Ag—Ln（Ln=La,Ce,Gd）液态合金短程有序性的热力学讨论

本文利用理想缔合液液模型，计算了１３００－１６００Ｋ温度范围内，Ａｇ－Ｌｎ（Ｌｎ＝Ｌａ，Ｃｅ，Ｇｄ）三个二元系的热力学数据；认为在液相中存在着Ａｇ３Ｌｎ和ＡｇＬｎ得缔合物，并利用浓度相互作用函数Ｓｃｃ（Ｏ）对这种短程有序性进行了讨论。     

Complexation, luminescence and energy transfer of Ln(III) ions with phenylphosphonic acid

Spectral characterisation of the Ln(III) ion complexes with phenylphosphonic acid (PPA) was made and the mode of Ln(III) ions coordination was established. From the absorption spectra the forces of the Nd³⁺ oscillator were obtained, the intensity of emission and luminescence lifetimes of Eu³⁺ and Tb³⁺ were measured. The Stern–Volmer constants K_sv^φ and K_sv^τ determined indicated the presence of associated forms of complexes. The quantum yield of luminescence of Eu³⁺ and Tb³⁺ complexes was found using Ru(bpy)₃²⁺as a standard. The complexes were characterised by quantum yields (Φ=0.4 and 0.008 for Tb and Eu ions). The solid state Eu³⁺ complex was studied by luminescence spectroscopy, IR and thermogravimetry. The complex was found thermally stable and with no water molecules in its structure.     

Ion-irradiation-induced structural transitions in orthorhombic Ln2TiO5

The response of a material to a high radiation field is important when selecting materials for nuclear applications, such as structural materials, nuclear waste forms and inert matrix fuels. In the present study, the radiation response of orthorhombic, rare-earth titanates, Ln₂TiO₅ (Ln = La, Nd, Sm, Gd, Dy and Y), was investigated by 1 MeV Kr²⁺ ion bombardment at temperatures ranging from 50 to 1073 K. In situ transmission electron microscopy revealed that the radiation tolerance and irradiation-induced structural transitions vary largely with composition. Y₂TiO₅ exhibits the lowest critical amorphization temperature (T_c = 623 K), above which crystals cannot be amorphized, which is consistent with its use in the form of nanoclusters in radiation-resistant oxide-dispersion-strengthened steels. The disordered fluorite structure type of Ln₂TiO₅, with smaller Ln cations, formed as an intermediate phase prior to becoming fully amorphous. The fluorite structure type of Ln₂TiO₅, containing more vacancies as compared with that of Ln₂Ti₂O₇, may exhibit enhanced ionic conductivity, which highlights an effective way of using ion beams to modify the properties of materials.     

A Safe and Brief Way for Preparing Anhydrous LnCl_3 (Ln=Sc, Y, La to Lu)

@李瑛 @王林山 @王育红     

LnNbO_4(Ln=Ce)陶瓷的微波介电性能

以轻稀土元素铈(Ce)替代A位离子,研究了铌酸铈陶瓷LnNbO_4(Ln代表La至Lu包含Y的稀土元素)的制备工艺、显微结构与介电性能.由于加热制度的不同,材料结构可在CeNbO_(4+0.25) 与CeNbO_4变化,多余的氧原子占据间隙位置而形成了Ce原子的8+2配位体结构,并因此造成介电性能的变化.     

New DySrAlO4 Compound Synthesis and Formation Process Correlations for LnSrAlO4 (Ln 5 Nd,Gd, Dy) Series

For the first time, DySrAlO₄ of K2NiF₄-type structure was synthesized. The parameters of DySrAlO4 elementary unit cell are determined as follows: a = 0.368 (4) nm, c = 1.229 (2) nm, V = 0.166 (4) nm³. The research of the complex aluminates LnSrAlO4 (Ln = Nd, Gd, Dy) solid-state process demonstrated the change of the formation mechanism among LnSrAlO₄ (Ln = Nd, Gd, Dy) series from DySrAlO₄ oxide. The performed analysis provided a possibility to realize why chemists couldn’t get DySrAlO₄ for a long period of time.     

