Bi_9V_2ClO_(18)新型光催化剂的制备与光催化活性评价

以BiOCl、Bi_2O_3、NH_4VO_3为原材料,采用固相合成法制备了Bi_9V_2ClO_(18)新型光催化剂,通过XRD、SEM和HRTEM对样品的物相、形貌和结晶质量进行了表征,测试了样品的紫外-可见漫反射吸收光谱。结果表明:其吸收边为465nm,禁带宽度为2.67eV。采用罗丹明B(RhB)、亚甲基蓝(MB)为目标污染物,测试了Bi_9V_2ClO_(18)光催化剂的可见光光催化活性。在可见光下辐射9h,RhB降解率达82%;可见光下辐射5h,MB降解率达83%。测试结果表明:所制备Bi_9V_2ClO_(18)材料是可见光响应型光催化剂,在可见光辐照下对罗丹明B和亚甲基蓝的光降解主要依赖于光催化剂的直接光降解机制。     

晶粒尺寸对ZnO纳米粒子光催化活性的影响

采用水热合成法制备纳米ZnO材料,并用所制备的纳米材料光催化降解罗丹明B溶液,以罗丹明B的降解率作为评价方式,考察了不同浓度的氧化锌对光催化性能的影响.运用XRD对制备的样品进行了表征.结果表明:随着水热溶液中原料配比的浓度增大,氧化锌晶粒尺寸逐渐减小,光催化的活性增强.当氧化锌样品的浓度为150m M时,10mg/40ml的罗丹明B在紫外灯下降解率达93%.     

TiO2-SiO2复合多孔材料的低成本制备及表征

以廉价的TiCl4和工业水玻璃为原料,采用溶胶-凝胶法,用无水乙醇对湿凝胶进行溶剂交换处理,通过常压干燥工艺制备了TiO2-SiO2多孔材料.利用SEM、FTIR、BET吸附对多孔材料的形貌和性质进行了研究,分析了TiO2-SiO2多孔材料吸附和光催化降解罗丹明B的性能.结果表明,用3 mol/L的TiCl4水溶液制得的TiO2-SiO2多孔材料对罗丹明B有较高的吸附率和光解率;n(Ti): n(Si)=2:1的TiO2-SiO2多孔材料对罗丹明B有较高的吸附率.而n(Ti):n(Si)=1:2的TiO2-SiO2多孔材料对罗丹明B有较高的光解率.     

Pb掺杂对Bi0.5Sb1.5Te3热电材料性能的影响

采用真空熔炼、高能球磨、冷压成型和气氛烧结工艺制备了Pb掺杂的P型Bi_(0.5)Sb_(1.5)Te_3块体热电材料.利用X射线衍射仪(XRD)、扫描电镜(SEM)、热电参数测试系统(Namicro-3)、激光热导仪(LFA-467)和DSC等测试技术,研究了Pb掺杂对Bi_(0.5)Sb_(1.5)Te_3热电材料的物相组成、表面形貌和热电性能的影响.结果表明:Pb掺杂能够抑制单质Te的析出及Pb原子取代Bi/Sb原子的位置,产生空穴,载流子浓度增大,电导率升高,Pb原子半径与Bi/Sb原子半径不同,增加晶格畸变,降低热导率,从而有效提高Bi_(0.5)Sb_(1.5)Te_3热电材料的综合性能.在300K时,Pb_(0.003)Bi_(0.497)Sb_(1.5)Te_3的电导率为8.35×10~4 S/m,塞贝克系数为179μV/K,热导率为0.716 W/(m·K),热电优值达到1.122.     

H3PW12O40-TiO2/SiO2的制备及光催化性能

以硅胶为载体,采用浸渍法制备了H3PW12O40-TiO2/SiO2催化剂.利用IR、TG-DTA、XRD、XPS对其结构进行表征.研究结果表明,催化剂中的活性组分二氧化钛为锐钛矿型,磷钨酸仍保持其Keggin结构的基本骨架,二氧化钛及磷钨酸二者均与载体之间存在着化学作用.通过对染料罗丹明B的超声光催化降解研究发现,含4gH3PW12O40的TiO2溶胶浸渍在11gSiO2上的催化效果最佳,且H3PW12O40可明显提高TiO2超声光催化降解罗丹明B的降解率.     

