(Ca,Fe)共掺铈酸镧陶瓷的近红外吸收性能

以氧化镧、氧化铈、氧化钙、氧化铁为原料,采用高温固相烧结工艺制备(Ca,Fe)共掺的系列铈酸镧红外吸收陶瓷(La2–xCaxCe2–yFeyO7)。结果表明:所有样品的晶相均为萤石结构;(Ca,Fe)共掺后引入了杂质能级,强化了自由载流子吸收,进而实现了样品近红外波段(750~2 500 nm)性能由高红外反射向高红外吸收的转变。当Ca引入量x为0.1、Fe引入量y为0.15时,样品近红外吸收性能较优,在750~2 500 nm波段的平均吸收率为88.7%,较未掺杂样品同波段的平均吸收率(4.9%)提高了17倍。     

新型纳米氧化钨的近红外吸收性能

采用化学沉淀法制备纳米氧化钨粉体,并用氢氮混合气对其进行还原处理,分析了还原处理温度对氧化钨化学组成的影响,用 X 射线粉末衍射仪表征了纳米氧化钨粒子的晶相与化学组成,采用扫描电子显微镜观察了该粒子还原处理前后的晶相形貌,并测定了由该纳米颗粒还原前后制得的胶状液体从可见光到近红外波长范围内的吸收光谱和透过光谱。研究表明：还原后的氧化钨纳米粒子对 1400～1600nm 和 1900～2200nm 波段的近红外光具有显著的吸收增强效应,同时对可见光具有很高的透过性,这种具有特殊光学吸收特性的纳米氧化钨可望在新型太阳能热屏蔽器件的设计中得到应用。     

Effect of Adhesion on Aggregation in Nanoparticle Dispersions

The detailed structure of a dispersed nanoparticle suspension has been studied by transmission electron microscopy and dynamic light scattering for comparison with an off-lattice gas computer model. For low adhesion between particles, the structure of the suspension is shown to be a “gas with clusters” phase of particles comprising aggregates ranging from singlets, doublets, triplets, etc. to 16-plets in a continuous distribution. Further increasing the adhesion between the particles reduces the number of singlets and causes larger aggregates to form, without precipitation, as some condensed phase appears in the gas. This phase appears as metastable clumps, which do not grow rapidly until adhesion is raised. Then, at high adhesion, flocculation occurs with aggregates growing with time and a large reduction in the number of singlets. Experiments on monosize 62-nm-diameter hematite particles in water confirm this behaviour. An off-lattice computational model based on a square well adhesion potential qualitatively described the dynamic light scattering and transmission electron microscopy results.     

Effect of Adhesion on Aggregation in Nanoparticle Dispersions

The detailed structure of a dispersed nanoparticle suspension has been studied by transmission electron microscopy and dynamic light scattering for comparison with an off-lattice gas computer model. For low adhesion between particles, the structure of the suspension is shown to be a “gas with clusters” phase of particles comprising aggregates ranging from singlets, doublets, triplets, etc. to 16-plets in a continuous distribution. Further increasing the adhesion between the particles reduces the number of singlets and causes larger aggregates to form, without precipitation, as some condensed phase appears in the gas. This phase appears as metastable clumps, which do not grow rapidly until adhesion is raised. Then, at high adhesion, flocculation occurs with aggregates growing with time and a large reduction in the number of singlets. Experiments on monosize 62-nm-diameter hematite particles in water confirm this behaviour. An off-lattice computational model based on a square well adhesion potential qualitatively described the dynamic light scattering and transmission electron microscopy results.     

硅酸盐水泥熟料Fe还原态的近红外吸收光谱特性研究

采用紫外可见近红外分光光度计对某水泥生产企业的氧化熟料和还原熟料、不同IM的氧化熟料和不同温度(900～ 1300℃)条件进行氧化(30 min)的还原熟料进行了检测分析,发现各类熟料的表观吸收率和处于λ=1437nm处的吸收峰均有差异,进一步归纳分析表明,熟料中的Fe3+的含量越高,处于λ=1437 nm处的光谱吸收越强,近红外波段处的表观吸收率也随之增大.近红外吸收光谱中的λ=1437 nm吸收峰和近红外波段处的表观吸收率可以用于表征硅酸盐水泥熟料中的Fe3+含量.     

