The formation of titanite coronae after rutile is common in retrograde high-to ultrahigh-pressure meta-mafic rocks,which provides a good opportunity to address the geochemical behavior of HFSE in crustal environments....The formation of titanite coronae after rutile is common in retrograde high-to ultrahigh-pressure meta-mafic rocks,which provides a good opportunity to address the geochemical behavior of HFSE in crustal environments.In the Sumdo eclogite,titanite occurs either as a corona around rutile grains or as semi-continuous veins cross-cutting the major foliation,whereas rutile grains occur either as inclusions in garnet or omphacite or as a relict core surrounded by titanite.Textural relationships and trace elements characteristics of rutile and titanite with different occurrences indicate that both minerals preferentially incorporate Nb and Hf over Ta and Zr in aqueous fluid.Moreover,the breakdown of omphacite and epidote could release substantial amounts of aqueous fluids enriched in Ca,Si,Fe and REE,which would react with rutile to form titanite coronae and veins.During this process,water-insoluble elements,like HFSE and HREE,behave like mobile elements,but they do not migrate substantially out of the system,instead,tending to react in situ.This suggests that the aqueous fluids released during the retrograde metamorphic reactions in mafic rocks could not substantially transfer fluidimmobile elements into the overlying mantle wedge in subduction environments.展开更多
We report the discovery of TiO_(2)-Ⅱ in the unmelted rock of the shocked Suizhou L6 chondrite.Natural TiO_(2)-Ⅱ was previously found in ultrahigh-pressure metamorphic and mantle-derived rocks,terrestrial impact stru...We report the discovery of TiO_(2)-Ⅱ in the unmelted rock of the shocked Suizhou L6 chondrite.Natural TiO_(2)-Ⅱ was previously found in ultrahigh-pressure metamorphic and mantle-derived rocks,terrestrial impact structures,and tektite.Our microscopic,Raman spectroscopic,electron microprobe and transmission electron microscopic investigations have revealed:(1) All observed TiO_(2)-Ⅱ grains are related with ilmenite and pyrophanite;(2) TiO_(2)-Ⅱ occurs as needle-and leaf-shaped inclusions in llmenite and patch-,tape-shaped body in pyrophanite;(3)The composition of TiO_(2)-Ⅱ is identical with that of its precursor rutile;(4) The Raman spectrum of TiO_(2)-Ⅱ is in good agreement with that of natural and synthesized α-PbO_(2)-type TiO_(2);(5) TiO_(2)-Ⅱ occurs mainly in the form of well-ordered nano-domains and small mis-orientation among the domains can be observed.(6) All electron diffraction reflections from TiO_(2)-Ⅱ can be indexed to α-PbO_(2)structure in space group Pbcn with lattice parameters of a=4.481 ?,b=5.578 A and c=4.921 A;(7) The exsolution inclusions of rutile from host ilmenite are mostly connected with an alternation process along the lamellar twinning plane of ilmenite induced by shockinduced high pressure and high temperature;(8) The P-T regime of 20-25 GPa and 1000 ℃ estimated for the Suizhou unmelted rock is suitable for phase transition of rutile into TiO_(2)-Ⅱ phase.展开更多
Two non-destructive analytical techniques (gamma spectrometer and X-ray diffractometer) were employed in the analysis of bauxite and rutile ore and their vicinity soil and control sourced within the Kanam and Wase min...Two non-destructive analytical techniques (gamma spectrometer and X-ray diffractometer) were employed in the analysis of bauxite and rutile ore and their vicinity soil and control sourced within the Kanam and Wase mineral exploration sites. The activity concentrations of natural radionuclides <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K in the soil samples received from bauxite and rutile mineral mining vicinities revealed high concentrations of <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K compared to the control soil samples sourced 500 m away from the mineral exploration vicinities. Radiological detriments RLI, AUI, Hin and Hex unveiled values exceeding the radiation standard concentration (>1) for soil. X-ray diffraction characterization of bauxite ore revealed the interlocking minerals of Bauxite (18)%, Albite (11)%, Garnet (15)%, Illite (6)% and Muscovite (43)% in various proportions obtained within the 2θ range (9.18 to 64.4) and a peak value (intensity, cps) of 3400. Pure bauxite percentage in the ore meets metallurgical grade (15 - 25)%. X-ray diffraction of rutile ore revealed the minerals of rutile (40)%, quartz (21.4)%, ilmenite (27)% and garnet (11.8)% found within the 2θ range (27.5 to 35.6) and a peak value intensity of 31.1 - 100.0 cps also meeting the metallurgical grade of 15% - 25%. The major environmental concern associated with the mineral-sands industry is the radiation hazards, pollution of ground-water sources from heavy metals, mineral transport with heavy equipment’s, dredging operations in fragile coastal area and clearing of vegetation.展开更多
Rutile separation from calcite, apatite and quartz by flotation was investigated. The results show that the rutile separation from calcium and silicon gangue minerals can be realized with alkyl-imino-bismethylene phos...Rutile separation from calcite, apatite and quartz by flotation was investigated. The results show that the rutile separation from calcium and silicon gangue minerals can be realized with alkyl-imino-bismethylene phosphoric acid (TF112) as a collector and sodium hexametaphosphate (SH) as a regulator.展开更多
