Synthesis,Crystal Structure and Photoluminescent Property of a Novel Dy^(3+) Coordination Compound Containing Rare(H_2O)_(22) Clusters

A novel Dy^（3＋） coordination compound,（H_2pipz）（H_3O）[Dy（pydc）_3]·11H_2O（1,pipz = piperazine and H_2pydc = pyridine-2,6-dicarboxylic acid）,has been hydrothermally synthesized and characterized by X-ray single-crystal diffraction,elemental analysis. It is interesting that the packing structure of compound 1 contains 22-core water clusters. Compound 1 is extended into a threedimensional supramolecular structure via O···H···O hydrogen bonding interactions. Furthermore,the luminescent property of compound 1 was also investigated.

Microstructure and Mechanical Property of Nanocrystalline NiZr_2 Intermetallic Compound

Single-phase NiZr2 intermetallic compound nanocrystalline samples were synthesized by fully crystallizing the parent amorphous NiZr2 alloy at the temperature interval of 653~1073 K for a certain period of time. High resolution electron microscope (HREM) observations on the nanophase NiZr2 reveal a Iamellar nano-tWin structure with (110) direction on the nanometer scale, being typically a few interatomic distances to a few nanometers. Microhardness measurements on the single-phase NiZr2 samples indicate that the hardness of nanotwinned NiZr2 is obviously increased in comparison to the amorphous counterpart. When the average grain size increases from 19.1 to 93.9 nm, the variation of the hardness with the average grain size obeys the normal Hall-Petch relation, whereas as the average grain size is smaller than 19.1 nm. the microhardness data deviate from the above relation.

Electrical Properties of Expanded Graphite Intercalation Compounds

The intercalation compounds of CuCl2 were synthesized with expanded graphite, whose magnitude of the electrical conductivity is about 10(3)S(.)cm(-1). Their electrical conductivity is 3 similar to6 times as high as that of the expanded graphite, and about 10 times as high as that of GIC made of the non-expanded graphite. The microanalysis results of chemical compounds by X-ray energy spectrum scanning of TEM testified that the atomic ratio of chloride and cupric is nonstoichoimetric. The multivalence and exchange of electrovalence of the cupric ion was confirmed by the XPS-ESCA. Vacancy of chlorine anion increases the concentration of charge carrier. The special stage structure, made of graphite and chloride, produces a weak chemical bond belt and provides a carrier space in the direction of GIC layer. These factors develop the electrical properties.

Crystal Structure and Magnetic Properties of a Dinuclear Terbium Compound Tb_2(μ_2-anthc)_4(anthc)_2(1,10-phen)_2

A dinuclear Tb（Ⅲ） compound, Tb_2（μ_2-anthc）_4（anthc）_2（1,10-phen）_2（1, Hanthc = 9-anthracenecarboxylic acid and 1,10-phen = 1,10-phenanthroline）, was synthesized under solvothermal condition and structurally characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the triclinic system, space group P1, with a = 12.5061（12）, b = 13.3168（10）, c = 15.0079（12） ？, α = 110.620（7）, β = 102.941（7）, γ = 107.036（7）o, V = 2081.8（3） ？~3, Z = 1, C_（114）H_（70）N_4O_（12）Tb_2, M_r = 2005.58, D_c = 1.600 g/cm^3, μ = 1.759 mm^（-1）, F（000） = 1008, the final R = 0.0294 and w R = 0.0608 for 8900 observed reflections with I 〉 2s（I）. In compound 1, two Tb（Ⅲ） ions are linked by four carboxylate groups of the bridging anthc– ligands to give a dinuclear Tb_2（μ_2-anthc）_4 unit wherein each Tb（III） ion is further capped by a terminal anthc– ligand and a 1,10-phen ligand in a chelating fashion. Detailed direct-current and alternating-current susceptibility measurements showed no slow magnetism relaxation phenomenon was observed for 1.

Crystal Structure and Magnetic Properties of a Two-dimensional Compound{(Me2NH2)4[Co(SIP)2]·2(DMF)·3(H2O)}n

-

AROMATIC BOND INCLUDING METALLIC ATOM IN COORDINATE COMPOUNDS AND SOME OF ITS PROPERTIES

Aromatic bond including metallic atom (Ni) is investigated by EHMO calculation.The NMR spectra and the mechanism for hydrolysis are discussed on the ground of results of computation.

