热喷涂法制备的La3+掺杂纳米TiO2粉末的表征

采用等离子热喷涂法以钛酸四丁酯为主要原料制备出稀土离子掺杂的纳米TiO2光催化剂.通过XRD,XPS,TEM,UV-Vis等检测手段对样品进行表征,同时检测了其光催化性能,并分析了掺杂对TiO2的影响机理.结果表明,所制备的La3 掺杂纳米TiO2是锐钛矿相和金红石相混晶结构,粒径分布在10～50nm之间;La3 掺杂能够促进锐钛矿向金红石的转变,同时抑制TiO2晶粒的长大;La3 掺杂使TiO2紫外-可见吸收光谱发生红移;适量La3 掺杂能显著提高TiO2的光催化活性,最佳掺杂浓度为0.5%(与Ti原子摩尔比),甲基橙降解率在90min内可达到82.4%.比纯TiO2高出13.2%.     

纳米多孔TiO2膜的晶化处理及其热稳定性研究

通过恒压阳极氧化法在HF酸和CrO3的混合电解液中，在纯钛TAl和钛合金TC4表面分别制备了纳米多孔无定型TiO2膜。研究了TAl和TC4表面无定型TiO2膜在空气中热处理的组织转变过程。TAl试样表面的纳米多孔TiO2膜在250℃左右出现锐钛矿相，480℃左右出现金红石相，在600℃左右锐钛矿相向金红石相的转变基本完成，孔结构在600℃左右基本消失；TC4试样表面的纳米多孔TiO2膜在310℃左右出现锐钛矿相，600℃左右出现金红石相，在680℃左右锐钛相向金红石相的转变基本完成，孔结构在700℃左右基本消失。TC4试样表面的氧化膜所含合金元素Al和V，对上述结晶转变温度和孔结构存在的最高温度的差别存在重要影响。     

微等离子体氧化制备TiO2薄膜的结构特性

利用微等离子体氧化方法在纯Ti金属表面生长出一层厚度达20μm的陶瓷氧化膜，并用X射线衍射、扫描电镜初步研究了氧化膜的组织结构和表面形貌。在不同电解质溶液条件下，得到3种不同类型结构组成的氧化膜：单一TiO2的锐钛型结构、TiO2锐钛型 金红石型的混合相结构、单一TiO2金红石结构。TiO2单一的锐钛型结构的氧化膜薄膜比较粗糙，TiO2金红石结构的氧化膜表面比较平滑，而混合相结构陶瓷膜的表面层为疏松的锐钛型结构TiO2，亚表层为金红石结构的TiO2。     

Y-TiO2薄膜的超声波—溶胶—凝胶法制备及表征（英文）

提出了一种制备Y掺杂TiO2薄膜的新方法。采用溶胶-凝胶法结合超声技术,以钛酸四丁酯为前驱体制备Y-TiO2溶胶,分别采用XRD、SEM、FT-IR和UV-vis对样品的组成与结构进行了表征。结果表明:Y3+掺杂可较好地抑制TiO2由锐钛矿相向金红石相的相变,提高了相变温度,抑制了晶粒生长。Y掺杂TiO2薄膜的晶型结构为锐钛矿相结构,晶型为锐钛矿相,粒度为6~16nm。Y3+掺杂能引起TiO2光学吸收边的"红移",带隙变窄,红移程度随掺杂量增加而增大,随温度升高而减小。薄膜表面平整,厚度约80nm。     

液料等离子热喷法制备Fe3+/TiO2纳米粉末

通过对液料等离子热喷前驱物添加掺杂成分实现了液料等离子热喷TiO2纳米粉末的掺杂改性,并利用TEM,XRD及XPS对其进行表征.结果表明,采用液料等离子热喷法可以制备Fe3 掺杂TiO2纳米粉末,所制备粉末形貌基本呈球形或近球形,粒径分布为10～35 nm,掺杂量小于2.0%时粉末为锐钛矿及金红石相混晶,Fd3 掺杂促进锐钛矿向金红石相的转变,掺杂量为10.0%时析出了Fe2Ti3O9相.Fe3 掺杂不会引起TiO2粒径的大范围波动.粉末中含有O,Ti,Fe和C等元素,Fe元素在TiO2中仍为 3价.     

