Segregation in Titanium Dioxide Co‐Doped with Indium and Niobium

This work reports the effect of oxygen activity on surface segregation for TiO₂ co‐doped with two cations, indium and niobium (0.076 at.% In + 0.103 at.% Nb). In this work, we studied the effect of annealing at 1273 K in the gas phase of controlled oxygen activity on surface segregation of both ions. The applied oxygen activity included pure oxygen, p(O₂) = 100 kPa, and argon, p(O₂) = 10 Pa. The segregation‐induced concentration gradients were determined using both secondary ion mass spectrometry and X‐ray photoelectron spectroscopy. The obtained results indicate that annealing of the studied TiO₂ specimens in argon results in cooperative segregation of both ions leading to the formation of a surface structure involving comparative concentrations of both cations. However, annealing in oxygen results in preferential segregation of indium leading to the formation of a In₂TiO₅‐type surface structure. The obtained results are considered in terms of the effect of multicomponent segregation on processing of the surface layer with controlled properties that are desired for specific applications. The present work indicates that oxygen activity may be used as the parameter in surface engineering of the solid solution.     

氯化法钛白综述

钛白粉生产工艺有硫酸法和氯化法两种,氯化法钛白粉生产比硫酸法生产流程短、工序少、可采用连续化生产,产品质量好,三废排放量少,因此氯化法钛白粉生产发展迅速.本文详细分析了国外和国内氯化钛白的发展分析历程和不同技术路径发展情况,并介绍了氯化钛白不同结构沸腾氯化炉的优缺点,以及氧化工序中三氯化铝发生装置,氧化系统防疤、除疤技...     

Tantalum Enrichment in Tantalum‐Doped Titanium Dioxide

This investigation has assessed the behavior of Ta enrichment in Ta‐doped TiO₂ under various conditions of controlled oxygen activity and temperature. The aim has been to establish the relationships between specific processing conditions and the resulting compositional variation within the surface and near‐surface region. Under the application of oxidizing conditions [p(O₂) = 101 kPa], it has been observed that Ta will strongly enrich the surface of Ta‐doped TiO₂ irrespective of the annealing temperature (over the range of 1173–1523 K). However, under reducing conditions [p(O₂) in the vicinity of 10^?10 Pa], Ta enrichment is observed at 1173 K, but Ta depletion from the surface and near‐surface is observed at 1348 and 1523 K. This is attributed to an apparent lack of stability of the surface phase, which could possibly be TiTa₂O₇. The results for the investigation contribute to the engineering of TiO₂‐based photoelectrode materials that possess improved charge separation properties.     

色母粒用钛白粉的表面有机改性及表征

研究了在水溶液中,采用超分散剂TO对色母粒用钛白粉进行表面处理,使用电镜、红外、毛细管等简单方法对钛白粉的亲油性、分散性进行表征。结果表明,钛白粉颗粒表面由亲水性变为亲油性,用于制备白母粒,其分散性能大大提高,遮盖力比未处理的提高了近2.5倍;加工性能也大大提高,最大转矩和平衡转矩减小近2.45N·m。     

二氧化钛纳米粒子的表面修饰及表征

本文利用溶胶-凝胶法制备了6-氨基己酸修饰的TiO2纳米粒子,并对所得产物进行FT-IR、UVVis、XRD和TEM表征,结果证明所得产物表面包覆有有机层,产物的粒径范围为50～60nm,颗粒形状为球形,品型主要为锐钛矿型。在醇溶胶中,产物对紫外光的吸收性能大大提高。     

T_iO_2的表面处理及其在PP中的分散行为

选用硅烷偶联剂KH–570对TiO_2进行表面处理,并采用热失重分析、红外光谱分析、两相沉降测试、接触角测试等对其进行表征。结果表明,KH–570改性使纳米TiO_2由亲水性变为亲油性,在溶剂中有较好的分散稳定性,并且接触角提高到107°。将改性后TiO_2与聚丙烯(PP)基体通过熔融共混制成复合膜,并采用扫描电子显微镜、差示扫描量热法进行分析。结果表明,未改性TiO_2存在较大的团聚,而改性后的TiO_2在PP中分散比较均匀,说明表面处理提高了TiO_2与PP的相容性。此外纳米TiO_2的添加对结晶和熔融行为影响不大。     

二氧化钛粉体的表面改性研究

针对二氧化钛和二氧化硅粉体的表面改性,研究了不同偶联剂种类、偶联剂含量和不同水解环境下粉体的改性效果.实验结果显示,对于不同种类偶联剂KH550、KH560、KH570改性二氧化钛,KH570改性的二氧化钛沉降体积最大,亲油化度也最大,改性效果较好.在中性预水解条件下偶联剂对二氧化钛粉体的改性效果均优于酸性和碱性条件....     

氯化法钛白粉表面处理影响因素研究

结合氯化法钛白粉性能要求,介绍了钛白粉无机表面处理的机理及工艺,分析了二氧化钛浆料的分散性、pH值、包膜处理剂的加入量及加入顺序、反应温度、反应速度和时间对钛白粉包膜的影响,提出了一种硅-铝二元包膜方法技术。结果表明此技术包膜均匀,得到的产品白度大于93.7%,消色力110~113之间,耐候性良好。     

Space Charge Segregation at Grain Boundaries in Titanium Dioxide: II, Model Experiments

A quantitative study of space charge solute segregation at grain boundaries in TiO₂ is conducted, using a new STEM method for the measurement of aliovalent solute accumulation. It is shown that the electrostatic potential at grain boundaries can be varied in sign and magnitude with doping, oxygen pressure, and temperature, and that the isoelectric point lies in slightly donor-doped compositions for samples annealed in air. The experimental results closely fit the space charge model in Part I. Space charge solute segregation is found even in defect regimes of high electron concentration. Approximately one in ten grain boundaries are "special" in exhibiting no detectable segregation; in one such instance a twin boundary is identified. Among boundaries with significant amounts of segregation, clear differences in potential also exist. From the potential determined in acceptor- and donor-doped compositions, the Frenkel energy (assumed to be lower than the Schottky energy in TiO₂) can be separated into its individual terms. An average value for the titanium vacancy formation energy of g_vTi = 2.4 eV and an upper limit to the titanium interstitial formation energy of g_Tii = 2.6 eV are obtained.     

