Effect of Rare-earth Chlorides on the Structure of Water

Abstract

The effect of rare-earth chlorides on the structure of water has been investigated at low concentrations by determining the ultrasonic velocity and density at several temperatures around temperatures corresponding to adiabatic compressibility minimum (TACM) and sound velocity maximum (TSVM) of water. Ultrasonic velocity is determined with an accuracy of ±0.003% using single crystal variable path interferometer and densities to an accuracy of ±0.002% using Pycnometer. The results are discussed in the light of structure breaking or structure making of the Rare-Earth chlorides in water.     

Access to Hydroxy‐Functionalized Polypropylene through Coordination Polymerization

Preparation of polyethylenes containing hydroxy groups has been already industrialized through radical copolymerization under harsh conditions followed by alcoholysis. By contrast, hydroxy‐functionalized polypropylene has proven a rather challenging goal in polymer science. Propylene can't be polymerized through a radical mechanism, and its coordination copolymerization with polar monomers is frustrated by catalyst poisoning. Herein, we report a new strategy to reach this target. The coordination polymerization of allenes by rare‐earth‐metal precursors affords pure 1,2‐regulated polyallenes, which are facilely transformed into poly(allyl alcohol) analogues by subsequent hydroboration/oxidation. Strikingly, the copolymerization of allenes and propylene gives unprecedented hydroxy‐functionalized polypropylene after post‐polymerization modification. Mechanistic elucidation by DFT simulation suggests kinetic rather than thermodynamic control.     

NaYF4:Nd3+,Yb3+纳米粒子用于生物体系温度测量

采用溶剂热法制备了Nd³⁺敏化Yb³⁺的近红外纳米探针NaYF₄:Nd³⁺,Yb³⁺,观察到材料在980与865 nm两处发光峰的强度比值随温度的升高而降低。通过对探针中Nd³⁺/Yb³⁺比例的调节,综合考虑材料的发光强度与温敏效率,确定了NaYF4:2%Nd, 20%Yb为所测条件下适用于测量生物体系温度的较优组成。材料转水相前后温敏效率均随着Yb³⁺离子掺杂增加而提高,环己烷中最高可达1.9%·K^-1,水相中最高为0.46%·K^-1。通过盖肉片模拟及激光加热活体成像实验,研究了温敏材料在生物环境中发光随温度的变化情况,以及组织遮挡前后荧光比值未发生明显变化的结果,初步验证了使用该探针测量生物体系温度的可行性。     

爆炸去磁脉冲功率发生器的实验和理论计算

设计了两种结构的爆炸去磁脉冲功率发生器:炸药透镜平面波冲击加载圆柱形磁体和中心装药冲击加载圆环形磁体，磁体材料都采用Nd2Fe14B永磁体。进行了爆炸冲击加载实验，测量了爆炸去磁脉冲发生器的输出电流、电压以及Nd2Fe14B永磁体中的冲击波速度。通过对爆炸去磁脉冲功率发生器基本原理的分析，建立了感生电动势的理论计算方法。用Maxwell 3D电磁场分析软件，对Nd2Fe14B永磁体进行了静磁场分析，给出了Nd2Fe14B永磁体的磁场强度分布规律。实验结果表明:爆炸去磁脉冲功率发生器每匝线圈能够产生约67 V的感生电动势,对于0.56 H的电感负载能够输出脉宽78.3 s、峰值1 212 A的脉冲电流。     

Effective model for rare-earth Kitaev materials and its classical Monte Carlo simulation

