有机溶胶凝胶法制备Al2O3纳米粉及其机理研究

将异丙醇铝分散在有机溶剂中，水解合成超细Al2O3纳米粉。针对纳米粉形成团聚的直接原因，改善了传统工艺，用IR，SEM验证了其合理性，并用TEM对煅烧后的产品进行了表征。     

溶胶-凝胶法制备Al2O3纳米粉

以Al(NO3) 3和NH3·H2 O为原料制备AlOOH勃姆石溶胶 ,加入PVA作为分散剂 ,干燥后制成干凝胶。干凝胶经不同温度下煅烧得到不同晶型的Al2 O3纳米粉。X—射线衍射分析结果表明 ,勃姆石干凝胶在煅烧过程中的物相变化为AlOOH→ε-Al2 O3→ -Al2 O3→δ -Al2 O3→θ -Al2 O3→α-Al2 O3,采用电子显微镜和BET比表面积法测量出Al2 O3纳米粉的颗粒大小     

溶胶-凝胶法制备α-Al2O3微晶陶瓷的研究

以一水氧化铝(AlOOH)为原料,采用溶胶-凝胶法,经搅拌分散、胶溶、凝胶以及凝胶干燥过程制备了α-Al2O3微晶陶瓷的前驱体,热处理得到α-Al2O3微晶陶瓷.通过TG(DTG)-DTA和XRD等分析测试手段,详细考察了胶溶剂、pH值、固含量等工艺参数对α-Al2O3微晶陶瓷性能的影响,得到了合适的工艺参数.     

溶胶-凝胶法掺杂合成α-Fe2O3纳米粉体

采用溶胶-凝胶法制得不同掺杂氧化物（W=5％）的α-Fe2O3纳米粉体材料，利用透射电子显微镜对粉体的粒径和形貌进行了观测；利用XRD对产品的物相进行了．分析，结合谢乐公式对晶体原始尺寸和晶胞进行了计算；对产品的干凝胶原粉做了TG—DTA分析以研究其热稳定性和相变温度。结果表明：合成的产物颗粒呈圆球形，粒径细小。其中掺杂Eu2O3和Y2O3合成的α-Fe2O3纳米粉体粒径较小，仅为22nm和25nm。     

溶胶-凝胶法制备Li-β-Al2O3纳米粉体

以硝酸锂、硝酸铝和碳酸氢铵为原料,采用溶胶-凝胶法制备了Li-β-Al2O3纳米粉体。研究了pH值、热处理温度和锂铝物质的量比[n（Li）/n（Al）]对制备Li-β-Al2O3纳米粉体的影响。用X射线衍射仪（XRD）、场发射扫描电镜（FE-SEM）和自动电位粒度仪对制备的粉体进行了表征。结果表明,当n（Li）/n（Al）=1∶5（为化学计量比时）,pH值在3.6左右时,可得到稳定透明的凝胶,经1000℃热处理后,产物为纯相的Li-β-Al2O3,FE-SEM结果表明粉体的粒度在100nm以内。     

柠檬酸盐溶胶-凝胶法低温合成纳米BaTiO3粉体

利用XRD,DTA,TGA,SEM,TEM等分析手段研究了柠檬酸盐溶胶一凝胶法低温合成Y2O3掺杂的BaTiO3粉体的方法,研究了溶液pH值、水含量、煅烧温度等因素对粉体的影响。结果表明,该方法能在600℃下2h合成单相的四方BaTiO3粉体,粉体的一次颗粒粒径达30nm。     

溶胶等离子喷射合成法制备α-Al2O3纳米材料

利用氢氧化铝溶胶的化学特性和等离子焰的特殊性能，提出了溶胶等离子喷射合成法制备纳米氧化铝，顺利解决了制约等等离子喷射合成纳米材料效率的前驱体溶解度问题，理论收集速度为27．54g/min。通过有机溶剂分散溶胶、二次焙烧等方法对团聚进行了控制，制得的粉末平均粒径为20nm，成发为α－Al2O3。     

溶胶-凝胶法制备氧化硅-氧化铝体系凝胶及合成过程研究进展

氧化硅-氧化铝（SiO₂-Al₂O₃）体系凝胶不仅应用广泛,而且其制备及反应机理还可借鉴到碱激发胶凝材料等领域。通过对溶胶-凝胶法合成氧化硅-氧化铝体系凝胶的制备过程及影响因素和影响规律、凝胶的性质和结构表征及合成机理研究进展进行综述,提出目前仍缺乏有关碱（土）金属离子对凝胶结构性能的影响研究以及硅铝含量变化的定量描述数据,建议拓宽研究范畴,结合核磁共振等检测方法,得出该体系结构性能变化准确数据,为氧化硅-氧化铝体系凝胶的设计和应用夯实基础。     