Spontaneous Magnetic Transitions and Corresponding Magnetoelastic Properties of Intermetallic Compounds RMn_2Ge_2(R=Gd, Tb and Dy)

The spontaneous magnetic transitions and corresponding magnetoelastic properties of intermetallic compounds RMn2Ge2（R=Gd, Tb and Dy） were investigated by using the X-ray diffraction method and magnetic measurement. The results showed that the compounds experience two magnetic transitions, namely the second-order paramagnetic to antiferromagnetic transition at temperature TN（TN=368, 423 and 443 K for Gd Mn2 Ge2, Tb Mn2 Ge2 and Dy Mn2 Ge2, respectively） and the first-order antiferromagnetic-ferrimagnetic transition at temperature Tt（Tt=96, 80 and 40 K for Gd Mn2 Ge2, Tb Mn2 Ge2 and Dy Mn2 Ge2, respectively） as the temperature decreases. The temperature dependence of the lattice constant a（T） displays a negative magnetoelastic anomaly at the second-order transition point TN and, at the first-order transition Tt, a increases abruptly for Gd Mn2 Ge2 and Tb Mn2 Ge2, Da/a about 10^（-3）. Nevertheless, the lattice constant c almost does not change at these transition points indicating that such magnetoelastic anomalies are mainly contributed by the Mn-sublattice. The transitions of the magnetoelastic properties are also evidenced on the temperature dependence of magnetic susceptibility χ. The first-order transition behavior at Tt is explained by the Kittel mode of exchange inversion.

Structures and Magnetic Properties of Europium-Transition Metal-Gallium Ternary Intermetallic Compounds with 1:3 Type

The crystal structures and magnetic properties of novel Eu TrGa3-r （T=Pd, It, Rh） in termetallic compounds are investigated by using powder x-ray diffraction and magnetic measurements. EuTrGa3-r crystallizes in orthorhombic structure with space group of Cmcm and Z = 4. There are four kinds of nonequivalent 4c crystal positions in EuTrGaa-r unit cell, which are occupied by 4Eu, 4GaⅠ, 4（GaⅡ, T） and 4GaⅢ, respectively. EuTrGa3-r ex- hibits the complex magnetic states in low-temperature regime, with the three-, two- and one-antiferromagnetic transitions occurring for T=Ir, T=Rh and T=Pd, respectively. It might be due to the Kondo effect： a localized antiferromagnetic interaction of the isolated impurity spins with the surrounding conduction electrons at low-temperature regime.

Crystal Structures,Luminescent Properties and Hirshfeld Surface Analyses of Zn(Ⅱ)and Cd(Ⅱ)Compounds Based on 1-(2-Carboxyl-phenyl)-3-(pyridin-2-yl)pyrazole

Two compounds,[Zn2（Hcppp）2（cppp）2（H2O）2]·2 NO3·6 H2O（1） and [Cd（Hcppp）2Cl2]· 3H2O（2）（Hcppp = 1-（2-carboxyl-phenyl）-3-（pyridin-2-yl）pyrazole）,are synthesized and characterized by IR,TGA and X-ray single-crystal/powder diffraction.Compound 1 crystallizes in monoclinic system,space group P21/c with a = 9.894（2）,b = 15.856（3）,c = 20.430（4） A,β = 101.70（3）°,V = 3138.5（11） A3,Z = 2,Mr = 1457.94,Dc = 1.543 g/cm^3,F（000） = 1504,R = 0.0278 and wR = 0.0749 for 6157 observed reflections（I 〉 2σ（I））.Compound 2 crystallizes in triclinic system,space group P1 with a = 9.1424（4）,b = 11.6427（5）,c = 16.1345（7） A,α = 102.6430（10）°,β = 95.4530（10）°,γ = 104.0060（10）°,V = 1605.94（12） A3,Z = 2,Mr = 767.88,Dc = 1.588 g/cm^3,F（000） = 776,R = 0.0307 and wR = 0.0764 for 6275 observed reflections（I 〉 2σ（I））.Compound 1 exhibits a binuclear structure while compound 2 shows a mononuclear structure.In compound 1,two cppp-ligands display the μ2-kN,N′：k O and two Hcppp ligands show the μ1-kN,N′ coordination modes.However,two Hcppp ligands connect one Cd（Ⅱ） cation and exhibit the μ1-kN,N′ binding mode in compound 2.The compounds are both studied using Hirshfeld surface analyses and 2D fingerprint plots.The luminescent properties are also discussed.

STUDIES ON THE PROPERTIES OF SCHIFF BASE TYPE ARYLMERCURY COMPOUNDS Ⅲ TRANSMETALLATION REACTION OF SCHIFF BASE TYPE ARYLMERCURY COMPOUNDS WITH METALLIC TIN

The transmetallation reaction of 4 Schiff base type arylmercury compounds with metallic tin has been carried out in refluxing xylene.It was found that the reaction proceeds in the same manner as that of chloro[2-(phenylazo)phenyl]mercury(Ⅱ) to give dichlorobisaryltin(Ⅳ).The ~1H NMR spectra of the products provide evidence for the presence of N→Sn intramolecular coordination.The formation of dichlorobisaryltin(Ⅳ)as a unique product probably arises from the N→Sn intramolecular coordination which results in the increasing of the stability of the molecule.

