Effect of Ni+2-substituted Fe2TiO5 on the H2-reduction and CO2 Catalytic Decomposition Reactions at 500℃

CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas, high activity nanosized Ni＋2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method. The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 （iron titanate） phase that has a nanocrystallite size of -80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases （-80 nm） NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only. Samples with Ni^＋2=0 shows the lowest reduction extent （20%）; as the extent of Ni＋2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis （TGA） experiments. The oxidation of the H2-reduced Ni＋2 substituted Fe2TiO5 at 500℃ was investigated. As Ni^＋2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction （XRD） and transmission electron microscopy （TEM） of oxidized samples show also the presence of carbon in the sample containing Ni＋2〉0, which appears in the form of nanotubes （25 nm）.     

Fe掺杂ZnO/TiO2光催化性能

采用溶胶-凝胶法制备了Fe掺杂ZnO/TiO2纳米催化剂粉体,利用多种技术手段对样品的组成、形貌、表面化学态、光学性能等进行表征分析,同时通过降解甲基橙溶液来评价样品的光催化性能.研究结果表明,掺杂Fe能稳定ZnO/TiO2的锐钛矿相,细化催化剂颗粒,并且促进光的吸收带隙红移.Fe-ZnO/TiO2的光催化活性相比Ti...     

Positron Annihilation Behaviors and Magnetic Properties of Single-phase Nd2Fe14B and Nanocomposite Nd2Fe14B／α- Fe Magnets

Positron annihilation behaviors have been studied in the single phase Nd2Fe14B magnet and the nanocomposite Nd2Fe14B/α-Fe magnet, prepared by melt spinning. The results showed that the number of vacancy-cluster at grain boundaries increases with increasing annealing temperature for the both types of magnets. The increase of this kind of defect can improve the coercivity of     

Fe3＋掺杂的纳米TiO2的水热法制备及光催化性能研究

以钛酸丁酯和Fe(NO3)3·9H2O为原料,采用水热法制备了Fe掺杂的纳米TiO2.利用XRD,TEM和UV-Vis对样品进行了表征,并研究了不同催化剂用量和pH值等因素对光催化降解次甲基蓝的影响.结果表明:Fe掺杂的纳米TiO2吸收带红移,吸收强度增大,在碱性条件下具有更好的光催化性能,催化剂最佳用量为1.0g/L.     

Study on the Phase Transformation Behavior of Nanosized Amorphous TiO2

Nanosized amorphous TiO2 powders with a specific surface area of 501 m^2.g^-1 were prepared by hydrolysis. After calcined at 400℃ for 2 h, the prepared amorphous TiO2 powders were fully transformed into anatase crystallites with a specific surface area of 141 m^2.g^-1. Differential scanning calorimetric (DSC) experiments were performed on the samples of nanosized amorphous TiO2 mixed with microsized anatase, nanosized anatase, or nanosized α-Al2O3 respectively. Effects of sample packing, anatase addition, or α-Al2O3 addition on the crystallization behavior of nanosized amorphous TiO2 were analyzed.     

微波法合成纳米TiO2及Fe3+掺杂纳米TiO2粉体的研究

通过控制盐的水解和微波辐射制备出晶粒尺寸为 6～ 2 5nm的TiO2 、Fe/TiO2 粉体。对水解温度、陈化时间、微波辐射的影响进行研究 ,发现TiO2 水解温度在 70～ 80℃、Fe/TiO2 水解温度在 6 5℃时 ,晶粒尺寸较小 ,而室温陈化时间的长短对晶粒尺寸没有大的影响 ,样品未微波辐射与微波辐射的晶粒尺寸、热性质等存在明显不同。通过XRD、TG DSC、TEM对制得的纳米粉体进行了表征     

Nb2O5掺杂对TiO2陶瓷性能的影响

在Nb2O5含量x为0.1～1.5%的范围内,研究了Nb2O5掺杂对TiO2压敏陶瓷电性能的影响.发现x＝0.7%的样品显示出最低的压敏电压(Eb=8.57V/mm )以及最高的相对介电常数2.385×104.分析认为Nb2O5掺杂的实质是Nb5 固溶于 TiO2中取代Ti4 使晶粒半导化,但掺杂量受晶格畸变作用有一定限制.     