Rutile titania(TiO2)was successfully prepared via hydrolysis of TiCl4 in the presence of AlCl3.The powders were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Tell...Rutile titania(TiO2)was successfully prepared via hydrolysis of TiCl4 in the presence of AlCl3.The powders were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET)surface area analysis.In the present system,AlCl3 functions as a nucleating agent and induces the formation of rutile TiO2.The influences of HCl and isopropanol concentrations on the purity and morphology of the rutile TiO2 were investigated.The purity of the rutile TiO2 increased with increasing concentration of HCl.Evenly dispersed rutile TiO2 particles with a spherical morphology were obtained when the HCl and isopropanol concentrations were 0.5 and 1 mol·L-1,respectively.Furthermore,the prepared TiO2 powders were used in adsorption tests of the heavy metal pollutant Cr(Ⅵ).Rutile TiO2 sample S-9 demonstrated greater adsorption performance and a removal efficiency that was greater than 99.95%after60 min of adsorption when the Cr(Ⅵ)concentration was 200 mg·L-1.The maximum adsorption capacity on rutile TiO2 was 28.9 mg·g-1.This work provides an easy path to prepare a high-performance rutile TiO2 adsorbent with potential applications in water pollution treatment.展开更多
The emulsifiable conditions of composite collector (FP-2) in industry are systematically researched in the paper. It is found that tpyes of the emulsifiers, emulsification temperature, the mixed proportion of FP-2 to ...The emulsifiable conditions of composite collector (FP-2) in industry are systematically researched in the paper. It is found that tpyes of the emulsifiers, emulsification temperature, the mixed proportion of FP-2 to emulsifier are the important parameters affecting emulsification effect and rutile flotation targets. When the proportion of FP-2 to enudsifier (E-4) is 100, by means of emulsification of mechanical stirring, the rutile flotation recovery is 85.6% and the grade is 75.3% , which approach the flotation targets of FP-2 used as collector by ultrasonic emulsification unit. The favorable conditions are set up for FP-2 in industry application. By means of XPS measurement, the chemical interaction of composite collector with rutile is found.展开更多
This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substit...This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substituted by wollastonite, and an optimal substitution ratio was obtained. Analyses based on scanning electron microscope, powder X-ray diffraction, and Raman scattering measurements demonstrated that the addition of wollastonite caused nearly no change in the basic structure of the coating. Coating with a substitution ratio of 25% showed high thermal stability, good cover effect, considerable moisture-proof and water resistance ability, great acidic and basic resistance, and improved performance and hardness in performance tests. Furthermore, the production cost was reduced significantly at this substitution ratio.展开更多
Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection spectra.The results showed that...Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection spectra.The results showed that rutile titania formed at 70℃without calcination in air.Nanometer rutile TiO_2 had good crystalline and small particle size.The formation mechanism of rutile was also discussed.The photocatalytic activity of the prepared particles was tested for the degradation of methyl orange.The photocatalytic activity of rutile TiO_2 was higher than those obtained from Degussa P-25 TiO_2.The reasons for high photocatalytic activity of futile were discussed.展开更多
TiO2 coatings are of technical importance owing to their promising applications to photocatalytical, electrical, optical and tribological coatings. Thermal spraying process has been widely used to deposit both metalli...TiO2 coatings are of technical importance owing to their promising applications to photocatalytical, electrical, optical and tribological coatings. Thermal spraying process has been widely used to deposit both metallic and nonmetallic coatings. During thermal spraying, spray particle at fully or partially melted condition is projected to a substrate and subsequently flattens, rapidly cools and solidifies. Therefore, a coating in lamellar structure is usually formed as a quenched microstructure. TiO2 coatings were deposited on different substrates through plasma spraying with fused-crushed powder in rutile phase as feedstock to reveal the crystalline orientation in the coatings. XRD results show that the coatings consist of rutile phase with a fraction of anatase phase, and the rutile phase presents a preferable crystalline orientation along [101] direction. It is found that the orientation factors of rutile phase in the thin coatings are significantly influenced by substrate materials. The thick coatings yield the same orientation factors of 0.22 to 0.23 on all substrates in spite of substrate materials. It is considered that the thermal properties of substrate materials are the dominant factors for the preferable crystalline orientation in rutile phase within plasmasprayed TiO2 coating.展开更多
The laser ablation technique was employed to prepare TiO2 nanoparticles by pulsed laser ablation of a titanium target immersed in the poly-(vinylpyrrolidone) solution using wavelength of 1 064 nm. The as-prepared prod...The laser ablation technique was employed to prepare TiO2 nanoparticles by pulsed laser ablation of a titanium target immersed in the poly-(vinylpyrrolidone) solution using wavelength of 1 064 nm. The as-prepared products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the rutile TiO2 nanoparticles are synthesized at room temperature and the average size is about 35 nm with narrow size distribution. A possible formation mechanism was discussed and the UV-vis absorption and photoluminescence were measured. The optical study shows that rutile nanoparticle possesses direct optical transition with band gap of 3.15 eV.展开更多
