钛硅酸钠（Na2Ti2O3SiO4·2H2O）对Cs的吸附热力学分析

钛硅酸钠(Crystalline Sillicotitanate, CST)对铯（Cs）的吸附热力学分析是研究钛硅酸钠吸附铯机理的重要途径之一。本工作通过研究不同温度下CST与不同浓度CsNO₃溶液反应,测定反应前后Cs⁺的浓度变化,得到了一系列参数。结果显示,不同的反应温度对应不同的饱和吸附量,当温度为298.15 、313.15和328.15 K时,饱和吸附量分别为212.8、217.4和232.6 mg/g。分别用Langmuir方程和Freundlich方程对实验数据进行拟合,结果表明,此吸附过程更符合Langmuir等温吸附。在不考虑温度对吸附焓和吸附熵影响的前提下,计算得到吸附焓ΔH=21.28 kJ/mol,ΔS=89.18 J/K/mol以及ΔG<0。以上结果表明,CST对Cs的吸附过程是一个自发进行、既有物理吸附又有化学吸附的吸热反应。     

掺Dy,Tm和Mn的MgSO4磷光体的热释光发光谱研究

用高温固相法研制了MgSO₄:Dy,MgSO₄:Tm和MgSO₄:Mn热释光材料,并通过将MgSO₄:Dy和MgSO₄:Mn混合,以及MgSO₄:Tm和MgSO₄:Mn混合烧结得到了双掺杂样品MgSO₄:Dy,Mn,MgSO₄:Tm,Mn。分别测量了这两种样品在不同热处理温度下的三维发光谱。实验结果表明热处理温度为700℃时的样品,在测量加热过程中观察到Dy和Mn离子分别发光,但超过800℃后,Mn发光强度逐渐变弱,而Tm、Dy的高温发光峰逐渐变强,其它温度的发光峰受到抑制。这表明热释光材料中形成的缺陷复合体结构与热处理温度相关,随着热处理温度的升高,愈来愈多的Mn离子与稀土离子结合紧密,因此在热释光发光谱中清楚地观察到Mn离子对稀土离子的能量转移和对Tm、Dy低于400℃发光峰进行抑制的发光过程。     

Rh/γ-Al2O3催化剂上甲烷-氘化氢间的氢氘交换性能

采用Rh/γ-Al₂O₃催化剂,在固定床微型反应器上实验考察进料组成、反应温度和反应物总流量对甲烷氢氘交换的催化性能的影响。结果表明：在进料组成不变的条件下,当温度低于642K时,甲烷的转化率随温度的升高而快速增加,当温度高于642K时,甲烷的转化率不随温度的升高而变化;在反应温度为524～792K、进料组成不变的条件下,当温度低于642K时,甲烷的转化率随反应物流量的增加而明显减小,当温度高于642K时,甲烷的转化率基本不随温度的升高而变化;在反应温度为524～792K、反应物总流量不变的条件下,当HD/CH₄流量比在1.1～2.5间变化时,甲烷的转化率随HD/CH₄流量比的增加而减小。     

In_(0.95)Ag_(0.045)Ga_(0.005)合金中的电四极相互作用

本文采用时间微分扰动角关联方法,测量了80—422K温度范围内~(111)Cd在In_(0.95)Ag_(0.043)Ga_(0.005)合金中的四极相互作用随温度的变化,进而导出晶格电场梯度的温度变化。在In_(0.95)Ag_(0.043)Ga_(0.005)合金中,晶格电场梯度的温度变化遵从T~(3/2)定律:V_(zz)(T)=V_(zz)(0)(1—BT~(3/2)),斜率B=7.48(47)·10~(-5)K~(-3/2)。在80、298和422K的电场梯度分布宽分别为0.1147(259)、0.0924(340)和1.344(175)。表明在液氮温度和室温时,合金的晶格结构特性较好,温度升高,晶格结构特性变坏。     

