Pure Indium Oxide Research Articles

Characterization and nuclear shielding performance of Sm doped In₂O₃ thin films

The widespread use of nuclear technology has increased interest in the concept of radiation shielding. Therefore, thin films are one of the applications of interest in both science and industry used in various applications such as laboratory equipment, optoelectronic materials, and radiation shielding materials. The present work synthesized pure indium oxide (In2O3) and samarium (Sm) doped In2O3 thin films by the spray pyrolysis method. The obtained samples were characterized by X-ray diffractometer, scanning electron microscopy (SEM), and Uv–vis spectrometer. The cubic crystalline form of synthesized In2O3 thin film was observed from the X-ray pattern. By introducing the Sm element, the crystalline peaks of In2O3 gradually decreased with increasing doping concentration. The experimental linear attenuation coefficients (μ) of different percentages (0, 5, 10, and 20%) Sm doped In2O3 thin films have been determined using 6 MeV energized X-ray via VARIAN® and PTW® ion chamber. Accordingly, some terms important in shielding were calculated using μ. The obtained results from these measurements can help understand the radiation shielding performance of In2O3: Sm thin films.

Efficient separation and purification of indium and gallium in spent Copper indium gallium diselenide (CIGS)

Copper indium gallium diselenide (CIGS), is a promising commercial thin-film solar cell, and its disposal after scrapping and recycling critical metals has attracted tremendous attention since CIGS can be considered an important type of urban mining. The main phase of spent CIGS is selenide, which is a hazardous contaminant that may have a potential impact on the environment and human body. In our previous study, selenium and copper in spent CIGS separated efficiently, while more scarce metals: indium and gallium were obtained in the form of mixed indium gallium oxide (IGO). Therefore, in this study, the separation and purification of indium and gallium was investigated in detail. The solution chemical behavior shows that the dissolution of indium gallium oxide (IGO) in an alkaline environment was significantly different. Selective alkali leaching is feasible to separate indium and gallium effectively. The process realized 97.26% gallium leaching out, while that of indium was 3.37%. Moreover, the mechanism of the leaching process and the removal of copper impurities were explored, with further purification, indium and gallium were obtained in the form of relatively pure indium oxide (96.04%) and gallium oxide (99.83%), respectively. This study will provide guidance for the recycling of critical metals from secondary waste.

Size Dependent Chemical Synthesis of Defective In2O3 Microcubes as NO2 Sensor

AbstractIndium oxide microcubes (IMCs) have been systematically synthesized by the hydrothermal method. The size of IMCs is systematically controlled by varying urea concentration (0.05–0.25 M) in the bath. The phase pure cubic indium oxide (In2O3) with preferred orientation along (222) direction is observed. The size of IMCs changes from 0.4 to 1.2 μm by varying urea concentrations. The urea concentration dependent plausible growth mechanism of IMCs is proposed. The defective IMCs have effectively used as NO2 sensors and have shown a gas response of 180 under the exposure of 80 ppm NO2 gas at low‐operating temperature (100 °C). However, IMCs exhibited shorter response (Rs = 4 s) and recovery time (Rc = 100 s) for 80 ppm NO2 gas. IMCs have shown selective to NO2 than NH3, CO2, and acetone.

Behavior and Mechanism of Indium Extraction from Waste Liquid-Crystal Display Panels by Microwave-Assisted Chlorination Metallurgy

Using ammonium chloride as a chlorination agent, indium in waste liquid-crystal display panels was successfully extracted by microwave-assisted chloride metallurgy under vacuum pressure. The optimal conditions for indium extraction from pure indium oxide were explored through single-factor and orthogonal experiments, achieving an indium extraction ratio of 98.91% when the temperature was 500°C, the Cl/In molar ratio was 8, and the heating duration was 3 min for pure In2O3. The Cl/In molar ratio exhibited the most important effect on the indium extraction ratio, followed by the heating temperature and duration. When extracting indium from waste liquid-crystal display panel powder (–13 µm) after ball milling, the indium extraction ratio was nearly 79.46% when using an ammonium chloride mass ratio of 0.6 wt.%, temperature of 500°C, and heating duration of 3 min. Excess gaseous hydrogen chloride reacts with ammonia to form ammonium chloride during the condensation, thereby avoiding emission of hydrogen chloride into the environment. The results of this work indicate that this technology represents a promising option for the extraction of indium from waste liquid-crystal display panels with a very short heating duration and relatively low chlorination agent loss, as well as no harmful gas emissions.