Rutile phase exhibits higher refractive index and h id ing power, good chemical stability, and is becoming a candidate material for the high-temperature separation and catalysis applications. The thermodynamically sta...Rutile phase exhibits higher refractive index and h id ing power, good chemical stability, and is becoming a candidate material for the high-temperature separation and catalysis applications. The thermodynamically stable feature of rutile among the three polymorphs of TiO 2 usually hinders ob taining nano-sized rutile phase by a conventional calcining way. However, acid peptization of amorphous TiO 2 is favorable to the formation of rutile phase. I n this work, well-crystallized and well-dispersed rod-like rutile particles w ith specific surface areas of 49.1 and 35.0 m 2/g were prepared by hydrothermal ly treating the acid peptized TiO 2 amorphous sols at relatively low temperatur es of 200 ℃ or 240 ℃, respectively. The formation of non-touching rutile part icles is attributed to high long-range electrostatic forces between particles i n the presence of the high concentration of the peptizer. The acid peptization w ould easily break the ≡Ti-O-Ti≡ bonds to form ≡Ti-OH or HO-Ti-OH species depending on the amount of acid, and create conditions for the formation of rut ile nuclei after structural rearrangements.展开更多
Titanium oxide (rutile, TiO2) and zircon (ZrSiO4), known insoluble ceramic materials, are commonly used for coatings of implant materials. We investigate the release of zirconium, titanium, aluminum, iron, and silicon...Titanium oxide (rutile, TiO2) and zircon (ZrSiO4), known insoluble ceramic materials, are commonly used for coatings of implant materials. We investigate the release of zirconium, titanium, aluminum, iron, and silicon from different micron-sized powders of 6 powders of natural rutile (TiO2) and zircon (ZrSiO4) from a surface perspective. The investigation includes five different synthetic body fluids and two time periods of exposure, 2 and 24 hours. The solution chemicals rather than pH are important for the release of zirconium. When exceeding a critical amount of aluminum and silicon in the surface oxide, the particles seem to be protected from selective pH-specific release at neutral or weakly alkaline pH. The importance of bulk and surface composition and individual changes between different kinds of the same material is elucidated. Changes in material properties and metal release characteristics with particle size are presented for zircon.展开更多
A green, rapid and facile method for synthesis of pure rutile TiO2 has been developed. Rutile TiO2 of high purity was synthesized by controlled hydrolysis of TiCl3 in aqueous medium at room temperature. Addition of ni...A green, rapid and facile method for synthesis of pure rutile TiO2 has been developed. Rutile TiO2 of high purity was synthesized by controlled hydrolysis of TiCl3 in aqueous medium at room temperature. Addition of nitric acid to TiCl3 greatly increased the rate of TiCl3 hydrolysis, crystallization and surface area of the prepared TiO2 powder. The phase obtained in this way was identified by X-ray diffraction. TiO2 synthesized by this method showed a unique flower-like assembly of nanotubes, very high surface area and high photocatalytic activity under visible light irradiation.展开更多
This study was carried out to investigate the interaction of oxalic acid with hydrochloric acid to attain the better performance for iron dissolution in comparison to absence of oxalic acid. The effects of oxalic acid...This study was carried out to investigate the interaction of oxalic acid with hydrochloric acid to attain the better performance for iron dissolution in comparison to absence of oxalic acid. The effects of oxalic acid on ratio of hydrochloric acid, acid concentration, ratio of liquid to solid, temperature and dissolution time are investigated for the dissolution of Fe and Ti from ilmenite to produce synthetic rutile. The DX7 software basing on an experimental design method with the central composite of response surface design is applied to specify the effects of the parameters and to optimize the leaching process. The optimum condition was determined by analysis of variance (ANOVA), indicating that the ratio of oxalic acid to hydrochloric acid for Fe dissolution and acid concentration for Ti dissolution were the most effective parameters. The results showed that the dissolution of Fe and Ti in 30% (w/w) hydrochloric acid solution was only 48.65% and 5.14%, respectively, while at the same condition and in the presence of oxalic acid with twice the ratio, these values are increased to 78.65% and 12.06%, respectively. The optimum values of parameters were as follows: oxalic acid to hydrochloric acid ratio (2:1), acid concentration (30%), ratio of liquid to solid (10), temperature (160 °C), and dissolution time (3 h). By applying the optimized parameters, Fe and Ti dissolution of 97.15% and 2.8% were predicted by the software with a desirability of 0.745. The results of leaching tests indicated that the Fe and Ti dissolution of 97.58% and 2.43%, were achieved, respectively, which are very close to the predicted value.展开更多