Soft X-ray Absorption Near Edge Structure Analysis on Lithium Manganese Oxide Prepared by Microwave Heating

Microwave heating, which is recognized as a time-saving and an energy-efficient process, was used to synthesize manganese oxide from various starting materials. LiOH and MnO₂ (electrochemically prepared manganese dioxide, EMD) were used as starting materials; ε-MnO₂-type lithium manganese oxide that showed excellent cycle ability was the result of 3 min of microwave heating. A change in electronic structure was investigated using manganese L -edge and oxygen K -edge X-ray absorption spectroscopy (XAS). The XAS results indicated that the oxidation-reduction reaction took place in the manganese 3 d and in the oxygen 2 p orbitals during the charge-discharge process and that Jahn-Teller distortion occurred in the reduced samples.     

纳米氧化铈制备进展

简述了纳米氧化铈的几种制备方法,着重介绍了液相制备法中的微乳液法,比较了各自的优缺点。并展望了今后制备技术的发展方向。     

Co-Nd复合氧化物纳米微粒的制备与表征

以硝酸钴,硝酸钕,柠檬酸为原料,采用溶胶-凝胶法制得Co-Nd复合氧化物的前驱体,分别置于马弗炉中于500、600、800、1 000℃下煅烧得黑色的微粒,用X射线衍射技术对产物的物相,粒径进行了表征.结果表明:800℃的产物晶型最好,且分布均匀,达到纳米级,平均粒径为30 nm.     

Infrared Properties of Magnesium Oxide

The absorption spectrum of polycrystalline and single-crystal magnesium oxide was determined in the 4000 to 166 cm⁻¹ spectral region. In the range 4000 to about 1100 cm⁻¹, the absorption coefficient of the polycrystalline MgO was higher than that of the single-crystal MgO owing to scattering by the grain boundaries. This scattering decreased with increase of the grain diameter. No difference in reflectivity could be detected between the polycrystalline and single-crystal material in the 4000 to 300 cm^−lwave number region. The optical constants, n and k, were determined by the classical dispersion theory, assuming a single oscillator. From the maximum reflectivity, the resonance frequency was at 428 cm⁻¹; the value obtained from the acoustical vibration was at 475 cm⁻¹. The corresponding s factors were 0.64 and 0.72, respectively.     

近红外染料的进展

近年来,近红外染料作为一类十分重要的有机功能染料,逐渐被人们认识和研究.本文就这种染料的结构类型、合成路线、应用方面的进展以及激光调Q、锁模技术的发展和应用进行了详细评述.     

反应时间对钽掺杂球形氧化钨性能的影响

以Ta Cl5和Na2WO4为原料,采用水热法在170℃保温6h~48h合成钽掺杂球形氧化钨。利用XRD、SEM等手段对产物进行物相、形貌表征。研究表明:水热反应时间为6h~48h均能获得三斜晶型的氧化钨球,球体尺寸在200nm~350nm之间。对不同反应时间条件下合成的氧化钨球进行紫外-可见光的吸收光谱分析可知,随着反应时间的增加,获得钽掺杂氧化钨样品对光的吸收能力增强,平均禁带宽度为3.72e V。     

Infrared Multiphoton Absorption by Methanol

The multiphoton absorption of CO₂ laser 9 μm P(18), P(20) and P(34) lines by methanol has been studied for fluences from 10⁻³ to ∼ 20 J/cm², pulse widths of 6 and 60 ns FWHM and methanol pressures from 0.067 to 13.3 kPa. The absorption depends on laser fluence, laser line and gas pressure but not on laser beam intensity. For each line studied the results can be expressed as a function of fluence and the product of pressure with pulse width. Absorption by a Q-branch transition (9P(34) pumping) shows a faster relaxation and a stronger absorption than R-branch transitions (9P(18) and 9P(20) pumping). The results obtained here are compared to multiphoton absorption data for an HF laser pumping the OH stretch vibration.     

Infrared Absorption Coefficients of Silica Glasses

The absorption coefficient values of several silicate glasses in the IR radiation range were determined. Four methods were employed in this study: (1) direct transmission by CO₂ laser, (2) direct transmission through ultrathin sections using an IR spectrometer, (3) glass particle dispersions in KBr pressed pellets, and (4) IR reflection spectral analysis. Wide variations in values were observed for some of these techniques. The reasons for the variations were explored, and evidence is presented to support the conclusion that the reflection measurements and the low-power transmission technique yield accurate values. The pellet technique was found to possess too many experimental variables which could not be controlled and gave erroneous data. The damage produced by direct transmission of high-power radiation was severe and introduced effects which gave spurious results.     