Fe、S共掺杂纳米TiO2的制备及性能研究

采用溶胶-凝胶法,以硫脲和三氯化铁为掺杂剂,制备了Fe-TiO2、S-TiO2和S-Fe-TiO2纳米光催化剂.通过XRD、SEM等方法对掺杂纳米TiO2进行了表征,以甲基橙为模型化合物对纳米TiO2粉体的光催化活性进行了评价.结果表明;纯TiO2、掺Fe-TiO2粉体全部为锐钛矿相,S-TiO2粉体中金红石相占8.1%,S-Fe-TiO2粉体中金红石相占26.9%.S和Fe、S共掺杂引起金红石相变温度的降低.掺Fe的纳米TiO2粉体粒子团聚少,分散要均匀,掺S和Fe、S共掺的TiO2粉体颗粒团聚现象较严重.S-TiO2和Fe-TiO2光催化荆在紫外光和日光灯下光催化活性都较好,而Fe-S-TiO2光催化活性没有提高.     

Fe3+-SiO2掺杂纳米TiO2的制备及其光催化降解甲基橙的研究

以三嵌段非离子表面活性剂P123为模板,采用水热法制备了Fe3+-SiPO2掺杂纳米TiO2,通过X射线衍射(XRD)、红外光谱(FT-IR)、紫外-可见吸收光谱(UV-Vis)等手段考察了Fe3+-SiO2掺杂纳米TiO2的结构与光学特性.实验结果表明:Fe3+、SiO2掺杂进入TiO2的晶格,可获得高纯度锐钛矿相纳米TiO2.Fe3+和SiO2的加入有助于抑制金红石相的形成和晶粒长大,提高了TiO2的热稳定性.Fe3+-SiO2掺杂将TiO2的光响应范围拓宽至可见光区,提高了纳米TiO2的光催化性能.与纯纳米TiO2相比,Fe3+-SiO2掺杂纳米TiO2光催化降解甲基橙的性能显著提高.     

Effect of Ni+2-substituted Fe2TiO5 on the H2-reduction and CO2 Catalytic Decomposition Reactions at 500℃

CO2 is a major component of the greenhouse gases, which causes the global warming. To reduce CO2 gas,high activity nanosized Ni 2 substituted Fe2TiO5 samples were synthesized by conventional ceramic method.The effect of the composition of the synthesized ferrite on the H2-reduction and CO2-catalytic decomposition was investigated. Fe2TiO5 (iron titanate) phase that has a nanocrystallite size of ～80 nm is formed as a result of heating Fe2O3 and TiO2 while the addition of NiO leads to the formation of new phases (～80 nm)NiTiO3 and NiFe2O4, but the mixed solid of NiO and Fe2O3 results in the formation of NiFe2O4 only.Samples with Ni 2=0 shows the lowest reduction extent (20%); as the extent of Ni 2 increases, the extent of reduction increases. The increase in the reduction percent is attributed to the presence of NiTiO3 and NiFe2O4 phases, which are more reducible phases than Fe2TiO5. The CO2 decomposition reactions were monitored by thermogravimetric analysis (TGA) experiments. The oxidation of the H2-reduced Ni 2 substituted Fe2TiO5 at 500℃ was investigated. As Ni 2 increases, the rate of reoxidation increases. Samples with the highest reduction extents gave the highest reoxidation extent, which is attributed to the highly porous nature and deficiency in oxygen due to the presence of metallic Fe, Ni and/or FeNi alloy. X-ray diffraction (XRD) and transmission electron microscopy (TEM) of oxidized samples show also the presence of carbon in the sample containing Ni 2＞0, which appears in the form of nanotubes (25 nm).     

TiO2载Cu2+、Zn2+无机抗菌剂的制备及性能研究

采用固相合成法制备以TiO2为载体,以Cu2 、Zn2 为主要抗菌成分的无机抗菌剂,研究了制备条件及Cu2 、Zn2 含量对抗菌性能的影响,结果表明:当热处理温度为450～600℃,保温时间为2h,Cu2 和Zn2 质量百分含量比为(0.66～1.18):(2～3)时,样品均具有较好的抗菌效果;具有最好抗菌效果的样品中,TiO2以锐钛矿相存在,同时羟基氧的生成及Cu2 和Cu 的共存,使得样品具有良好的抗菌效果.     

