Electric field enhancements in In2O3-coated single-walled carbon nanotubes

In₂O₃ nanoparticles are coated on the surfaces of single-walled carbon nanotubes (SWCNTs) by a successive ionic layer adsorption and reaction process. The thickness of the In₂O₃ nanoparticle film is tuned by controlling the number of coating cycles. The electric field around the In₂O₃-coated SWCNTs is compared with that of pristine SWCNTs. Field enhancement of the In₂O₃-coated SWCNTs is confirmed by conductive atomic force microscopy at low electric field (contact mode: 1 V to −1 V) and also field emission (FE) analysis at high electric field (0–4.2 V/μm). The uniformity and emission stability are also measured via FE analysis. Near infrared and X-ray photoemission spectroscopy data are suggested to explain the charge transfer, bandgap change between the In₂O₃ nanoparticles and SWCNTs, and the electric field enhancements in the In₂O₃-coated SWCNTs at both low and high electric field.     

Side-by-Side In(OH)<Subscript>3</Subscript> and In<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanotubes: Synthesis and Optical Properties

A simple and mild wet-chemical approach was developed for the synthesis of one-dimensional (1D) In(OH)₃ nanostructures. By calcining the 1D In(OH)₃ nanocrystals in air at 250 °C, 1D In₂O₃ nanocrystals with the same morphology were obtained. TEM results show that both 1D In(OH)₃ and 1D In₂O₃ are composed of uniform nanotube bundles. SAED and XRD patterns indicate that 1D In(OH)₃ and 1D In₂O₃ nanostructures are single crystalline and possess the same bcc crystalline structure as the bulk In(OH)₃ and In₂O₃, respectively. TGA/DTA analyses of the precursor In(OH)₃ and the final product In₂O₃ confirm the existence of CTAB molecules, and its content is about 6%. The optical absorption band edge of 1D In₂O₃ exhibits an evident blueshift with respect to that of the commercial In₂O₃ powders, which is caused by the increasing energy gap resulted from decreasing the grain size. A relatively strong and broad purple-blue emission band centered at 440 nm was observed in the room temperature PL spectrum of 1D In₂O₃ nanotube bundles, which was mainly attributed to the existence of the oxygen vacancies.     

Synthesis of nano-sized indium oxide (In2O3) powder by a polymer solution route

Indium oxide (In₂O₃) is a n-type semiconductor with various applications in thin film coatings, on the basis of its optical properties, and in gas sensing equipment, due to its high sensitivity to various oxides such as CO_x and NO_x. In this study, a synthesis process for obtaining In₂O₃ nanoparticles is examined. The precursor used is indium nitrate hydrate (InN₃O₉·H₂O) because of its high solubility in water. By dissolving the nitrate salt in a PVA (polyvinyl alcohol) solution, the precursor is dispersed homogeneously, which reduces the agglomeration of the resulting powder. Calcination at a low temperature of 200–250 °C burns out the organic materials of the PVA with NO_x gas emission and allows the oxidation of the indium, resulting in indium oxide nanoparticles. The influence of the PVA solution characteristics and the heat treatment temperature on the powder morphology and size was analyzed by using SEM, TEM, XRD, TGA/DSC, and four point BET for a specific surface area analysis. The measured specific surface area varies from 3 m²/g to 76 m²/g depending on the calcination temperature, and the particle size of the synthesized powders is under 10 nm for the samples heat treated at 300 °C.     