Two pure hexagonal phases of titanium dioxide, anatase and rutile, were grown on c-cut Al2O3 substrates via pulsed-laser deposition by changing only the growth and annealing conditions, but without changing the substr...Two pure hexagonal phases of titanium dioxide, anatase and rutile, were grown on c-cut Al2O3 substrates via pulsed-laser deposition by changing only the growth and annealing conditions, but without changing the substrate, target, or working gas. Purity of each phase was confirmed by x-ray diffraction, the quality of each film was studied using atomic force microscopy and scanning electron microscopy, and the interface between each substrate and film was studied using x-ray photoelectron spectroscopy. A binding layer of Ti2O3 was found to explain anatase growth under the very large lattice mismatch conditions.展开更多
The Otele, Matomb and Nguibassal localities correspond to the SW part of th<span style="font-family:;" "=""><span style="font-family:Verdana;">e Yaoundé Group. Field...The Otele, Matomb and Nguibassal localities correspond to the SW part of th<span style="font-family:;" "=""><span style="font-family:Verdana;">e Yaoundé Group. Field observations, rocks and stream sediments of the study </span><span style="font-family:Verdana;">area were examined using rock tin sections, granulometric, morphoscopic an</span><span style="font-family:Verdana;">d </span><span style="font-family:Verdana;">X-ray fluorescence analysis to identify their distribution, the nature of the ba</span><span style="font-family:Verdana;">se</span><span style="font-family:Verdana;">ment, provenance useful minerals and some weathering process that affect th</span><span style="font-family:Verdana;">em to show the exploration significance of these outcomes. From these it appears that, three rocks types occur in the areas: gneisses, micaschists and amphibolite, respectively with the following minerals assemblage: (Fks + Bt + Qz + Ky + Pl + Msc + Grt + Op), (Bt + Qz + Msc + Fks + Op + Ky + Grt) and (Amp + Bt + Pl + Kfs + Qz + Px + Grt + Op). Sedimentological analyses reveal the dominance of unworn grains of rutile quartz and kyanite that suggest a short </span><span style="font-family:Verdana;">transport;while less abundant minor shiny dulls and sub-rounded grains su</span><span style="font-family:Verdana;">g</span><span style="font-family:Verdana;">gest a long transport. Sediments collected are homometric, well sorted, well cla</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;">sified, with immature rutile due to their angular shapes. Silica is the most im</span><span style="font-family:Verdana;">port</span><span style="font-family:Verdana;">ant major element ranging in concentration between 47</span><span style="font-family:Verdana;">.56 wt% SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> in amphibolite to 61.21 wt% SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> in gneiss. Stream sediments chemistry equally </span><span style="font-family:Verdana;">showed that silica and alumina are the remarkable elements with values of 53.</span><span style="font-family:Verdana;">92 wt% and 13.33 wt% respectively with important increase of TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> ranging between 51.77 and 95.03</span></span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">wt%. The TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> percentage met in minerals of the global fraction and rutile concentrate come from the same minerals in the rock, </span><span style="font-family:Verdana;">and percentage increases when linked to heavy minerals observation sugg</span><span style="font-family:Verdana;">ested the Ti percentage to mainly come from rutile. Impurities present in the rutile </span><span style="font-family:Verdana;">lattice include: V, Nb, Ta, Cr and CaO. Rutile </span></span><span style="font-family:Verdana;">was </span><span style="font-family:Verdana;">found </span><span style="font-family:Verdana;">to </span><span style="font-family:Verdana;">come from the sa</span><span style="font-family:Verdana;">me area but with several source rocks (Felsic and mafic). High Nb contents (277</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">- 768.33 ppm) as compared to Cr (394</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">- 444.33 ppm) associated to the elevated </span><span style="font-family:Verdana;">ratio of LREE/HREE coupled to the negative Eu anomalies in rocks and sedi</span><span style="font-family:Verdana;">ment</span><span style="font-family:Verdana;">s of the study area are indicative of felsic source material. Moreover, </span><span style="font-family:Verdana;">enrichment in Cr as compared to Nb at Nguibassal suggested rutile to originate from mafic rocks.</span></span>展开更多
In this work, structural and optical properties of the TiO2 films deposited on unheated substrates by dual cathode dc unbalanced magnetron sputtering at long substrate-target distance (ds-t) were studied. Titanium dio...In this work, structural and optical properties of the TiO2 films deposited on unheated substrates by dual cathode dc unbalanced magnetron sputtering at long substrate-target distance (ds-t) were studied. Titanium dioxide (TiO2) thin films were deposited on unheated Si (110) wafers, glass slides and carbon coated copper grids at different substrate to target (ds-t) distances. The structural properties of TiO2 thin films were characterized by X-ray diffraction (XRD) and transmission electron microcopy (TEM) with selected-area electron diffraction (SAED), surface morphology using atomic force microscopy (AFM) and optical transmission spectra using a spectrophotometer. XRD results show that TiO2 films deposited at various ds-t distances have only rutile crystal structure. The crystallinity and thickness of the films increased while the roughness decreased with decreasing ds-t distance. The refractive indices of the deposited films were found to be in the range of 2.51 - 2.82 and increased with decreasing ds-t distance.展开更多