Infrared Absorption Spectrum of Silicon Dioxide

The absorption spectra of fused silica and α-quartz were investigated in the 2600 to 50 cm⁻¹ wave number region. Only part of the absorption frequency bands of the crystal quartz appeared in the fused state and some of them were shifted to higher wave numbers. The principal absorption frequencies in the fused silica were at 1126, 809, 452, and 200 cm⁻¹ It is proposed that the infrared spectrum of the fused silica results from two vibrating units, of point group T_d and D_{3 h} , simultaneously. In the vitreous state, some of the Si-O-Si bonds are disrupted allowing random orientation of the tetrahedral SiO₄ groups (point group T_d). As a consequence of the formation of nonbridging oxygen, the force constant will be increased, as indicated by the shift of the vibrational frequencies to higher values. For every nonbridging oxygen atom formed, the silicon atom previously connected to it would be left with a positive hole. The point group D _{3 h} is due to such a silicon atom and its v ₃ and v ₄ modes coincide with the v ₃ and v ₄ modes of the T_d point group.     

近红外光谱分析技术在石油化工中的应用

介绍近红外光谱分析技术的工作原理、光谱的预处理方法、定量分析方法、定性分析方法,综述了近红外光谱分析技术在石油化工领域中的应用现状,并对目前近红外光谱分析技术的发展方向作了简单的评论。     

岛状硅酸盐宝石矿物的近红外光谱特征研究

利用傅里叶变换红外光谱仪对岛状硅酸盐宝石矿物的近红外光谱进行测试分析,结果表明:该类矿物的近红外吸收主要以水分子与羟基的倍频、组合频峰为主;7000 ～ 7246 cm-归属于为结构水伸缩振动的一级倍频,5000 ～5260 cm-峰形宽缓,归属为吸附水振动,4628 ～4347 cm-1一般为-OH与金属阳离子-OH的吸收峰;OH与不同的金属阳离子结合往往形成不同的振动带,托帕石中Al-OH的吸收在4525 cm-1、4645 cm-1,蓝晶石的Al-OH吸收在4525 cm-1、4622 cm-1,绿帘石Fe-OH的吸收在4437 cm-1;蓝晶石近红外光谱羟基的吸收源于结构中不同位置的O不受Si的约束被OH取代而产生;近红外光谱水峰可以判断锆石与变生锆石.     

近红外光谱技术在药物分析中的应用

近红外光是介于可见光和中红外光之间的电磁波,根据美国实验和材料检测协会(ASTM)的定义是指波长在780~2 526nm的电磁波,通常分为近红外短波和近红外长波。近红外光谱属于分子振动光谱的倍频和主频吸收光谱,穿透力较强。近红外光谱分析技术是大型化工、食品加工、制药等领域生产所必须的重要分析技术之一。阐述了近红外光谱技术在药物分析中的应用及该技术的特点和分析方法原理。     

Infrared Absorption Spectroscopy in Zirconia Research

Infrared absorption spectra are shown for monoclinic ZrO₂ and for cubic stabilized ZrO₂. Nine bands are reported in monoclinic ZrO₂ in the region 800 to 200 cm^−l, whereas only one broad band is observed in cubic ZrO₂ over the same frequency range.     

氧化钨改性的氧化钛固体超强酸催化剂的研究

通过偏钨酸铵水溶液浸渍TiO2(xH2O粉末和空气中高温焙烧制备了氧化钨改性的TiO2固体超强酸催化剂,用N2-吸附、Hammett指示剂法、NH3-TPD、吡啶吸附-FT-IR、XRD和LRS进行了表征.WO3含量低于15% (wt)之前,氧化钨物种和TiO2之间的强相互作用稳定了氧化钨物种以及氧化钨物种在TiO2的表面上高度分散, 氧化钨抑制了TiO2的锐钛矿晶相向金红石晶相的转变,催化剂的表面积、孔容、孔径和酸量随着WO3含量的增加而增大.WO3含量超过15 %(wt),500℃焙烧催化剂中出现WO3晶相.加入少量的WO3,催化剂的酸强度和酸量明显增加,其表面上同时存在L酸中心和B酸中心以及L酸中心和B酸中心可以相互转化.氧化钨改性的TiO2固体超强酸在草酸和异戊醇的酯化反应中具有良好的催化性能.