Search2012 Vol. 19, No. 12
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2012, vol. 19, no. 12, pp.
1069-1076.
https://doi.org/10.1007/s12613-012-0672-5
Abstract:
The electronic structures of three types of lattice defects in pyrites (i.e., As-substituted, Co-substituted, and intercrystalline Au pyrites) were calculated using the density functional theory (DFT). In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dixanthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order:As-substituted < perfect < Co-substituted < intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidization compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S-Fe bond is larger compared to the S-S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S-Fe bond and a decrease in the covalence level of the S-S bond, which affect the natural floatability of the pyrites.
The electronic structures of three types of lattice defects in pyrites (i.e., As-substituted, Co-substituted, and intercrystalline Au pyrites) were calculated using the density functional theory (DFT). In addition, their band structures, density of states, and difference charge density were studied. The effect of the three types of lattice defects on the pyrite floatability was explored. The calculated results showed that the band-gaps of pyrites with Co-substitution and intercrystalline Au decreased significantly, which favors the oxidation of xanthate to dixanthogen and the adsorption of dixanthogen during pyrite flotation. The stability of the pyrites increased in the following order:As-substituted < perfect < Co-substituted < intercrystalline Au. Therefore, As-substituted pyrite is easier to be depressed by intensive oxidization compared to perfect pyrite in a strongly alkaline medium. However, Co-substituted and intercrystalline Au pyrites are more difficult to be depressed compared to perfect pyrite. The analysis of the Mulliken bond population and the electron density difference indicates that the covalence characteristic of the S-Fe bond is larger compared to the S-S bond in perfect pyrite. In addition, the presence of the three types of lattice defects in the pyrite bulk results in an increase in the covalence level of the S-Fe bond and a decrease in the covalence level of the S-S bond, which affect the natural floatability of the pyrites.
2012, vol. 19, no. 12, pp.
1077-1082.
https://doi.org/10.1007/s12613-012-0673-4
Abstract:
The characteristics of aerosol flotation, which include the effect of the concentration and particle size of kerosene aerosol on the molybdenum (Mo) flotation index and the effect of kerosene aerosol dosing method on the kerosene dosage and flotation time, were studied in the flotation of low-grade refractory molybdenum ores using kerosene aerosol. The results revealed that the particle size and concentration of kerosene aerosol had little effect on the Mo grade but had significant effect on the Mo recovery. A smaller particle size and a lower concentration of kerosene aerosol were beneficial to the Mo aerosol flotation. For the received Mo ore samples, the optimized particle size of kerosene aerosol was 0.3-2 μm and the optimized aerosol concentration was 14 mg/L. The compressed air atomizer had a more uniform distribution of aerosol particles than the ultrasonic atomizer, and the aerosol concentration was controlled easily, so the compressed air atomizer was more suitable for the research of aerosol flotation. Compared with conventional flotation in which kerosene was directly added into the ore pulp, the flotation time was reduced by ~30%, and the dosage was decreased by ~20% in aerosol flotation, while the Mo flotation index was similar.
The characteristics of aerosol flotation, which include the effect of the concentration and particle size of kerosene aerosol on the molybdenum (Mo) flotation index and the effect of kerosene aerosol dosing method on the kerosene dosage and flotation time, were studied in the flotation of low-grade refractory molybdenum ores using kerosene aerosol. The results revealed that the particle size and concentration of kerosene aerosol had little effect on the Mo grade but had significant effect on the Mo recovery. A smaller particle size and a lower concentration of kerosene aerosol were beneficial to the Mo aerosol flotation. For the received Mo ore samples, the optimized particle size of kerosene aerosol was 0.3-2 μm and the optimized aerosol concentration was 14 mg/L. The compressed air atomizer had a more uniform distribution of aerosol particles than the ultrasonic atomizer, and the aerosol concentration was controlled easily, so the compressed air atomizer was more suitable for the research of aerosol flotation. Compared with conventional flotation in which kerosene was directly added into the ore pulp, the flotation time was reduced by ~30%, and the dosage was decreased by ~20% in aerosol flotation, while the Mo flotation index was similar.
2012, vol. 19, no. 12, pp.