CuO掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3无铅压电陶瓷的研究

用传统固相反应法在不同温度下烧结制备了不同含量CuO掺杂的0.45(Ba0.7Ca0.3)TiO3-0.55Ba(Zr0.2Ti0.8)O3(BCZT45)无铅压电陶瓷,研究了CuO掺杂对BCZT45陶瓷微观形貌、相结构、介电和压电性能的影响。X射线衍射(XRD)结果表明所有陶瓷均形成了钙钛矿结构,Cu2+固溶进入BCZT45晶格,Cu2+部分取代Ti4+引起晶格畸变。加入CuO改善了BCZT45陶瓷的烧结性能,降低了烧结温度,使陶瓷在1350℃即可烧结,提高了陶瓷密度。随着CuO含量的增加,陶瓷的介温曲线向低温方向移动。掺杂少量CuO后,BCZT45陶瓷的压电常数增大,随着CuO掺杂量的增加又急剧降低。掺杂CuO含量为0.25mol%的BCZT45陶瓷具有最好的电学性能:压电常数d33=340pC/N,室温介电常数εr=3147,介电损耗tanδ=0.025。     

多孔钛板表面TiO2纳米管阵列膜的制备及表征

利用四辊卧式粉末轧机制备多孔钛板,并通过阳极氧化工艺在轧制多孔钛板上制备TiO2纳米管阵列膜。采用扫描电子显微镜（SEM）和X射线衍射仪（XRD）分别对TiO2纳米管阵列膜的形貌和物相进行表征,并对TiO2纳米管阵列膜的热稳定性和生物相容性进行了研究。结果表明,多孔钛板上初步制备的TiO2纳米管阵列膜为无定形相结构,在不同温度下可转化为锐钛矿型、金红石型或锐钛矿与金红石型的混合物;细胞培养实验表明,经阳极氧化及450℃退火处理后,粉末轧制多孔钛板表面细胞的黏附量比未经处理的多,且细胞发育良好。     

TiO2掺杂SmTaO4陶瓷热物理性能研究

热障涂层是燃气轮机高温部件保护的重要材料之一,SmTaO4陶瓷具有优异的高温相稳定性和力学性能,有望成为新型热障涂层材料。本研究采用固相法制备TiO2掺杂SmTaO4陶瓷,研究结果表明：掺杂TiO2未改变SmTaO4陶瓷晶体结构,样品均为单斜相,掺杂2% mol TiO2的SmTaO4陶瓷烧结过程中出现的第二相为Sm0.33TaO3;随着TiO2含量增加,SmTaO4陶瓷的热导率先下降后上升,当TiO2掺杂含量为2%时,热导率最低为1.42W?m?1?K?1,低于SmTaO4（1.59W?m-1?K-1,900℃）,与7-8YSZ相比（2.1~2.7 W?m?1?K?1,100~900℃）下降了近30%。掺杂2%TiO2的SmTaO4陶瓷热膨胀性系数最大值为10.8×10-6K-1,大于YSZ（~10.0×10-6K-1）和SmTaO4（9.62×10-6K-1,1200℃）,与纯SmTaO4相比,TiO2掺杂提高了SmTaO4陶瓷的热膨胀系数。因此,TiO2掺杂SmTaO4陶瓷有望作为新型热障涂层材料使用。     

电子束对Sol-gel法制备的TiO2的显微形貌和相变的影响

用Sol-gel方法制备了纳米级TiO2,用XRD分析了粉末的相结构和尺寸,并用原位TEM和SED技术详细分析了电子束对不同结构TiO2的影响.XRD结果表明:250℃以下干燥的样品为无定形TiO2,360℃和600℃热处理的样品由锐钛矿相组成,750℃热处理的样品由锐钛矿(体积分数30%)和金红石(体积分数70%)两相组成,当温度为950℃时,全部转变为金红石.在电子束照射下,除了110℃干燥的团聚体在短时间内未观察到锐钛矿和金红石相外,在250℃和360℃加热的样品中均观察到了金红石相,甚至全部为金红石相.颗粒尺寸增大,电子束对相变的影响减弱,600℃保温1 h的样品在电子束照射下短时间内未出现金红石相;然而当样品处于锐钛矿和金红石双相时,电子束又促进了金红石相的形成,这与氧缺陷的增加有关.此外,在电子束的照射下,无定形的TiO2样品中还出现了TiC相.     

