金红石型Ti1-2xCrxMoxO2黑色色料制备及其性能研究

以TiO₂、Cr₂O₃和MoO₃为主要原料,采用固相反应法合成了金红石型Ti_1-2xCr_xMo_xO₂(x=0、0.05、0.10、0.15、0.20)色料。研究了Cr/Mo共掺杂量和煅烧温度对Ti_1-2xCr_xMo_xO₂色料的晶型结构、呈色性能和微观形貌等的影响。研究结果表明,5%~15%摩尔分数的Cr/Mo等量共掺杂都获得单相金红石型结构黑色色料,均可促进锐钛矿向金红石转变,且Mo掺杂有利于提高Cr在TiO₂晶格中的固溶度。随Cr/Mo共掺杂量增加,样品的黑度(L^*值)呈先减小后增大的趋势,而红色度(a^*值)和黄色度(b^*值)都表现出相反的趋势。煅烧温度在950~1 100 ℃时,样品的色度参数变化相对较小。在1 100 ℃煅烧得到的Ti_0.70Cr_0.15Mo_0.15O₂色料黑色呈色性能最佳,其L^*、a^*和b^*值分别为24.41、2.12和-2.53,且在陶瓷釉中表现出良好的呈色性能和化学稳定性。适量Cr/Mo共掺杂使TiO₂晶格产生畸变和电荷缺陷,从而吸收绝大部分可见光,是其呈现黑色的主要原因。     

Preparation of Titanium Oxide Layer on Silica Glass Substrate with Titanium Naphthenate Precursor

Nanocrystalline TiO₂ thin films on silica glass substrates were prepared by using a naphthenic acid precursor. As-deposited thin films were heat treated at 500, 600, 700 and 800^∘C for 30 min in air. The TiO₂ thin films were analyzed by High Resolution X-ray diffraction, ultra violet—visible—near infrared spectrophotometer, field emission—scanning electron microscope and scanning probe microscope. After annealing at 600 and 700^∘C, the XRD patterns consist of only anatase peaks of TiO₂ film. Rutile(110) peak begins to appear at an annealing temperature of 800^∘C. Relative high transmittance at visible range was obtained for all films except the film annealed at 800^∘C. Optical band gap, E_g, is in the range between 3.53 and 3.78 eV except the TiO₂ film annealed at 500^∘C. The best hydrophilicity was achieved with a high-temperature annealing.     

Synthesis of titanate, TiO2 (B), and anatase TiO2 nanofibers from natural rutile sand

Titanate nanofibers were synthesized by hydrothermal method (150 °C for 72 h) using natural rutile sand as the starting materials. TiO₂ (B) and anatase TiO₂ (high crystallinity) nanofibers with the diameters of 20-100 nm and the lengths of 10-100 μm were obtained by calcined titanate nanofibers for 4 h at 400 and 700 °C (in air), respectively. The samples characterized by XRD, SEM, TEM, SAED, HRTEM, and BET surface area. This synthesis method provides a simple route to fabricate one-dimensional nanostructured TiO₂ from low cost material.     

Co-, Fe-, Ni-doped and co-doped rutile GeO2: insights from ab-initio calculations

Rutile germanium oxide (rutile GeO₂), a semiconductor, can act as a half-metallic compound and is a promising material for spintronic and optoelectronic applications. Calculations were performed using the Korringa–Kohn–Rostoker (KKR) approach and the coherent potential approximation (CPA), which were further combined with two approximations, the local density approximation (LDA) and the self-interaction corrected LDA approximation (LDA-SIC), to study the electronic structure of bulk rutile GeO₂ doped and co-doped with three transition-metal impurities: Fe, Co, and Ni. The doping value was set to 10%, while the co-doping level was set to 5% for each impurity. The main findings of this work are: (1) a direct ultrawide bandgap of 4.80 eV is observed and the rutile GeO₂ exhibits an N-type semiconducting property. (2) Doped and co-doped GeO₂ acquire a magnetic behavior and exhibit half-metallicity. (3) The mechanism responsible for these properties is also studied. (4) The critical temperature can reach 334 K when GeO₂ is doped with Fe, while it rises to 398 K when it is co-doped with Fe and Co. (5) The spin polarization can be improved by co-doping. It can be inferred that rutile GeO₂ doped or co-doped with (Co, Fe) transition metals can be considered to be potential candidates for spintronic and optoelectronic applications.     

