Structural aspect of possible interrelation between fragility (length) of glass forming melts and Poisson’s ratio of glasses

The analysis of the development of the notion of fragility (length) of glass forming melts and the nature of Poisson’s coefficient of glasses is presented for the period from 60s of 20th century, basing on structural relations. It is shown that the most distinct structural correlations have been obtained in the framework of ideas of Zachariasen and Hägg, activation theory of viscous flow, and lattice theory of Mie and Grüneisen. It is shown that the existence of universal correlations between fragility and Poisson’s ratio is physically baseless yet. The reason is that the systems under comparison are in frozen and in metastable states and the physical meanings of the properties under consideration are incompatible. The possibility of particular correlations between fragility of glass forming melts and Poisson’s ratio is discussed. Such correlations possibly exist within special groups of substances which have related structures. The theory of viscous flow for the transition from glass to metastable liquid is refined in the framework of the elastic continuum theory.     

New selective nickel(II)-N3 nitrogen bond in adenine: Synthesis and structure of [(tren) (adenine) (monochloro)nickel(II)] chloride and [(tren)(imidazole)(monoaqua)nickel(II)] dichloride

With the aim to obtain further insight into the nature of the Ni(II)-nitrogen bond in complexes with nucleobases, we have synthesized two novel Ni(II) ternary complexes constituted by Ni(II), tris(2-aminoethyl)amine (tren) and neutral adenine (AdH) or imidazole (ImH). The reaction of NiCl₂·6H₂O with tren and imidazole yields the ternary [Ni(tren)(ImH)(H₂O)]Cl₂·H₂O complex and the same reaction with adenine instead of imidazole gives the ternary [Ni(tren)(AdH)Cl]Cl complex. The complexes have been studied by spectrophotometric and spectroscopic measurements and by X-ray diffraction. The ternary complex of adenine is monoclinic, space groupC2/c, and exhibits a pseudo-octahedral geometry, being Ni(II) coordinated to the four nitrogen atoms of the tetradentate tren ligand, to a Cl^– ion and to the pyrimidine N3 site of a neutral adenine. Such an exclusive Ni-N3 bonding [2.081(4)Å] is now reported for the first time. The ternary complex of imidazole is monoclinic, space groupP2₁/n. Its pseudo-octahedral geometry is similar to that found in the above adenine complex although a water molecule instead of a Cl^– ion is now present in the coordination sphere. In fact, Ni(II) is coordinated to tetradentate tren, to the imidazole N1 nitrogen and to a water molecule. Electronic and¹H NMR spectra in solution indicate that the octahedral structures found in the solid state are substantially maintained in solution. Furthermore, the present investigation suggests that the adenine Ni-N3 and imidazole Ni-N1 bonds have the same chemical nature, involving mainly - and only partially-bonding. The Ni-N3 bonding is discussed in connection with biological implications and possible applications.     

Photoluminescence properties of PVP/Eu(TTA)2(Phen3PO)2NO3 nanocomposites

Thin films (1-10 μm thickness) of nanocomposites (NC) based on organic coordinated compound (OCC) Eu(TTA)₂(Phen₃PO)₂NO₃ (where TTA is thenoyltrifluoroacetonate (C₈H₅F₃O₂S), Phen - 1,10-phenanthroline (C₁₂H₈N₂)) and polymer - polyvinylpyrrolidone ((C₆H₉NO)_n) (PVP)) were obtained by chemical methods. NC were characterized by measurements of optical transmission, and photoluminescence (PL) at different concentrations of Eu(TTA)₂(Phen₃PO)₂NO₃ in NC. Using the optical transmission spectra, the characteristic parameters of NC such as threshold of absorbance and the position of the absorption edge on the concentration of the OOC in NC, etc., were determined. The light displacement of threshold absorption to infrared region was observed with increasing of concentration of coordinated material in NC. It was established that the excitation spectrum at which the photoluminescence in NC take place cover the range of wavelength from 200 to 410 nm. The PL of nanocomposites was detected as specific for internal transitions 4f-4f of the Eu³⁺ ion ⁵D₀ → ⁷F_i (i = 0,1,2,3 and 4) centred at 537, 580, 615, 650 and 702 nm, respectively at T = 300 K. The dominant PL was observed at 615 nm and its halfwidth is less than 10 nm. The intensity of photoluminescence at 615 nm of NC is 2 times higher than the value of intensity of PL of Eu(TTA)₂(Phen₃PO)₂NO₃ powders at equal conditions of excitation.     