Combustion characteristics of three-tube burner in growth chamber for preparation of single crystal by the Verneuil method were investigated,and the effects of nozzle structure and flow rate on the surface temperature...Combustion characteristics of three-tube burner in growth chamber for preparation of single crystal by the Verneuil method were investigated,and the effects of nozzle structure and flow rate on the surface temperature of molten cap were analyzed.The results showed that hydrogen flowed out from the nozzle diffused with inner and outer oxygen,and two flame produced in the center and near the wall of growth chamber.The surface temperature of molten cap were gradually reduced from the center outward.The temperature of molten cap decreased gradually with increasing the nozzle aperture of inner oxygen,and varied slightly with the diameter of hydrogen and outer oxygen nozzle.The temperature of molten cap decreased gradually with increasing the flow rate of inner and outer oxygen,while increased with the flow rate of hydrogen.展开更多
基金supported by the National Science Foundation of China(Grant Nos.92055202)the Second Tibetan Plateau Scientific Expedition and Research(Grant No.2019QZKK0702)the China Geological Survey(Grant Nos.DD20221817 and DD20221630)。
文摘The formation of titanite coronae after rutile is common in retrograde high-to ultrahigh-pressure meta-mafic rocks,which provides a good opportunity to address the geochemical behavior of HFSE in crustal environments.In the Sumdo eclogite,titanite occurs either as a corona around rutile grains or as semi-continuous veins cross-cutting the major foliation,whereas rutile grains occur either as inclusions in garnet or omphacite or as a relict core surrounded by titanite.Textural relationships and trace elements characteristics of rutile and titanite with different occurrences indicate that both minerals preferentially incorporate Nb and Hf over Ta and Zr in aqueous fluid.Moreover,the breakdown of omphacite and epidote could release substantial amounts of aqueous fluids enriched in Ca,Si,Fe and REE,which would react with rutile to form titanite coronae and veins.During this process,water-insoluble elements,like HFSE and HREE,behave like mobile elements,but they do not migrate substantially out of the system,instead,tending to react in situ.This suggests that the aqueous fluids released during the retrograde metamorphic reactions in mafic rocks could not substantially transfer fluidimmobile elements into the overlying mantle wedge in subduction environments.
文摘We report the discovery of TiO_(2)-Ⅱ in the unmelted rock of the shocked Suizhou L6 chondrite.Natural TiO_(2)-Ⅱ was previously found in ultrahigh-pressure metamorphic and mantle-derived rocks,terrestrial impact structures,and tektite.Our microscopic,Raman spectroscopic,electron microprobe and transmission electron microscopic investigations have revealed:(1) All observed TiO_(2)-Ⅱ grains are related with ilmenite and pyrophanite;(2) TiO_(2)-Ⅱ occurs as needle-and leaf-shaped inclusions in llmenite and patch-,tape-shaped body in pyrophanite;(3)The composition of TiO_(2)-Ⅱ is identical with that of its precursor rutile;(4) The Raman spectrum of TiO_(2)-Ⅱ is in good agreement with that of natural and synthesized α-PbO_(2)-type TiO_(2);(5) TiO_(2)-Ⅱ occurs mainly in the form of well-ordered nano-domains and small mis-orientation among the domains can be observed.(6) All electron diffraction reflections from TiO_(2)-Ⅱ can be indexed to α-PbO_(2)structure in space group Pbcn with lattice parameters of a=4.481 ?,b=5.578 A and c=4.921 A;(7) The exsolution inclusions of rutile from host ilmenite are mostly connected with an alternation process along the lamellar twinning plane of ilmenite induced by shockinduced high pressure and high temperature;(8) The P-T regime of 20-25 GPa and 1000 ℃ estimated for the Suizhou unmelted rock is suitable for phase transition of rutile into TiO_(2)-Ⅱ phase.
文摘Two non-destructive analytical techniques (gamma spectrometer and X-ray diffractometer) were employed in the analysis of bauxite and rutile ore and their vicinity soil and control sourced within the Kanam and Wase mineral exploration sites. The activity concentrations of natural radionuclides <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K in the soil samples received from bauxite and rutile mineral mining vicinities revealed high concentrations of <sup>238</sup>U, <sup>232</sup>Th, and <sup>40</sup>K compared to the control soil samples sourced 500 m away from the mineral exploration vicinities. Radiological detriments RLI, AUI, Hin and Hex unveiled values exceeding the radiation standard concentration (>1) for soil. X-ray diffraction characterization of bauxite ore revealed the interlocking minerals of Bauxite (18)%, Albite (11)%, Garnet (15)%, Illite (6)% and Muscovite (43)% in various proportions obtained within the 2θ range (9.18 to 64.4) and a peak value (intensity, cps) of 3400. Pure bauxite percentage in the ore meets metallurgical grade (15 - 25)%. X-ray diffraction of rutile ore revealed the minerals of rutile (40)%, quartz (21.4)%, ilmenite (27)% and garnet (11.8)% found within the 2θ range (27.5 to 35.6) and a peak value intensity of 31.1 - 100.0 cps also meeting the metallurgical grade of 15% - 25%. The major environmental concern associated with the mineral-sands industry is the radiation hazards, pollution of ground-water sources from heavy metals, mineral transport with heavy equipment’s, dredging operations in fragile coastal area and clearing of vegetation.
