稀土掺杂γ—Fe2O3气敏材料研究

采用化学共沉淀法合成了具有良好气敏特性的γ—Fe_2O_3微粉。通过稀土掺杂使γ—Fe_2O_3的显微结构得到改善,相转变温度得到提高,进而改善了γ-Fe_2O_3气敏材料的稳定性,提高了气体检测灵敏度。另外,不同稀土元素的掺杂使γ—Fe_2O_3气敏材料的气敏选择性得到改善。     

氧化法制备纳米级α—Fe2O3气敏陶瓷粉体的比较

分别用空气氧化和Ｈ２Ｏ２氧化沉淀法制得了纳米级。α－Ｆｅ２Ｏ３气陶瓷粉料，对粉体进行了ＸＲＤ物相分析及晶粒度，晶格畸变率的测定，以ＴＥＭ观察其形貌并测得了平均粒径，采用迎头色谱法测定其比表面积。     

Nd2O3掺杂对SnO2气敏性质的影响

SnO_2是目前应用最广的一种气敏材料。我们曾经报道掺入La_2O_3,CeO_2,Pr_6O_(11),和Nd_2O_3后可使半导体元件的灵敏度提高,尤以对乙醇、乙醚、丙酮为显著。掺Nd_2O_3元件对乙炔的灵敏度也有提高。本文考察了SnO_2粒度和被测气氛的物化性质对掺Nd_2O_3元件灵敏度的影响。SnO_2采用水解SnCl_4法制备,纯度经光谱分析测定合格,试样用标准筛分目。在SnO_2中加1wt%Nd_2O_3(光谱纯)和适量水及甲基纤维素,混磨15分钟。将制成的悬浊液滴在一对铂     

气敏半导体材料Cd2Sb2O6.8的制备及其性能研究

采用化学共沉淀法,在较低温度(750℃)下制备了具有缺陷烧绿石结构的复合氧化物Cd₂Sb₂O_6.8的纯相超微粉;研究了制备条件对物相、结构和气敏性能的影响,并对其反应过程机理进行了探讨,气敏性能测试结果表明,纯相Cd₂Sb₂O_6.8气敏元件对乙炔气体有较高的灵敏度和较好的选择性.     

WO3基气敏材料研究进展

综述了近年来国内外对WO3基气敏材料的研究状况,对制备工艺、防团聚技术、掺杂效应及气敏机理等进行了分析比较,并对今后的研究方向提出了一些看法。     

WO_3基气敏材料研究进展

综述了近年来国内外对WO3 基气敏材料的研究状况 ,对制备工艺、防团聚技术、掺杂效应及气敏机理等进行了分析比较 ,并对今后的研究方向提出了一些看法     

Sn-Zn-Fe复合氧化物气敏材料的制备与气敏性能

在材料的合成与制备、组成与结构、性能及使用效能四者之间存在着强烈的相互依赖关系[1 ] 。一种材料的性质与其组成及结构息息相关 ,而组成与结构又是合成和制备的结果。合成与制备是提高材料质量的关键 ,也是开发新材料、新器件的中心环节。鉴于此 ,本文在前面工作[2～ 4] 的基础上 ,应用正交试验方法[5] ,探讨ｐＨ值、温度、搅拌速度三共沉淀反应条件对Ｓｎ Ｚｎ Ｆｅ复合氧化物气敏性能的影响。1　实验部分1 1　敏感材料的制备按表 1设计的正交试验方案 ,取物质的量相同的Ｓｎ、Ｚｎ、Ｆｅ氯化物混合液 ,在不同温度、搅拌速度条件下 ,…     

常温SnO_2-α-Fe_2O_3气敏元件制备

用a-Fe_2O_3研制成的加热式气敏元件功耗大(约1.5W)。常温SnO_2-a-Fe_2O_3气敏元件功耗低(约0.1W),灵敏度高,响应恢复快,稳定,具有一定选择性。 气敏元件制备方法:按62.5％,6.2％和31.3％称取SnO_2,a-Fe_2O_3和硅胶,加水研磨2小时,使其呈浆糊状,点入模具内,放入一对φ0.05mm铂丝电极,晾干,脱模,在860～890℃空气中烧结95分钟。     

Thermal oxide synthesis and characterization of Fe_3O_4 nanorods and Fe_2O_3 nanowires

Fe3O4 nanorods and Fe2O3 nanowires have been synthesized through a simple thermal oxide reaction of Fe with C2H2O4 solution at 200-600℃ for 1 h in the air. The morphology and structure of Fe3O4 nanorods and Fe2O3 nanowires were detected with powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The influence of temperature on the morphology development was experimentally investigated. The results show that the polycrystals Fe3O4 nanorods with cubic structure and the av...     