磁性MOFs材料Fe3O4@SiO2@UiO-66-SO3H对Co(Ⅱ)的吸附性能

通过水热法制备了磁性MOFs材料Fe₃O₄@SiO₂@UiO-66-SO₃H,并利用红外光谱仪（FT-IR）、X射线衍射仪（XRD）、比表面积测试（BET）、振动样品磁强计（VSM）、X射线光电子能谱仪（XPS）等对材料结构、形貌和性能进行表征。考察了溶液pH值、时间、温度、Co(Ⅱ)初始浓度对Fe₃O₄@SiO₂@UiO-66-SO₃H吸附性能的影响。结果表明,在pH=8.3、温度为298 K下,Fe₃O₄@SiO₂@UiO-66-SO₃H对Co(Ⅱ)的理论最大吸附量为106 mg/g;吸附过程符合准二级动力学模型和Langmuir等温模型,吸附是一个自发的吸热过程。Fe₃O₄@SiO₂@UiO-66-SO₃H在外加磁场下易从水溶液中分离,5次循环后仍具有较强的吸附性能。     

弥散型燃料中Zr与Gd_2O_3的相容性研究

采用包覆热轧法制备了Zr/Gd_2O_3扩散偶,分别在673K和1 073K温度下对Zr/Gd_2O_3扩散偶进行了不同时间的扩散热处理。采用金相显微镜(OM)初步观察Zr/Gd_2O_3界面特征,用场发射扫描电镜(SEM)进一步观察Zr/Gd_2O_3界面形貌,用能谱仪(EDS)分析Zr/Gd_2O_3界面附近元素分布情况,并从热力学角度分析了Zr与Gd_2O_3的相容性。结果表明:2种温度下Zr与Gd_2O_3的相容性很好。     

稀土氧化物Gd2O3、Nd2O3、Sm2O3和Dy2O3在KCl-LiCl-Li2O熔盐中的电解

采用循环伏安法和计时电位法研究了Li₂O在KCl-LiCl熔盐中的电化学行为,并利用卷积伏安法计算了923 K下O₂^-在KCl-LiCl熔盐中的扩散系数（D),得到D=0.5×10^-5 cm²/s。以Gd₂O₃、Nd₂O₃、Sm₂O₃和Dy₂O₃为阴极,在KCl-LiCl-Li₂O(w=1%)熔盐中进行电解（恒电压3.40 V、电解温度923 K、电解时间25 h）。通过X射线衍射分析(XRD),证实稀土氧化物被部分还原为金属,并分析了电解过程中可能发生的反应。同时利用PRS模型（该模型可将固态阴极内离子的极限扩散速率与固态氧化物孔隙P、金属/氧化物摩尔体积R、阴极还原后的体积收缩率S等参数关联）分析了这些稀土氧化物的电解还原模型,得到Gd₂O₃、Nd₂O₃、Sm₂O₃和Dy₂O₃的最优孔隙率分别为18.7%、24.2%、30.6%、16.7%,最短电解时间分别为133、157、143、119 h,将这些结果与电解实验结果进行对比,发现阴极的孔隙率和电解时间均不满足金属氧化物完全被还原的要求,并给出了相应的解释。     

Gd3+掺杂YBCO体系超导电性的正电子研究

为探究稀土离子Gd3 的Y位掺杂对YBa2Cu3O7-δ(YBCO)体系晶体结构和局域电子结构的影响,利用正电子湮没和X-射线衍射(XRD)实验对Y1-xGdxBa2Cu3O7-δ(x=0-1.0)系列样品进行了系统研究.XRD实验表明,Gd离子的Y位替代使得样品晶胞参数增大,但所有样品均保持与YBCO相同的单相正交结构.输运测量表明,各实验样品超导转变温度Tc均在90 K以上,且整体上随Gd3 离子含量的增加而增加.正电子实验结果给出局域电子密度ne随Gd掺杂浓度x的增加而减小.     

聚变堆中第一壁材料钨的紧束缚理论研究

为研究辐照时处于电子激发态下第一壁材料钨(W)的结构演化规律和热力学性质,采用紧束缚方法对聚变堆中W的物理性质进行理论研究。结果表明,体系在高能粒子辐照下诱导的电子激发导致了体系中被辐照的区域自发出现微孔、晶格急剧膨胀、熔点下降等现象。具体地,在中等电子温度(～5 000 K)以下,W的晶格膨胀主要由晶格温度驱动,但在电子温度较高时电子温度导致被辐照区域的晶格膨胀效应不可被忽略。特别是当电子温度很高(10 000 K)时,即便晶格温度不高,电子温度也会导致很大程度晶格膨胀。这对认识聚变堆中第一壁材料W在服役过程中的物理状态十分重要。     