Nano Sensor Using One Dimensional Porous Indium Oxide and Pattern Recognition Method of Its Electronic Information

Due to its high sensitivity, low price and fast response speed, gas sensors based on metal oxide nanomate-rials have attracted many researchers to modify and explore the materials. First, pure indium oxide (In2O3) nanotubes (NTs)/porous NTs (PNTs) and Ho doped In2O3 NTs/PNTs are prepared by electrospinning and calcination. Then, based on the prepared nanomaterials, the 6-channel sensor array is obtained and used in the electronic nose sensing system for wine product identification. The system obtains the frequency signals of different liquor products by means of 6-channel sensor array, analyzes the extracted electronic signal characteristic information by means of ordinary least squares, and introduces the pattern recognition method of moving average and linear discriminant to identify liquor products. In the experiment, compared with pure In2O3 NTs sensor, pure In2O3 PNTs sensor has higher sensitivity to 100 ppm ethanol gas, and the sensitivity is further improved after mixing Ho. Among them, 6 mol% Ho + In2O3 PNTs have the highest sensitivity and the shortest response time; based on the electronic nose system composed of prepared nanomaterial sensor array, frequency signals of different Wu Liang Ye wines are collected. With the extension of acquisition time, the corresponding frequency first decreases and then becomes stable; the extracted liquor characteristic signal is projected into two-dimensional space and three-dimensional space. The results show that the pattern recognition system based on this method can extract the characteristic signals of liquor products and distinguish them.

Evolution of Optical, Electrical, and Structural Properties of Indium Tungsten Oxide upon High Temperature Annealing

Optical, structural and electrical properties of thermally co‐evaporated indium tungsten oxide (IWOx) thin films with varied stoichiometry, from pure tungsten oxide to pure indium oxide (InOx) are investigated upon stepwise annealing, up to 700 °C. The thin films are candidate materials for carrier selective contacts in different types of solar cells, such as silicon hetero junction and perovskite solar cells. Three different phases for the thin films with different stoichiometry and crystallization temperatures of Tc > 500 °C for tungsten‐rich layers and Tc ≈ 200 °C for indium‐rich layers are found. The pronounced optical absorption of the as‐deposited InOx‐rich layers is strongly decreased after crystallization. Tungsten oxide rich layers show low optical absorption in the as‐deposited state as well as for all applied annealing temperatures. The lateral conductivity of the pure indium oxide can be increased from 1.24 × 10−2 up to 0.83 S cm−1 after 700 °C annealing. The conductivity of the pure tungsten oxide increases slightly after crystallization from 2.55 × 10−5 to 8.25 × 10−5 S cm−1 after annealing at 700 °C. However, for mixed oxide layers with ≈25% InOx‐fraction in the mixture, the highest conductivity of 4.0 × 10−6 S cm−1 cannot be increased by the applied annealing process.

Computational study and characteristics of In2S3 thin films: effects of substrate nature and deposition temperature

In this work, we investigate the effects of both growth temperature and substrate nature on different properties of indium sulfide thin films prepared by chemical vapor deposition method using triphenylphosphine sulfide as a sulfur precursor. The structural, morphological, and optical properties of the resulting thin films were characterized using x-ray diffraction, scanning electron microscopy (SEM) and UV–vis spectroscopy respectively. The structural study has proved that pure nanocrsytalline β-indium sulfide films were obtained at 300 and 400 °C regardless of the substrate nature, while higher growth temperature (500 °C) leads to the formation of pure indium oxide films. From the SEM images, it is derived that the surface morphology of the obtained films was independent to both growth temperature and substrate nature. The electronic structure of β-In2S3 was computed using density functional theory calculations. The optical properties of the obtained films such as energy band-gap, extinction coefficient, refractive index, dielectric constant and optical conductivity were investigated theoretically and experimentally. It was shown that these parameters were mainly controlled by the substrate type and the phase formed. The theoretical optical investigation was in full agreement with the experimental results. Oscillator energy, dispersion energy and Urbach energy were also estimated. Blue and violet PL emissions indicate the useful application of the obtained films as blue and violet light emitters.

