Synthesis of micro-sized Sb2O3 hierarchical structures by carbothermal reduction method

Micro-sized Sb₂O₃ hierarchical structures were prepared by carbothermal reduction method, using antimony doped tin oxide (ATO) nanoparticles and graphite powder as source materials. The products were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM). Furthermore, the possible growth mechanism of the as-synthesized samples was discussed. The room-temperature photoluminescence (PL) measurement exhibited one relatively strong violet emission peak at about 420 nm under the 325 nm excitation wavelength and another violet emission peak, about three times stronger in intensity than the former, at about 435 nm under the 365 nm excitation wavelength. In addition, the optimal excitation wavelength of 363 nm was obtained and the luminescence causes were speculated.     

Optical properties of In2O3 films prepared by spray pyrolysis

In₂O₃ thin films have been deposited on glass substrates by spray pyrolysis. InCl₄ was used as the solute to prepare the starting solution with a concentration of 0.1 M. The films were grown at different substrate temperatures ranging from 300 to 400 °C. The as-grown layers were optically characterized in order to evaluate the absorption coefficient, optical band gap, refractive index, extinction coefficient and other optical parameters. The influence of substrate temperature on these parameters was reported and discussed.     

Material properties and growth control of undoped and Sn-doped In2O3 thin films prepared by using ion beam technologies

Undoped (IO) and Sn-doped In₂O₃ (ITO) films have been deposited on glass and polymer substrates by an advanced ion beam technologies including ion-assisted deposition (IAD), hybrid ion beam, ion beam sputter deposition (IBSD), and ion-assisted reaction (IAR). Physical and chemical properties of the oxide films and adhesion between films and substrates were improved significantly by these technologies. By using the IAD method, non-stoichiometry and microstructure of the films were controlled by changing assisted oxygen ion energy and arrival ratio of assisted oxygen ion to evaporated atoms. Relationships between structural and electrical properties in ITO films on glass substrates were intensively investigated by using the IBSD method with changing ion energy, reactive gas environment, and substrate temperature. Smooth-surface ITO films (R_rms ≤ 1 nm and R_p-v ≤ 10 nm) for organic light-emitting diodes were developed with a combination of deposition conditions with controlling microstructure of a seed layer on glass. IAR surface treatment enormously enhanced the adhesion of oxide films to polymer substrate. The different dependence of IO and ITO films' properties on the experimental parameters, such as ion energy and oxygen gas environment, will be intensively discussed.     

Controlled synthesis and photocatalytic properties of porous hollow In2O3 microcubes with different sizes

Uniform single-crystalline In(OH)₃ hollow microcubes have been synthesized in large quantities via a hydrothermal reaction of InCl₃ with NaF and ethylene glycol (EG) at 140–220 °C for 12 h. Porous In₂O₃ hollow microcubes with a polycrystalline cubic structure can be obtained via calcining In(OH)₃ precursors at 400 °C for 2 h in air. Controlled Synthesis of In(OH)₃ and In₂O₃ hollow microcubes with the average edge lengths in the range of 2.0–4.7 μm can be achieved by changing the hydrothermal reaction temperature. The In(OH)₃ hollow microcubes were formed via an EG-assisted oriented attachment growth route using HF bubbles as the templates. Photocatalytic activities of the as-synthesized porous In₂O₃ hollow microcubes were studied at room temperature. The results indicated that the hollow In₂O₃ nanostructures display high photocatalytic activity in the photodegradation of rhodamine B and methyl orange.     

Varistor properties of ZnO-Pr6O11-CoO-Cr2O3-Y2O3-In2O3 ceramics

The varistor properties of the ZnO-Pr₆O₁₁-CoO-Cr₂O₃-Y₂O₃-In₂O₃ ceramics were investigated for different concentrations of In₂O₃. The increase of In₂O₃ concentration slightly increased the sintered density (5.60-5.63 g/cm³) and slightly decreased the average grain size (3.4-2.9 μm). The breakdown field increased from 6023 to 14822 V/cm with increasing concentration of In₂O₃. The nonlinear coefficient increased from 17.6 to 44.6 for up to 0.005 mol%, whereas the further doping caused it to decrease to 36.8. In₂O₃ acted as an acceptor due to the donor concentration, which decreases in the range of 1.02 × 10¹⁷ to 0.24 × 10¹⁷/cm³ with increasing concentration of In₂O₃.     