基于气动悬浮的高温氧化物熔体热物性测量

堆芯熔融物的热物性是研究反应堆严重事故进程及堆内堆外现象机理的重要基础参数。当堆芯熔化时，堆内温度达3 000 K,形成U-Zr-O-Fe多元混合物，而气动悬浮技术是优选的高温下测量堆芯熔融物基础热物性的技术。本文描述了一套基于气动悬浮和激光加热技术的密度、表面张力和黏度的测量装置，目前已实现高温氧化物密度的实验测量。装置采用收缩-扩张型锥形喷嘴悬浮球状样品，采用CO₂连续激光器加热并熔化样品，采用双色红外测温仪监测样品的温度并进行激光器功率反馈控制；采用高速相机记录样品轮廓的变化，并结合图像分析法计算样品的体积，最后得到被测材料在高温下的密度。实验测量得到2 750～3 200 K范围内氧化锆熔体的密度，其在熔点(2 988 K)处的密度为4.717 g/cm~3,温度系数为-7.202×10^-4 g/(cm~3·K)。     

La2/3Ca1/3MnO3薄膜结构与输运性质

用磁控溅射方法在不同单晶衬底材料上制备了一系列含La2／3Ca1／3MnO3(LCMO)薄膜。当薄膜厚度大于200A,在我们实验条件下可观测到金属．绝缘体转变,且转变温度随厚度和衬底材料而变化。渗流电阻模型被用来解释薄膜材料的电输运特性,结合薄膜外延特性(晶格失配)和薄膜与衬底的相互作用,及薄膜表面、界面粗糙度的测量可知薄膜的剩余电阻、极化子的激活能、金属．绝缘体转变温度等密切与薄膜质量相关。     

Metal location and thickness in a multilayered sheet by measuring Kα/Kβ, Lα/Lβ and Lα/Lγ X-ray ratios

When a multilayered material is analyzed by means of energy-dispersive X-ray fluorescence analysis, then the X-ray ratios of Kα/Kβ, or Lα/Lβ and Lα/Lγ, for an element in the multilayered material, depend on the composition and thickness of the layer in which the element is situated, and on the composition and thickness of the superimposed layer (or layers).Multilayered samples are common in archaeometry, for example, in the case of pigment layers in paintings, or in the case of gilded or silvered alloys. The latter situation is examined in detail in the present paper, with a specific reference to pre-Columbian alloys from various museums in the north of Peru.     

The crystal structure of Th3B2C3

The crystal structure of Th₃B₂C₃ has been determined by single crystal X-ray analysis. The lattice parameters of the monoclinic cell (first setting) are: $\text{a = 3.703 (2)}\text{A}\text{?}\text{, b = 9.146 (4)}\text{A}\text{?}\text{, c = 3.773 (1)}\text{A}\text{?}\text{and γ = 100.06 (7)°}$; space group: P2/m (C$\text{1}\text{2}{}_{\mathrm{h}}$), Z = 1. Intensity measurements were obtained from a fourcircle diffractometer. The structure was solved by Patterson methods and refined by full matrix least squares calculation. For an asymmetric set of 401 independent reflexions the final R-value is 0.079. The structure contains octahedra, tetrahedra and trigonal prisms of Th-atoms. The trigonal prisms are centered by boron atoms, Th-octahedra by carbon atoms Cl; Carbon atoms C2 actually have octahedral coordination 5 Th + 1 B. The structural chemistry of Th₃B₂C₃ with respect to the crystal structures of ThC and ThBC is discussed.     

Unimolecular isomerization from (CH3)3CNC to (CH3)3CCN induced by infrared free electron laser

Irradiation of IR Free Electron Laser at Tokyo University of Science (FEL-TUS) to t-butyl isonitrile ((CH₃)₃CNC) in the gas phase induced the isomerization reaction to trimethylacetonitrile ((CH₃)₃CCN). From the kinetic analyses, the isomerization reaction was attributed to the IR multiphoton activated unimolecular process. The wide frequency tunability of FEL-TUS enabled us to reveal that the excitation of the NC as well as the CN stretching motion efficiently drove the isomerization.     