溶胶-凝胶法制备氧化铝薄膜

以Al(NO3)3·9H2O作为前驱体制备AlOOH溶胶,通过提拉法在不锈钢表面形成氧化物薄膜。探讨了热处理制度和表面处理对薄膜形成过程的影响,并通过XRD和SEM等分析手段对氧化铝薄膜形成过程的物相组成和表面质量进行了分析。实验结果表明:温度在500～800℃,升温速率控制在1.5℃/min,可以得到表面致密的氧化铝薄膜,所制得的薄膜成分以晶态氧化铝和非晶态氧化铝共存,其中晶态氧化铝以γ-氧化铝的形式存在。     

纳米α-Fe2O3的溶胶-凝胶法合成和表征的研究

以FeCl3.6H2O为铁源,采用溶胶-凝胶工艺制备出分散性较好、粒径均匀的纳米α-Fe2O3。系统研究了表面活性剂、pH、煅烧温度对纳米Fe2O3的晶型和粒径的影响,并借助XRD、FTIR、TEM测试手段对产物进行表征。研究发现：加入不同表面活性剂,Fe2O3粒子晶型转变的温度不同。当采用的表面活性剂为十二烷基苯磺酸钠（SDBS）,500℃煅烧前驱物时,发现制备过程中溶液的pH对产物粒子的晶型有较大的影响。     

Preparation of mullite ceramics with equiaxial grains from powders synthesized by the sol-gel method

Four different alumina content of mullite ceramics were fabricated by powders synthesized using the sol-gel method. The synthesis process of powders, microstructure evolution, mechanical and optical properties of the mullite ceramics were studied. The XRD results showed that the precursors transformed into aluminosilicate spinel phase at 1000 °C and mullite phase at 1200 °C. Equiaxial grains were easy to form in the alumina-rich mullite ceramics while elongated grains were easy to form in the alumina-poor mullite ceramics. With the increase of alumina content, the grain size of the samples firstly increased and then decreased, the number of elongated grains decreased while equiaxed grains increased. The flexural strength, compression strength, fracture toughness, and Vickers hardness all decreased firstly and then increased. While the infrared transmittance increased firstly and then decreased. The transmittance at 4 μm (thickness of 0.75 mm) of the ceramics containing 66mol% Al₂O₃ reached the highest (72%) when sintered at 1780 °C because of the equiaxial grains.     

Effect of annealing temperature on the structural and magnetic properties of Ba-Pb-hexaferrite powders synthesized by sol-gel auto-combustion method

The annealing temperature (T_a) dependent development in phase purity, morphology and magnetic properties of Ba_xPb_1-xFe₁₂O₁₉ (x?=?0, 0.2, 0.4, 0.6, 0.8 and 1) powders synthesized via sol-gel auto-combustion route were studied. The hexagonal phase of PbFe₁₂O₁₉ forms directly via solid-state-reaction between α-Fe₂O₃ and PbO during annealing of the combustion product at T_a ~ 900?°C, but the BaFe₁₂O₁₉ phase forms at T_a ~ 1200?°C through the formation of BaFe₂O₄ and α-Fe₂O₃ as intermediate-phases at low T_a. The Ba_xPb_1-x Fe₁₂O₁₉-phase purity of the samples depend on T_a. For T_a >?1000?°C, PbO evaporates from Pb-containing samples. With increasing T_a, growth of hexagonal-shaped sharp-edged particles was observed for Barium-rich samples, however, the sharp-edges dissolute for Lead-rich samples. High saturation magnetization was observed for Ba-rich samples annealed at 1100?°C. For all the studied samples, magnetic coercivity increases with x but decreases with T_a. The magnetic properties were correlated with the structure, microstructure and grain-size of the samples.     

自蔓延低温燃烧-溶胶凝胶合成Ce0.8Sm0.2O1.9及烧结性能

用甘氨酸作还原剂、硝酸盐作氧化剂,采用溶胶-凝胶与自蔓延低温燃烧相结合的方法制备了超细Ce_0.8Sm_0.2O_1.9 (SDC)固溶体,对所合成的粉体分别采用XRD、SEM和BET法进行了表征。结果表明,600℃焙烧产物是具有较高相纯度的单一立方相萤石型结构固溶体,根据XRD估算晶粒度为13～30 nm。甘氨酸与金属硝酸盐(G/N)摩尔比对粉体的微观形貌和烧结性能有很大影响, 当G/N相似文献   

Improved microstructure and sintering temperature of bismuth nano-doped GDC powders synthesized by direct sol-gel combustion