Gas sensor based on ordered mesoporous In2O3

We present the preparation of a semiconductor gas sensor based on ordered mesoporous In₂O₃. The In₂O₃ was synthesized by structure replication procedure from cubic KIT-6 silica. A detailed analysis of the morphology of the mesoporous powders as well as of the prepared sensing layer will be shown. Unique properties arise from the synthesis method of structure replication such as well defined porosity in the mesoporous regime and nanocrystallites with high thermal stability up to 450 °C. These properties are useful for the application in semiconducting gas sensors. Test measurements show sensitivity to methane gas in concentrations relevant for explosion prevention.     

Synthesis of GaN nanorods by ammoniating Ga2O3 films on In2O3 layer deposited on Si (111) substrates

GaN nanorods were synthesized by ammoniating Ga₂O₃/In₂O₃ thin films deposited on Si (111) with magnetron sputtering. X-ray diffraction, Scanning electronic microscope and high-resolution TEM results show that they are GaN single crystals, the sizes of which vary from 2 to 7 μm in length and 200 to 300 nm in diameter. In₂O₃ middle layer plays an important role in the GaN nanorod growth.     

Room temperature ferromagnetism in Ni doped In2O3 nanoparticles

In the present work, Ni doped In₂O₃ nanoparticles were prepared using simple co-precipitation method. From the x-ray diffraction analysis it is observed that all samples exhibit single phase polycrystalline nature. All the diffraction lines correspond to the bixbyite type cubic structure. A UV visible analysis reveals that optical band gap decreases from 4.63 to 3.84 eV with Ni doping. DC magnetization measurements reveal that Ni doped In₂O₃ nanoparticles exhibit room temperature ferromagnetism.     

Photoluminescence properties of Y2O3:Tb and YBO3:Tb green phosphors synthesized by hydrothermal method

In this work, two Tb³⁺ activated green phosphors: Y₂O₃:Tb³⁺ and YBO₃:Tb³⁺ were prepared by hydrothermal method. Photoluminescence properties of both phosphors were studied in details. Both phosphors exhibit similar luminescent characteristics symbolized by the dominant green emission at 545 nm. Concentration quenching occurs at the Tb³⁺ concentration of 1.60 atomic% and 2.57 atomic% for Y₂O₃:Tb³⁺ and YBO₃:Tb³⁺, respectively. Luminescence decay properties were characterized to better understand the mechanism of concentration quenching. Based on the calculation, the concentration quenching in both phosphors was caused by the dipole–dipole interaction between Tb³⁺ ions.     

Solvothermal synthesis of In(OH)3 nanorods and their conversion to In2O3

In this work, we demonstrate that monodisperse indium hydroxide (In(OH)₃) nanorods constructed with parallel wire-like subunits have been fabricated via a acrylamide-assisted synthesis route without any template. NH₃ from the hydrolysis of acrylamide acts as the OH⁻ provider. The structure and morphology of as-prepared products have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and thermogravimetric analysis (TG). A detailed mechanism has been proposed on the basis of time-dependent experimental results. Furthermore, by annealing In(OH)₃ precursors at 500 °C for 3 h in air, In₂O₃ samples were obtained with the designed morphology.     

Influence of Ga2O3 addition on transparent conductive oxide films of In2O3-ZnO

Influence of incorporation of Ga in amorphous In-Zn-O transparent conductive oxide films was investigated as a function of Zn/(Zn + In). For In-Zn-O films with no Ga₂O₃, the range of Zn/(Zn + In) ratio where the amorphous phase appears became narrow at a substrate temperature of 250 °C. With increasing Ga₂O₃ quantity, amorphous films were obtained even at a high substrate temperature of 250 °C in a wider range of Zn/(Zn + In) than that of In-Zn-O films with no Ga₂O₃. This means that the trend of crystallization at higher substrate temperature was disturbed with additional Ga incorporation. For the film deposited from ZnO:Ga (Ga₂O₃: 4.5-7.5 wt%) and In₂O₃ targets, we obtained a resistivity of 2.8 × 10⁻⁴ Ω cm, nearly the same value as that for an In-Zn-O film with no Ga₂O₃. The addition of more than 7.5 wt% Ga₂O₃ induced a widening of the optical band gap.     