Preparation of In0.5Sc1.5Mo3O12 nanofibers and its negative thermal expansion property

Orthorhombic In_0.5Sc_1.5Mo₃O₁₂ nanofibers were prepared by electrospinning followed by a heat treatment. The effects of post-annealing temperatures on the phase composition, microstructure and morphology were investigated by XRD, SEM, HRTEM and XPS. Negative thermal expansion (NTE) behaviors of the In_0.5Sc_1.5Mo₃O₁₂ nanofibers were analyzed by high-temperature XRD. Results indicate that the as-prepared In_0.5Sc_1.5Mo₃O₁₂ nanofibers show an amorphous structure with smooth and homogeneous shape. The average diameter of the as-prepared In_0.5Sc_1.5Mo₃O₁₂ nanofibers is around 515 nm. Well crystallized orthorhombic In_0.5Sc_1.5Mo₃O₁₂ nanofibers could be prepared after post-annealing at 550 °C for 2 h with an average diameter of about 192 nm. The crystallinity of In_0.5Sc_1.5Mo₃O₁₂ nanofibers gradually improved with the increase of annealing temperature. However, too high post-annealing temperature leads to a damage of sample's fiber structure. The high-temperature XRD results reveal that In_0.5Sc_1.5Mo₃O₁₂ nanofibers show an anisotropic NTE, and the coefficients of thermal expansion (CTEs) along a-axis and c-axis were −5.95 × 10⁻⁶ °C⁻¹ and -3.54 × 10⁻⁶ °C⁻¹, while the one along b-axis is 5.61 × 10⁻⁶ °C⁻¹. The volumetric CTE of In_0.5Sc_1.5Mo₃O₁₂ nanofibers is −3.90 × 10⁻⁶ °C⁻¹ and the linear one is 1.3 × 10⁻⁶ °C⁻¹ in 25–700 °C.     

Facile synthesis of In2O3 nanoparticles with high response to formaldehyde at low temperature

In₂O₃ nanoparticles with uniform particle size (10-25 nm) were obtained using the facile precipitation strategy at room temperature with following calcined treatment. The gas-sensing performance of In₂O₃ nanoparticles with different calcined temperatures was investigated. The results demonstrated that the In₂O₃ nanoparticles calcined at 500°C exhibited highest sensing response (R_a/R_g = 68.1) to 10 ppm HCHO at 100°C with good selectivity, stability, reproducibility, and ultra-low limit of detection (1 ppm). The results of XPS, UV, and other characterizations indicated that In₂O₃-500 possessed the most absorbed oxygen species, the highest carrier mobility, and lowest band gap energies. Our work offers new insights into the development of sensing materials to the detection of volatile organic compounds (VOCs).     

Structural evolution of non-isothermally formed dysprosium sesquioxide nanoparticles and their optical and electrical conductivity properties

This paper describes the utilization of dysprosium acetate non-isothermal decomposition as a route for Dy₂O₃ nanoparticles preparation. Thermal events emerging during the heat treatment of dysprosium acetate was monitored using thermogravimetric analysis (TGA). The structural properties of the various solids obtained at the temperature range of 200–900 °C were investigated using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). It was found that 700 °C adequate for both the complete precursor decomposition and the crystallization process of the desired Dy₂O₃ nanoparticles. The morphology of the obtained Dy₂O₃ nanoparticles was examined by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Photo Luminescence (PL) was used for investigating the optical features of the obtained Dy₂O₃ nanoparticles. Moreover, the electrical conductivity of these nanoparticles has been investigated in the temperature range of 200–500 °C.     

Hydrothermal synthesis and characterization of In2O3-ZnGa2O4 nanocomposites and their application in IGZO ceramics

Poly-crystalline In₂O₃-ZnGa₂O₄ nanocomposites were successfully synthesized by hydrothermal method with a mixed solution of In, Ga and Zn nitrates with equal mole ratio (In: Ga: Zn=1:1:1) and the ammonia was used as the precipitant. The effects of hydrothermal temperature and pH value of the mixed solution on the properties of the nanocomposites were investigated. The microstructure of the prepared In₂O₃-ZnGa₂O₄ nanocomposites was characterized by SEM and TEM, respectively. The growth mechanisms of In₂O₃-ZnGa₂O₄ nanocomposites were also preliminarily discussed in this study. Results reveal that the IGZO ceramics prepared by In₂O₃-ZnGa₂O₄ nanocomposites own a high relative density of 99.5% and low resistivity of 1.2?mΩ·cm, which can be applied to the preparation of IGZO thin film with superior performance.     