重氧空位对金红石型和锐钛矿型TiO2导电性能影响的模拟计算

基于密度泛函理论框架下的第一性原理平面波超软赝势方法,构建了未掺杂与相同重氧空位金红石型和锐钛矿型TiO_1.9375超胞模型,分别对模型进行了几何结构优化、能带结构分布和态密度分布的计算. 结果表明,氧空位后金红石型和锐钛矿型TiO₂体系体积均变大,同时,锐钛矿型TiO_1.9375超胞的稳定性、迁移率以及电导率均高于金红石型TiO_1.9375超胞. 计算结果和实验结果相一致. 关键词： 重氧空位 2')" href="#">金红石型和锐钛矿型TiO₂ 导电性能 第一性原理     

Flux growth of straw‐like rutile monocrystals

Millimetric straw‐like rutile monocrystals were grown by the flux growth technique. A suitable mixture of flux (MoO₃, V₂O₅, Li₂CO₃) and amorphous TiO₂ gel was slowly cooled down to 750°C from 1250°C or 1350°C. The best yields of straw‐like rutile were obtained with a nutrient/flux ratio and a cooling rate in the range 0.015‐0.006 and 1.8‐1.9 K h^‐1, respectively. The hollowed crystals were characterized by powder and single‐crystal X‐ray diffraction, scanning electron microscopy, microthermometry, and µ‐Raman spectroscopy. As for skeletal crystal, the formation of axial canals in rutile is attributed to a lack of nutrient due to the viscosity of the melt and the high growth rate along [001]. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dissociation of liquid water on defective rutile TiO2 (110) surfaces using ab initio molecular dynamics simulations

In order to obtain a comprehensive understanding of both thermodynamics and kinetics of water dissociation on TiO₂, the reactions between liquid water and perfect and defective rutile TiO₂ (110) surfaces were investigated using ab initio molecular dynamics simulations. The results showed that the free-energy barrier (~4.4 kcal/mol) is too high for a spontaneous dissociation of water on the perfect rutile (110) surface at a low temperature. The most stable oxygen vacancy (V_o1) on the rutile (110) surface cannot promote the dissociation of water, while other unstable oxygen vacancies can significantly enhance the water dissociation rate. This is opposite to the general understanding that V_o1 defects are active sites for water dissociation. Furthermore, we reveal that water dissociation is an exothermic reaction, which demonstrates that the dissociated state of the adsorbed water is thermodynamically favorable for both perfect and defective rutile (110) surfaces. The dissociation adsorption of water can also increase the hydrophilicity of TiO₂.     

飞秒强激光对二氧化钛金红石晶体相变的影响

该文章报道了利用显微激光拉曼光谱仪研究近红外飞秒强激光脉冲诱导二氧化钛金红石单晶所引起的相变.实验辐照时间为60s,当激光辐照平均功率增加时,锐钛矿相的拉曼振动模式强度增强,金红石相的拉曼振动模式强度减弱.通过金红石相和锐钛矿相粉体等拉曼光谱的实验,肯定了随着辐照激光功率的增大,.可以通过拉曼光谱中锐钛矿A1g B1g(515 cm-1)振动模式标志峰和金红石相Eg(445 cm-1)振动标志峰分别对应面积的比判断其相变量.     

金红石结构TiO2晶体点缺陷形成能的经验途径计算

基于经验参数化途径,通过对晶体结构、晶格形成能、介电性质和弹性实验数据拟合确定金红石结构氧化物晶体TiO₂的电子壳模型参数和非Coulomb互作用势参数.计算点 缺陷形成能.论证Schottky缺陷是金红石结构TiO₂中的本征缺陷. 关键词： 2')" href="#">金红石TiO₂ 点缺陷形成能 电子壳模型 经验途径计算     

氟金云母钛珠光颜料的制备及表征

利用硫酸沸腾水解法制备了氟金云母钛珠光颜料前驱体,并通过差热-热重分析确定了珠光颜料前驱体的煅烧工艺.通过正交实验考察了反应温度、初始pH值、反应时间、搅拌速度、钛液浓度、晶型促进剂(SnCl_4)对前驱体包覆率的影响,得到了制备珠光颜料前驱体的最佳工艺条件以及影响包覆率的各因素的主次顺序.借助SEM、XRD、FT-IR以及EDS对煅烧前后的粉体进行了表征.测试结果表明:在优化的工艺条件下制得的珠光颜料表面致密光滑,包覆层为金红石型TiO_2,包覆率为27.3;.