In2O3 System Research Articles

Effect of co-doping Nb2O5 with equal amount of Eu2O3 or In2O3 on the electrical properties of TiO2-based varistors

In this work, TiO2 varistors with enhanced nonlinear coefficient, low breakdown voltage, high relative dielectric constant and low dielectric loss were fabricated by co-doping of Nb2O5 with equal amount of Eu2O3 or In2O3. The results indicated an appropriate proportion of dopant could improve the comprehensive performance of the varistors. For the TiO2–Nb2O5–Eu2O3 system, the breakdown voltage and relative dielectric constant of the samples decreased first and then increased, while the nonlinear coefficient increased first and then decreased with the increase of doping content, the best value appears at the doping content of 1.00 mol% (E1mA = 2.14 V/mm, α = 4.6, εr = 2.72 × 105, tanδ = 0.25). It is noted that the secondary phase formed on the grain boundary as Eu2Ti2O7, thus the growth of grain was hindered and the dielectric performances deteriorated. By contrast, for the TiO2–Nb2O5–In2O3 system, the secondary phase was not found. As a result, a low breakdown voltage, low dielectric loss and high nonlinear coefficient were obtained, reaching the best at the doping content of 5.0 mol% (E1mA = 4.6 V/mm, α = 8.4, εr = 1.85 × 105, tanδ = 0.16). The influence of this doping system on the electrical performance can be explained by Internal Barrier Layer Capacitance theory (IBLC), which is related to the potential barrier at the grain boundary.

Sensory Effect toward Hydrogen in a Nanostructured CeO2–In2O3 System

Sensory Effect toward Hydrogen in a Nanostructured CeO2–In2O3 System

Photoinduced Defect Engineering: Enhanced Photothermal Catalytic Performance of 2D Black In2 O3- x Nanosheets with Bifunctional Oxygen Vacancies.

Photothermal CO2 reduction technology has attracted tremendous interest as a solution for the greenhouse effect and energy crisis, and thereby it plays a critical role in solving environmental problems and generating economic benefits. In2 O3- x has emerged as a potential photothermal catalyst for CO2 conversion into CO via the light-driven reverse water gas shift reaction. However, it is still a challenge to modulate the structural and electronic characteristics of In2 O3 to enhance photothermocatalytic activity synergistically. In this work, a novel route to activate inert In(OH)3 into 2D black In2 O3- x nanosheets via photoinduced defect engineering is proposed. Theoretical calculations and experimental results verify the existence of bifunctional oxygen vacancies in the 2D black In2 O3- x nanosheets host, which enhances light harvesting and chemical adsorption of CO2 molecules dramatically, achieving 103.21 mmol gcat -1 h-1 with near-unity selectivity for CO generation and meanwhile excellent stability. This study reveals an exciting phenomenon that light is an ideal external stimulus on the layered In2 O3 system, and its electronic structure can be adjusted efficiently through photoinduced defect engineering; it can be anticipated that this synthesis strategy can be extended to wider application fields.

Ferromagnetic order in substitutional Fe-doped In2O3 powder

We report an experimental investigation of the room-temperature ferromagnetism of an Fe-doped In2O3 system. (In1−xFex)2O3(x = 0.00, 0.02, 0.06,0.10,0.14 or 0.18) powders were prepared by a standard solid-state reaction method followed by sintering in air at 1200 °C for 48 h. The influence of Fe-doping concentration on the structural and magnetic properties of the In2O3 samples was studied. X-ray diffraction analysis reveals that Fe ions are incorporated into the In3+ sites of the In2O3 lattice without altering the cubic bixbyite structure. Magnetic characterization shows ferromagnetic behavior at room temperature for all the Fe-doped In2O3 samples. The observed ferromagnetism is attributed to the oxygen vacancies induced by substitution of Fe into In3+ sites and vacuum annealing. A model of ferromagnetic exchange interactions was proposed to explain the ferromagnetism in this system.