1083-1087.
https://doi.org/10.1007/s12613-012-0674-3
Abstract:
Clay samples containing 8.15% iron oxides and 27.49% alumina were leached in oxalic acid. Leaching experiments were performed in aqueous solutions of oxalic acid of 0.2-2 mol/L at 40-80℃ for up to 90 min. The mixed kinetic mechanism, i.e., t/τ=[(1-2X/3)-(1-X)2/3]+b[1-(1-X)1/3], seemed to be the most appropriate one to fit the kinetic data of leaching iron oxides contained in clay in the aqueous oxalic acid solutions. The Arrhenius activation energy for leaching in the 1.8 mol/L oxalic acid was found to be 41.035 kJ/mol.
Clay samples containing 8.15% iron oxides and 27.49% alumina were leached in oxalic acid. Leaching experiments were performed in aqueous solutions of oxalic acid of 0.2-2 mol/L at 40-80℃ for up to 90 min. The mixed kinetic mechanism, i.e., t/τ=[(1-2X/3)-(1-X)2/3]+b[1-(1-X)1/3], seemed to be the most appropriate one to fit the kinetic data of leaching iron oxides contained in clay in the aqueous oxalic acid solutions. The Arrhenius activation energy for leaching in the 1.8 mol/L oxalic acid was found to be 41.035 kJ/mol.
2012, vol. 19, no. 12, pp.
1088-1092.
https://doi.org/10.1007/s12613-012-0675-2
Abstract:
Viscosity is an important physical property of blast furnace slags and has a great influence on blast furnace operations. Because of time consumption and difficulties encountered during high temperature experimental measurement, viscosity data are also limited, so a reasonable and accurate estimation model is required to provide the data for controlling and optimizing the blast furnace process. In the present study a viscosity model was proposed for blast furnace slags. In the model the activation energy was calculated by the optical basicity corrected for cations required for the charge compensation of AlO45-, and the temperature dependence was described by the Weymann-Frenkel equation. The estimated viscosity values of the CaO-Al2O3-SiO2, CaO-Al2O3-SiO2-MgO, and CaO-Al2O3-SiO2-MgO-TiO2 systems fit well with experiment data, with the mean deviation less than 25%.
Viscosity is an important physical property of blast furnace slags and has a great influence on blast furnace operations. Because of time consumption and difficulties encountered during high temperature experimental measurement, viscosity data are also limited, so a reasonable and accurate estimation model is required to provide the data for controlling and optimizing the blast furnace process. In the present study a viscosity model was proposed for blast furnace slags. In the model the activation energy was calculated by the optical basicity corrected for cations required for the charge compensation of AlO45-, and the temperature dependence was described by the Weymann-Frenkel equation. The estimated viscosity values of the CaO-Al2O3-SiO2, CaO-Al2O3-SiO2-MgO, and CaO-Al2O3-SiO2-MgO-TiO2 systems fit well with experiment data, with the mean deviation less than 25%.
2012, vol. 19, no. 12, pp.
1093-1099.
https://doi.org/10.1007/s12613-012-0676-1
Abstract:
The aim of this work is to investigate the effect of cold working and sandblasting on the microhardness, tensile strength and corrosion rate of AISI 316L stainless steel. The specimens were deformed from 17% to 47% and sandblasted for 20 min using SiC particles with a diameter of 500-700 μm and an air flow with 0.6-0.7 MPa pressure. The microhardness distribution and tensile test were conducted and a measurement on the corrosion current density was done to determine the corrosion rate of the specimens. The result shows that the cold working enhances the bulk microhardness, tensile and yield strength of the specimen by the degree of deformation applied in the treatment. The sandblasting treatment increases the microhardness only at the surface of the specimen without or with a low degree of deformation. In addition, the sandblasting enhances the surface roughness. The corrosion resistance is improved by cold working, especially for the highly deformed specimen. However the follow-up sandblasting treatment reduces the corrosion resistance. In conclusion, the cold working is prominent to be used for improving the mechanical properties and corrosion resistance of AISI 316L stainless steel. Meanwhile, the sandblasting subjected to the cold worked steel is only useful for surface texturing instead of improving the mechanical properties and corrosion resistance.