Ag3PO4/GO光催化剂的制备及性能研究

以氧化石墨烯(GO)为基底,利用离子交换法制备了球形和立方体表面结构的Ag₃PO₄/GO复合光催化剂。通过X射线衍射(XRD)、扫描电子显微镜(SEM)和紫外-可见光谱(UV-Vis DRS)对样品进行了表征。罗丹明B的光催化降解实验结果表明：Ag₃PO₄/GO催化剂在100 min内对20 mg/L罗丹明B的去除率可达98.5%,明显高于球形Ag₃PO₄ (83.8%)及立方形Ag₃PO₄ (88.1%)。另外,Ag₃PO₄/GO复合材料在光催化降解重复性实验中表现出良好的稳定性,循环五次后对罗丹明B的去除率仍可达95%以上。     

熔盐法制备Mn掺杂TiO_2纳米线及其光催化性能

以硝酸锰(Mn(NO_3)_2)为锰源,P25纳米粒子为钛源,采用熔盐法制备掺杂锰的金红石TiO_2光催化剂。使用SEM、TEM、XRD、EDS等手段对其形貌、结构、物相进行表征,并以罗丹明B为目标污染物,通过调节Mn的掺杂量,探索Mn的掺杂量对可见光催化降解罗丹明B的影响。结果表明:Mn/Ti原子比为1/50的样品(10-MnTiO_2)对罗丹明B降解作用最好,该样品为一维线状结构,结晶度高,且直径分布均一,纵横比高达400以上,其有效催化面积最大。     

同轴静电纺丝技术制备PVA@TiO_2纳米纤维及光催化性能研究

采用同轴静电纺丝技术,以二氧化钛(TiO2)水溶液为壳层、聚乙烯醇(PVA)水溶液为芯层进行同轴静电纺丝,成功制备出了PVA@TiO2纳米纤维光催化材料。通过热重-差热分析(TG-DTA)、X射线衍射、扫描电镜对样品进行了表征。结果显示:TiO2纳米粒子的负载量高达91%,是同类方法的2倍之多,同时具有良好的负载牢固的性能;研究了其在紫外光照射下光催化降解罗丹明B的能力,实验表明,20mL的1×10-5 mol/L罗丹明B溶液在10min内完全降解。     

TiO_2-SiO_2复合多孔材料的低成本制备及表征

以廉价的TiCl4和工业水玻璃为原料,采用溶胶一凝胶法,用无水乙醇对湿凝胶进行溶剂交换处理,通过常压干燥工艺制备了TiO2-SiO2多孔材料。利用SEM、FTIR、BET吸附对多孔材料的形貌和性质进行了研究,分析了TiO2-SiO2多孔材料吸附和光催化降解罗丹明B的性能。结果表明,用3mol／L的TiCl4水溶液制得的TiO2-SiO2多孔材料对罗丹明B有较高的吸附率和光解率;n（Ti）：n（Si）=2：1的TiO2-SiO2多孔材料对罗丹明B有较高的吸附率,而n（Ti）：n（Si）=1：2的TiO2-SiO2多孔材料对罗丹明B有较高的光解率。     

微米级CuFe/CuFeO_2的制备及其类Fenton催化性能

采用两步法,采用水热法以Fe(NO_3)_3·9H_2O、Cu(NO_3)_2·5H_2O作为前驱体,水为溶剂,正丙醛为还原剂,制备了CuFeO_2微米颗粒.为进一步提高其催化活化H_2O2的性能,使用硼氢化钠对其进行了还原处理制备微米CuFe/CuFeO_2催化剂.利用XRD、SEM和XPS对其进行了物相,形貌和表面元素的表征,结果表明所制备的材料为Cu、Fe和CuFeO_2的微米级复合物.以罗丹明B(RhB)为目标污染物,评价了其Fenton催化性能.结果表明:在25℃,CuFe/CuFeO_2催化剂用量为0.5 g/L,H_2O2浓度为40 mmol/L,RhB浓度为10μmol/L,初始pH=5.0时,CuFe/CuFeO_2催化剂在30 min内可降解94.4%的RhB,表观速率常数是相同条件下未处理CuFeO_2的11.6倍.这说明CuFe和CuFeO_2复合可明显增强其催化活化H_2O2的能力.     