In2O3 nanowires for gas sensors: morphology and sensing characterisation

Thin and densely packed In₂O₃ nanowires have been synthesised on alumina substrates via transport and condensation method, starting from nanoparticles of indium or palladium as catalysts for the condensation process. Indium catalyst promoted wires growth according to vapour-solid (VS) mechanism, while palladium catalyst leads to wires formation based on vapour-liquid-solid (VLS) condensation. Electron microscopy and related diffraction analysis demonstrated that the wires are monocrystalline, with atomically sharp termination of the lateral sides, and are free from extended defects. The sensing properties of nanowires bundles have been tested to acetone using the flow through technique in the temperature range between 100 and 500 °C.     

High-rate deposition of high-quality Sn-doped In2O3 films by reactive magnetron sputtering using alloy targets

Sn-doped In₂O₃ (ITO) films were deposited on heated (200 °C) fused silica glass substrates by reactive DC sputtering with mid-frequency pulsing (50 kHz) and a plasma control unit combined with a feedback system of the optical emission intensity for the atomic O* line at 777 nm. A planar In-Sn alloy target was connected to the switching unit, which was operated in the unipolar pulse mode. The power density on the target was maintained at 4.4 W cm^− 2 during deposition. The feedback system precisely controlled the oxidation of the target surface in “the transition region.” The ITO film with lowest resistivity (3.1 × 10^− 4 Ω cm) was obtained with a deposition rate of 310 nm min^− 1 and transmittance in the visible region of approximately 80%. The deposition rate was about 6 times higher than that of ITO films deposited by conventional sputtering using an oxide target.     

The reaction mechanism of the spray Ion Layer Gas Reaction process to deposit In2S3 thin films

The spray Ion Layer Gas Reaction (ILGAR) is a well-established, patented and commercial process used primarily to deposit In₂S₃ as buffer layers in thin film solar cells. In this paper we investigate the growth mechanism of the spray In₂S₃ ILGAR process by characterising the intermediate growth stages of films, following the growth mechanism with a quartz crystal microbalance and tracking the gaseous side-and-intermediate products during film growth, using a mass spectrometer. A basic growth mechanism model is then proposed based on an aerosol assisted chemical vapour deposition of an In(O_x,Cl_y,(OH)_z) film, as the first stage process, followed by the conversion of the intermediate film using H₂S gas to In₂S₃.     

Structural instability of Sn-doped In2O3 thin films during thermal annealing at low temperature

We report on observations of structural stability of Sn-doped In₂O₃ (ITO) thin films during thermal annealing at low temperature. The ITO thin films were deposited by radio-frequency magnetron sputtering at room temperature. Transmission electron microscopy analysis revealed that the as-deposited ITO thin films are nanocrystalline. After thermal annealing in a He atmosphere at 250 °C for 30 min, recrystallization, coalescence, and agglomeration of grains were observed. We further found that nanovoids formed in the annealed ITO thin films. The majority of the nanovoids are distributed along the locations of the original grain boundaries. These nanovoids divide the agglomerated larger grains into small coherent domains.     

Structural study of amorphous In2O3 film by grazing incidence X-ray scattering (GIXS) with synchrotron radiation

Grazing incidence X-ray scattering (GIXS) using synchrotron radiation is a very useful method for structural analysis of amorphous films. We investigated the structure of amorphous In₂O₃ film utilizing GIXS at BL19B2 in SPring-8. Radial distribution function (RDF) was obtained from the measurement data. Structural models were constructed by molecular dynamics (MD) and reverse Monte-Carlo (RMC) simulations, and the calculated RDFs from the simulations were compared with that observed. It was found that the average oxygen coordination number around In ions was almost 6 and the average length 2.12 Å, which was smaller by about 3% than that of 2.18 Å in crystalline In₂O₃. It was concluded that the atomic arrangement of the amorphous In₂O₃ was characterized by the increase in the number and the boarder angle of distribution of corner-sharing In-O-In bond compared with crystalline In₂O₃.     

