Oxygen vacancy control of electrical,optical, and magnetic properties of Fe0.05Ti0.95O2 epitaxial films

High-quality Fe-doped TiO₂ films are epitaxially grown on MgF₂ substrates by pulsed laser deposition. The x-ray diffraction and Raman spectra prove that they are of pure rutile phase. High-resolution transmission electron microscopy (TEM) further demonstrates that the epitaxial relationship between rutile-phased TiO₂ and MgF₂ substrates is 110 TiO₂₂. The room temperature ferromagnetism is detected by alternative gradient magnetometer. By increasing the ambient oxygen pressure, magnetization shows that it decreases monotonically while absorption edge shows a red shift. The transport property measurement demonstrates a strong correlation between magnetization and carrier concentration. The influence of ambient oxygen pressure on magnetization can be well explained by a modified bound magnetization polarization model.     

金红石晶种的X射线衍射分析及其转化率测定

介绍了一种钛白粉生产过程中金红石晶种的转化率测定方法.通过X射线衍射法（XRD）分析金红石晶种物相组成：金红石型TiO₂（R）、锐钛型TiO₂（A）、NaCl.在样品预处理过程中,通过控制体系的pH值靠近金红石晶种等电点,经离心脱盐,消除了金红石晶种中NaCl（111）面对金红石（110）面衍射峰的重叠干扰,同时提高低含量锐钛体积分数,采用"绝热法"定量测定了晶种的金红石转化率.     

Solubility behavior of titanium(IV) oxide in alkaline media at elevated temperatures

A platinum-lined, flowing autoclave facility was used to investigate the solubility behavior of titanium dioxide (TiO₂) in aqueous sodium phosphate, sodium hydroxide and ammonium hydroxide solutions between 17 and 288°. Baseline Ti(IV) solubilities were found to be on the order of one nanomolal, which were enhanced by the formation of anionic hydroxo- and phosphato-complexes. The measured solubility behavior was examined via a titanium(IV) ion hydrolysis/complexing reaction equilibria were obtained from a least squares analysis of the data. The existence of three new Ti(IV) ion complexes is reported for the first time: Ti(OH)₄(HPO₄)^2–, Ti(OH)₅(H₂PO₄)^2– and Ti(OH)₅(HPO₄)^3–. The triply-charged anionic complex was the dominant Ti(IV) species in concentrated, alkaline phosphate solutions at elevated temperatures. This complex is expected to exhibit C.N.=4 (i.e., Ti(OH)₂OPO ₄ ^3– ). A summary of thermochemical properties for species in the systems TiO₂-H₂O and TiO₂-P₂O₅-H₂O is also provided.     

Preparation and characterization of hollow spheres of rutile

Hollow spherical particles of rutile were obtained by coating colloidal polystyrene beads with a titanium oxide hydrate layer and subsequently calcining at elevated temperatures under an oxygen atmosphere. In order to investigate the optimum conditions for the preparation of these hollow beads the maximum temperature and heating rate were systematically varied. The dimensions of the voids and the shell thickness of the hollow beads can be tailored by the size of the polystyrene beads and the thickness of the inorganic layer, respectively.     

Conductivity of anodic TiO2 nanotubes: Influence of annealing conditions

The present work reports on the resistivity of anodic TiO₂ nanotubes as function of annealing temperature and atmosphere. Significant effects of several orders of magnitude are observed and explained by different crystallinity and self‐doping level. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

TiO_2晶型及其相变的高温拉曼光谱研究

本文测量了锐钛矿型和金红石型TiO2常温至1923K的高温拉曼光谱,观察了锐钛矿型TiO2在1373K～1473K间发生相变,不可逆转化为金红石型TiO2,分析了特征峰随温度变化的规律以及两种结构相的温度依赖性。并为不同晶型TiO2的研究、生产和应用提供重要的实验依据。     

离子注入金红石单晶生成的金属Ni纳米晶的磁学性能研究

研究了能量为64keV、注量1×1017cm-2的Ni离子注入金红石TiO2单晶制备的植入金属纳米晶的微观结构和磁学性能。注入层的结构和磁学性能采用透射电子显微分析（TEM）和超导量子干涉磁强计（SQUID）进行分析。结果表明,金红石单晶中有尺寸为3～18nm的金属Ni纳米晶生成,注入区域基体明显非晶化。10K温度下金属Ni纳米晶的矫顽力约为16.8kA·m-1,比Ni块材的矫顽力大。样品的零场冷却/有场冷却（ZFC/FC）曲线表明,金属Ni纳米晶的截止温度约为85K。     

Exchange mechanism of half-metallic ferromagnetism of TiO2 doped with double impurities: A first-principles ASW study

The electronic structure and ferromagnetic properties of rutile TiO₂ doped with double-impurities Ti_1−2xCr_xMn_xO₂ has been investigated using first-principles calculations within the density-functional theory (DFT) and the local density approximation (LDA), functional for treating the effects of exchange and correlation. They were performed using the scalar-relativistic implementation of the augmented spherical wave (ASW). The advantages of doping TiO₂ with double impurities instead of single impurities are the increase of the total moment of the system and the exhibition of the half-metallic ferromagnetic nature in Cr- and Mn-doped TiO₂ rutile. These behaviors are due to the hybridization of Cr 3d states and nearest-neighboring O 2p states. The spin-spin interaction between magnetic impurities examined by the total energy between parallel and antiparallel aligned states indicated that the Cr and Mn impurities are energetically favorable to be parallel coupled, which mean that the ferromagnetic state is more stable than the ferrimagnetic one. We proposed a bond magnetic polarons (BMP) model, based on localized carriers, to explain the mechanism of ferromagnetism in these systems.     

Synthesis of Gray Ceramic Pigments with Rutile Structure from Alkoxides

In this study, V _x Ti_{1 – x} O₂ (0 x 0.20) rutile solid solutions have been synthesized from gels built from hydrolysis-condensation of V(IV) oxyacetilacetonate and Ti(IV) isopropoxide mixture (polymeric gel). These solid solutions are stable at high temperature (1200–1400°C) and into glazes. The colouration of the glazes together with the thermal stability of these rutile solid solutions indicates their potential usefulness as gray ceramic pigments. The results obtained are compared with those obtained from V₂O₅ and TiO₂ (anatase) mixtures (ceramic method). From alkoxides, noticeable change in coloration is obtained on glazes, when x < 0.10.