacancies in the lattice. In this paper, the reason for the formation of ohmic contact is attributed to the fact that the germanium vacancy and indium vacancy are occupied by gallium atoms as donors to increasing the N-type doping concentration. The optimized annealing process can improve the ohmic contact performance of n-(Al<sub>0.27</sub>Ga<sub>0.73</sub>)<sub>0.5</sub>In<sub>0.5</sub>P with low doping concentration, but the specific contact resistivity has no obvious relationship with the annealing process when the of doping concentration of n-(Al<sub>0.27</sub>Ga<sub>0.73</sub>)<sub>0.5</sub>In<sub>0.5</sub>P increased. The Schottky barrier is high at low doping concentration of n-(Al<sub>0.27</sub>Ga<sub>0.73</sub>)<sub>0.5</sub>In<sub>0.5</sub>P. So inter diffusion in the annealing process could significantly increase the doping concentration of n-(Al<sub>0.27</sub>Ga<sub>0.73</sub>)<sub>0.5</sub>In<sub>0.5</sub>P and reduce the Schottky barrier height. Nevertheless, the Schottky barrier of the sample with high doping concentration is low enough what is not sensitive with inter diffusion. It provides a new method for the preparation of N-electrode of AlGaInP thin film light-emitting-diodes chip, as so as avoid the problem of n<sup>+</sup>-GaAs absorption in the conventional N-electrode preparation method and the problem of electrode dropping. However, there are still some shortcomings in this paper. The disadvantage is that the high doping concentration of n-AlGaInP will affect the crystal quality, which will reduce the luminous efficiency of LED. Therefore, in order to prepare ohmic contact with excellent properties on n-AlGaInP with lower doping concentration, optimizing the electrode design and the surface treatment of semiconductor materials are the keys to follow-up research.

Effect on the reduction of the barrier height in rear-emitter silicon heterojunction solar cells using Ar plasma-treated ITO film

In this study, we investigated the effect of plasma treatment on an indium tin oxide (ITO) film under an ambient Ar atmosphere. The sheet resistance of the plasma-treated ITO film at 250 W (37.6 Ω/sq) was higher than that of the as-deposited ITO film (34 Ω/sq). Plasma treatment was found to decrease the ITO grain size to 21.81 nm, in comparison with the as-deposited ITO (25.49 nm), which resulted in a decrease in the Hall mobility. The work function of the Ar-plasma-treated ITO (WFITO=4.17 eV) was lower than that of the as-deposited ITO film (WFITO = 5.13 eV). This lower work function was attributed to vacancies that formed in the indium and oxygen vacancies in the bonding structure. Rear-emitter silicon heterojunction (SHJ) solar cells fabricated using the plasma-treated ITO film exhibited an open circuit voltage (VOC) of 734 mV, compared to SHJ cells fabricated using the as-deposited ITO film, which showed a VOC of 704 mV. The increase in VOC could be explained by the decrease in the work function, which is related to the reduction in the barrier height between the ITO and a-Si:H (n) of the rear-emitter SHJ solar cells. Furthermore, the performance of the plasma-treated ITO film was verified, with the front surface field layers, using an AFORS-HET simulation. The current density (JSC) and VOC increased to 39.44 mA/cm2 and 736.8 mV, respectively, while maintaining a WFITO of 3.8 eV. Meanwhile, the efficiency was 22.9% at VOC = 721.5 mV and JSC = 38.55 mA/cm2 for WFITO = 4.4 eV. However, an overall enhancement of 23.75% in the cell efficiency was achieved owing to the low work function value of the ITO film. Ar plasma treatment can be used in transparent conducting oxide applications to improve cell efficiency by controlling the barrier height.

Role of point defects in the electrical and optical properties of In2O3

Using hybrid density-functional calculations we investigate the effects of native point defects on the electrical and optical properties of ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$. We analyze formation energies, transition levels, and local lattice relaxations for all native point defects. We find that donor defects are in general more energetically favorable than acceptor defects, except near O-rich conditions, where oxygen interstitials and indium vacancies have low formation energy in $n$-type ${\mathrm{In}}_{2}{\mathrm{O}}_{3}$. The oxygen vacancy is the lowest-energy donor defect with transition level $(2+/+)$ slightly below and $(+/0)$ slightly above the conduction-band minimum (CBM), with a predicted luminescence peak at 2.3 eV associated with the transition ${V}_{\mathrm{O}}^{0}\phantom{\rule{4pt}{0ex}}\ensuremath{\rightarrow}\phantom{\rule{4pt}{0ex}}{V}_{\mathrm{O}}^{+}$. Despite being a shallow donor, the oxygen vacancy becomes electrically inactive for Fermi levels at or higher than $\ensuremath{\sim}0.1$ eV above the CBM. This indicates that conductivity due to oxygen vacancies will saturate at rather low carrier concentrations when compared to typical carrier concentrations required for transparent conducting oxides in many device applications.