Mechanical properties and microstructure of Al2O3/TiAl in situ composites doped with Cr2O3

Al₂O₃/TiAl composites were successfully fabricated from powder mixtures of Ti, Al, TiO₂ and Cr₂O₃ by a hot-press-assisted exothermic dispersion method. The effect of the Cr₂O₃ addition on the microstructures and mechanical properties of Al₂O₃/TiAl composites was characterized, and the results showed that the Rockwell hardness, flexural strength and fracture toughness of the composites increased as the Cr₂O₃ content increased. When the Cr₂O₃ content was 2.5 wt%, the flexural strength and the fracture toughness attained peak values of 925 MPa and 8.55 MPa m^1/2, respectively. This improvement of mechanical properties was due to the more homogeneous and finer microstructure developed from the addition of Cr₂O₃ and an increase in the ratio of α₂-Ti₃Al to γ-TiAl matrix phases.     

A novel method to prepare Cr2O3 nanoparticles

By the reaction system of CrO₃ and HCHO in aqueous solution, Cr₂O₃ nanoparticles were first prepared via hydrothermal synthesis. The process can be easily scaled up. The reaction time was only 1 h and the reaction temperature was 170 °C. The products were loosely agglomerated Cr₂O₃ particles of 50-70 nm in average particle size calculated from the Scherrer's formula, whose microstructure and that of the precursor were investigated by SEM. And IR, TG and BET were other characterization methods to study the process. The findings showed that the higher calcination temperature and the higher total concentration were factors to result in the larger average particle size.     

Y2O3添加量对Al2O3/ZrO2共晶陶瓷显微组织及力学性能的影响

为探索第三组元Y₂O₃添加对Al₂O₃/ZrO₂共晶陶瓷显微组织与机械性能的影响,本文利用低温度梯度的高温熔凝法制备了直径为20 mm的Al₂O₃/ZrO₂(Y₂O₃)共晶陶瓷块体,采用SEM、EDS及XRD技术对共晶陶瓷进行微结构分析,并利用维氏压痕法对其硬度和断裂韧性进行测试。SEM结果表明,凝固组织由群集的共晶团结构组成,随着Y₂O₃添加量的增加,共晶团形态由胞状转变为枝晶状,内部相间距在1~2 μm范围内变化。力学测试表明,Y₂O₃摩尔分数小于1.1%时,由于组织内部存在低硬度m-ZrO₂及微裂纹缺陷,故陶瓷硬度较低,约为(9.53±0.22 )GPa;当Y₂O₃摩尔分数为1.1%时,陶瓷硬度最大,约为(18.05±0.27)GPa;当Y₂O₃的摩尔分数大于1.1%时,由于共晶团边界区内气孔缺陷及粗大组织增多,引起陶瓷硬度值略有下降。低Y₂O₃摩尔分数添加时,陶瓷断裂韧性相对较高,约为(6.30±0.16)MPa·m^1/2,这与其内部存在大量微裂纹缺陷有关;随着Y₂O₃添加量的增加,陶瓷的微裂纹数量减少、边界区内缺陷增多,断裂韧性降低。     

La2O3、Nd2O3、Y2O3对高岭石高温相变动力学的影响

利用综合热分析技术、X射线衍射(XRD)、傅里叶变换红外光谱(FT-IR)和扫描电镜(SEM)研究了La_2O_3、Nd_2O_3、Y_2O_3对高岭石高温条件下转变成莫来石过程的作用,并采用Kissinger方程、Ozawa方程以及JMA修正方程(Ⅰ)和(Ⅱ)分析了La_2O_3、Nd_2O_3、Y_2O_3对高岭石高温相变动力学的影响。结果表明:3种稀土氧化物的掺入对高岭石的相变动力学参数产生了影响,相变活化能和频率因子与未掺入稀土氧化物的高岭石相比有所降低,析晶方式则未发生变化,均属于体积晶化。对比掺入3种稀土氧化物的高岭石相变活化能和频率因子可以看出,Y_2O_3对于高岭石高温条件下相变的促进作用最为明显,相变活化能最低。稀土氧化物对于高岭石高温相变产物影响不大,主晶相为莫来石相,次晶相为方石英相,但稀土氧化物的掺入使得方石英相的结晶度明显提高。