不锈钢表面TiO2薄膜的溶胶-凝胶法制备及其性能

通过溶胶-凝胶法在316L不锈钢表面制备TiO2薄膜.研究发现,经500℃热处理1h的TiO2主要由锐钛矿相构成,随着热处理温度的提高,锐钛矿相逐渐转变为金红石相.降解结晶紫水溶液和对水的接触角结果测试表明,随着涂膜次数的增加,TiO2薄膜的光催化性和亲水性都有一定的提高.电化学腐蚀测试说明,表面涂有TiO2薄膜的316L不锈钢的耐腐蚀性提高,薄膜对基体起到了一定的保护作用.     

Porous TiO2 coating using the solution precursor plasma spray process

Porous titania coatings were deposited from aqueous solution containing titanium isopropoxide using the solution precursor plasma spray (SPPS) process. Effects of plasma power on coating microstructure and phase composition were investigated. X-ray diffraction and Raman spectra analyses indicated that the amount of anatase and rutile phases in the as-sprayed coatings can be adjusted by simply changing the plasma power. With the increase of plasma power, the coating anatase content decreases and the rutile content increases. Scanning electron microscope characterization shows that all of the as-sprayed coatings are very porous.     

Crystal structure analysis and thermoelectric properties of p-type pseudo-binary (Al2Te3)x–(Bi0.5Sb1.5Te3)1−x (x = 0 0.2) alloys prepared by spark plasma sintering

Sm³⁺-doped TiO₂ nanocrystalline has been successfully prepared by low temperature combustion synthesis (LCS). Results showed that the samarium doping was found to be able to significantly inhibit the anatase–rutile phase transformation. Photocatalytic degradation experiments indicated that doping samarium ions in TiO₂ could enhance photocatalytic activity in photocatalytic degradation of methylene blue. The increase in photocatalytic activity is probably due to prevention of electron–hole recombination and the existence of a synergistic effect between anatase and rutile. The highest enhancement in photoreactivity was obtained at 0.5 mol% samarium ions doping, which may be in favor of the most efficient separation of the charge carriers. It has been found that the photocatalytic activity is drastically increased under the presence of a small amount of anatase phase (only 5.9% anatase) compared to pure rutile, and the sample calcined at 600 °C with 51.61% rutile shows the highest photocatalytic activity, which suggests the existence of a synergistic effect between anatase and rutile powders in the Sm³⁺-doped TiO₂, which is similar to that of undoped TiO₂.     

Properties of TiO2 support and the performance of Au/TiO2 Catalyst for CO oxidation reaction

Gold catalysts were prepared on TiO₂ supports of different phase structures (i.e., anatase, rutile and biphasic), TiO₂ crystal size (i.e., 9–23 nm), surface and textural properties (i.e., hydration and surface area). The CO oxidation on the gold catalysts was carried out in an operando-DRIFTS set-up equipped with DRIFTS reactor cell connected on-line to CO gas analyser and gas chromatograph enabling real time monitoring of surface reaction and simultaneous reaction rate measurements. Gold catalysts supported on pure anatase TiO₂ were more resistant to sintering compared to catalysts supported on rutile and bi-phasic TiO₂. Besides catalyst sintering, deposition of surface carbonates is an important cause of catalyst deactivation. The best gold catalyst was prepared on 13 nm anatase TiO₂. It displays both increased activity and stability for CO oxidation reaction at room temperature. Surface and textural properties of TiO₂ also play a role on the performance of the Au/TiO₂ catalyst.     

Dominant microstructural feature over photocatalytic activity of high velocity oxy-fuel sprayed TiO2 coating

TiO₂ photocatalytic coatings were deposited through high velocity oxy-fuel spray using anatase powder and rutile powder as feedstock. The as-sprayed TiO₂ coating was composed of anatase phase and rutile phase. The anatase content in the coating was significantly influenced by fuel gas flow and melting condition of spray powder. A high anatase content of 35% was achieved for the coating deposited using rutile powder. The anatase content in the coating deposited using anatase powder reached 55-65%. The as-sprayed TiO₂ coating was photocatalytically reactive for degradation of acetaldehyde in air. The photocatalytic activity was influenced by spray conditions. The surface morphology and phase structure of coatings deposited at different spray conditions were investigated to clarify the relationship between the coating microstructure and activity. It is found that the photocatalytic activity is significantly influenced by anatase content and surface area.     

