烧绿石型富氧相Ce_2Zr_2O_8与缺氧相Nd_2Zr_2O_7的振动光谱及XPS对比研究

采用石墨还原法成功制备了富氧相Ce2Zr2O8,选用缺氧相Nd2Zr2O7替代其前驱体CeZrO3.5+δ进行结构对比分析,利用X射线衍射(XRD)、拉曼光谱(Raman)、红外光谱(IR)及X射线光电子能谱(XPS)对样品体、表晶体结构进行表征。XRD结果表明,Ce2Zr2O8相具有典型烧绿石结构特征,表征Ce/Zr阳离子有序排列的超结构峰非常明显,但其Zr—O配位体由前驱体中的[ZrO6]八面体转变为[ZrO8]立方体,[ZrO8]配位体形成大大降低了Ce2Zr2O8的结构稳定性。Raman和IR结果表明,Ce2Zr2O8相的振动光谱谱带比其前驱体替代物Nd2Zr2O7显著增多,说明氧离子的富集导致Ce2Zr2O8相中某些振动简并峰消除简并,该结果进一步证实了其结构对称性较前驱体更低。XPS结果表明,Ce2Zr2O8相表面Ce(Ⅳ)特征峰(916.3eV)非常明显,没有Ce(Ⅲ)特征峰(885eV)出现,说明该相前驱体中的Ce3+已被完全氧化成Ce4+;Ce2Zr2O8相中Zr(3d)结合能与萤石相Gd1.2U0.8Zr2O7+y接近证实其表面形成了与体相一致的[ZrO8]配体;O(1s)低位结合能升高表明Ce2Zr2O8体相氧种介于晶格氧和吸附氧之间,高位氧峰出现说明其表面含有吸附氧,吸附氧与Ce2Zr2O8体相结合强度介于CeO2和Nd2Zr2O7之间。     

Level scheme in 160Tm towards complete high-spin structure

High-spin states of ¹⁶⁰Tm have been studied through the ¹⁴⁶Nd(¹⁹F, 5n) reaction at a beam energy of 102 MeV. The previously known πh_11/2⊙νi_13/2 yrast band and πh_11/2⊙νh_9/2 side band are confirmed, and several low-lying levels are observed. A 4-quasiparticle band feeding into the yrast band based on the πg_7/2⊙νh_9/2⊙νi_13/2² is suggested. Other two bands are observed and assigned to be based on the πd_3/2⊙νi_13/2 and πg_7/2⊙νi_13/2 configurations, respectively.     

第一性原理模拟U在Gd2Zr2O7烧绿石中的固溶

采用第一性原理密度泛函理论模拟U在Gd₂Zr₂O₇烧绿石中的固溶,在低浓度U掺杂时,Gd₂Zr₂O₇烧绿石保持烧绿石结构;随着U掺杂浓度增加,Gd₂(Zr_{2-y}U_y)O₇和(Gd_{2-y}U_y)Zr₂O₇体系的晶格常数发生线性变化．计算结果表明,由于总能较低,U原子更偏向于替代无序换位后Gd₂Zr₂O₇晶格中B位的Gd原子．     

High Spin States in Odd--Odd 160Tm Nucleus

High-spin states of ^160Tm are studied by the ^146 Nd（^19F, 5n） reaction at a beam energy of 102 MeV. The previously known πh11/2 ＋ vi13/2 yrast band and πh11/2 ＋ vh9/2 side band are confirmed. The level scheme is enriched and more low-lying levels are observed. A new side band is observed and assigned as the favoured signature partner of πd3/2 ＋ vi13/2. The spin of this band is assigned with the energy level systematics. It is pointed out that the B （M1）/B （E2） ratios increase rapidly at the high frequency approaching the second crossing in the π h11/2 ＋ vi13/2 braid, which is closely related to the alignment gain of the aligned i13/2 quasineutron.