Study of WO3–In2O3 nanocomposites for highly sensitive CO and NO2 gas sensors

Pure semiconductor tungsten oxide (WO3), indium oxide (In2O3) and mixed nanocomposites with different WO3 to In2O3 ratios were successfully synthesized by simple sol-gel method following calcination at 600 °C. The morphology, phase composition and features of crustal structure of the materials were studied by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transition electron microscopy and electron paramagnetic resonance spectroscopy. It was found that the nanocomposite materials are characterized by fine crystallinity of 8–38 nm, highly defective crystal cells and presence of delocalized electrons in their structures, which can significantly affect gas sensitivity. The gas sensors based on WO3–In2O3 composite structures exhibited excellent CO and NO2 detecting performance at optimal operating temperature of ∼240 °C and ∼140 °C, respectively.

Theoretical and experimental studies of La- substituted In2O3 nano- layer via the modified Becke-Johnson (mBJ) potential

Optoelectronic properties of nanolayer of pure indium oxide (In2O3) and substituted with La are investigated by the both density functional theory (DFT) method and the experimental spray pyrolysis technique. The reported experimental results are X-ray diffraction (XRD) and absorption coefficient spectra and the theoretical results are band structure, density of states (DOS), dielectric functions, refractive index and absorption coefficient. Obtained results show that, substituting In atom by La decreases the value of the band gap mainly due to the number of states originating from La- d states in the bottom of the conduction band. It is found that the refractive index of indium oxide nanolayers increases with the substitution of In with La. The experimentally obtained results confirm the calculated theoretical results.

Porous indium oxide hollow spheres (PIOHS) for asymmetric electrochemical supercapacitor with excellent cycling stability

Porous indium oxide hollow spheres (PIOHS) of 1–2 μm in diameter were synthesized using a cost-effective hydrothermal method followed by the calcination. First, solid carbon-In2O3 composite sphere was formed using indium salt and glucose as indium and carbon precursor, respectively. Porous and hollow structure of pure indium oxide was formed after the successful removal of carbon that acted as a sacrificial template during the high-temperature calcination. Various characterization tools such as electron microscopy, Raman spectroscopy, and electrochemical techniques were used to characterize the synthesized PIOHS. From BET measurements, the specific surface area was estimated as 128 m2 g−1 and the electrode made of PIOHS showed maximum specific capacitance of 320 F g-1 at 1 A g−1 current density during electrochemical studies. This material exhibited 56% rate capability at 10 A g−1 with 86% cycling stability after 3500 cycles at 5 A g−1. The full cell asymmetric supercapacitor was demonstrated with PIOHS as a cathode with a specific capacitance, energy density and power density of 30.84 F g−1, 10.96 W h kg-1 and 80 W kg−1, respectively at 0.1 A g−1 current density along with the specific capacitance retention of 97.1% after 1000 cycles at 1 A g−1 current density. The excellent electrochemical performance of the fabricated full-cell device is mainly attributed to the high surface area, unique three-dimensional porous hollow architecture and better charge transfer kinetics of PIOHS.

Electronic structure of indium-tungsten-oxide alloys and their energy band alignment at the heterojunction to crystalline silicon

The electronic structure of thermally co-evaporated indium-tungsten-oxide films is investigated. The stoichiometry is varied from pure tungsten oxide to pure indium oxide, and the band alignment at the indium-tungsten-oxide/crystalline silicon heterointerface is monitored. Using in-system photoelectron spectroscopy, optical spectroscopy, and surface photovoltage measurements, we show that the work function of indium-tungsten-oxide continuously decreases from 6.3 eV for tungsten oxide to 4.3 eV for indium oxide, with a concomitant decrease in the band bending at the hetero interface to crystalline silicon than indium oxide.