New DySrAlO_4 Compound Synthesis and Formation Process Correlations for LnSrAlO_4(Ln=Nd,Gd,Dy) Series

For the first time, Dy Sr AlO_4 of K_2NiF_4-type structure was synthesized. The parameters of Dy Sr AlO_4 elementary unit cell are determined as follows: a = 0.368(4) nm, c = 1.229(2) nm, V = 0.166(4) nm~3. The research of the complex aluminates Ln Sr Al O4(Ln = Nd, Gd, Dy) solid-state process demonstrated the change of the formation mechanism among Ln Sr AlO_4(Ln = Nd, Gd, Dy) series from Dy Sr AlO_4 oxide. The performed analysis provided a possibility to realize why chemists couldn't get Dy Sr AlO_4 for a long period of time.     

Sonochemical synthesis and characterization of uniform lanthanide orthophosphate(LnPO_4, Ln=La and Ce) nanorods

Uniform lanthanide orthophosphate(Ln PO4,Ln = La and Ce) nanorods were successfully synthesized by a simple ultrasonic irradiation method using lanthanide nitrate salt(Ln(NO3)3 6H2 O, Ln = La and Ce) and sodium phosphate(Na3PO4) in aqueous solutions with the p H of1–3. The products were characterized by X-ray diffraction(XRD), scanning electron microscopy(SEM), transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), Fourier transform infrared spectrometer(FT-IR), and UV–visible(UV-Vis) spectroscopy. In this research, the products are nanorods of monoclinic La PO4 and hexagonal Ce PO4 structures and the vibration modes of PO43-, including the strong peaks at227 nm for La PO4, and at 225 and 278 nm for Ce PO4.     

High-temperature thermoelectric properties of Ln(Co,Ni)O3 (Ln = La,Pr, Nd,Sm, Gd and Dy) compounds

The high-temperature thermoelectric properties of polycrystalline LnCo_0.95Ni_0.05O_3±δ (Ln = La, Pr, Nd, Sm, Gd and Dy) compounds have been investigated. The substitution of the lanthanide element produces changes in the crystal structure and in the unit cell lattice parameters. A semiconductor to metal transition takes place for all the compounds at 500 K < T < 800 K. The transition temperature, also monitored by differential scanning calorimetry, shifts to higher temperature with the decrease in the size of the lanthanide element. The Seebeck coefficient has positive values up to T = 1240 K. The thermal conductivity is mainly dominated by the lattice contribution. The dimensionless figure of merit ZT can be enhanced at different temperatures depending on which lanthanide element occupies the A-site in the ABO₃ perovskite-type phases.     

焦绿石型Ln2Zr2O7陶瓷的研究进展

焦绿石相结构的稀土锆酸盐陶瓷(Ln2Zr2O7)是一类先进的功能材料,具有各种不同的物理化学性质.本文简要阐述了Ln2Zr2O7陶瓷的微观结构特征,介绍了制备Ln2Zr2O7陶瓷的工艺方法,并对Ln2Zr2O7陶瓷在热障涂层、固体电解质、催化剂、放射性核废料等方面的应用进行了综述.     

Photoelectrochemical study of lanthanide titanium oxides, Ln2Ti2O7 (Ln = La, Sm, and Gd)

Photocatalytic activities for hydrogen evolution of lanthanide titanium oxides, Ln₂Ti₂O₇ (Ln = La, Pr, Nd, Sm, Gd, Dy, Ho, Er, and Yb) prepared by a solid-state reaction were studied. Hydrogen gas was clearly evolved in distilled water suspension of La₂Ti₂O₇ and Sm₂Ti₂O₇. From the photoelectrochemical measurements, the values of the flat band potential were estimated to be −0.04, −0.02, +0.27 eV for La₂Ti₂O₇, Sm₂Ti₂O₇, Gd₂Ti₂O₇, respectively, versus the normal hydrogen electrode (NHE). The values of the band gap energy were calculated to be about 3.29, 2.79, 2.82 eV for La₂Ti₂O₇, Sm₂Ti₂O₇, Gd₂Ti₂O₇, respectively. The photocatalytic activities of Ln₂Ti₂O₇ (La, Sm, and Gd) were discussed along with detailed band structures estimated in this study. From the band structures, Sm₂Ti₂O₇ is a possible candidate of photocatalyst responding to visible light.     

Thermal and structural properties of KPO3·Ln(PO3)3 glasses (Ln=rare earth ion)

Glass transition temperatures T_g and Raman spectra of KPO₃·Ln(PO₃)₃ (Ln=rare earth ion) glasses were measured for all rare earth members (except Pm). From the series behavior of the T_g and Raman data, it is concluded that the coordination number around rare earth ions changes, probably from nine to eight, in the middle of the rare earth series.     

