Enthalpy measurements of La2Te3O9 and La2Te4O11

Enthalpy increment measurements on La₂Te₃O₉(s) and La₂Te₄O₁₁(s) were carried out using a Calvet micro-calorimeter. The enthalpy values were analyzed using the non-linear curve fitting method. The dependence of enthalpy increments with temperature was given as: H°(T) − H°(298.15 K) (J mol⁻¹) = 360.70T + 0.00409T² + 133.568 × 10⁵/T − 149 923 (373 ? T (K) ? 936) for La₂Te₃O₉ and H°(T) − H°(298.15 K) (J mol⁻¹) = 331.927T + 0.0549T² + 29.3623 × 10⁵/T − 114 587 (373 ? T (K) ? 936) for La₂Te₄O₁₁.     

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。     

Reactivity of hydrogen peroxide towards Fe3O4, Fe2CoO4 and Fe2NiO4

The kinetics of CRUD oxidation by H₂O₂ has been studied using aqueous suspensions of metal oxide powder. Fe₃O₄, Fe₂CoO₄ and Fe₂NiO₄ were used as model compounds for CRUD. In addition, the activation energies for the reaction between H₂O₂ and the three CRUD models were determined. The rate constants at room temperature were determined to 6.6 (±0.4) × 10⁻⁹, 3.4 (±0.4) × 10⁻⁸ and 1.6 × 10⁻¹⁰ m min⁻¹ for Fe₃O₄, Fe₂CoO₄ and Fe₂NiO₄, respectively. The corresponding activation energies are 52 ± 4, 44 ± 5 and 57 ± 7 kJ mol⁻¹, respectively. The mechanism of the reaction is briefly discussed indicating that the final solid product in all three cases is Fe₂O₃. In addition to the experimental studies, the theoretical grounds for kinetics of reactions in particle suspensions are discussed. The theoretical discussion is also used to explain the somewhat unexpected trends in reactivity observed experimentally.     

Radiation effects on PbO-Al2O3-B2O3-SiO2 glasses by FTIR spectroscopy

The infrared absorption spectra of PbO-Al₂O₃-B₂O₃-SiO₂ glasses have been measured in the spectral range 600-4000 cm⁻¹ before and after absorbed dose of 50 Gy, 4 kGy and 50 kGy to investigate the structural change due to irradiation. The structural change due to composition has also been discussed. The experimental results clearly indicate that after irradiation, a significant change in structure of lead alumino borosilicate glass network is observed. It was shown that BO₄ groups decreases and BO₃ groups increases with the increase of Al₂O_3.     

XRD investigation of ion irradiated Ti3Si0.90Al0.10C2

Ti₃SiC₂ is one of the most promising materials belonging to M_n+1AX_n phases, which exhibit good damage tolerance, thermal stability and mechanical properties.Recently, in the frame of research on future gas cooled fast nuclear reactors, Ti₃SiC₂ has been considered as an innovative candidate material, which could be incorporated in some core components such as fuel cladding. At the present time, however, very few data are available concerning the behaviour of this material after irradiation. In this work, Ti₃Si_0.90Al_0.10C₂ samples were irradiated with high energy Kr and Xe ions and characterized by X-ray diffraction. Patterns were analysed in terms of change in peak intensity, peak position and width. Rietveld refinements were also performed. Increase in micro-strains and lattice parameter with irradiation dose was highlighted. The formation of β-Ti₃SiC₂, which has never been observed by experimental XRD on non irradiated material, was proposed for the highly irradiated samples. A partial recovery of the microstructure with temperature was found.     

HfO2 and Ta2O5 as grain growth inhibitors in Eu2O3

Because of the high neutron capture cross section for five consecutive europium isotopes, Eu₂O₃ is of interest as a control material for nuclear reactors. A tendency toward excessive grain growth degrades its mechanical properties. Small amounts of HfO₂ and Ta₂O₅ were added to the Eu₂O₃ in attempts to suppress this grain growth. Three at % substitution of Hf for     