铌掺杂Bi3.15Nd0.85Ti3O12陶瓷材料铁电性能

采用高温固相法制备了铌掺杂Bi3.15Nd0.85Ti3O12铁电材料.利用X射线衍射仪、拉曼光谱仪分析样品物相结构,阻抗分析仪和铁电性能测量仪测试电性能.发现制备的陶瓷材料均为单一的层状钙钛矿结构,反映TiO6八面体内部振动情况的850cm-1处拉曼峰随着Nb掺杂量的增加明显上移,表明:TiO6参与取代过程,Ti4+被具有较小离子半径的Nb5+取代.Nb的引入使样品的介电损耗明显降低,居里温度呈下降趋势.随着Nb掺杂量的增加,材料的剩余极化强度先增大后减小,当x=0.03时2Pr达到极大值19.3μC/cm2,矫顽场为57.5 kV/cm.     

Mass Production of Bi_3NbO_7/Bi_2Zn_(2/3)Nb_(4/3)O_7 Composites and Their Visible-light Photocatalytic Activity

Series Bi_3NbO_7/Bi_2Zn_(2/3)Nb_(4/3)O_7 (BN/BZN) composites were synthesized through a facile solid state reaction method. The products were characterized by X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM) and UV-vis diffuse reflectance spectroscopy(DRS). When BN: BZN=0.1 mole ratio, the BN/BZN composite showed the best visible-light-driven photocatalytic performance, which decomposed nearly 100% of Rh B(10 ppm, p H=3-4) within 40 min. The results demonstrated that in-situ solid state synthesis of BN/BZN composites could be an efficient strategy to develop new photocatalyst for environmental remediation.     

纯Bi_(12)SiO_(20)晶体光激发截面的测量

本文用瞬态光电流方法测量了纯Bi1 2 SiO2 0 (BSO)晶体的光激发截面。当脉冲宽度为 7ns、光强为1 35KW/cm2 、波长为 532纳米的脉冲激光照射BSO晶体时 ,得到瞬态光电流的上升时间为 55微秒 ,可计算出BSO晶体的光激发截面S =5 0 4× 1 0 - 2 0 cm2 。利用光激发截面的数值可得出施主浓度ND=3 2× 1 0 1 9cm- 3。     

Effects of Ta addition on the microstructure and mechanical properties of Ti_(40)Zr_(25)Ni_8Cu_9Be_(18) amorphous alloy

The effects of Ta addition on the microstructure and mechanical properties of Ti40Zr25Ni8Cu9Be18 bulk amorphous alloy were investigated by using X-ray diffraction (XRD), transmission electron microscopy (TEM), scan electron microscopy (SEM) and compressive testing. As a result, the addition of Ta (0-8at%) prompted the successive precipitation of quasicrystalline phase, CuTi2 phase and bcc β-Ti solid solution. Additionally, the addition of less Ta content (3at%-5at%) led to the formation of amorphous ma- trix/nanoquasicrystal/CuTi2 complex phase structure; and nanoquasicrystals, as reinforcement precipitates, improved the fracture strength of Ti-Zr-Ni-Cu-Be-Ta alloys, which led to the high compressive fracture strength 1856 MPa of Ta5 alloy. With increasing Ta content (5at%-8at%), although the ductile dendritic β-Ti solid solution was precipitated, the strength and plasticity decreased to a great extent resulting from the growth of quasicrystalline phase and CuTi2 phase.     

Microstructures and Electrical Properties of Bi_(0.5)-(Na_(1-x-y)K_xLi_y)_(0.5)TiO_3 Lead-free Piezoelectric Ceramics

The microstructures and electrical properties of Bi0.5(Na1-x-yKxLiy)0.5TiO3 lead-free piezoelectric ceramics were studied.These ceramics were prepared by conventional ceramic technique.XRD analysis reveals that the ceramics possess almost pure perovskite phase when y≤0.2.The SEM results show that,with more amounts of Li+,the crystalline grain growing speed is accelerated,and the sintering temperature can effectively be decreased.The measurements of piezoelectric properties indicate that the ceramics with relatively low amount of Li+ and high amount of K+ have comparatively large piezoelectricity.The dielectric measurements show that the ceramics have properties like relaxor ferroelectrics and diffuse phase transition(DPT) at Td and Tc,respectively.The results of ferroelectric measurements reveal the system has relatively higher remanent polarization Pr(27.6 μC/cm2) and lower coercive field Ec(37.5 kV/cm).     