In2O3 nanosheets array directly grown on Al2O3 ceramic tube and their gas sensing performance

Arrayed In₂O₃ nanosheets were synthesized directly via a two-step solution approach on an Al₂O₃ ceramic tube. Their morphology and structure were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–Vis absorption spectroscopy, and scanning electron microscopy (SEM). The results reveal that the length of each nanosheet is about 1 µm, the width of the bottom of nanosheet is about 200 nm. Importantly, the In₂O₃ nanosheets with large specific surface area possess highly sensing performance for ethanol detection. The response value to 100 ppm ethanol is about 45 at an operating temperature of 280 °C, and the response and recovery time are extremely short. It is expected that the directly grown In₂O₃ nanosheets with large specific surface area and excellent sensing properties will become a promising functional material in monitoring and detecting ethanol.     

ZnO-enhanced In2O3-based sensors for n-butanol gas

A series of high-response and fast-response/recovery n-butanol gas sensors was fabricated by adding ZnO to In₂O₃ in varying molar ratios to form ZnO-In₂O₃ nanocomposites via a facile co-precipitation hydrothermal method. Morphological characterizations revealed that the shape of pure In₂O₃ was changed from irregular cubes into irregular nanoparticles, 30–50?nm in size, with the addition of ZnO. Compared with the pure In₂O₃ gas sensor, the ZnO-In₂O₃ gas sensor exhibits superior n-butanol sensing performance. With the introduction of ZnO, the response of the sensor to n-butanol was improved from 17 to 99.5 at 180?°C for a [Zn]:[In] molar ratio of 1:1. In addition, the ZnO-In₂O₃ gas sensors show a reduced optimal working temperature, excellent selectivity to n-butanol, and good repeatability. The response of the ZnO-enhanced In₂O₃-based sensors showed a strong linear relationship with the n-butanol gas concentration, allowing for the quantitative detection of n-butanol gas.     

Structure deformation of indium oxide from nanoparticles into nanostructured polycrystalline films by in situ thermal radiation treatment

A microstructure deformation of indium oxide (In₂O₃) nanoparticles by an in situ thermal radiation treatment in nitrous oxide plasma was investigated. The In₂O₃ nanoparticles were completely transformed into nanostructured In₂O₃ films upon 10 min of treatment time. The treated In₂O₃ nanoparticle sample showed improvement in crystallinity while maintaining a large surface area of nanostructure morphology. The direct transition optical absorption at higher photon energy and the electrical conductivity of the In₂O₃ nanoparticles were significantly enhanced by the treatment.     

NO2 gas sensing responses of In2O3 nanoparticles decorated on GO nanosheets

Nanomaterials offer a wide range of applications in environmental nanotechnology. Hazardous pollutants in the environment are needed to be detected and controlled effectively to avoid human health risks. In this paper, we described the fine-controlled growth of In₂O₃ nanoparticles embedded on GO nanosheets by a facile precipitation method. The In₂O₃@GO nanocomposites exhibited outstanding gas sensing performance as compared with pure In₂O₃ nanoparticles towards NO₂. At 225 °C, the sensor displayed high selectivity, best response (78) to 40 ppm NO₂, quick response, and recovery times of 106s/42s. The improved sensing performances of the nanocomposite were attributed to large surface area, high gas adsorption-desorption capability, and the formation of p-n heterojunctions between In₂O₃ nanoparticles and GO nanosheets. The excellent gas detecting activities validate In₂O₃@GO nanocomposites as a promising candidate in the NO₂ gas sensor industry.     

Microwave Synthesis and Characterization of Spinel-type Zinc Aluminate Nanoparticles

In the present work, ZnAl₂O₄ nanoparticles have been synthesized with the aid of Zn(OAc)₂·2H₂O and Al(NO₃)₃·9H₂O as starting reagents in the presence of microwave irradiation. Besides, the effect of preparation parameters such as microwave power and irradiation time on the morphology and particle size of products was studied by SEM images. The as-prepared ZnAl₂O₄ nanoparticles were characterized extensively by techniques like XRD, TEM, SEM, FT-IR, PL, and EDS. Photoluminescence studies of the ZnAl₂O₄ nanoparticles displayed quantum confinement behavior with band gap of 3.2 eV. The XRD studies showed that pure orthorhombic ZnAl₂O₄ nanoparticles have been produced after calcination.     