热-水-力-化学耦合作用下Ca0.86Nd0.14Ti0.86Al0.14SiO5固溶体的化学稳定性

以CaCO₃、Nd₂O₃、TiO₂、SiO₂、Al₂O₃为原料,用固相法制备掺钕榍石固溶体（Ca_0.86Nd_0.14Ti_0.86Al_0.14SiO₅）。采用PCT法进行浸泡实验,借助X射线衍射（XRD）、扫描电镜（SEM）、电感耦合等离子体发射光谱（ICP-OES）等分析手段,研究掺钕榍石固溶体在热 水 力 化学（THMC）耦合作用下的化学稳定性。结果表明,在pH值为5～9、温度150～200 ℃、压强0.476～1.554 MPa的耦合作用下,Ca_0.86Nd_0.14Ti_0.86Al_0.14SiO₅固溶体具有良好的化学稳定性;pH值、温度（压力）对Ca_0.86Nd_0.14Ti_0.86Al_0.14SiO₅固溶体中Si⁴⁺、Al³⁺、Nd³⁺的归一化浸出率无明显影响;Ca²⁺在200 ℃（1 554 MPa）时的抗浸出性能较150 ℃时的好;在浸泡初期（1～21 d）Ca²⁺在pH值为9时的抗浸出性能优于pH值为5和7时的,浸泡后期（28、42 d）3种溶液中固溶体的Ca²⁺抗浸出性能趋于一致;Ti⁴⁺在pH值为9时的抗浸出性能较pH值为5和7时的好。     

NHO3氧化去除Np—Pu反萃液中的H2C2O4

研究了用ＮＨＯ３氧化去除ＴＲＰＯ流程反萃Ｎｐ－Ｐｕ的Ｈ２Ｃ２Ｏ４反萃液中Ｈ２Ｃ２Ｏ４的条件。７．５ｍｏｌ．Ｌ＾－１ＨＮＯ３－０．３ｍｏｌ．Ｌ＾－１Ｈ２Ｃ２Ｏ４混合液于９０℃下蒸发１３０ｈ和１００℃下蒸馏回流６ｈ，Ｈ２Ｃ２Ｏ４可完全分解去除；混合液中添加适量催化剂ＭｎＣＯ３，于１００℃下蒸发或蒸馏回流，Ｈ２Ｃ２Ｏ４分解加速，１－１．５ｈ内Ｈ２Ｃ２Ｏ４完全分解。蒸发或蒸馏回流过程中产生的ＨＮＯ２把Ｎｐ     

Thermal expansion studies on UMoO5, UMoO6, Na2U(MoO4)3 and Na4U(MoO4)4

In the present work, thermal expansion behavior of lower valent sodium uranium molybdates, i.e., Na₂U(MoO₄)₃ and Na₄U(MoO₄)₄ were studied under vacuum in the temperature range of 298-873 K using high temperature X-ray diffractometry (HTXRD). Expansion behaviors of UMoO₅ and UMoO₆ were also studied in vacuum from 298 to 873 K and 773 K, respectively. UMoO₅ was synthesized by reacting UO₂ with MoO₃ in equi-molar proportion in evacuated sealed quartz ampoule at 1173 K for 14 h. Na₂U(MoO₄)₃ and Na₄U(MoO₄)₄ were prepared by reacting UMoO₅ and MoO₃ with 1 and 2 moles of Na₂MoO₄, respectively, at 873 K in evacuated sealed quartz ampoule. XRD data of UMoO₅ and UMoO₆ were indexed on orthorhombic and monoclinic systems, respectively, whereas, the data of Na₂U(MoO₄)₃ and Na₄U(MoO₄)₄ were indexed on tetragonal system. The lattice parameters and cell volume of all the four compounds, fit into polynomial expression with respect to temperature, showed positive thermal expansion (PTE) up to 873 K.     

Er2Fe17—xAlx（x=2,5）化合物的中子衍射研究

利用Rietveld分析方法对Er2Fe17-xAlx(x=2,5)在室温下的中子衍射数据进行了精修。Er2Fe15Al2化合物具有Th2Ni17型六角结构,空间群为P63／mmc,Al原子分别占据12j(占位数0．21）和12k(占位数0.13)位;Er2Fe12Al5化合物具有Th2Zn17型三角结构,空间群为R3m,Al原子分别占据18f(占位数0．35）、18h(占位数0．36）和6c(占位数0．37）位。所有的Fe原子磁矩间为铁磁性耦合。Er原子磁矩与Fe原子磁矩间为亚铁磁耦合。在2个样品中,磁矩均位于垂直于六重轴的平面内,呈面磁晶各向异性。给出了居里温度Tc,并对磁性能和结构之间的关系进行了简单的讨论。     

Molecular dynamics simulations of C2, C2H, C2H2, C2H3, C2H4, C2H5, and C2H6 bombardment of diamond (1 1 1) surfaces

The sticking and erosion of C₂H_x molecules (where x=0-6), at 300 and 2100 K onto hydrogenated diamond (1 1 1) surfaces was investigated by means of molecular dynamics simulations. We employed both quantum-mechanical and empirical force models. Generally, the sticking probability is observed to somewhat increase when the radical temperature increases and strongly decrease with increasing number of H atoms in the molecule.     

