共查询到20条相似文献,搜索用时 46 毫秒
1.
用溶胶-凝胶法制备的纳米 TiO_2粉末的结构 总被引:14,自引:0,他引:14
本文采用溶胶-凝胶法制备出纳米 TiO_(2)粉末,并通过热重分析(TG)、差示扫描量热分析(DSC)、X 射线衍射(XRD)、透射电镜(TEM)等实验手段研究了其微观结构及形貌随着热处理温度(T_a)变化的规律。当热处理温度低于500℃时,TiO_2粉末的平均晶粒和颗粒尺寸均小于20nm,所有晶粒均为锐钛矿结构。当热处理温度高于550℃时,TiO_2颗粒及晶粒迅速长大,并且样品中开始出现金红石结构的TiO_2晶粒。当热处理温度高于800℃时,样品中所有晶粒均为金红石结构。 相似文献
2.
溶胶—凝胶法制备纳米钛酸锶 总被引:17,自引:1,他引:16
采用溶胶-凝胶方法,从Sr(AC)2-Ti(OC4H9)4-H2O-isoC3H7OH体系中合成了钛酸锶粉末。DTA和XRD的分析结果表明,在500℃时,开始有立方晶相的SrTiO3生成;反应在800℃基本完成,由Scherrer公式计算,粒径在47.1nm到49.7nm之间。DTA和FT-IR分析结果表明,锶离子和酸根离子均匀地分散于凝胶基体之中,我们还研究了反应物、溶剂等因素对形成钛酸锶凝胶的 相似文献
3.
以正硅酸乙酯 (TEOS)和 Ca(NO3 ) 2 · 4 H2 O为前驱物用溶胶 -凝胶法制备单矿物C2 S粉末。用甘油乙醇法测定 C2 S粉末的游离 Ca O含量 ;用 X射线衍射、红外光谱分析探讨了加水量、溶剂种类以及热处理制度等工艺参数对 C2 S粉末形成的影响 ;用扫描电镜观察水化 2天的 C2 S粉末以证实其活性。 相似文献
4.
以硝酸铜、柠檬酸和氨水为原料,利用柠檬酸溶胶-凝胶法制备含铜凝胶,在氮气气氛下将干凝胶煅烧得到纳米铜粉,探讨成胶反应温度、原料配比、pH等因素对制备过程的影响,确定最低煅烧温度;采用热重-差热分析和红外光谱分析对柠檬酸溶胶-凝胶法制备纳米铜粉的过程进行分析,利用X射线衍射和扫描电镜对实验产物进行结构、形貌表征。结果表明,将柠檬酸与硝酸铜的物质的量比控制为1∶2时溶解混合,调节pH为7,在80℃下制成凝胶,在100℃下干燥后,250℃下煅烧0.5 h,可制得粒径为7090 nm的球型铜粉;推断干凝胶的结构主要为柠檬酸根与铜离子以双齿配位,以及部分为桥式配位。 相似文献
5.
6.
7.
溶胶-凝胶法制备纳米复合材料的研究进展 总被引:1,自引:0,他引:1
溶胶-凝胶法用于制备纳米粒子复合材料,因组分、制备途径和结构等可优化设计,故产物性能优异。本文介绍了溶胶-凝胶法制备的纳米粒子复合材料在光学、电子、磁学、生物、催化等领域的应用和最新研究进展。 相似文献
8.
9.
10.
11.
12.
H. Kuwahara H. Matsuoka I. Tamura J. Takada S. Kikuchi Y. Tomii 《Journal of Materials Science》1992,27(3):637-640
The plasma nitriding behaviour of Fe-18Cr-9Ni alloy was compared with gas nitriding. The alloy was nitrided under the following
conditions: specimen temperature: 823 K, nitriding time: mainly 108 ks, total pressure: 0.4–0.7 kPa, mixture ratio of N2 and H2∶ 0.25, discharge voltage: 350–450 V, current: 0.8–1.1 A. Formation of a surface layer of iron nitrides was not observed.
Formation of a homogeneous internal nitriding layer, consisting of small precipitates of CrN and the γ-phase matrix, was,
however, noted. The lattice constant at the specimen surface was smaller than that at greater depth. This may have been because
the sputtering effect decreased the dissolved nitrogen content at the specimen surface. The sputtering of iron nitrides at
the specimen surface by the plasma was experimentally confirmed through γ′-Fe4N formation on Si beside an alloy specimen. The characteristics of the plasma nitriding mentioned above are discussed in relation
to the sputtering. 相似文献
13.