The hunt for the third acceptor in CuInSe2 and Cu(In,Ga)Se2 absorber layers

The model for intrinsic defects in Cu(In,Ga)Se2 semiconductor layers is still under debate for the full range between CuInSe2 and CuGaSe2. It is commonly agreed by theory and experiment, that there are at least one shallow donor and two shallow acceptors. Spatially resolved photoluminescence on CuGaSe2 previously revealed a third acceptor. In this study we show with the same method that the photoluminescence peak at 0.94 eV in CuInSe2, previously attributed to a third acceptor, is a phonon replica. However another pronounced peak at 0.9 eV is detected on polycrystalline CuInSe2 samples grown with high copper and selenium excess. Intensity and temperature dependent photoluminescence measurements reveal that this peak originates from a DA-transition from a shallow donor (<8 meV) into a shallow acceptor A3 (135 10) meV. The DA3 transition has three distinct phonon replicas with 28 meV spectral spacing and a Huang Rhys factor of 0.75. Complementary admittance measurements are dominated by one main step with an activation energy of 125 meV which corresponds well with the found A3 defect. The same defect is also observed in Cu(In,Ga)Se2 samples with low gallium content. For [Ga]/([Ga] + [In])-ratios of up to 0.15 both methods show a concordant increase of the activation energy with increasing gallium content shifting the defect deeper into the bandgap. The indium vacancy is discussed as a possible origin of the third acceptor level in CuInSe2 and in Cu(In,Ga)Se2.

In-vacancy engineered plate-like In(OH)3 for effective photocatalytic reduction of CO2 with H2O vapor

In this work, a series of In(OH)3 with abundant indium vacancies were synthesized by hydrothermal method using mixed solvent of ethylenediamine(En) and water for photocatalytic reduction of CO2 with H2O vapor. The morphology, particle size, crystallinity, pore structure, and vacancy concentration of photocatalysts were successfully regulated by adjusting the ratio of En and water in mixed solvent, which were characterized by XRD, FT-IR, TG-DTA, SEM, HRTEM, UV–vis DRS, PL spectra, XPS, and EPR. Moreover, the effect of En/water ratio on the adsorption capacity to CO2 and photo-electrical properties of In(OH)3 were further investigated by in-situ FTIR, PL spectra, UV–vis DRS, CV, and EIS. In(OH)3 prepared in mixed solution exhibited much higher photocatalytic activity for CO2 reduction with H2O vapor compared to that prepared with water only solvent. The enhanced photocatalytic performance can be attributed to the special morphology, smaller particle size, larger BET surface area, and especially generated indium vacancies creating defect energy levels in the bandgap, which improved visible light absorption, carrier separation, and CO2 chemisorption. This work paves the way to enable a non-visible-light response material with high visible-light photocatalytic activity by regulating vacancy concentration via a facile method.

Self-compensation induced vacancies for significant phonon scattering in InSb

Phonon scattering by point defects via mass differences and strain fluctuations could effectively reduce the lattice thermal conductivity. The atomic mass difference can be maximized by introducing the vacancies thus leading to a significant phonon scattering. Usually, the vacancies are introduced by tuning the stoichiometry or forming solid solution with certain compound that contains intrinsically high concentration of vacancies. In this work, we demonstrate that vacancies can be effectively induced by the self-compensation effect via chemical doping. Indium (In) vacancies in InSb were induced by Te-doping and a substantial reduction in thermal conductivity was observed. Room temperature lattice thermal conductivity of the melted and then hot-pressed InSb (without In vacancies) is ~ 14.5 W m−1 K−1 but only ~ 3.8 W m−1 K−1 for InSb0.96Te0.04 (with In vacancies), a reduction of ~ 74%. The advantage of using this strategy for phonon engineering lies in the fact that a substantial reduction in thermal conductivity can be achieved even when the dopant concentration is rather low. Since the self-compensation effect is widely observed in different compounds, it indicates that the vacancy engineering strategy used here is also applicable to a variety of other materials to effectively reduce the lattice thermal conductivity.

Effects of an in vacancy on local distortion of fast phase transition in Bi-doped In3SbTe2

Indium vacancies in Bi-doped In3SbTe2 (BIST) cause local distortion or and faster phase transition of BIST with good stability. The formation energy of the In vacancy in the BIST is relatively lower compared to that in IST due to triple negative charge state of the In vacancy (V 3− In) and higher concentration of the V 3− In in BIST. The band gap of BIST is substantially reduced with increasing concentrations of the V 3− In and the hole carriers, which results in a higher electrical conductivity. The phase-change memory (PRAM) device fabricated with the BIST shows very fast, stable switching characteristics at lower voltages.

Indium vacancy induced d0 ferromagnetism in Li-doped In2O3 nanoparticles

Li-doped In2O3 nanoparticles with room temperature d0 ferromagnetism were prepared by a sol-gel method. X-ray diffraction, X-ray photoelectron spectroscopy and photoluminescence were carried out to investigate the effects of Li incorporation on the lattice defects. As the content of Li increases, non-monotonic changes in shifts of XRD peak (2 2 2) and the intensity ratios of indium vacancies related photoluminescence peak (PII) with respect to oxygen vacancies related peak (PI) are observed. Results show that at low doping level (≤2 at.%) Li prefers to occupy In sites, while with further doping the interstitial sites are more favorable for Li. Combined with the consistent non-monotonic change in saturation magnetization, we think that indium vacancies resulting from Li-doping play an important role in inducing d0 ferromagnetism in our Li-doped In2O3 nanoparticles, and the FM coupling is mainly mediated by the LiIn-ONN-VIn-ONN-LiIn chains.