热分解法制备Ni_(0.5)Zn_(0.5)Fe_2O_4纳米颗粒

采用热分解法制备Ni_(0.5)Zn_(0.5)Fe_2O_4纳米颗粒,研究表面活性剂用量、回流温度和回流时间对产物尺寸、形貌以及分散性的影响。通过X射线衍射仪(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)对样品的结构、形貌与磁性能进行了表征。结果表明:增加表面活性剂的用量,产物的粒径减小,分散性明显提高,而提高回流温度和延长回流时间则会使产物粒径增加,但粒径分布也会变宽。在三辛基氧化膦(TOPO)用量为0.6mmol,260℃回流1h条件下制备产物的饱和磁化强度为49.38A·m2/kg,矫顽力为7143.20A/m,剩余磁化强度为5.76A·m2/kg,表现为亚铁磁性。     

水泥熟料固化重金属Cu2+和Zn2+及水化浸出行为分析

危废处理是当前的热点问题,水泥窑协同处置作为一种有效的处理方式,逐步为社会所接受。多数的危废中包含Cu²⁺和Zn²⁺,文章研究了危废中重金属Cu²⁺和Zn²⁺在水泥熟料中的固化性能和在熟料中的分布,并探讨了重金属在水泥净浆中的浸出行为和环境安全性。通过熟料易烧性X射线衍射(XRD),矿物相分离萃取,浸出实验得出:Cu²⁺和Zn²⁺均改善了熟料易烧性;Cu²⁺促进了C₄AF的生成,同时也促进了C₃S晶粒的生长,并固溶在其中;Zn²⁺与熟料形成新的矿物相Ca₁₄Al₁₀Zn₆O₃₅。通过相对分布系数(D)和分配系数(K_f)说明Cu²⁺主要分布在硅酸盐相中,硅酸盐相固化Cu²⁺的能力强于中间相;Zn²⁺主要分布在中间相中,中间相固化Zn²⁺的能力强于硅酸盐相。掺量为2.0%的Cu²⁺和Zn²⁺在水泥净浆7 d龄期的浸出浓度最大,分别为1.724和0.387 mg·L^-1。水泥熟料固化Cu²⁺和Zn²⁺在水泥使用过程中不会对环境造成二次污染。     

铜离子掺杂对TiO2纳米颗粒膜结构和性能的影响

采用溶胶-凝胶法在普通的载玻片上制备了锐钛矿型TiO2和过渡金属Cu离子掺杂TiO2薄膜.通过XRD,UV-VIS,XPS,AFM表征了合成的薄膜,表明铜离子掺入后,薄膜变得更加致密.铜离子以Cu2O的形式存在.在紫外光照射下,TiO2薄膜表现出明显的亲水性.对于掺铜的TiO2薄膜,随着铜掺杂量的增加,铜(I)对亲水性能的抑制作用亦增强.     

Influence of the presence of Fe2+ ion in nickel-zinc ferrite

The presence of small amounts of Fe²⁺ ion in nickel zinc ferrite significantly influences some of its magnetic properties. The lattice parameter increases slightly and the increase Δa is independent ofx. The variation of magnetization with zinc concentration is explained on the basis of the Yafet-Kittel model. Increase in the Néel temperature on Fe²⁺ substitution in Zn _x Ni_1-x Fe₂O₄ is remarkable. This has been explained on the basis of a four sublattice model. Our analysis shows thatJ _AB (d ⁵-d ⁵) interaction is most affected. The influence of Fe²⁺ ions on the relaxation processes in the Mössbauer line shapes of Ni-Zn ferrite is also investigated and is compared with Cu²⁺ doped Ni-Zn ferrite.     

The effect of magnetic layer thickness on magnetic properties of Fe/Cu multilayer nanowires

Fe/Cu multilayer nanowires were ac-pulse electrodeposited into the anodic aluminum oxide templates prepared by a two-step mild anodization technique. Transmission electron microscopy images showed the distinct layers with a relatively high contrast. A highly pure layer (∼99%) was achieved by tuning the proper ions ratio and optimizing the off-time between pulses of each layer in the single electrodeposition bath. Fe/Cu multilayer nanowires with 38 nm diameter were obtained. The effect of reducing the Fe layer thickness on the magnetic properties of Fe/Cu multilayer nanowires was investigated. It was seen that reducing the Fe layer thickness, thereby variation of rode- to disc-like multilayer nanowires, caused to rotate the magnetic easy axis from parallel to perpendicular to the wires axis.