锌锶共掺杂TiO_2多孔涂层的抗菌及生物相容性

为改善钛的抗菌性能和生物活性,采用微弧氧化(MAO)技术在纯钛表面制备了锌掺杂TiO_2涂层(M-Zn)、锶掺杂的TiO_2涂层(M-Sr)和锌锶共掺杂TiO_2涂层(M-Zn/Sr)。利用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对制备的涂层的组织结构和成分进行分析;采用平板计数法研究了涂层的抗菌性能;利用细胞荧光染色和甲基噻唑基四唑(MTT)的方法探究了细胞在材料表面的生长状况。结果表明:形成的TiO_2涂层都是典型的多孔结构,主要由金红石和锐钛矿相组成,锌、锶的掺杂对涂层形貌影响不大。M-Zn/Sr涂层中锌、锶的原子数分数分别为7.9%和1.7%。M-Zn及M-Zn/Sr涂层大肠杆菌展现了良好的抗菌性能,抗菌率接近100%。M-Zn、M-Sr和M-Zn/Sr均能促进成骨细胞增殖,M-Zn/Sr涂层具有抗菌和细胞增殖的双重功能。     

Effects of Calcination on Structural, Photocatalytic Properties of TiO2 Nanopowders Via TiCl4 Hydrolysis

Photocatalytic degradation of methyl orange (MO) in water was examined using TiO₂ nanopowders under solar irradiation. These photocatalysts were successfully synthesized by hydrolysis of titanium tetra chloride (TiCl₄) in the temperature range of 70-95 °C and calcined at higher temperatures of between 400 and 900 °C. The samples prepared were characterized using x-ray powder diffraction, scanning electron microscope (SEM) and Fourier transform infrared spectrophotometer (FTIR). UV-Vis spectrometer was used for analyzing the concentration of MO in solution at different time intervals during the photodegradation experiment. Parameters affecting the photodegradation rate such as catalyst crystallinity, concentration of the catalyst, MO concentration, and pH of the solution have been investigated. The results indicate that TiO₂ nanopowder was antase at low calcination temperatures in the range of 400-500 °C. The sample calcined at 600 °C is composed of both anatase and rutile phase. Further increase in the temperature enhanced the intensities of diffraction peaks of the rutile phase. The size of the crystallites for all the samples prepared were found to be in the 6-13 nm range and from SEM micrographs it was in the range of 19-43 nm. The mixture of both phases exhibited a higher photoactivity in comparison with pure anatase or rutile catalysts.     

Dielectric relaxation behaviors of pure and Pr6O11-doped CaCu3Ti4O12 ceramics in high temperature range

Pure and Pr₆O₁₁-doped CaCu₃Ti₄O₁₂ (CCTO) ceramics were prepared by conventional solid-state reaction method. The compositions and structures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of Pr-ion concentration on dielectric properties of CCTO were measured in the ranges of 60 Hz-3 MHz and 290-490 K. The third phase of Ca₂CuO₃ was observed from the XRD of CCTO ceramics. From SEM, the grain size was decreased obviously with high valence Pr-ion (mixing valence of Pr³⁺ and Pr⁴⁺) substituting Ca²⁺. The room temperature dielectric constant of Pr-doped CCTO ceramics, sintered at 1323 K, was an order of magnitude lower than the pure CCTO ceramics due to the grain size decreasing and Schottky potential increasing. The dielectric spectra of Pr-doped CCTO were flatter than that of pure CCTO. The loss tangent of Pr-doped CCTO ceramics was less than 0.20 in 2 × 10²-10⁵ Hz region below 440 K. The complex impedance spectra of pure and Pr-doped CCTOs were fitted by ZView. From low to high frequency, three semicircles were observed corresponding to three different conducting regions: electrode interface, grain boundary and grain. By fitting the resistors R and capacitors C, the activation energies of grain boundary and electrode contact were calculated. All doped CCTOs showed higher activation energies of grain boundary and electrode than those of pure CCTO ceramics, which were concordant with the decreasing of dielectric constant after Pr₆O₁₁ doping.