Dinuclear Face‐Sharing Bi‐octahedral Tungsten(VI) Core and Unusual Thermal Behavior in Complex Th Tungstates

Two new thorium tungstates A₆Th₆(WO₄)₁₄O (A=K and Rb) were synthesized by high‐temperature solid‐state reactions. The structures of both phases are based on a rare dinuclear confacial bi‐octahedral [W₂O₉]^6? core, encapsulated in a [Th₆W₇O₄₆(W₂O₉)]^32? cage showing a cross‐section geometry similar to a six‐leafed lily. The adjacent cages are connected in two dimensional layers by WO₄ tetrahedral linkers. Due to the dissimilarities in mutual orientations of adjacent layers in these two structures, K₆Th₆(WO₄)₁₄O crystallizes in space group of R32 while Rb₆Th₆(WO₄)₁₄O stabilizes in P$\bar 6$ 2c. The high‐temperature phase transition was observed in Rb₆Th₆(WO₄)₁₄O and investigated using high‐temperature PXRD technique. The results demonstrate a very unusual thermal behavior of this compound. The Raman and IR spectra of both phases were analyzed with respect to their complex structures.     

Separation of Metal Pairs using Bis (2-Ethylhexyl) Phosphoric Acid (HDEHP); Separation of Cerium from Uranium and from Thorium

A systematic study was performed on the extraction and separation of uranium-cerium and thorium-cerium pairs for HDEHP from pure hydrochloric and sulphuric acid solutions as well as from their binary mixtures. The effect of water miscible alcohols and actone on the separation of these elements was also investigated. The separation of uranium and thorium from macroamounts of cerium can be best achieved from. 2.4 M HCl in presence of 50% isopropyl alcohol. There are other media plausible for the separation of trace cerium from uranium and thorium matrices.     

TBP萃淋树脂分离ICP-MS测定八氧化三铀中的钍和锆

采用TBP萃淋树脂萃取色层分离,ICP–MS法测定U_3O_8中痕量杂质元素Th和Zr。U_3O_8样品先经硝酸溶解,再用盐酸转化成氯化铀酰,以TBP萃淋树脂作为固定相,6 mol/L盐酸作为流动相,使铀与待测杂质元素Th和Zr进行分离,用ICP–MS测定淋洗液中杂质元素Th和Zr的含量。Th和Zr的检出限分别为0.008 5μg/L和0.068μg/L,线性方程分别为y=55.789x–0.001 2和y=23.889x–0.001 7,线性相关系数r2=1。测定结果的相对标准偏差均小于5%(n=5),加标回收率在96%~103%之间。用该法测定U_3O_8标准物质,测定结果与标准值一致。该法操作简便,分离快速,测定结果准确、可靠。     

XAS study of murataite-based ceramics and crystalline film of ThO2

The local environment of thorium in murataite ceramics (Al,Ca,Ti,Mn,Fe,Zr,Th)O_x and ThO₂(001) crystalline film on Si(100) substrate as a reference was explored by X-ray absorption spectroscopy (XAS) for the first time. It was found that Th⁴⁺ is located in the center of a cube formed by 8 oxygen atoms [r(Th–O) = 2.37 ± 0.03 Å] in murataite ceramics and ThO₂ film. The Th⁴⁺ second coordination sphere [r(Th–M) ≈ 3.5 Å] in murataite is represented by 3d metals: titanium, iron or manganese     

Twinned tetragonal structure and equation of state of NaTh2F9

The crystal structure and stability of NaTh₂F₉ have been studied using thermal analysis, powder X-ray diffraction at atmospheric conditions, and single-crystal X-ray diffraction at high pressure. Sodium dithorium fluoride is stable at least up to 5.0 GPa at room temperature and to 954 K at ambient pressure. In contrast to earlier investigations, which have reported the structure to be cubic (, Z=4), we observe a tetragonal distortion of the lattice. The actual crystal structure (, Z=4) is twinned and composed of corner-sharing distorted ThF₉ tricapped trigonal prisms and distorted NaF₆ octahedra. The twinning element is a three-fold axis from cubic symmetry. The ThF₉ polyhedra are rigid and it is the volume changes of the octahedra around the Na atoms that have the major contribution to the bulk compressibility. The zero-pressure bulk modulus B₀ and the unit-cell volume at ambient pressure V₀ are equal to 99(6) GPa and 663.1(1.0) Å³, respectively, with the fixed first pressure derivative of the bulk modulus B′=4.00. An inspection of the known crystalline phases in the system NaF-ThF₄ reveals that their bulk moduli increase with the increasing ThF₄ content.     

Thorium under strong compression—a test case for the evaluation of EOS data by different forms and procedures

Abstract

X-ray diffraction on Thorium under pressures to 300 GPa at ambient temperature provides new EOS data for both the (low pressure) fcc phase as well as for the (high pressure) bct phase. A detailed evaluation of these data and a comparison with previous results shows systematic differences in the fitted parameters resulting from the use of different EOS forms and from the correlations in the parameters used in all these fitting procedures. The absolute uncertainties in these parameters are elucidated and special attention is given to the compatibility of different EOS forms for phases which are related by second order transitions.     

1,10-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)癸二酮-[1,10]对希土、钍和铀萃取行为的研究

本文研究了新型的双酰代吡唑酮类整合萃取剂1,10-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)癸二酮-[1,10](H_2A)的氯仿溶液从硝酸介质中对11个希土离子,钍和铀的萃取行为。测定了pH_(1/2)值,用斜率法求得萃合物的组成,确定了各自的萃取平衡反应,计算了萃取平衡常数,合成了希土固态萃合物,并对其组成、UV、IR及TG-DTA谱进行了研究。