Gas Sensitivity of ITO Composite Prepared by Sol-Gel Method

Indium oxide and indium tin oxide composite (ITO) were prepared by sol-gel dip-coating (SGDC) technique. The particles annealed at (200 ◦C, 400 ◦C). The structure and surface morphology of particles were characterized by X-ray diffraction (XRD), Atomic Force Microscope (AFM), FT-IR and UV/visible measurements. The XRD and AFM indicate decreasing in the particle size and improve of optical and electrical properties of composite with increasing of tin oxide addition. The hall measurement were used to obtain information about the type of conductivity of indium oxide and indium tin oxide thin films and carrier concentration and mobility and resistivity, the results of Hall measurements show that the In2O3 and ITO composite have n-type. The thin film of composite ITO at composition (80:20) mole ratio has high sensitivity toward CO gas compared with pure indium oxide.

Synthesis and study of solid solutions based on indium oxide in the In2O3–ZrO2(HfO2) systems as a material for fuel cell interconnectors

Nanocrystalline (8–10 nm) solid solutions on the basis of indium oxide in the systems In2O3–ZrO2 and In2O3–HfO2 are synthesized by hydroxide coprecipitation. It is established that the use of polyvinyl alcohol decreases the degree of agglomeration of precipitates and increases the dispersity of the synthesized powders. The optimal conditions for the consolidation of powders on the basis of In2O3 are selected. It is shown that In2O3 doping with zirconium and hafnium dioxides significantly increases the electrical conductivity of solid solutions compared to pure indium oxide. The influence of temperature and oxygen partial pressure on the conductivity of solid solutions on the basis of In2O3 was investigated.

Synthesis, characterization and study of band gap variations of vanadium doped indium oxide nanoparticles

In this study, effects of vanadium doping in crystal lattice structure of indium oxide (In2O3) were investigated. Indium oxide nanoparticles with different amounts of dopant concentrations were fabricated by a facile and cost effective method. X-ray diffraction (XRD) analysis revealed the formation of cubic phase for doped and undoped samples. It was observed that the lattice parameters of doped samples were decreased respect to the pure indium oxide, but the crystallite sizes and the particles’ sizes of doped samples were increased in result of substitution of vanadium in crystal lattice of In2O3. The scanning electron microscope (SEM) images of samples showed that all samples have spherical shapes, and their distribution sizes are between 10 and 70nm. It was found that the average sizes of nanoparticles were increased linearly with the amounts of dopant concentration. A red shift was founded in the band gap of vanadium doped samples respect to pure In2O3. The maximum of the band gap shift was observed for samples with 0.025 M concentration of dopant. Based on impedance spectroscopy data, it was found that impedances of samples are increased by increasing of dopant concentration for all frequencies which were tested in this study.

Study on structural and optical behaviors of In2O3 nanocrystals as potential candidate for optoelectronic devices

Pure indium oxide (In2O3) nanoparticles was synthesized by an inexpensive and solid state reaction method using indium nitrate in muffle furnace at 400 °C for 4 h. The synthesized product was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, FT-Raman, scanning electron microscopy (SEM) with energy dispersive spectroscopy, high resolution transmission electron microscopy (HR-TEM), photoluminescence (PL) and UV–Vis spectroscopy. XRD pattern confirmed the crystalline nature and cubic structure of synthesized composition. Crystallite size, microstrain and dislocation density were evaluated from the XRD data. The functional groups present in the sample were identified by FT-IR spectroscopy. The vibrational modes of the product were investigated by FT-Raman spectrum. The microstructure and elemental identification were done by SEM with EDX analysis. The HR-TEM image depicts the morphology and size of the prepared nanoparticles. The blue shift in the absorption edge was observed from the UV–Vis spectrum. The PL spectrum showed two emission peaks corresponding to blue emission.

Highly conducting, transparent, and flexible indium oxide thin film prepared by atomic layer deposition using a new liquid precursor Et2InN(SiMe3)2.

Highly conductive indium oxide films, electrically more conductive than commercial sputtered indium tin oxide films films, were deposited using a new liquid precursor Et2InN(SiMe3)2 and H2O by atomic layer deposition (ALD) at 225-250 °C. Film resistivity can be as low as 2.3 × 10(-4)-5.16 × 10(-5) Ω·cm (when deposited at 225-250 °C). Optical transparency of >80% at wavelengths of 400-700 nm was obtained for all the deposited films. A self-limiting ALD growth mode was found 0.7 Å/cycle at 175-250 °C. X-ray photoelectron spectroscopy depth profile analysis showed pure indium oxide thin film without carbon or any other impurity. The physical and chemical properties were systematically analyzed by transmission electron microscopy, electron energy loss spectroscopy, X-ray diffraction, optical spectrometer, and hall measurement; it was found that the enhanced electrical conductivity is attributed to the oxygen deficient InOx phases.