Crystal structure of a novel tertiary phosphine coordination complex: dichlorobis(tribenzylphosphine)nickel(II)

The title compound dichlorobis(tribenzylphosphine)nickel(II), Ni[P(CH₂C₆H₅)₃]₂Cl₂, belongs to a type of tertiary phosphine coordination complex, M(PR₃)₂X₂. There are two molecules in the unit cell which do not appear to interact chemically. Both molecules have a trans-square planar configuration with each nickel atom on a center of symmetry. Three benzyl groups are bonded to each phosphorus atom as rotors in a propeller, and the threefold axis is along the P—Ni bond, which has a mean length of 2.23(1) Å. Crystal data: C₄₂H₄₂Cl₂NiP₂, Triclinic, space group , a = 10.4892(15) b = 10.5249(12) c = 19.453(2) Å, = 83.872(8), = 76.839(9), = 62.241(8)°, V = 1850.5(4) ų, Z = 2. There is an intramolecular hydrogen bond between the C3 and C11 atoms.     

Growth of GaInAs(P) and GaInAsP/GaInAs MQW structures by CBE

We discuss the growth of lattice matched GaInAs, GaInAsP and GaInAsP/GaInAs multiple quantum well structures for high speed laser applications. Optical cavities, including five 90 Å GaInAs quantum wells with GaInAsP barriers and waveguides showed a 4 K photoluminescence line width of 8.7 meV. Transmission electron microscopy and X-ray diffraction confirm the good control over the growth of these structures.     

Structural investigation of gallium oxide (β-Ga2O3) nanowires grown by arc-discharge

Gallium oxide nanowires were synthesized by electric arc discharge of GaN powders mixed with a small amount of Ni and Co. The crystal structure of nanowires was determined by multi-channel X-ray diffractometry (MC-XRD), FT-Raman spectroscopy and transmission electron microscopy (TEM). The analyzed results clearly show that the synthesized nanowires are monoclinic gallium oxide (β-Ga₂O₃). Final morphology and microstructure of β-Ga₂O₃ nanowires were changed depending on the presence of the transition metals into the nanowires. The β-Ga₂O₃ nanowires grown by the assistance of transition metals demonstrate a smooth edge surface while containing twin defects at the center. The transition metals have enhanced the step growth of nanowires. However, in the case of the β-Ga₂O₃ nanowires, where the transition metals are not shown on the surface, the nanowires demonstrate rather thin and long shapes with amorphous gallium oxide layers on the nanowire surface.     

P／I界面处理对a-Si：H柔性太阳能电池性能的影响

采用等离子体辅助化学汽相沉积(PECVD)技术制备本征非晶硅薄膜,对p/i界面进行处理.在此基础上,制备P型微晶硅(μc-Si:H)薄膜与柔性太阳能电池.对P型硅薄膜及太阳能电池的性能进行研究.结果表明:对p/i界面采用H等离子体处理,再引入一定厚度的成核层,可以成功得到高电导率的P型微晶硅窗口层,提高柔性太阳能电池的光伏特性.其中的成核层,不仅促进微晶相P层的生长,还可以起到界面缓冲层的作用.     

Influence of the spectator cation on the structure of anionic pyridine-2,6-dicarboxylato complexes of cobalt(II), nickel(II), and copper(II)