Thermodynamics of phase changes in systems BaS-Ln<Subscript>2</Subscript>S<Subscript>3</Subscript> (Ln=Pr,Sm, Gd,Tb, Er,Lu)

Thermodynamic analyses of phase changes were carried out for the systems BaS-Ln₂S₃ with Ln=Pr, Sm, Gd, Tb, Er, and Lu, and the phase diagrams have been experimentally constructed. Formation of the Ba₃Ln₂S₆ sulfides with Ln=Tb through Lu was predicted from the thermodynamic behavior of melts, and the existence of these phases has been experimentally confirmed. Heats of melting were estimated for the sulfides Ln₂S₃, BaLn₂S₄, and Ba₃Ln₂S₆.     

Synthesis, structure determination and magnetic susceptibilities of the oxides Ln3Li5Sb2O12 (Ln ≠ Pr, Nd, Sm)

The oxides Ln₃Li₆Sb₂O₁₂ (Ln≠Pr, Nd, Sm) were prepared in air by heating a mixture of Ln₂O₃, LiNO₃and Sb₂O₃ in the temperature range 1023–1243 K. Lattice parameters as well as atomic coordinates in the space group 12,3 (Z≠8) are established from X-ray powder diffraction data by the Rietveld method. Magnetic susceptibilities from 4.2 to 300 K follow a Curie-Weiss law above 50 K (Ln≠Pr) or 70 K (Ln≠Nd). This is attributed to the splitting of the ground state associated with the Ln³⁺ ions by the influence of the crystal field. The magnetic moments, 3.54 and 3.61 μ_D for praseodymium and neodymium respectively, agree with those calculated by Hund's formula. The Sm³⁺ behaviour can be explained by taking into account that the splitting of the multiplets is not too large compared to kT. The magnetic moment observed at room temperature for this cation is 1.6 μ_B.     

Mutual separation characteristics for binary oxides Y2O3-Ln2O3 （Ln= Sc, La, Nd, Sm） using stepwise selective chlorination-chemical vapor transport reaction mediated by vapor complexes KLnCl4

Mutual separation characteristics for binary oxide mixtures Y2 O3-Sc2 O3, Y2 O3-La2 O3, Y2 O3-Nd2 O3and Y2 O3-Sm2 O3 using a stepwise selective chlorination-chemical vapor transport(SC-CVT) reaction mediated by vapor complexes KLnCl4 were investigated. The total transported yields of the chlorides produced from the oxide mixtures are in the order of NdCl3 ＞SmCl3 ＞LaCl3 ＞YCl3 ＞ScCl3 , the main deposition temperature of the chlorides is in the order of ScCl3 ＜YCl3 ＜SmCl3 ＜NdCl3 ＜LaCl3, and the largest separation factor values are 1 100 for Y . Sc,14.88 for Y : La, 9.86 for Y . Nd and 16.45 for Y . Sm in the temperature range from 1 000 K to 1 120 K, while 157.7 for La : Y, 51.6 for Nd : Y and 12.4 for Sm : Y in the temperature range from 1 200 K to 1 300 K, respectively. The results were discussed on the difference of KScCl4, KYCl4 and KLnCl4 and the selective chlorination of binary oxides at 800 K. Furthermore, the separation characteristics of vapor rare earth complex KLnCl4 were studied compared with those of LnAlnCl3n 3.     

Linear analysis on the stability of lanthanide vapor complexes LnAl3Cli2(Ln = La to Lu)

The reactions LnCl3 (s) + (3/2)Al2Cl6 (g) = LnAl3Cl12 (g) for Ln = La to Lu were studied by quenching experi-ments in roughly the same temperature and pressure ranges (588-851 K and 0.01-0.22 MPa). Stability constants Kθ oflanthanide complexes LnAl3Cl12 were calculated from the measurements. The values of lg Kθ change linearly with theionpotential (Z+/r) of lanthanide(Ⅲ) from La to Gd and from Tb to Lu, respectively, indicating the Gd break. There exist in-clined W effect between lg Kθ and the total angular momentum L of lanthanide(Ⅲ). And hereby lanthanide elements aredivided into four segments, La-Nd, Pm-Gd, Tb-Ho, and Er-Lu. In each segment, the linearity is maintained.