Sensor Properties of Nanostructured Systems Based on Indium Oxide with Co3O4 or ZrO2 Additives

The effect of Co3O4 and ZrO2 additives on the sensory response of In2O3-based nanostructured composites to H2 and CO is studied. It is shown that the addition of small amounts of Co3O4 or ZrO2 to In2O3 leads to a sharp increase in the sensory response to hydrogen. The maximum sensory response of the ZrO2−In2O3 composite to 1100 ppm of hydrogen increases from 80 to 270 as the ZrO2 content changes 0 to 20 wt %. The response to CO varies only slightly. For Co3O4−In2O3 composites, the maximum response to H2 and CO increases with the Co3O4 content within 0−10 wt %. A further increase in the Co3O4 content leads to a significant decrease in the response, with composites containing ∼60 wt % Co3O4 being characterized by a very low efficiency. In the Co3O4−In2O3 system with a content of up to 60 wt % Co3O4, electronic conduction is realized, which changes to hole conduction at Co3O4 within 80−100 wt %. In the ZrO2−In2O3 system, electric current flows through In2O3 nanocrystals, i.e., n-type conduction takes place. Possible reasons for the observed effects are discussed.

Origin of the Magnetism in Undoped and Mn-Doped In 2 O 3 : A First-Principles Study

The magnetism of undoped and Mn-doped In2O3 has been investigated by employing density functional calculations. For undoped In2O3, a neutral In vacancy in In2O3 leads to the formation of a net moment of 3 μ B, which originates from the strong spin polarization of 2p orbitals of O atoms. While, Mn-doped In2O3 system shows robust ferromagnetism which can be attributed to the p-d hybridization between Mn and their neighboring O atoms. In addition, because two O atoms between the two Mn atoms are removed, the ground state of the system have a transformation from the ferromagnetic to the antiferromagnetic state, which further demonstrates that the ferromagnetism is mediated through the p-d interaction.

Conductivity of nanostructured India oxide films containing Co3O4 or ZrO2

The effect of additives of cobalt and zirconium oxides on the conductivity of nanostructured composites based on indium oxide is studied. It is shown that addition of up to 20 wt % ZrO2 to In2O3 leads to a sharp decrease in the conductivity of the composite. For the Co3O4−In2O3 system, the conductivity decreases up to a Co3O4 content of 60 wt %, after which it increases. At a Co3O4 content in the Co3O4−In2O3 system of up to 60 wt %, n-type conduction takes place, changing to p-type at 80 to 100 wt % Co3O4. Zirconium oxide exhibits practically no n-type conduction, so electric current in the ZrO2−In2O3 system flows through In2O3 nanocrystals, i.e., n-type conduction takes place. Possible causes of the observed effects are considered.

Preparation and characterization of highly transparent and conductive indium-zinc oxide thin films deposited by pyrolysis spray technique

Ternary compound films of ZnO–In2O3 system were prepared by spray pyrolysis method. The films were deposited on heated glass substrates by pyrolytic decomposition of zinc chloride and indium chloride in distilled water with different ratio x of [Zn] to [Zn + In] (x = [Zn]/[Zn + In]). The phase change, chemical composition, electrical and optical properties of the Zn–In oxides were investigated over wide range of ratio x. Quasi-amorphous sub-oxide films with thickness of 200–400 nm were first obtained, the films were then annealed in Argon atmosphere at 550 °C for 1 h. To optimize the physical properties of sprayed ZnO–In2O3 thin films, we carry out on a systematic study of their microstructural characterization and transport properties. Continuous structural variation from In2O3 to ZnO through Zn2In2O5 and Zn3In2O6 was observed on the deposited films with increasing the ratio x. Maximum of conductivity of 1.47 × 103 Ω−1 cm−1 was reached for x = 0.5 (at.%). We also concluded that the transport properties of the films are greatly governed by their microstructure.

Unknown phase equilibria in the ternary oxide V2O5–CuO–In2O3 system in subsolidus area

The syntheses of two compounds Cu2In3VO9 and CuInVO5, forming in the ternary system V2O5–CuO–In2O3, are described. The compound CuInVO5 has been for the first time obtained as the pure phase. The temperatures and modes of melting of the compounds are determined, and their IR spectra are analysed. The phase diagram of V2O5–CuO–In2O3 system in subsolidus area is constructed by DTA and XRD methods. This system is shown to consist of 11 subsidiary subsystems in which three solid phases coexist at equilibrium. The melting temperatures of these subsystems are also determined.