Carbon deposition from a γ-irradiated CO2/CO/CH4/C2H6 gas mixture on the manganese oxides MnO, Mn3O4 and Mn2O3

The composition of oxides formed on steel surfaces within power reactors may influence heat transfer efficiency. Previous studies have indicated that carbon is deposited on spinal-type oxides containing manganese, iron, cobalt, nickel and chromium. In this investigation, characterised manganese oxides have been subjected to γ-irradiation under conditions similar to those experienced in reactors in an effort to understand the catalytic processes involved in deposit initiation and growth. Mn₃O₄ and Mn₂O₃, under the conditions present in the γ-cell, were reduced to MnO during the time of exposure. Relative carbon deposition rates were observed to follow the trend MnO>Mn₃O₄≈Mn₂O₃.     

Thermodynamic modelling of LiF-LnF3 and LiF-AnF3 phase diagrams

The phase diagrams of the LiF-LnF₃ series, where Ln = La-Sm, and of LiF-AnF₃, where An = U, Pu, have been optimized using Redlich-Kister functions. The phase diagrams of LiF-AmF₃ and LiF-PuF₃-AmF₃ have been calculated. The necessary Gibbs energy functions for americium trifluoride were defined by use of a semi-empirical method. The excess Gibbs energy terms, which are expressed as Redlich-Kister polynomials and describe the effect of interaction between the two fluoride components in the liquid phase, were obtained by translating the trends observed in the lanthanide trifluoride series into the actinide series. A single eutectic has been found in the LiF-AmF₃ system with the eutectic point at ?33 mole% AmF₃ and at ?951 K.     

基于铌酸银的耐高温放射性碘吸附剂的制备及性能

通过机械混合法制备了一种基于铌酸银(AgNbO_3)的耐高温放射性碘吸附剂(AgNbO_3/Al_2O_3)。和常规载银吸附剂(Ag/Al_2O_3)相比,AgNbO_3/Al_2O_3吸附剂的吸附性能更为稳定;特别是在650℃以上时,其对放射性碘的去污因子远高于常规载银吸附剂。表征测试结果表明,该吸附剂结构稳定性良好,可耐受较长时间的高温。热重测试和高温脱附试验等结果表明,碘化银在AgNbO_3/Al_2O_3吸附剂表面稳定性的提高是该吸附剂在高温时吸附性能更佳的主要原因,其将来有望用于核事故中的应急处置。     

Gd2O3-Nd2O3-ZrO2-CeO2体系的高温固相反应研究

为研究Gd₂O₃-Nd₂O₃-ZrO₂-CeO₂四元氧化物体系的高温固相反应,以Gd₂O₃、Nd₂O₃、ZrO₂、CeO₂混合粉体为原材料,在1 673 K和1 773 K温度下煅烧24、48、72 h,分别制备了系列样品,并对合成样品进行了XRD和SEM分析。结果表明,合成产物为具有缺陷萤石相且伴有少量烧绿石相的Gd_2-xNd_xZr_2-xCe_xO₇（0≤x≤2）晶体化合物。随着煅烧温度的升高和煅烧时间的延长,产物中立方烧绿石相的化合物增多,晶粒尺寸变大,且有少量未知相生成。进而探讨了锆基陶瓷固化多核素的潜在应用,并提出了未来研究的相关热点问题。     

Bulk-compositional changes of Ni2Al3 and NiAl3 during ion etching

Bulk-compositional changes of Ni₂Al₃ and NiAl₃ in a Ni-50 wt% Al alloy during ion etching have been investigated by transmission electron microscopy and energy dispersive X-ray spectroscopic analyses. After etching with 7, 5 and 3 keV Ar⁺ ions for 15, 24 and 100 h nickel contents in both Ni₂Al₃ and NiAl₃ exceeded greatly those in the initial compounds and increased with the decrement of the sputtering energy. After 100 h etching with 3 keV Ar⁺ ions the compositions of these two compounds reached a similar value, about Ni_80-83Al_12-15Fe_3-4Cr_1-2 (at%). A synergistic action of preferential sputtering, radiation-induced segregation and radiation-enhanced diffusion enables the altered-layers at the top and bottom of the film extend through the whole film. The bulk-compositional changes are proposed to occur in the unsteady-state sputtering regime of ion etching and caused by an insufficient supply of matter in a thin film.