The aim of this work is to investigate the effect of cold working and sandblasting on the microhardness, tensile strength and corrosion rate of AISI 316L stainless steel. The specimens were deformed from 17% to 47% and sandblasted for 20 min using SiC particles with a diameter of 500-700 μm and an air flow with 0.6-0.7 MPa pressure. The microhardness distribution and tensile test were conducted and a measurement on the corrosion current density was done to determine the corrosion rate of the specimens. The result shows that the cold working enhances the bulk microhardness, tensile and yield strength of the specimen by the degree of deformation applied in the treatment. The sandblasting treatment increases the microhardness only at the surface of the specimen without or with a low degree of deformation. In addition, the sandblasting enhances the surface roughness. The corrosion resistance is improved by cold working, especially for the highly deformed specimen. However the follow-up sandblasting treatment reduces the corrosion resistance. In conclusion, the cold working is prominent to be used for improving the mechanical properties and corrosion resistance of AISI 316L stainless steel. Meanwhile, the sandblasting subjected to the cold worked steel is only useful for surface texturing instead of improving the mechanical properties and corrosion resistance.
2012, vol. 19, no. 12, pp.
1100-1106.
https://doi.org/10.1007/s12613-012-0677-0
Abstract:
Texture evolution in extruded and hot-rolled Al-Mg-Li aeronautical alloys during in-situ tension was investigated by using electron backscattered diffraction (EBSD). A field emission scanning electron microscope (FE-SEM) and a MICROTEST-5000 tensile stage were used to carry out in-situ tension tests and observations. The crystallographic texture of the extruded sample changed from weak cube texture {001}〈100〉 to texture {018}〈081〉 during tension fracture. However, strong Brass {110}〈112〉 in the hot-rolled sample was modified into a mixture texture component of Brass {110}〈112〉 and S {123}〈634〉 during tension fracture. Texture evolution in the two samples during tension can be explained by the rotation of grain orientation.
Texture evolution in extruded and hot-rolled Al-Mg-Li aeronautical alloys during in-situ tension was investigated by using electron backscattered diffraction (EBSD). A field emission scanning electron microscope (FE-SEM) and a MICROTEST-5000 tensile stage were used to carry out in-situ tension tests and observations. The crystallographic texture of the extruded sample changed from weak cube texture {001}〈100〉 to texture {018}〈081〉 during tension fracture. However, strong Brass {110}〈112〉 in the hot-rolled sample was modified into a mixture texture component of Brass {110}〈112〉 and S {123}〈634〉 during tension fracture. Texture evolution in the two samples during tension can be explained by the rotation of grain orientation.
2012, vol. 19, no. 12, pp.
1107-1113.
https://doi.org/10.1007/s12613-012-0678-z
Abstract:
High-velocity compaction (HVC) provides an effective means in the field of powder metallurgy (P/M) to reduce the porosity as well as to ameliorate the mechanical properties of products. In this study, the green density of an aluminum alloy is found to be 2.783 g·cm-3. The ejection force for the aluminum alloy is in the range of 23 to 80 kN and the spring back is found to be less than 0.40%. The hardness of the green body is in the range of HRB 30 to 70. The bending strength of the green body is in the range of 6 to 26 MPa, which are higher than that of other aluminum alloys prepared by the traditional compaction method.
High-velocity compaction (HVC) provides an effective means in the field of powder metallurgy (P/M) to reduce the porosity as well as to ameliorate the mechanical properties of products. In this study, the green density of an aluminum alloy is found to be 2.783 g·cm-3. The ejection force for the aluminum alloy is in the range of 23 to 80 kN and the spring back is found to be less than 0.40%. The hardness of the green body is in the range of HRB 30 to 70. The bending strength of the green body is in the range of 6 to 26 MPa, which are higher than that of other aluminum alloys prepared by the traditional compaction method.
2012, vol. 19, no. 12, pp.