Ferroelectric properties of Bi_(3.25)La_(0.75)Ti_(3)O_(12) thin films prepared by sol-gel method

The Bi3.25La0.75Ti3O12 thin films were fabricated on the Pt/Ti/SiO2/Si substrates using sol-gel method. The structure and morphology of the films were characterized us-ing X-ray diffraction and atomic force microscopy. The thin films showed a perov- skite phase and dense microstructure. The 2Pr and 2Vc of the Bi3.25La0.75Ti3O12 thin films annealed at 700℃ were 18.6 μC/cm2 and 4.1 V, respectively, under an applied voltage 10 V. After the switching of 1×1010 cycles, the Pr value decreased to 90% of its pre-fatigue values. The films showed good insulating behavior according to the test of leakage current. The dielectric constant and the dissipation factor of the Bi3.25La0.75Ti3O12 thin films were about 176 and 0.046 at 1 kHz, respectively.     

聚合物造粒对Bi2Se0.3Te2.7粉末流动性和热电性能的影响

采用聚合物造粒的方法,将聚乙烯醇溶液(PVA)和n型Bi₂Se_0.3Te_2.7粉末按一定的配比混合,研究聚合物造粒对Bi₂Se_0.3Te_2.7热电性能的影响。结果表明:造粒后粉体样品的粒径尺寸明显增加,流动性显著提升,其中以PVA与Bi₂Se_0.3Te_2.7质量比1 :10造粒样品的流动性最好;造粒前后,块体样品的电导率、Seebeck系数以及热导率变化范围约在10%以内,总体ZT值变化不大,并且以PVA与Bi₂Se_0.3Te_2.7质量比1 :10造粒样品和Bi₂Se_0.3Te_2.7样品的ZT值在测试范围内几乎相同,均在475 K时达到最大值,约为0.56左右。     

Bi_(3.25)La_(0.75)Ti_3O_(12)纳米材料的水热合成研究

以分析纯硝酸铋、硝酸镧、钛酸四丁酯为原料,采用水热法制备了Bi3.25La0.75Ti3O12(BLT)纳米材料。用XRD和SEM对样品的物相和形貌进行了表征。讨论了矿化剂(NaOH)浓度和水热反应时间对BLT物相的影响。表明合成产物为正交相钙钛矿结构Bi3.25La0.75Ti3O12纳米片,厚度约10 nm,平均边缘尺寸约100 nm。当反应温度为200℃时,反应时间在12 h到48 h,矿化剂浓度在1 mol/L到2 mol/L范围内能有效合成Bi3.25La0.75Ti3O12。     

Domain structure and defects of highly ordered Bi_4Si_3O_(12) micro-crystals

Highly ordered Bi4Si3O12 micro-crystals were prepared at normal atmosphere. Phase identification of the prepared crystals was accomplished by X-ray diffractometer (XRD). Domain structure and defects were characterized by environmental scanning electron microscopy (ESEM). XRD shows that the obtained micro-crystals are of eulytite structure with chemical formulation of Bi4Si3O12. A highly ordered growth pattern is confirmed due to the faster growth of the {124} faces than that of the {204} faces by ESEM. The ...     

Optical Waveguide and Nonlinear Properties of Bi_3NdTi_3O_(12) Thin Films

Neodymium-substituted bismuth titanate (Bi3NdTi3O12, BNT) thin films were prepared on quartz substrates by a metal-organic solution deposition process. The crystalline structure was evaluated by X-ray diffraction. Waveguide property was investigated by using prism coupling technique and optical transmittance measurement. The optical nonlinearities of the film were measured by the top-hat Z-scan techniques and a large positive nonlinear refractive index, nonlinear refractive coefficient and two-photon absorption coefficient were determined to be 3.84×107 esu, 0.7523 cm2/GW and 4.81×104 cm/GW, respectively. These results reveal that the BNT film may be a kind of new multifunctional materials.