Atomic layer deposition of pure In2O3 films for a temperature range of 200–300 °C using heteroleptic liquid In(DMAMP)2(OiPr) precursor

In₂O₃ films were deposited by atomic layer deposition (ALD) using a newly synthesized heteroleptic In precursor, In(DMAMP)₂(OⁱPr), and O₃ at 150–300 °C. Self-limiting growth characteristics were exhibited for a wide ALD temperature range of 200–300 °C and growth rate of 0.029–0.033 nm/cycle. At a low temperature of 150 °C, the amorphous In₂O₃ film was deposited, while polycrystalline In₂O₃ films were achieved at 200–300 °C. The In₂O₃ films grown in this ALD temperature range had high densities of 7.0–7.2 g/cm³, which are comparable to those of bulk In₂O₃. At all growth temperatures (150–300 °C), no carbon or nitrogen impurities were detected, suggesting high reactivity of the In(DMAMP)₂(OⁱPr) precursor. The ALD In₂O₃ films showed n-type electronic property with high electron concentrations of 1.6 × 10²⁰–3.6 × 10²⁰/cm³ and a Hall mobility of 31–39 cm²/V·s.     

Preparation and characterization of multiwalled carbon nanotube/In2O3 composites

We have prepared multiwalled carbon nanotube (MWCNT)/In₂O₃ composites using a simple impregnation method. The precursor compound indium(III) chloride (InCl₃) was used to cover the surface of MWCNTs and distilled water was used as solvent. The applied mass ratio was 4:1 (In₂O₃/MWCNT), and during the calcination process different temperatures (300, 350 and 400 °C) were investigated. The produced materials were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission and scanning electron microscopy, and a thermogravimetric analysis was executed also. The average thickness of the produced surface layer and the average sizes of the In₂O₃ particles were calculated with the Scherrer formula and the ImageJ-program. The results show that the heat treatment temperature affected the characteristic morphology and the crystal structure of the as-prepared composite. These multiwalled carbon nanotube-based composites are promising candidates as gas sensors and catalyst.     

Solvothermal Synthesis of In2−xCoxO3 (0.05 ≤ x ≤ 0.15) Dilute Magnetic Semiconductors: Optical,Magnetic, and Dielectric Properties

Highly crystalline and monophasic nanoparticles of In_2?xCo_xO₃ (0.05 ≤ x ≤ 0.15) were successfully synthesized by the solvothermal method through an oxalate precursor route. Collective evidence from X‐ray diffraction and reflectance measurements suggest that the Co²⁺ is incorporated into the In₂O₃ lattice site. Effect of cobalt dopant on the growth and morphology of indium oxide was studied by transmission electron microscopy. It has been observed that particle size decreases from 23 to 9 nm on increasing the Co concentration. High surface area has been obtained, with values ranging between 66 and 151 m²/g, respectively. Values for the dielectric constant were around 40. All these solid solutions show paramagnetic behavior with weak antiferromagnetic interactions.     

Preparation and electrochemical performance of In-doped ZnO as anode material for Ni–Zn secondary cells

In-doped ZnO (IZO) samples were synthesized by a simple co-precipitation method. X-ray diffraction (XRD) patterns, Raman spectra and scanning electron microscopy (SEM) images show that IZO with 2.5 wt% In₂O₃ has a pure wurtzite structure and a plate-like morphology. IZO with 16.3 wt% In₂O₃ (theoretical value) mainly shows a wurtzite structure. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge–discharge measurement were utilized to examine the electrochemical performances of IZO with 2.5 wt% In₂O₃ as anode material for Ni–Zn simulated cells. Compared with the physical mixture of ZnO with In₂O₃, IZO increases the charge-transfer resistance of zinc electrode. Furthermore, the initial discharge capacity of IZO is 569 mAh g⁻¹, and the discharge capacity decays slightly with the capacity retention ratio of 95.2% over 73 cycles, which is much higher than that of the physical mixture of ZnO with In₂O₃.     