1114-1120.
https://doi.org/10.1007/s12613-012-0679-y
Abstract:
This study investigated the microstructural characteristics, metallurgy, microhardness, and tensile strength of AZ31 and AZ61 magnesium alloy weldments, fabricated in a CO2 laser welding process with the adjustment of various parameters. The results show that the AZ31 weldment contains equiaxed grains within the fusion zone (FZ). By contrast, the FZ of the AZ61 weldment contains refined cellular grains and the partially melted zone (PMZ) contains bulk grains. We infer that the difference in aluminum content between the two magnesium alloys results in different supercooling rates and solid grain structures. For both weldments, the ultimate tensile strength (UTS) decreases following the CO2 laser welding process. However, no significant difference is noted between the UTS of the two weldments, suggesting that tensile strength is insensitive to the Al content of the magnesium alloy. The CO2 laser welding process is shown to increase the microhardness of both magnesium alloys. Furthermore, grain refinement is responsible for the maximum hardness in the FZ of both weldments. The AZ61 weldment has a higher content of Al, resulting in a greater grain refinement.
This study investigated the microstructural characteristics, metallurgy, microhardness, and tensile strength of AZ31 and AZ61 magnesium alloy weldments, fabricated in a CO2 laser welding process with the adjustment of various parameters. The results show that the AZ31 weldment contains equiaxed grains within the fusion zone (FZ). By contrast, the FZ of the AZ61 weldment contains refined cellular grains and the partially melted zone (PMZ) contains bulk grains. We infer that the difference in aluminum content between the two magnesium alloys results in different supercooling rates and solid grain structures. For both weldments, the ultimate tensile strength (UTS) decreases following the CO2 laser welding process. However, no significant difference is noted between the UTS of the two weldments, suggesting that tensile strength is insensitive to the Al content of the magnesium alloy. The CO2 laser welding process is shown to increase the microhardness of both magnesium alloys. Furthermore, grain refinement is responsible for the maximum hardness in the FZ of both weldments. The AZ61 weldment has a higher content of Al, resulting in a greater grain refinement.
2012, vol. 19, no. 12, pp.
1121-1127.
https://doi.org/10.1007/s12613-012-0680-5
Abstract:
A mathematic model of rolling pressure during a novel semisolid shearing-rolling process was established. The rolling pressure in this process is higher than that in the conventional rolling. The increment of rolling pressure in the backward slip zone is higher than that in the forward slip zone, and the neutral plane moves toward to the roll gap entrance. The maximum and the average rolling pressures increase with the decrease of strip thickness, and the effects of strip thickness on the rolling pressure is more obvious in the forward slip zone than in the backward slip zone. Meanwhile, the neutral plane moves toward the roll gap exit with the decrease of strip thickness. The maximum and average rolling pressures increase with the decrease of strip width, and the strip width affects the pressure more obviously in the backward slip zone than in the forward slip zone. At the same time, the neutral plane moves toward the roll gap entrance with the decrease of strip width. The maximum and average rolling pressures increase with increasing roll radius, and the neutral plane moves toward the roll gap exit.
A mathematic model of rolling pressure during a novel semisolid shearing-rolling process was established. The rolling pressure in this process is higher than that in the conventional rolling. The increment of rolling pressure in the backward slip zone is higher than that in the forward slip zone, and the neutral plane moves toward to the roll gap entrance. The maximum and the average rolling pressures increase with the decrease of strip thickness, and the effects of strip thickness on the rolling pressure is more obvious in the forward slip zone than in the backward slip zone. Meanwhile, the neutral plane moves toward the roll gap exit with the decrease of strip thickness. The maximum and average rolling pressures increase with the decrease of strip width, and the strip width affects the pressure more obviously in the backward slip zone than in the forward slip zone. At the same time, the neutral plane moves toward the roll gap entrance with the decrease of strip width. The maximum and average rolling pressures increase with increasing roll radius, and the neutral plane moves toward the roll gap exit.
2012, vol. 19, no. 12, pp.