Recently, the family of rare-earth chalcohalides were proposed as candidate compounds to realize the Kitaev spin liquid (KSL) [Chin. Phys. Lett. 38 047502 (2021)]. In the present work, we firstly propose an effective spin Hamiltonian consistent with the symmetry group of the crystal structure. Then we apply classical Monte Carlo simulations to preliminarily study the model and establish a phase diagram. When approaching to the low temperature limit, several magnetic long range orders are observed, including the stripe, the zigzag, the antiferromagnetic (AFM), the ferromagnetic (FM), the incommensurate spiral (IS), the multi-Q, and the 120° ones. We further calculate the thermodynamic properties of the system, such as the temperature dependence of the magnetic susceptibility and the heat capacity. The ordering transition temperatures reflected in the two quantities agree with each other. For most interaction regions, the system is magnetically more susceptible in the ab-plane than in the c-direction. The stripe phase is special, where the susceptibility is fairly isotropic in the whole temperature region. These features provide useful information to understand the magnetic properties of related materials.     

Frequency upconversion in rare-earth doped fluoroindate glasses

We present recent results on frequency upconversion (UPC) obtained in fluoroindate glasses (FIG) doped with Ho³⁺, Tm³⁺ and Nd³⁺ ions and codoped with Pr³⁺/Nd³⁺ and Yb³⁺/Tb³⁺ ions. The results for the Ho³⁺-doped samples show strong evidence of energy transfer (ET) between Ho³⁺ ions resonantly excited at 640 nm. The origin of the blue-green upconverted fluorescence observed was identified and the dynamics of the signals revealed the pathways involved in the UPC process. In the case of Tm³⁺-doped FIG, the samples were resonantly excited at 650 nm and the main mechanism that contributes for the red-to-blue upconversion is excited-state absorption (ESA). The FIG samples codoped with Pr³⁺/Nd³⁺ were excited at 588 nm in resonance with transitions starting from the ground state of the Nd³⁺ and the Pr³⁺ ions. It was observed that the presence of Nd³⁺ ions enhanced the Pr³⁺ emission at 480 nm by two orders of magnitude. Multiphonon (MP)-assisted upconversion is also discussed for Nd³⁺-doped FIG pumped at 866 nm. Emission at 750 nm with a peculiar linear dependence with the laser intensity was observed and explained. A rate-equation model that includes MP absorption via thermally coupled electronic excited states of Nd³⁺ was developed and describes well the experimental results. The role played by effective phonon modes is clearly demonstrated. MP-assisted UPC process was also studied in Yb³⁺/Tb³⁺-codoped FIG samples excited at 1064 nm, which is off-resonance with electronic transitions starting from the ground state. It was determined that the mechanism leading to Tb³⁺ emission in the blue is due to ET from a pair of excited Yb³⁺ ions followed by ESA in the Tb³⁺ ions.     

Mössbauer effect studied in rare-earth oxides (REu)O3 (R = Pr,Nd, Sm)

Abstract

Both X-ray diffraction and the Mössbauer effect have been used to study the double rare-earth oxide solid solutions (REu)O³ (R = Pr, Nd, Sm), which were synthesized with a combination of high pressure and high temperature for the first time. It is shown that all products are of the B-type (monoclinic) structures of single phase. The hyperfine interactions depend strongly on the ligand volume of Eu ions.     

将自由基转化为负离子的光催化稀土材料

设计制造了具有负离子功能的稀土-半导体氧化物组装材料，并进行了自由基的测试。测试表明，该材料不仅在紫外光照射条件下能产生大量活性氧自由基，而且在无光照条件下也能产生大量活性氧自由基，突破了常规半导体氧化物不能在可见光条件下催化的难点。同时表明，材料所产生的自由基量与负离子量有直接对应关系。这意味着，在稀土离子的光催化及变价的氧化-还原过程中存在羟基自由基转化为负离子的可能。依此提出了在光催化作用下稀土离子与材料表面吸附的H2O和O2的循环变化模型图。     

稀土元素对崇仁麻鸡生长发育的影响

为了探讨稀土元素对家禽生长发育的影响，用稀土作添加剂对崇仁麻鸡进行饲养实验研究。实验采用对照法，饲养时间８周。结果表明，较低剂量的稀土添加剂能促进鸡的生长发育。