采用溶胶-凝胶燃烧法制备出掺钐钇铝石榴石(YAG:Sm)荧光粉,并研究了凝胶化加热温度、柠檬酸/硝酸盐比值(MRCM)、pH值等因素对前驱体和YAG粉体性能的影响。结果表明:当加热温度为80℃,MRCM=1~2,pH值在1~3时,凝胶化时间较短,胶体成型情况良好;随着热处理温度的升高,前驱体从金属羧酸盐变成无定形碳酸盐,至900℃转变为纯YAG相。Sm3+:YAG在550~750nm波段内的发射峰对应于Sm3+的4G5/2→6HJ(J=5/2,7/2,9/2和11/2)能级跃迁,其中对应4G5/2→6H7/2跃迁的发射峰强度最大。 相似文献
14.
15.
Hideyuki Kuwahara Hiroaki Matsuoka Jun Takada Shiomi Kikuchi Youichi Tomii Toru Takayama 《Journal of Materials Science》1990,25(9):4120-4124
An Fe-18Cr-9Ni alloy, which it had not previously been possible to nitride at temperatures below 873 K, was found to form nitrides in an ammonia gas atmosphere at temperatures as low as 823 K after annealing at low hydrogen pressure at 1473 K. Microstructure and hardness were examined on cross-sections of the nitrided specimens. An internal nitriding layer had formed beneath an external nitriding layer on the specimen surface. Vickers hardness was above 1000 throughout the internal nitriding layer. The nitrides formed at the specimen surface and in the internal nitriding layer were identified using grazing incidence X-ray diffraction and ordinary X-ray diffraction methods, respectively. The external nitriding layer, which was about 6 to 10 m thick, formed on the surface, which consisted of -Fe2–3N, -Fe4N, and CrN. Two types of chromium nitride were precipitated by ammonia gas nitriding of the present alloy: CrN in the external nitriding layer and Cr2N in the internal nitriding layer. 相似文献
16.
以溶胶-凝胶法制备得到的TiO_2纳米粉体为原料,采用微波法制备TiO_2纳米管,用透射电子显微镜和扫描电子显微镜对纳米管和纳米粉体进行表征,结果表明,制得的TiO_2纳米管形貌比较完整,其外径为8-15nm、内径为5-10nm、长50-100nm,同时发现,未经HCl酸洗的TiO_2纳米管在电镜下非常完整,而经过HCl酸洗的TiO_2纳米管则局部遭到破坏。 相似文献
17.
用溶胶-凝胶技术制备六角晶系BaFe12O19铁氧体超微粉末,采用热分析技术和XRD技术分析了其形成规律,运用扫描探针显微镜分析其微观形态,并测定了常温磁性能。结果表明:BaFe2O4和BaFe12O19的转变温度分别为414.55℃、755.78℃;800℃处理后得到的BaFe12O19超微粉末呈三种不同的形态,分别为圆形、带孔洞的圆形和圆环形;平均粒径为450nm左右;其厚度小于其直径;1000℃处理后的样品完全是BaFe12O19结构,其ds小于粗晶BaFe12O19铁氧体,而Hc大于粗晶肪BaFe12O19铁氧体。 相似文献
18.
19.
采用EDTA络合溶胶-凝胶法合成了中温固体氧化物燃料电池的电解质LSGM8282(La0.8Sr0.2Ga0.8-Mg0.2O3-δ)和LSGMF5(La0.8Sr0.2 Ga0.8Mg0.15Fe0.05O3-δ),比较了LSGM8282和LSGMF5的比表面积、交流阻抗谱、电导率、密度、XRD和FT-IR等,研究了Fe掺杂对LSGM8282性能的影响.结果表明,Fe掺杂使LSGM8282离子的电导率由3.62×10-2S/cm提高到5.21×10-2S/cm,致密度由95.13%提高到97.93%.由此可见,Fe的掺杂使LSGM8282的各种性能均得到一定提升,LSGMF5比LSGM8282更适合作中温SOFC电解质材料. 相似文献