文摘Rutile separation from calcite, apatite and quartz by flotation was investigated. The results show that the rutile separation from calcium and silicon gangue minerals can be realized with alkyl-imino-bismethylene phosphoric acid (TF112) as a collector and sodium hexametaphosphate (SH) as a regulator.
基金financially supported by the National Natural Science Foundation of China(Nos.51734002 and51774027)。
文摘Rutile titania(TiO2)was successfully prepared via hydrolysis of TiCl4 in the presence of AlCl3.The powders were characterized by X-ray powder diffraction(XRD),scanning electron microscopy(SEM),and Brunauer-Emmett-Teller(BET)surface area analysis.In the present system,AlCl3 functions as a nucleating agent and induces the formation of rutile TiO2.The influences of HCl and isopropanol concentrations on the purity and morphology of the rutile TiO2 were investigated.The purity of the rutile TiO2 increased with increasing concentration of HCl.Evenly dispersed rutile TiO2 particles with a spherical morphology were obtained when the HCl and isopropanol concentrations were 0.5 and 1 mol·L-1,respectively.Furthermore,the prepared TiO2 powders were used in adsorption tests of the heavy metal pollutant Cr(Ⅵ).Rutile TiO2 sample S-9 demonstrated greater adsorption performance and a removal efficiency that was greater than 99.95%after60 min of adsorption when the Cr(Ⅵ)concentration was 200 mg·L-1.The maximum adsorption capacity on rutile TiO2 was 28.9 mg·g-1.This work provides an easy path to prepare a high-performance rutile TiO2 adsorbent with potential applications in water pollution treatment.
基金Funded by Hubei Natural Science Foundation (No. 99J118).
文摘The emulsifiable conditions of composite collector (FP-2) in industry are systematically researched in the paper. It is found that tpyes of the emulsifiers, emulsification temperature, the mixed proportion of FP-2 to emulsifier are the important parameters affecting emulsification effect and rutile flotation targets. When the proportion of FP-2 to enudsifier (E-4) is 100, by means of emulsification of mechanical stirring, the rutile flotation recovery is 85.6% and the grade is 75.3% , which approach the flotation targets of FP-2 used as collector by ultrasonic emulsification unit. The favorable conditions are set up for FP-2 in industry application. By means of XPS measurement, the chemical interaction of composite collector with rutile is found.
文摘This study aims to prepare a composite polyurethane coating through a facile synthesis process. Titanium dioxide, which is a component of the prepared hydroxyl acrylic resin polyurethane varnish, was partially substituted by wollastonite, and an optimal substitution ratio was obtained. Analyses based on scanning electron microscope, powder X-ray diffraction, and Raman scattering measurements demonstrated that the addition of wollastonite caused nearly no change in the basic structure of the coating. Coating with a substitution ratio of 25% showed high thermal stability, good cover effect, considerable moisture-proof and water resistance ability, great acidic and basic resistance, and improved performance and hardness in performance tests. Furthermore, the production cost was reduced significantly at this substitution ratio.
基金The present research was supported by the High Technology and Development Project of the China (Grant:2003AA302320)National Natural Science Foundation of China (Grant:50021009)Basic Research Foundation of Tsinghua University (JC200206).
文摘Nanocrystalline titania was prepared by the homogeneous-precipitation method at temperature lower than 120℃. The properties of powders were identified by XRD,TEM and diffuse reflection spectra.The results showed that rutile titania formed at 70℃without calcination in air.Nanometer rutile TiO_2 had good crystalline and small particle size.The formation mechanism of rutile was also discussed.The photocatalytic activity of the prepared particles was tested for the degradation of methyl orange.The photocatalytic activity of rutile TiO_2 was higher than those obtained from Degussa P-25 TiO_2.The reasons for high photocatalytic activity of futile were discussed.
基金Project supported by the Natural Science Foundation of Xi'an Jiaotong University, China
文摘TiO2 coatings are of technical importance owing to their promising applications to photocatalytical, electrical, optical and tribological coatings. Thermal spraying process has been widely used to deposit both metallic and nonmetallic coatings. During thermal spraying, spray particle at fully or partially melted condition is projected to a substrate and subsequently flattens, rapidly cools and solidifies. Therefore, a coating in lamellar structure is usually formed as a quenched microstructure. TiO2 coatings were deposited on different substrates through plasma spraying with fused-crushed powder in rutile phase as feedstock to reveal the crystalline orientation in the coatings. XRD results show that the coatings consist of rutile phase with a fraction of anatase phase, and the rutile phase presents a preferable crystalline orientation along [101] direction. It is found that the orientation factors of rutile phase in the thin coatings are significantly influenced by substrate materials. The thick coatings yield the same orientation factors of 0.22 to 0.23 on all substrates in spite of substrate materials. It is considered that the thermal properties of substrate materials are the dominant factors for the preferable crystalline orientation in rutile phase within plasmasprayed TiO2 coating.