STUDIES ON THE PROPERTIES OF SCHIFF BASE TYPE ARYLMERCURY COMPOUNDS.II ^(199)Hg NMR SPECTRA OF MERCURATED DERIVATIVES OF SUBSTITUTED BENZYLIDENEANILINES

^(199)Hg NHR spectra of 18 Schiff base type arylmercury compounds have been studied.It was further confirmed that in the molecule of XC_6H_4CH=NC_6H_3-2-HgC1-4-CH_3 there exists an intramolecular N→Hg coordination via a four-membered ring.For the series of XC_6H_4CH=NC_6H_3-2-HgCl-4-CH_3(X is a para-or mera-substituent),there is a good linear correlation between δ^(199)Hg and Hammett's o constants.The influence of substituents of C-pheny1 ring on the δ ^(199)Hg can be explained in terms of the intramolecular N→Hg coordination.

Syntheses, Crystal Structures, and Magnetic Properties of Mn(Ⅱ) and Co(Ⅱ) Coordination Polymers Constructed from Pyridine-tricarboxylate Ligand

Two coordination polymers, namely {[Mn（HL_1）（phen）]·4H_2O}_n（1） and [Co_2（HL_2）_2（H_2O）_2]_n（2） have been constructed hydrothermally using H_3L_1 and H_3L_2（H_3L_1 = 2-（5-carboxypyridin-2-yl）terephthalic acid, H_3L_2 = 2-（4-carboxypyridin-3-yl）terephthalic acid）, phen, MnCl_2×4H_2O and CoCl_2×6H_2O. The products were isolated as stable crystalline solids and were characterized by IR spectroscopy, elemental, thermogravimetric（TGA）, powder（PXRD） and single-crystal X-ray diffraction analyses. Compound 1 features a 3D framework structure, which was topologically classified as a trinodal 4,6,6-connected net with the unique topology defined by the point symbol of（3^（10）.5.6~4）4（3^（10）.6.7~4）2（5.6~2.8~2.9）. Compound 2 possesses a 2D metal-organic layer, which was topologically classified as a binodal 4,4-connected layer defined by the point symbol of（4~3.6~2.8）. The layers are further extended into a 3D supramolecular framework via hydrogen bonds. The magnetic properties for both compounds were also investigated, indicating antiferromagnetic interactions between the adjacent metal ions.

Synthesis, Crystal Structure and Magnetic Properties of a Cobalt(Ⅱ) Complex with Quinoxaline-substituted Nitronyl Nitroxide Radicals

A new complex with the formula [Co（acac）_2（NITQ）_2]×2CH_2Cl_2 1（acac = acetylacetone, NITQ = 2-（2′-quinoxalinyl）-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide）, was synthesized and elucidated structurally as well as magnetically in detail. The crystal belongs to the monoclinic system, space group P2_1/c with a = 9.6896（1）, b = 20.539（4）, c = 12.147（2） ？, β = 93.84（3）°, M_r = 997.65, V = 2412.1（8） ？~3, Z = 2, Dc = 1.374 g/cm, F（000） = 1038, m = 0.635 mm^（-1）, the final R = 0.0539 and w R = 0.1289 for 5998 observed reflections（I 〉 2σ（I））. The Co（Ⅱ） ion is coordinated by two nitrogen atoms of quinoxaline rings from two NITQs and four oxygen atoms from two acac ions to complete a distorted octahedral coordination environment. Compound 1 is further linked into a three-dimensional（3D） supramolecular network by hydrogen-bonding, Cl×××O weak contact and π···π stacking interactions. The magnetic measurements show compound 1 exhibits weak ferromagnetic interactions.

EFFECTS OF HDDR PROCESS ON STRUCTURE AND MAGNETIC PROPERTIES OF Nd(Fe,Ti)_(12)N_δ PREPARED BY MECHANICAL ALLOYING

The effects of the hydrogenation-disproportionation-desorption-recombination (HDDR) process on the structure and the magnetic properties of the mechanical alloying (MA) prepared Nd8Fe84 Ti8 alloy and its nitride counterpart have been studied in detail. It has been found that Nd(Fe, Ti)12Hδ is formed in the temperature range from 300 to 550°℃. The disproportionation is ready to start at 550°℃ and is complete at 960°℃.The desorption and the recombination are almost synchronized. The phase of Nd(Fe,Ti)7 is formed at 750°℃ during the HDDR treatment. With increasing temperature of HDDR process, the metastable structure of TbCu7 type is gradually transformed into the structure of ThMn12 type. The intrinsic coercivity and the maximum magnetic energy product increase with increasing temperature of HDDR process.

