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The separation of light actinides plays an important role in the fields of nuclear industry, environmental radiochemistry, nuclear forensics, etc. Solid phase extraction(SPE) is one of the main methods for the separation of light actinides, and the key of this method is to select adsorbents with excellent adsorption performance and good physicochemical stability. Porous metal phosphonates are a kind of inorganic-organic hybrid materials combined of metal centers and organic phosphonic acid ligands. Generally, they exhibit high specific surface area, abundant active sites and good physicochemical stability, as well as excellent adsorption properties due to the outstanding binding ability of phosphonic groups to light actinides. Therefore, they are expected to be used as adsorbents for light actinides. In this review, the synthesis and structure of porous metal phosphonates are summarized, and their application in the separation of light actinides is focused, including the adsorption properties, adsorption mechanism, the physiochemical stability and practical treatment methods of these materials, etc. In the end, the development of this field is prospected.

Microstructure evolution and hardening effect of pure tungsten and Wâ€"1.5%ZrO2 alloy under carbon ion irradiation are investigated by using transmission electron microscopy and nano-indentation. Carbon ion irradiation is performed at 700 °C with irradiation damages ranging from 0.25 dpa to 2.0 dpa. The results show that the irradiation defect clusters are mainly in the form of dislocation loop. The size and density of dislocation loops increase with irradiation damages intensifying. The Wâ€"1.5%ZrO2 alloy has a smaller dislocation loop size than that of pure tungsten. It is proposed that the phase boundaries have the ability to absorb and annihilate defects and the addition of ZrO2 phase improves the sink strength for irradiation defects. It is confirmed that the Wâ€"1.5%ZrO2 alloy shows a smaller change in hardness than the pure tungsten after being irradiated. From the above results, we conclude that the addition of ZrO2 into tungsten can significantly reduce the accumulation of irradiated defects and improve the irradiation resistance behaviors of the tungsten materials. [ABSTRACT FROM AUTHOR]

Ab initio calculations based on the density functional theory have been performed to investigate the migrations of hydrogen (H) and helium (He) atoms in &bgr;-phase scandium (Sc), yttrium (Y), and erbium (Er) hydrides with three different ratios of H to metal. The results show that the migration mechanisms of H and He atoms mainly depend on the crystal structures of hydrides, but their energy barriers are affected by the host-lattice in metal hydrides. The formation energies of octahedral-occupancy H (Hoct) and tetrahedral vacancy (Vtet) pairs are almost the same (about 1.2 eV). It is of interest to note that the migration barriers of H increase with increasing host-lattice atomic number. In addition, the results show that the favorable migration mechanism of He depends slightly on the Vtet in the Sc hydride, but strongly on that in the Y and Er hydrides, which may account for different behaviours of initial He release from ScT2 and ErT2. [ABSTRACT FROM AUTHOR]

Abstract: As a part of the program to develop metal hydride technology for storing and processing tritium, the tritium absorption–desorption of LaNi4.25Al0.75 was investigated. The pressure–composition–temperature (P–C–T) curves, activation characteristics and the absorption–desorption rate of tritium from LaNi4.25Al0.75T x at different temperature were measured. And standard enthalpy ΔH θ and entropy ΔS θ changes for T2 absorption and desorption were calculated from van’t Hoff plots based on the measured P–C–T relations. The calculated value of ΔH θ and ΔS θ during the formation of the LaNi4.25Al0.75T2.5 phase is (−31.8±0.8)kJmol−1 and (−76.5±2.4)Jmol−1 K−1, and the value of desorption is (−36.5±0.5)kJmol−1 and (−84.2±1.5)Jmol−1 K−1, respectively. Composition difference between the origin tritium gas and tritium released from 7-day-aged LaNi4.25Al0.75 tritide was analyzed by quadrupole mass spectrometer. [Copyright &y& Elsevier]

The chemico-physical properties including structural, electronic, vibrational and thermodynamic properties of α-quartz Si 1 -x Ce x O 2 and stishovite Si 1 -x Ce x O 2 (x varies from 0.0 to 0.5) have been researched by the density functional theory (DFT). For α-quartz Si 1 -x Ce x O 2 , when Ce content x gently augments from 0.0 to 0.5, the lattice constants a and c increase from 4.999 Å to 6.722 Å and from 5.494 Å to 7.360 Å respectively. With regard to stishovite Si 1 -x Ce x O 2 , the constants a and c increase from 4.234 Å to 5.235 Å and from 2.688 Å to 3.532 Å, respectively. The calculated band gap decreases first and then increases for both two structures. For α -quartz and stishovite Si 1 -x Ce x O 2 , the calculated results of vibrational characters indicate that the increasing of Ce concentration from 0.0 to 0.5 leads to the peak vibrational frequency reducing from about 35.947 THz down to about 26.702 THz and from 30.494 THz down to about 21.981 THz, respectively. This metamorphic variation shows that these modes have a lower dispersive rate of change and phonon group velocities. Finally, the thermodynamic properties associated with phonons have been achieved and explored. • As Ce content x augments from 0.0 to 0.5, the lattice constant increases for Si 1 -x Ce x O 2. • As the increasing of Ce content from 0.0 to 0.5, the band gap first decreases and then increases. • The increase of Ce content leads to the decreasing of phonon vibration frequency. • The increase of Ce concentration leads to F and E decrease, while S and C V augment. [ABSTRACT FROM AUTHOR]

Raman spectroscopy was used for experimental research on D2 signal to noise ratio (SNR) under different conditions. The 32 mW Ar+ laser was injected into the Raman quartz glass cells to study the effect of grating, laser power, exposure time and the gas pressure on D2 Raman spectra SNR. D2 Raman spectral signal to noise ratio is proportional to the laser power, exposure time and gas pressure. The standard curve of the pressure and SNR for this experimental apparatus was obtained. Three sets of random samples were used to verify the formula SNR(J 2 --> 2) = 10.6 x 10(-4) p+1.271 34. When the deuterium pressure is 21 280 Pa, the relative error is 4.8%. When the pressure increases to 67 235 Pa, the relative error is down to 1.46%.

Analysis of laser Raman spectroscopy has turned into the efficient research method of substance structure and composition analysis. In the present paper, the principle of laser Raman spectroscopy and its characteristics of analysis method are introduced. Applicability of laser Raman spectroscopy to hydrogen isotope analysis is analyzed. The analytical applications of laser Raman spectroscopy method in radiation reaction of tritium, hydrogen isotope examination and quantitative analysis are presented from reported literature.