基金Project(09R23) supported by the Scientific Research Starting Foundation of Nantong UniversityProjects(50671100, 10604055) supported by the National Natural Science Foundation of China
文摘The laser ablation technique was employed to prepare TiO2 nanoparticles by pulsed laser ablation of a titanium target immersed in the poly-(vinylpyrrolidone) solution using wavelength of 1 064 nm. The as-prepared products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results indicate that the rutile TiO2 nanoparticles are synthesized at room temperature and the average size is about 35 nm with narrow size distribution. A possible formation mechanism was discussed and the UV-vis absorption and photoluminescence were measured. The optical study shows that rutile nanoparticle possesses direct optical transition with band gap of 3.15 eV.
文摘Rutile phase exhibits higher refractive index and h id ing power, good chemical stability, and is becoming a candidate material for the high-temperature separation and catalysis applications. The thermodynamically stable feature of rutile among the three polymorphs of TiO 2 usually hinders ob taining nano-sized rutile phase by a conventional calcining way. However, acid peptization of amorphous TiO 2 is favorable to the formation of rutile phase. I n this work, well-crystallized and well-dispersed rod-like rutile particles w ith specific surface areas of 49.1 and 35.0 m 2/g were prepared by hydrothermal ly treating the acid peptized TiO 2 amorphous sols at relatively low temperatur es of 200 ℃ or 240 ℃, respectively. The formation of non-touching rutile part icles is attributed to high long-range electrostatic forces between particles i n the presence of the high concentration of the peptizer. The acid peptization w ould easily break the ≡Ti-O-Ti≡ bonds to form ≡Ti-OH or HO-Ti-OH species depending on the amount of acid, and create conditions for the formation of rut ile nuclei after structural rearrangements.
文摘Titanium oxide (rutile, TiO2) and zircon (ZrSiO4), known insoluble ceramic materials, are commonly used for coatings of implant materials. We investigate the release of zirconium, titanium, aluminum, iron, and silicon from different micron-sized powders of 6 powders of natural rutile (TiO2) and zircon (ZrSiO4) from a surface perspective. The investigation includes five different synthetic body fluids and two time periods of exposure, 2 and 24 hours. The solution chemicals rather than pH are important for the release of zirconium. When exceeding a critical amount of aluminum and silicon in the surface oxide, the particles seem to be protected from selective pH-specific release at neutral or weakly alkaline pH. The importance of bulk and surface composition and individual changes between different kinds of the same material is elucidated. Changes in material properties and metal release characteristics with particle size are presented for zircon.
文摘A green, rapid and facile method for synthesis of pure rutile TiO2 has been developed. Rutile TiO2 of high purity was synthesized by controlled hydrolysis of TiCl3 in aqueous medium at room temperature. Addition of nitric acid to TiCl3 greatly increased the rate of TiCl3 hydrolysis, crystallization and surface area of the prepared TiO2 powder. The phase obtained in this way was identified by X-ray diffraction. TiO2 synthesized by this method showed a unique flower-like assembly of nanotubes, very high surface area and high photocatalytic activity under visible light irradiation.
文摘This study was carried out to investigate the interaction of oxalic acid with hydrochloric acid to attain the better performance for iron dissolution in comparison to absence of oxalic acid. The effects of oxalic acid on ratio of hydrochloric acid, acid concentration, ratio of liquid to solid, temperature and dissolution time are investigated for the dissolution of Fe and Ti from ilmenite to produce synthetic rutile. The DX7 software basing on an experimental design method with the central composite of response surface design is applied to specify the effects of the parameters and to optimize the leaching process. The optimum condition was determined by analysis of variance (ANOVA), indicating that the ratio of oxalic acid to hydrochloric acid for Fe dissolution and acid concentration for Ti dissolution were the most effective parameters. The results showed that the dissolution of Fe and Ti in 30% (w/w) hydrochloric acid solution was only 48.65% and 5.14%, respectively, while at the same condition and in the presence of oxalic acid with twice the ratio, these values are increased to 78.65% and 12.06%, respectively. The optimum values of parameters were as follows: oxalic acid to hydrochloric acid ratio (2:1), acid concentration (30%), ratio of liquid to solid (10), temperature (160 °C), and dissolution time (3 h). By applying the optimized parameters, Fe and Ti dissolution of 97.15% and 2.8% were predicted by the software with a desirability of 0.745. The results of leaching tests indicated that the Fe and Ti dissolution of 97.58% and 2.43%, were achieved, respectively, which are very close to the predicted value.
文摘Two pure hexagonal phases of titanium dioxide, anatase and rutile, were grown on c-cut Al2O3 substrates via pulsed-laser deposition by changing only the growth and annealing conditions, but without changing the substrate, target, or working gas. Purity of each phase was confirmed by x-ray diffraction, the quality of each film was studied using atomic force microscopy and scanning electron microscopy, and the interface between each substrate and film was studied using x-ray photoelectron spectroscopy. A binding layer of Ti2O3 was found to explain anatase growth under the very large lattice mismatch conditions.