Investigation on the Effect of Dopant Concentration on the Change in Shape of ITO Nanoparticles - Prepared Using Alcoholysis Method

A simple room temperature ethanol assisted alcoholysis synthesis was adopted for the preparation of Sn doped indium oxide nanoparticles. Initially, pure indium oxide nanoparticles prepared using the method results in nanocubes, sized about 80 nm was identified using TEM analysis. When the dopant Sn was added at lower concentration the formed cubes were found to contain tiny particles inside nanocubes. As the concentration of Sn increases, it is observed that the particles were no more in cubical shape. For higher concentration of Sn, the formed particles were taken the shape of nanorods which are bunched together. This is one of the interesting results obtained for room temperature chemical synthesis. The concentration of the metal dopant was analyzed using XPS analysis and the obtained XRD pattern showed the dopant shift in 2θ. This work can be further extended to the field of gas sensors. Because, the metal oxide based gas sensors systems depends on the size and shape of the nanoparticles which can improve the sensing behavior of the material.

Annealing Effects on Electrical Properties of Pure and Tin-Doped Indium Oxide Thin Films

The annealing effects on the properties of ITO and pure In2O3 thin films have been investigated. The thin films were deposited with various O2 flow ratios to total gas flow by pulsed dc magnetron sputtering. The post-deposition annealing of the thin films was carried out for 30 minutes at various temperatures ranging up to 500 degrees C in air. It was found through the comparison of the carrier density of ITO and In2O3 thin films that the carrier electrons of the ITO thin films came from both of the dopant Sn and oxygen vacancies under the annealing less than 400 degrees C. Therefore, the ITO thin films deposited with lower O2 flow ratio exhibited higher carrier density due to many oxygen vacancies; in consequence, they exhibited lower resistivity at the annealing up to 400 degrees C. On the other hand, the carrier density of ITO thin films was almost identical regardless of O2 flow ratio when they were annealed at 500 degrees C. This fact indicates that most carrier electrons of the ITO thin films were brought by the dopant Sn at the annealing temperature of 500 degrees C. However, the ITO thin films deposited with lower O2 flow ratio exhibited higher Hall mobility; as a result, they showed lower resistivity at the annealing of 500 degrees C. Atomic force microscope, X-ray diffraction and X-ray reflectivity measurements revealed that the ITO thin films deposited with lowe O2 flow ratio exhibited dense structure even after they were annealed at 500 degrees C. Hence, the carrier electrons of the dense ITO thin films deposited with low O2 flow ratio can conduct better, as a result, the ITO thin films exhibited high Hall mobility and low resistivity.

Effect of vacuum-annealing on the d0 ferromagnetism of undoped In2O3 films

Vacuum-annealing was carried out on the pure indium oxide films deposited on Si (100) substrates by radiofrequency magnetron sputtering. Oxygen-deficiency states and room temperature d0 ferromagnetism were both detected in the as-grown and vacuum-annealed films. With more oxygen vacancies appeared through vacuum-annealing, the saturation magnetization increased rapidly from 0.5 to 5.5emu/cm3. The connection between the highly oxygen-deficiency states and the strong magnetic moment suggests that oxygen vacancies play a crucial role in mediating the ferromagnetism in In2O3 films. We think that this d0 ferromagnetism mainly stems from V0+ and oxygen vacancy clusters in the interfaces or grain boundaries.

Quasiparticle optoelectronic properties of pure and doped indium oxide

Optoelectronic properties of pure In2O3 and doped with Cr and Zn (as n and p type) have been investigated using density functional theory (DFT). The calculations are performed by using the quasiparticle calculations (GWA) and the full potential linearized augmented plane wave (FL-LAPW) within the generalized gradient approximation (GGA). The calculated band structures for pure and doped In2O3 with n and p type impurities from these theoretical methods are different. The obtained results by the quasiparticle calculations are close to the experimental results. In comparison with various DFT methods, the calculated optical spectra by GWA are also in good agreement with the experiment.