SELECTIVE PRODUCTION OF C_2 AND C_3ALCOHOLS FROM SYNTHESIS GAS

IntroductionTheaimofprcscllt\t-orbisthedot'clopmcntofcatal}-stsu'hicharchighl}'sclccti\'ctothes"nthcsisofCZandC3alcoholsfronls}'llgas.Cocatal}'stscanenhancetheproductionofCZalcohol.butthe}'arcalsoacti\'cfortheF-Ts}.nthcsisint'hichtheproductdistributionfol…     

可见光下尖晶石型氧化物ZnFe_2O_4的制备及性能研究

A spinel-type oxides ZnFe_2O_4 photocatalysts were prepared by citric acid complex method,and characterized with XRD,TG- DTA,FT-IR,TEM techniques.The photocatalytic activities were investigated by the degradation of C_3H_(22)N_6O_6S_2Na_2 by artificial visible Light.The results show that the photocatalytic activity of ZnFe_2O_4 is stable,under experimental conditions,the degradation rate of C3H22N6O6S2 is over 90% in 60min.     

Enhancement of H2 Sensing Properties of In2O3-based Gas Sensor by Chemical Modification with SiO2

The sensitivity and selectivity to H2 of a new In203-based gas sensor were improved significantly by surface chemical modification. A dense layer of SiO2 near the surface of the porous In2O3 bead was formed by chemical vapor deposition (CVD) of diethoxydimethysilane (DEMS). The dense layer functioned as a molecular sieve, thereby the diffusion of gases with large molecular diameters, except for 1-12, was effectively controlled, resulting in a prominent selectivity and high sensitivity for H2. The working mechanism of the sensor was also presented.     

纳米氧化锌的乳液合成、结构表征与气敏性能

利用化学沉淀法、乳液法及微乳液法合成了不同晶粒尺寸的纳米氧化锌气敏材料；用X射线衍射和透射电镜、研究了材料的晶体结构和陶瓷微结构，并利用科西-科西法和德拜-谢乐法计算了材料的平均晶粒度和晶格畸变；和静态配气法测试了材料对乙醇、汽油、氢气、丁烷、六氟化硫的气体灵敏度。实验结果表明：微乳液法和阴离子表面活性剂乳化法合成的氧化锌具有颗粒小，气体灵敏度高和工作温度低的特点。     

OXIDATIVE COUPLING OF METHANE OVER Mn_2O_3-Na_2WO_4/SiO_2 CATALYST IN THE ABSENCE OF DILUTE GAS

The oxidative coupling of methane over Mn2O3-Na2WO4/SiO2 catalyst has been investigated in the absence of dilute gas. 16.4% of C2 yield and 80.4% of the selectivity to C2 hydrocarbons were obtained at CH4/O2 = 8.5/1.5. The effect of flow rate on the selectivity to C2 hydrocarbons and CH4 conversion was different under the reaction condition of different ratio of CH4 to oxygen. The flow rate had a more remarkable effect on the selectivity at the lower ratio of methane to oxygen. The addition of steam into the reaction gas can increase C2 yield to some extent, but that of HC1 decrease the selectivity to C2 hydrocarbons.     

水煤气变换催化剂Co—Mo—K／Al2O3的酸性对活性的影响

用吡啶吸附法研究了Co-Mo-K/Al_2O_3催化剂的酸性,K的加入,由于改变了催化剂的酸性,使其活性得以提高,硫的丢失也可改变酸性,但使催化剂的活性降低。初步探讨了催化剂酸性对活性影响的实质,提出了新的反应机理。