First-principles Calculations of Strengthening Compounds in Magnesium Alloy： A General Review

First-principles computation methods play an important role in developing and designing new magnesium alloys.In this article,we present an overview of the first-principles modeling techniques used in recent years to simulate ideal models of the structure of strengthening compounds in Mg alloys.For typical Mg compounds,structural stability,mechanical properties,electronic structure and thermodynamic properties have been discussed.Specifically,the elastic anisotropies of these compounds are examined,which is highly correlated with the possibility of inducing micro-cracks.Furthermore,some heterogeneous nucleation interfaces investigated by first-principles method are reviewed.Some of the theoretical results are compared with available experimental observations.We hope to illustrate that the first-principles computation can help to accelerate the design of new Mg-based materials and the development of materials genome initiative.Remaining problems and future directions in this research field are considered.

Effects of iron compounds on pyrolysis behavior of coals and metallurgical properties of resultant cokes

The utilization of highly reactive and high-strength coke can enhance the efficiency of blast furnace by promoting indirect reduction of iron oxides.Iron compounds,as the main constituent in iron-bearing minerals,have aroused wide interest in preparation of highly reactive iron coke.However,the effects of iron compounds on pyrolysis behavior of coal and metallurgical properties of resultant cokes are still unclear.Thus,three iron compounds,i.e.,Fe;O;,Fe;O;and FeC;O;·2H;O,were adopted to investigate their effects on coal pyrolysis behavior and metallurgical properties of the resultant cokes.The results show that iron compounds have slight effects on the thermal behavior of coal blend originated from thermogravimetric and differential thermogravimetric curves.The apparent activation energy varies with different iron compounds ranging from 94.85 to 110.11 kJ/mol in the primary pyrolysis process,while lower apparent activation energy is required for the secondary pyrolysis process.Iron compounds have an adverse influence on the mechanical properties and carbon structure of cokes.Strong correlations exist among coke reactivity,coke strength after reaction,and the content of metallic iron in cokes or the values of crystallite stacking height,which reflect the dependency of thermal property on metallic iron content and carbon structure of cokes.

Microstructure and Magnetic Property Variation with Addition of Rare Earth Element Dy in Co-Ni-Al Ferromagnetic Shape Memory Alloy

The influence of rare earth element Dy on martensitic transformation and magnetic properties of Co-Ni-Al alloy was studied.The results showed that the microstructure of the sample has a dual-phase structure（γ-phase and martensite）.The rare earth element Dy was segregated in Co-richγ-phase and took the place of Co after its addition into the Co-Ni-Al alloy.As Dy content increased to over 0.5at.%,the grain was refined and the rare earth intermetallic compounds Co5 Dy were precipitated inγ-phase.Meanwhile,one-step thermo-elastic martensitic transformation occurred in the sample,wherein the phase transformation temperature significantly increased with rising Dy content.The martensite had a tetragonal L10 structure with a（111）twinning plane.Furthermore,the sample exhibited obvious hysteresis behaviors in the magnetic hysteresis loops.In addition,the saturation magnetization,coercivity,retentivity and magnetocrystalline anisotropy were significantly enhanced owing to the bigger radius of Dy which took the place of Co in the alloy.

Role of membrane and compound properties in affecting the rejection of pharmaceuticals by different RO/NF membranes

This study was conducted to assess the merits and limitations of various high-pressure membranes, tight nanofiltration （NF） membranes in particular, for the removal of trace organic compounds （TrOCs）. The performance of a low-pressure reverse osmosis （LPRO） membrane （ESPA1）, a tight NF membrane （NF90） and two loose NF membranes （HL and NF270） was compared for the rejection of 23 different pharmaceuticals （PhACs）. Efforts were also devoted to understand the effect of adsorption on the rejection performance of each membrane. Difference in hydrogen bond formation potential （HFP） was taken into consideration. Results showed that NF90 performed similarly to ESPA1 with mean rejection higher than 95%. NF270 outperformed HL in terms of both water permeability and PhAC rejection higher than 90%. Electrostatic effects were more significant in PhAC rejection by loose NF membranes than tight NF and LPRO membranes. The adverse effect of adsorption on rejection by HL and ESPA1 was more substantial than NF270 and NF90, which could not be simply explained by the difference in membrane surface hydrophobicity, selective layer thickness or pore size. The HL membrane had a lower rejection of PhACs of higher hydrophobicity （log D〉0） and higher HFP （〉0.02）. Nevertheless, the effects of PhAC hydrophobicity and HFP on rejection by ESPA1 could not be discerned. Poor rejection of certain PhACs could generally be explained by aspects of steric hindrance, electrostatic interactions and adsorption. High-pressure membranes like NF90 and NF270 have a high promise in TrOC removal from contaminated water.

Structure, magnetic properties, and thermal stability of Sm(1-x)Tm_xCo_5compounds

Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm content.Magnetic measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.