1128-1133.
https://doi.org/10.1007/s12613-012-0681-4
Abstract:
The influence of oxygen content on the microstructure and mechanical properties of Ti-23Nb-0.7Ta-2Zr (at%) alloy in as-cast and cold-rolled states was investigated systematically in this paper. It is found that the alloy containing oxygen element is only composed of a single β phase, while the alloy without oxygen element consisted of β and α″ phases. Although the grain size becomes larger, the elastic deformation ratio, strength, and hardness of the alloy are all increased with an increase of oxygen content. The as-cast alloy has excellent plastic deformation ability, but the cold-rolled alloy containing oxygen element exhibits brittle characteristics. A conclusion can be drawn that oxygen element can stabilize β phase, inhibit the phase transformation from β to α″, and furthermore help to increase the strength and elastic deformation ability of the alloy.
The influence of oxygen content on the microstructure and mechanical properties of Ti-23Nb-0.7Ta-2Zr (at%) alloy in as-cast and cold-rolled states was investigated systematically in this paper. It is found that the alloy containing oxygen element is only composed of a single β phase, while the alloy without oxygen element consisted of β and α″ phases. Although the grain size becomes larger, the elastic deformation ratio, strength, and hardness of the alloy are all increased with an increase of oxygen content. The as-cast alloy has excellent plastic deformation ability, but the cold-rolled alloy containing oxygen element exhibits brittle characteristics. A conclusion can be drawn that oxygen element can stabilize β phase, inhibit the phase transformation from β to α″, and furthermore help to increase the strength and elastic deformation ability of the alloy.
2012, vol. 19, no. 12, pp.
1134-1141.
https://doi.org/10.1007/s12613-012-0682-3
Abstract:
A NiTi shape memory alloy (SMA) modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy (AFM), Auger electron spectroscopy (AES), and grazing incidence X-ray diffraction (GIXRD) measurements were conducted to investigate the surface characteristics, including surface topography, elemental depth profiles, and surface phase structures. The surface roughness of the Ta-implanted NiTi increases after oxidation, and the higher the oxidation temperature is, the larger the value is. The surface of the Ta-implanted NiTi oxidized at 723 K is a nanolayer mainly composed of TiO2/Ta2O5 and TiO with depressed Ni content. The Ta-implanted NiTi oxidized at 873 K is mainly covered by rutile TiO2 in several micrometers of thickness. Potentiodynamic polarization tests indicated that the corrosion resistance of the Ta-implanted NiTi was improved after thermal oxidation at 723 K, but a negative impact was found for the Ta-implanted NiTi oxidized at 873 K.
A NiTi shape memory alloy (SMA) modified by Ta ion implantation was subjected to oxidation treatment in air at 723 and 873 K. Atomic force microscopy (AFM), Auger electron spectroscopy (AES), and grazing incidence X-ray diffraction (GIXRD) measurements were conducted to investigate the surface characteristics, including surface topography, elemental depth profiles, and surface phase structures. The surface roughness of the Ta-implanted NiTi increases after oxidation, and the higher the oxidation temperature is, the larger the value is. The surface of the Ta-implanted NiTi oxidized at 723 K is a nanolayer mainly composed of TiO2/Ta2O5 and TiO with depressed Ni content. The Ta-implanted NiTi oxidized at 873 K is mainly covered by rutile TiO2 in several micrometers of thickness. Potentiodynamic polarization tests indicated that the corrosion resistance of the Ta-implanted NiTi was improved after thermal oxidation at 723 K, but a negative impact was found for the Ta-implanted NiTi oxidized at 873 K.
2012, vol. 19, no. 12, pp.
1142-1148.
https://doi.org/10.1007/s12613-012-0683-2
Abstract:
A simple and new point contact tungsten trioxide (WO3) sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration (ppm level) environmental pollutants such as NO2. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were applied to characterize the phase and the microstructure of the samples, respectively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor (W-WO3-W) showed rectifying characteristics and an ideal sensing performance of about 110℃. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy (EIS) at a relatively low temperature of 150℃ but faded away above 200℃, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.
A simple and new point contact tungsten trioxide (WO3) sensor, which can be prepared by the oxidation of tungsten filaments via in-situ induction heating, likely detects low concentration (ppm level) environmental pollutants such as NO2. X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were applied to characterize the phase and the microstructure of the samples, respectively. It was found that the synthesized WO3 films exhibited a monoclinic phase and were composed of hierarchical microcrystals and nanocrystals. The point contact WO3 sensor (W-WO3-W) showed rectifying characteristics and an ideal sensing performance of about 110℃. A single semicircle in Nyquist plots was recorded by electrochemical impedance spectroscopy (EIS) at a relatively low temperature of 150℃ but faded away above 200℃, which revealed that the sensing process was governed by a determining factor, i.e., grain boundaries at the contact site.