To improve the microstructural and electrochemical properties of Gadolinium-doped ceria (GDC) electrolytes, materials co-doped ceria with bismuth oxide (1–5 mol%) have been successfully prepared in a one-step sol-gel combustion synthetic route. Sol-gel combustion facilitates molecular mixing of the precursors and substitution of the large Bi³⁺ cations into the fluorite structure, considerably reducing the sintering temperature. Adding Bi₂O₃ as a dopant increases the GDC densification to above 99.7% and reduces its traditional sintering temperature by 300 °C. Impedance analyses show that the addition of bismuth enhances the conductivity (3.1?10^?2?1.7?10^?1 S·cm^?1 in the temperature range 600–800 °C) and improves the performance of the solid electrolyte in intermediate-temperature solid oxide fuel cells.     

A study of magnetic film nanocomposites and powders of xerogels synthesized by the sol-gel method

Nanostructured film materials and powders of xerogels have been obtained from sols on the basis of MeO _x -SiO₂ (Me = Fe, Co, Ni, Er) systems and the four-component Fe₂O₃-NiO-Co₃O₄-SiO₂ system using the sol-gel method. Nanocomposite materials have been studied by atomic-force microscopy, X-ray phase analysis methods, and the four-point Brunauer-Emmett-Teller method on thermal desorption of nitrogen. The conditions of the formation of the crystalline phases of metal oxides have been determined and the possibility of obtaining nanostructured materials under conditions of self-assembling with the developed surface has been demonstrated.     

Preparation of zirconia ceramics from powder synthesized by a sol-gel method

Differential thermal and x-ray-phase analysis methods are used to study properties of ZrO₂ powder stabilized with yttrium oxide, prepared by sol-gel technology using an organo-mineral solution. Optimization of powder preparation, including firing and deagglomeration treatment, makes it possible to prepare dense ceramic with a sintering temperature of 1350°C with an average grain size of 250 – 290 nm. Deagglomerated powder may be used as an addition in the preparation of high quality refractories based on oxide raw material.     

Preparation of transparent AlON from powders synthesized by novel CRN method

Aluminum oxynitride (AlON) powders were synthesized by a novel carbothermal reduction and nitridation (CRN) method. Homogenous and fluffy AlOOH/C core-shell nanoparticle precursor was hydrothermally synthesized with aluminum nitrate hydrate, sucrose and urea as starting materials. Then single-phase AlON powders were synthesized by CRN method at 1700 °C for 2 h. The phase transition and growth of Al₂O₃ particles was effectively retarded by the amorphous carbon nano-layers on the surface of precursor, resulting in significantly lower reaction temperature and further smaller particle size. Based on above fine AlON raw material, transparent AlON ceramic was prepared by pressureless sintering at 1880 ℃ with the in-line transmittance above 80 %.     

溶胶-凝胶法制备链霉素分子表面印迹聚合物及其性能表征

以四氢呋喃、乙醇和水的混合溶液(体积比6∶1∶1)为分散剂,3-氨基丙基三乙氧基硅烷和苯基三乙氧基硅烷为功能单体,正硅酸乙酯为交联剂,氨水为催化剂,通过溶胶-凝胶法在二氧化硅微球表面制备了分子印迹聚合物。用分子对接的方法初步分析了链霉素与功能单体和交联剂之间的相互作用,验证了它们形成氢键的可能性。活化时间会影响分子印迹微球的形貌。吸附实验表明,分子印迹微球比非印迹聚合物微球对链霉素具有更优越的吸附性能和选择性。     

溶胶-凝胶法TiO2粉体的制备及表征

采用了一个新的体系合成TiO2粉体,在这个体系中,以钛酸四丁酯为前驱体,盐酸为稳定剂和催化剂,冰乙酸作为抑制剂。对制备TiO2粉体的影响因素进行了分析,并用TEM、XRD对该粉体进行了表征。     

Structural characterization and electrochemical performance of lithium trivanadate synthesized by microwave sol-gel method

The Li_1+xV₃O₈ material was successfully synthesized at 450 °C in short sintering duration by microwave sol-gel route. X-ray diffraction suggests oxygen defects in the lattice. Based on Randles-Sevcik formula, cyclic voltammograms measurements were conducted to measure Li⁺ ion diffusion coefficient. The material exhibits high discharge capacity of 250 mA g⁻¹ at 0.2 mA/cm² after 30 cycles in the range of 2.0-4.0 V. Alternating current impedance tests show that the growth of the charge transfer resistance at 0.4 mA/cm² is more rapid than that of at 0.2 mA/cm² as the galvanostatical charge-discharge continues.