超分散剂对钛白粉的表面处理及在色母粒中的应用

采用超分散剂对钛白粉进行表面处理,探寻了超分散剂表面处理的最佳工艺,找到了适宜的表面处理工艺条件(pH=8,50℃,超分散剂用量7%),使用该条件下处理的钛白粉制备白母粒,用于塑料制品中,钛白粉的分散性、白度、遮盖力、加工性能都大大提高。     

磷元素在钛白粉表面处理及应用中的影响

研究了磷含量对钛白粉应用性能的影响,发现随着磷元素的增加,产品的打浆黏度升高,白度普遍升高,在应用涂料体系中光泽度先升再降,遮盖力逐渐升高,涂料白度无明显变化,而在乳胶漆体系中增加了遮盖力,对消色力也有明显提升。     

影响氯化法钛白粉表面处理效果的因素

介绍了氯化法钛白粉无机表面处理过程中对钛白粉主要性能的影响,并结合氯化法钛白生产过程分析了影响表面处理效果的主要因素。     

电子墨水用TiO_2显色颗粒的表面改性及其分散性能的研究

为使电子墨水用TiO2显色颗粒能较好地悬浮在有机介质中,利用超声波处理方法,采用硅烷偶联剂(γ-甲基丙烯酰氧基丙基三甲氧基硅烷)在水体系中对TiO2进行表面改性,得到亲油性的TiO2颗粒。研究了硅烷偶联剂用量、pH、超声波处理时间对TiO2亲油化度的影响。实验结果表明,当m(硅烷偶联剂)∶m(TiO2)=3∶10,pH=6,超声波处理时间为30 min时,改性TiO2的亲油化度达到50.51%。傅立叶变换红外光谱(FTIR)图表明硅烷偶联剂已接枝到TiO2颗粒表面。改性TiO2在乙醇中静置24 h只有40%发生沉降,之后基本保持稳定,而未经改性的TiO2仅8 h就几乎完全沉降。经表面改性后TiO2颗粒在乙醇溶剂中的Zeta电位提高到-36.90mV。索氏抽提后,改性TiO2的亲油化度仍能达到47%,TiO2和硅烷偶联剂之间结合力较强。     

不同表面处理的钛白粉在色母粒中的应用

采用不同的有机处理剂对钛白粉进行表面处理,找到了一种最适合塑料专用钛白粉的有机处理剂。用动态毛细管法表征处理前后钛白粉的表面亲油性能,并采用红外光谱分析了处理前后钛白粉的结构变化。结果表明,经表面处理后的钛白粉在加工色母粒过程中,其分散性和着色力都得到了提高。     

钽铁、铌铁精矿中硅量的测定

钽铁、铌铁精矿中硅含量的测量分为5%以下使用硅钼蓝分光光度法;5%~20%使用重量法和硅钼蓝分光光度法相结合的方法。本实验分别从条件试验、干扰试验、回收试验、精密度试验、方法对比试验等方面对试验结果进行考察。试验结果表明,该法精密度和准确度均好,适用于钽铁、铌铁精矿中0.50%~20.00%硅的测定。     

纳米二氧化钛光催化剂的制备及其表面改性的研究进展

简述了纳米二氧化钛材料的结构、性能及光催化机理,综述了其常用的制备方法,且针对纳米二氧化钛应用的局限性,重点总结了目前常见的二氧化钛表面改性的方法及研究进展。     

防晒化妆品用纳米氧化钛的表面处理及紫外吸收性能

对作为紫外线吸收剂的纳米氧化钛在化妆品中的应用进行了探讨,详细介绍了纳米氧化钛的表面改性方法,以及钠米氧化钛紫外线吸收效果及其评价方法。     

超声分散法制备表面修饰二氧化钛的研究

利用超声分散法以钛酸丁酯为主要原料,制备硬脂酸修饰二氧化钛粉体。并对产品进行了表征。通过正交实验方法获得了硬脂酸修饰的二氧化钛的最佳的制备工艺条件。结果表明:水/钛酸丁酯为0.75,pH为3,硬脂酸加入量为1.5 g、焙烧温度为500℃时硬脂酸修饰二氧化钛的油溶性最好。     

钛精矿中二氧化钛的测定

介绍了一种直接测定钛精矿中的二氧化钛的含量的新方法。拟定在不经分离沉淀的情况下，采用H2SO4-HNO3-HF熔矿，H2O2光度法测定钛精矿中的二氧化钛，用国家一级标准物质GBW07224(ωTiO2为10．63％)和GBW07225(ωTiO2为9．72％)进行了精密度实验，RSD(n=6)为8．33％、6．59％。加标准回收试验结果TiO2的回收率为99．34％～101．4％。经国家标准物质验证，测定结果与标准值相符，方法适用于1％～70％之间的二氧化钛测定。     

Shock Compression of Titanium Hydride and Titanium,Tantalum, and Zirconium Deuterides

Combustion, Explosion, and Shock Waves - This paper presents the results of an experimental study of shock compression of titanium hydride (TiH2) and the deuterides of...