2012, vol. 19, no. 12, pp.
1149-1153.
https://doi.org/10.1007/s12613-012-0684-1
Abstract:
Tungsten films growing on copper substrates were fabricated by metallorganic chemical vapor deposition (MOCVD). The chemical purity, crystallographic phase, cross-sectional texture, and resistivity of the deposited films both before and after annealing treatment were investigated by X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and four-point probe method. It is found that the films deposited at 460℃ are metastable β-W with (211) orientation and can change into α-W when annealed in high-purity hydrogen atmosphere at high temperature. There are small amounts of C and O in the films, and the W content of the films increases with increasing deposition temperature and also goes up after annealing in high-purity hydrogen atmosphere. The films have columnar microstructures and the texture evolution during their growth on copper substrates can be divided into three stages. The resistivity of the as-deposited films is in the range of 87-104 μΩ·cm, and low resistivity is obtained after annealing in high-purity hydrogen atmosphere.
Tungsten films growing on copper substrates were fabricated by metallorganic chemical vapor deposition (MOCVD). The chemical purity, crystallographic phase, cross-sectional texture, and resistivity of the deposited films both before and after annealing treatment were investigated by X-ray energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and four-point probe method. It is found that the films deposited at 460℃ are metastable β-W with (211) orientation and can change into α-W when annealed in high-purity hydrogen atmosphere at high temperature. There are small amounts of C and O in the films, and the W content of the films increases with increasing deposition temperature and also goes up after annealing in high-purity hydrogen atmosphere. The films have columnar microstructures and the texture evolution during their growth on copper substrates can be divided into three stages. The resistivity of the as-deposited films is in the range of 87-104 μΩ·cm, and low resistivity is obtained after annealing in high-purity hydrogen atmosphere.
2012, vol. 19, no. 12, pp.
1154-1161.
https://doi.org/10.1007/s12613-012-0685-0
Abstract:
Morphology- and size-controlled In(OH)3 nanocrystals were synthesized via a novel, low-cost and low-temperature (70℃) route in the absence of any template and surfactant. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED). The morphology and size of In(OH)3 nanostructures can be controlled by adjusting the reaction conditions such as the reaction time, the concentration of the alkali, and the alkaline source. A possible mechanism for the evolution of the morphology- and size-controlled In(OH)3 was proposed. In addition, the optical properties of the In(OH)3 prepared by this method were studied by diffuse reflection spectra (DRS) and photoluminescence (PL) spectroscopy, and the results exhibit an obvious change of adsorption edges. The thermal behaviors of the as-prepared products were also explored by thermo-gravimetric (TG) and differential scanning calorimetry (DSC) measurements. According to the results of TG-DSC, the pure phase and uniformity of the In2O3 nanocube and nanorod can be obtained by annealing In(OH)3 precursors directly at 300℃.
Morphology- and size-controlled In(OH)3 nanocrystals were synthesized via a novel, low-cost and low-temperature (70℃) route in the absence of any template and surfactant. The as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) with selected area electron diffraction (SAED). The morphology and size of In(OH)3 nanostructures can be controlled by adjusting the reaction conditions such as the reaction time, the concentration of the alkali, and the alkaline source. A possible mechanism for the evolution of the morphology- and size-controlled In(OH)3 was proposed. In addition, the optical properties of the In(OH)3 prepared by this method were studied by diffuse reflection spectra (DRS) and photoluminescence (PL) spectroscopy, and the results exhibit an obvious change of adsorption edges. The thermal behaviors of the as-prepared products were also explored by thermo-gravimetric (TG) and differential scanning calorimetry (DSC) measurements. According to the results of TG-DSC, the pure phase and uniformity of the In2O3 nanocube and nanorod can be obtained by annealing In(OH)3 precursors directly at 300℃.
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