文摘The Otele, Matomb and Nguibassal localities correspond to the SW part of th<span style="font-family:;" "=""><span style="font-family:Verdana;">e Yaoundé Group. Field observations, rocks and stream sediments of the study </span><span style="font-family:Verdana;">area were examined using rock tin sections, granulometric, morphoscopic an</span><span style="font-family:Verdana;">d </span><span style="font-family:Verdana;">X-ray fluorescence analysis to identify their distribution, the nature of the ba</span><span style="font-family:Verdana;">se</span><span style="font-family:Verdana;">ment, provenance useful minerals and some weathering process that affect th</span><span style="font-family:Verdana;">em to show the exploration significance of these outcomes. From these it appears that, three rocks types occur in the areas: gneisses, micaschists and amphibolite, respectively with the following minerals assemblage: (Fks + Bt + Qz + Ky + Pl + Msc + Grt + Op), (Bt + Qz + Msc + Fks + Op + Ky + Grt) and (Amp + Bt + Pl + Kfs + Qz + Px + Grt + Op). Sedimentological analyses reveal the dominance of unworn grains of rutile quartz and kyanite that suggest a short </span><span style="font-family:Verdana;">transport;while less abundant minor shiny dulls and sub-rounded grains su</span><span style="font-family:Verdana;">g</span><span style="font-family:Verdana;">gest a long transport. Sediments collected are homometric, well sorted, well cla</span><span style="font-family:Verdana;">s</span><span style="font-family:Verdana;">sified, with immature rutile due to their angular shapes. Silica is the most im</span><span style="font-family:Verdana;">port</span><span style="font-family:Verdana;">ant major element ranging in concentration between 47</span><span style="font-family:Verdana;">.56 wt% SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> in amphibolite to 61.21 wt% SiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> in gneiss. Stream sediments chemistry equally </span><span style="font-family:Verdana;">showed that silica and alumina are the remarkable elements with values of 53.</span><span style="font-family:Verdana;">92 wt% and 13.33 wt% respectively with important increase of TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> ranging between 51.77 and 95.03</span></span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">wt%. The TiO</span><sub><span style="font-family:Verdana;">2</span></sub><span style="font-family:Verdana;"> percentage met in minerals of the global fraction and rutile concentrate come from the same minerals in the rock, </span><span style="font-family:Verdana;">and percentage increases when linked to heavy minerals observation sugg</span><span style="font-family:Verdana;">ested the Ti percentage to mainly come from rutile. Impurities present in the rutile </span><span style="font-family:Verdana;">lattice include: V, Nb, Ta, Cr and CaO. Rutile </span></span><span style="font-family:Verdana;">was </span><span style="font-family:Verdana;">found </span><span style="font-family:Verdana;">to </span><span style="font-family:Verdana;">come from the sa</span><span style="font-family:Verdana;">me area but with several source rocks (Felsic and mafic). High Nb contents (277</span><span style="font-family:;" "=""> </span><span style="font-family:Verdana;">- 768.33 ppm) as compared to Cr (394</span><span style="font-family:;" "=""> </span><span style="font-family:;" "=""><span style="font-family:Verdana;">- 444.33 ppm) associated to the elevated </span><span style="font-family:Verdana;">ratio of LREE/HREE coupled to the negative Eu anomalies in rocks and sedi</span><span style="font-family:Verdana;">ment</span><span style="font-family:Verdana;">s of the study area are indicative of felsic source material. Moreover, </span><span style="font-family:Verdana;">enrichment in Cr as compared to Nb at Nguibassal suggested rutile to originate from mafic rocks.</span></span>
文摘In this work, structural and optical properties of the TiO2 films deposited on unheated substrates by dual cathode dc unbalanced magnetron sputtering at long substrate-target distance (ds-t) were studied. Titanium dioxide (TiO2) thin films were deposited on unheated Si (110) wafers, glass slides and carbon coated copper grids at different substrate to target (ds-t) distances. The structural properties of TiO2 thin films were characterized by X-ray diffraction (XRD) and transmission electron microcopy (TEM) with selected-area electron diffraction (SAED), surface morphology using atomic force microscopy (AFM) and optical transmission spectra using a spectrophotometer. XRD results show that TiO2 films deposited at various ds-t distances have only rutile crystal structure. The crystallinity and thickness of the films increased while the roughness decreased with decreasing ds-t distance. The refractive indices of the deposited films were found to be in the range of 2.51 - 2.82 and increased with decreasing ds-t distance.
基金This work was supported by the Projects of National Natural Science Foundation of China,No.51872033 and No.51732007by the Project of Dalian Natural Science Foundation,No.2019J12GX044by the Project of Natural Science Foundation of Liaoning Province,No.2019-ZD-0572.
文摘Combustion characteristics of three-tube burner in growth chamber for preparation of single crystal by the Verneuil method were investigated,and the effects of nozzle structure and flow rate on the surface temperature of molten cap were analyzed.The results showed that hydrogen flowed out from the nozzle diffused with inner and outer oxygen,and two flame produced in the center and near the wall of growth chamber.The surface temperature of molten cap were gradually reduced from the center outward.The temperature of molten cap decreased gradually with increasing the nozzle aperture of inner oxygen,and varied slightly with the diameter of hydrogen and outer oxygen nozzle.The temperature of molten cap decreased gradually with increasing the flow rate of inner and outer oxygen,while increased with the flow rate of hydrogen.