Fast Response NO2 Gas Sensor Based on In2O3 Nanoparticles

In this research, hydrothermal‐calcination route was applied to synthesize In₂O₃ nanoparticles for gas sensor application. Hydrothermal synthesis with duration of 5 h at 180°C resulted in In(OH)₃ nanorods. Then, in the calcination step, considering controlled rate of heating and temperature, In₂O₃ nanoparticles with rough surfaces were obtained. In the next step, these nanoparticles were deposited by low frequency AC electrophoretic deposition between the interdigitated electrodes to fabricate gas sensor. Deposition in the frequency of 10 kHz resulted in the chained nanoparticles in the interelectrode space. At the end, gas sensitivity measurements were conducted at 150°C–300°C and revealed that fabricated sensor had fast response and recovery times to NO₂ gas.     

Preparation and optical properties of Sn- and Ga-doped indium oxide semiconductor nanoparticles

Indium tin oxide (ITO) nanoparticles and gallium-doped indium tin oxide (GITO) nanoparticles with various molar ratios of dopants were prepared by a solution method in oleylamine. Characterization of crystal, morphology, and optical properties was carried out using X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible (UV–Vis), photoluminescent (PL), and Fourier transform infrared spectroscopy (FT-IR). XRD patterns show that with increasing of Sn, the crystal structure of ITO nanoparticles varies gradually from standard cubic bixbyite In₂O₃ to amorphous and to standard tetragonal SnO₂, whereas the GITO nanoparticles retain the crystal structure of ITO. The smallest particle size is around 10 nm, and the morphology of the particles is nearly spherical. The smallest particles, though coated with oleylamine, tend to aggregate forming larger flower-like particles. Defect level emission at the present of dopants was observed in the PL spectra of the ITO and GITO nanoparticles.     

New versatile synthesis for low dimension superparamagnetic YBa2Cu3O7−x nanoparticles

This paper describes the synthesis and characterization of YBa₂Cu₃O_7−x (YBCO) nanoparticles obtained through an environmentally friendly chemistry approach. Y-, Cu- acetates and Ba trifluoroacetate were used for the synthesis of the precursor gel. Moreover, sucrose and pectin reagents were added as chelating agents inducing the formation of small size oxide nanoparticles. The thermal decomposition process of the precursor powder was investigated by thermal analysis correlated with mass spectrometry. The chemical nature, structure and morphology of the particles were investigated by X-Ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy. According to XRD analysis the nanoparticles have an orthorhombic structure and the average diameter between 18–30 nm, additionally confirmed by TEM measurements. The superparamagnetic behavior at room temperature of the YBCO nanoparticles has been clearly evidenced by magnetization measurements. Furthermore, the effect of the annealing atmosphere on the magnetic properties has been studied.     

Template-free synthesis of neodymium hydroxide nanorods by microwave-assisted hydrothermal process,and of neodymium oxide nanorods by thermal decomposition

Based on the 150 °C and 1 h microwave-assisted hydrothermal reaction of Nd(NO₃)₃ dissolved in deionized water with pH 10 adjusted by concentrated NH₄OH solution, the phase and morphology of the product, characterized by XRD, SEM and TEM analyses, were specified as hexagonal Nd(OH)₃ nanorods 50 nm in diameter and 700 nm long, growing along the [0 0 1] direction. TGA analysis showed the evaporation of adsorbed water and dehydration of Nd(OH)₃ to synthesize the final pure Nd₂O₃ product. With 500 °C and 2 h calcination of the Nd(OH)₃ self-template precursor, Nd₂O₃ nanorods were synthesized, retaining both the morphology and growth direction of the precursor.