Experimental and First-Principles Theoretical Study of Structural and Electronic Properties in Tantalum-Doped In2O3 Semiconductor: Finding a Definitive Hyperfine Interaction Assignment

In this work we present an experimental and theoretical study from first-principles of the structural, electronic, and hyperfine properties of Ta-doped In2O3 semiconductor. The ab initio electronic structure calculations in the Ta-diluted In2O3 system enabled to obtain the structural lattice distortions and the hyperfine parameters when the Ta atom is placed at each cationic site of the bixbyite crystal structure. To this purpose we used the full-potential augmented plane wave plus local orbital (FP-APW+lo) method, within the density functional theory. The obtained results indicate that the substitutional Ta probe-impurity produces strong changes on the local structure. In addition, we performed accurate time-differential perturbed γ–γ angular correlations (TDPAC) key experiments in 181Hf(→181Ta)-implanted In2O3 samples with high crystallinity, in order to obtain high quality measurements of the electric-field gradient tensor (EFG) that unraveled the controversy settled in the literature and overcome diss...

The Electronic Structures and Magnetic Properties of Un-doped In2O3: the First-Principle Calculation

The electronic structures and magnetic properties of native defects in cubic In2O3 are investigated systematically by the LDA + U first-principle calculations based on the density functional theory. It is found that the In2O3 system is a strongly correlated electron system; therefore, the coulomb potential of In-4d and O-2p should be considered. In this paper, the coulomb potential corrections are U In−4d=3 eV and U O−2p=5 eV. The magnetic moments of O interstitial, In vacancy, and In interstitial are 2 uB, 3 uB, and 1 uB, respectively, which are consistent with the analysis of group theory and molecular orbital theory. Moreover, the distributions of these magnetic moments are both local and extended. The magnetic couplings of O interstitials, In vacancies, and In interstitials are ferromagnetic, anti-ferromagnetic, and paramagnetic respectively, which are determined by electronic structures of defects. The formation energy of O interstitial is high, while that of the O Frenkel defect (that is the O interstitial-vacancy) is −4.98 eV. These results could provide the practical understanding to the room-temperature ferromagnetism in un-doped In2O3 system.

P57] Subsolidus phase relations in Li2O–CaO–In2O3 system at 1000 °C

P57] Subsolidus phase relations in Li2O–CaO–In2O3 system at 1000 °C

Thermoelectric Transport Properties of Fe-Enriched ZnO with High-Temperature Nanostructure Refinement.

Thermoelectric properties of Fe-doped ZnO materials are investigated and correlated with the phase and microstructural evolution. Both a ZnO solid solution phase and a ZnFe2O4 spinel phase are observed. Analysis was made of temperature measurements of Seebeck coefficients as combined with the law of mixture to estimate the Fermi level in the constituent phases, which are further correlated with the Fe solute concentration in ZnO lattices and the overall electrical conductivity. In addition, the thermoelectric figure of merit is found to increase with the actual Fe content in ZnO lattices, due to the reduced thermal conductivity by point defect scattering of phonons and enhanced electrical transport via electron doping. The maximum achievable power factor of Fe-doped ZnO material is found to be similar to that of the ZnO-In2O3 system. Another important finding of the present work is the significant nanostructure refinement in 18 month old FeO1.5-doped ZnO after high-temperature thermal treatment, leading to further reduced thermal conductivity, which is beneficial and promising for high-temperature thermoelectric performance.

Enhanced thermoelectric performance of In2O3-based ceramics via Nanostructuring and Point Defect Engineering.

The issue of how to improve the thermoelectric figure of merit (ZT) in oxide semiconductors has been challenging for more than 20 years. In this work, we report an effective path to substantial reduction in thermal conductivity and increment in carrier concentration, and thus a remarkable enhancement in the ZT value is achieved. The ZT value of In2O3 system was enhanced 4-fold by nanostructuing (nano-grains and nano-inclusions) and point defect engineering. The introduction of point defects in In2O3 results in a glass-like thermal conductivity. The lattice thermal conductivity could be reduced by 60%, and extraordinary low lattice thermal conductivity (1.2 W m−1 K−1 @ 973 K) below the amorphous limit was achieved. Our work paves a path for enhancing the ZT in oxides by both the nanosturcturing and the point defect engineering for better phonon-glasses and electron-crystal (PGEC) materials.

Recasting the Callaway and von Baeyer thermal conductivity model on defective oxide materials: the ZnO-In2O3 system as an example.

Point defects and nanoscale interfaces effectively scatter short and mid-to-long wavelength phonons, respectively, thereby considerably reducing the thermal conductivity. In this paper, a classical physical model of phonon transport and scattering, the Callaway and von Bayer method, is recast with the introduction of the phonon mean free path cut-off, or equivalently, the minimum phonon relaxation time. To illustrate the method, we compute the thermal conductivity for the ZnO-In2O3 binary system in which the compositionally dependent structure is available, including solid solutions consisting of point defects and natural superlattices. The calculated thermal conductivity is in good agreement with the experimental measurements, and suggests a threshold value of about 50 nm for the interface spacing, above which the thermal conductivity becomes less sensitive to the interfaces with increasing temperature. A useful design clue is implied for the nanostructural engineering of high temperature thermoelectrics and thermal barrier coatings.