Swift heavy ion irradiation-induced microstructure modification of two delta-phase oxides: Sc4Zr3O12 and Lu4Zr3O12

Swift gold ions (185 MeV) were used to systematically investigate the radiation damage response of delta phase compounds Sc₄Zr₃O₁₂ and Lu₄Zr₃O₁₂ in the electronic energy loss regime. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD investigations indicate a phase transformation from ordered rhombohedral to disordered fluorite (O-D) in both compounds, with the Sc compound transforming at a higher ion fluence compared with the Lu compound. This result is consistent with our previous study on Sc₄Zr₃O₁₂ and Lu₄Zr₃O₁₂ under displacive radiation environment in which the nuclear energy loss is dominant. High resolution TEM revealed that individual ion tracks maintain crystalline structure, while the core region experiences an O-D phase transformation. TEM observations also suggest that for the doses in which the tracks overlap, the O-D phase transformation occurs across the entire ion range.     

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.     

Electrical properties of annealed, fully metamict REE2FeBe2Si2O10

The electrical properties of annealed, fully metamict gadolinite REEFe²⁺Be₂Si₂O₁₀ are studied as a function of annealing temperature. Changes due to annealing are also probed by ⁵⁷Fe Mössbauer spectroscopy and X-ray diffraction. The electrical conductivity measured at f = 100 Hz between 110 and 750 K varies markedly, ranging from 10⁻¹⁰ to 10⁻⁶ S m⁻¹ for untreated samples and 10⁻⁹ to 10⁻³ S m⁻¹ for sample annealed in argon at 1373 K. Average measured activation energies for electrical conduction are 0.47 and 0.63 eV for ranges of 400-450 K and 500-600 K, respectively. The dielectric permittivity shows strong dispersion effects above 235 K. After high temperature annealing, the electrical conductivity shows a marked dispersion below 604 K. The combination of polaron hopping and hydroxyl anion migration is proposed for the electrical conduction mechanism.     

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.     

Th(NO_3)_4-UO_2(NO_3)_2-HNO_3-H_2O/30%TBP-正十二烷萃取体系主要组分分配比模型

利用文献报道的Th(NO3)4-UO2(NO3)2-HNO3-H2O/30%TBP-正十二烷体系各组分的分配比实验数据对现有的分配比模型进行分析和比对,提出了一个计算该体系各组分分配比的新模型。利用34组实验数据对新模型进行了验证,符合情况良好。计算结果表明,本文提出的模型明显优于原模型,可作为Th(NO3)4-UO2(NO3)2-HNO3-H2O/30%TBP-正十二烷萃取体系中Th(Ⅳ)、U(Ⅵ)和HNO3萃取行为计算机模拟的基础。模型建立的条件为:温度,25℃;U(Ⅵ)浓度,0~100g/L;Th(Ⅳ)浓度,0~232g/L;硝酸浓度,0~4.5mol/L。     

Effect of Ag and Li ion irradiation on superconducting Tl2Ca2Ba2Cu3O10 single crystals

The effect of irradiation by 50 MeV Li³⁺ and 200 MeV Ag¹⁵⁺ ions on single crystals of Tl₂Ca₂Ba₂Cu₃O₁₀ (Tl2223) superconductor has been investigated at different fluences. Isothermal magnetization hysteresis loops have been recorded at different temperatures using a SQUID magnetometer and the effect of irradiation on the critical current density, irreversible field, second magnetization peak and pinning force has been studied. Irradiation by 200 MeV Ag¹⁵⁺ ions resulted in increased hysteresis and irreversibility field while no change in second magnetization peak position and critical temperature was observed. A broadening in the hysteresis loop before the second magnetization peak was also observed for the crystals irradiated by Li³⁺ ions. Annealing of irradiated crystals at 500 °C resulted in reduction of point defects created by Li³⁺ ions.     

Effects of γ-irradiation on the optical properties of a-(Sb0.1Ge0.3Se0.6) and Ag5(Sb0.1Ge0.3Se0.6)95 thin film material

The amorphous behaviour of (Sb_0.1Ge_0.3Se_0.6) and Ag₅(Sb_0.1Ge_0.3Se_0.6)₉₅ chalcogenide thin film materials deposited at room temperature onto glass substrates by thermal evaporation process was investigated using X-ray diffraction technique. The surface morphology as well as the elemental chemical composition of the as-deposited films was investigated via scanning electron microscopy. The optical transmission and reflection spectra of as-deposited films and that exposed for different γ-dose were recorded at room temperature in the wavelength range of 600-2500 nm. Systematic studies of the refractive index, extinction coefficient and optical band gap have been presented as a function of the γ-dose. The dispersion of the refractive index for such films is discussed in terms of the single-oscillator Wemple-DiDomenico model, which was presented.