Processing-phase diagrams: a new tool for solution-deposited thin-film development applied to the In5O(OPri)13–In2O3 system

Understanding processing–property relationships of a precursor is important for achieving the desired properties in opto-electronic thin-films. This work highlights the construction of a processing-phase diagram of the novel In2O3 precursor In5O(OPri)13 for transparent conducting oxide applications. The decomposition behavior of the precursor was profiled with thermogravimetry, differential scanning calorimetry, and temperature programmed desorption mass spectroscopy. Decomposition occurred at 150–230 °C. Higher temperature exothermic reactions were identified as structural rearrangement/ordering processes. The precursor powder was found to crystallize into the bixbyite structure at 300–350 °C, presenting a non-crystalline phase-processing window for the material. Crystallization of a film was monitored with in situ X-ray diffraction annealing, which showed a markedly higher crystallization onset of 500 °C and a much larger non-crystalline oxide window. The decomposition and crystallization behavior of the precursor powders and films were combined into a master processing-phase diagram. Solution deposited, crystalline In2O3 films annealed under Ar–4%H2 achieved a conductivity of 165 S cm−1 with high visible transparency (80%) and exhibited a mobility of 9.6 cm2 V−1 s−1 with a carrier concentration of 1.1 × 1020 cm−3.

Roles of oxygen vacancy on ferromagnetism in Ni doped In2O3: A hybrid functional study

The roles of oxygen vacancies on the electronic and magnetic properties of Ni doped In2O3 have been studied by first-principles calculations based on hybrid functional theory. Our results predict that the Ni-doped In2O3 system displays a ferromagnetic semiconducting character. However, the presence of oxygen vacancies results in antiferromagnetic coupling between the neighboring Ni pair bridged by an oxygen vacancy. The antiferromagnetic coupling is found to arise from the predominant role of superexchange due to the strong Ni 3d–O 2p hybridization. Consequently, the oxygen vacancies play a key role in the lower saturation magnetization of Ni:In2O3 polycrystalline sample, as observed in experiments.

Phase diagram of CdO–V2O5–In2O3 system

The subsolidus phase equilibria of the ternary system CdO–V2O5–In2O3 were investigated by differential thermal analysis (DTA) and X-ray diffraction technique (XRD). It has been shown that the system consists of ten subsidiary systems in which three solid phases coexist in equilibrium in each subsystem. CdV2O6 and In2O3-were proved to react in the solid phase and at the molar ratio of 3:2 and the formation of a new compound Cd3In4V6O24 was observed. This new compound undergoes incongruent melting at 920°C with deposition of solid In2O3. Cd3In4V6O24 crystallises in the monoclinic system with elementary cell parameters of a=0.8793(1)nm, b=1.578(1)nm, c=0.7506(7)nm, γ=96.6°, Z=2.

Stability of indium–tin-oxide and its optical properties: A first-principles study

Various doping sites of Sn in the In2O3 system have been modeled and simulated by the first-principles. The energy favorable site of Sn in In2O3 is found to be on the b-site, which is consistent with experiments. The doping of Sn into interstitial sites is experimentally possible due to the fluctuation in energy, and the intrinsic oxygen vacancies in In2O3 favor the formation of Sni. As Sni in doped ITO can drastically change the transparency in the visible light range, it is necessary to control the preparatory conditions to avoid Sn doping in interstitial sites for realizing ideal transparency in visible light range. By using the LDA+U approach, the band structures of In2−xSnxO3 (x≤0.125) are calculated, which are in substantially better agreement with the experimental values than previous first-principles results.

Thermal stability of In2(MoO4)3 and phase equilibria in the MoO3–In2O3 system

Thermal stability of a compound forming in a binary system MoO3–In2O3 was investigated by DTA/TG, XRD and SEM methods in this study. For the first time, the diagram of phase equilibria established in the whole range of concentrations of this system's components has been constructed. The temperature and concentration ranges of the components of MoO3–In2O3 system in which the compound In2(MoO4)3 co-exists in solid state with MoO3 or In2O3 or with the liquid were determined. The composition and melting point of the eutectic mixture consisting of In2(MoO4)3 and MoO3 were found.