The structures of anionic pyridine-2,6-dicarboxylato (pdc^2–) complexes of cobalt, nickel, and copper have been studied. The stoichiometries and structures are very much dependent on whether KOH, Et₄NOH, or NaOH is used in the synthesis to deprotonate the H₂pdc ligand. Crystallographic results are: (1) K₂[Co(pdc)₂] · 7H₂O, orthorhombic, Pnna, Z = 4, a = 20.637(2)Å, b = 13.480(1)Å, c = 8.200(1)Å (2) K₂[Ni(pdc)₂] · 7H₂O, orthorhombic, Pnna, Z = 4, a = 20.648(1)Å, b = 13.375(1)Å, c = 8.2393(8)Å (3) [Co₂(H₂O)₅(pdc)₂] · 2H₂O, monoclinic, P2₁/c, Z = 4, a = 8.3880(6)Å, b = 27.384(2)Å, c = 9.6110(8)Å, = 98.271(6)° (4) [Ni(Hpdc)₂] · 3H₂O, monoclinic, P2₁/c, Z = 4, a = 13.679(1)Å, b = 10.0450(9)Å, c = 13.767(2)Å, = 115.184(7)° (5) Na₆[Co(H₂O)₆][Co(pdc)₂]₄ · 28H₂O, monoclinic, P2₁/n, Z = 2, a = 13.363(1)Å, b = 8.437(1)Å, c = 40.689(3)Å, = 91.288(5)° (6) Na[Ni(Hpdc)(pdc)] · 11.5H₂O, monoclinic, C2/m, Z = 4, a = 15.200(2)Å, b = 22.299(2)Å, c = 8.3596(7)Å, = 118.894(7)° (7) Na[Cu(Hpdc)(pdc)] · 3H₂O, monoclinic, P2₁/n, Z = 4, a = 9.516(4)Å, b = 14.917(6)Å, c = 12.247(5)Å, = 92.00(5)°. The potassium and sodium complexes have extensive K⁺—H₂O and Na⁺—H₂O networks. The fact the Et₄N⁺ ion does not appear in any of the complexes is likely due to the fact that it is incapable of forming the intricate cation—water and hydrogen-bonding networks observed in all of the other structures.     

Structure and characterization of O,O-diethylthiophosphorylhydrazine o-vanillin Schiff base nickel(II) complex: NiC24H36N4O8P2S2

The crystal and molecular structure of the complex of Ni[(C₂H₅O)₂PSNHNCPh(o-O)OMe]₂ has been determined by X-ray crystallography. The compound crystallizes in the monoclinic system, space group P2₁/n, with lattice parameters a = 14.805(3), b = 7.9550(16), c = 15.176(3) Å, = 117.94(3), and Z = 2. The unit cell contains two centrosymmetric molecules of O,O-diethylthiophosphorylhydrazine o-vanillin Schiff base nickel(II). The nickel(II) ion is coordinated in a slightly distorted trans square-planar configuration, the distortion consisting of a reduction of the N—Ni—O angle with the chelate rings from the ideal value of 90° to 87.69°. The coordination geometry of nickel(II) is square planar with two equivalent Ni—N and Ni—O bonds. The two phenyl rings and the phosphorylhydrazine moieties are in one plane forming an extensive delocalized system. Within each molecule, the two ligands are linked by a pair of N—H···O hydrogen bonding interactions. In the solid state, the title compound form a hydrogen bonding network through C—H···O intermolecular hydrogen bonding.     

Fabrication and characterization of transparent conductive ZnO:Al thin films prepared by direct current magnetron sputtering with highly conductive ZnO(ZnAl2O4) ceramic target

Using a highly conductive ZnO(ZnAl₂O₄) ceramic target, c-axis-oriented transparent conductive ZnO:Al₂O₃ (ZAO) thin films were prepared on glass sheet substrates by direct current planar magnetron sputtering. The structural, electrical and optical properties of the films (deposited at different temperatures and annealed at 400°C in vacuum) were characterized with several techniques. The experimental results show that the electrical resistivity of films deposited at 320°C is 2.67×10⁻⁴ Ω cm and can be further reduced to as low as 1.5×10⁻⁴ Ω cm by annealing at 400°C for 2 h in a vacuum pressure of 10⁻⁵ Torr. ZAO thin films deposited at room temperature have flaky crystallites with an average grain size of ∼100 nm; however those deposited at 320°C have tetrahedron grains with an average grain size of ∼150 nm. By increasing the deposition temperature or the post-deposition vacuum annealing, the carrier concentration of ZAO thin films increases, and the absorption edge in the transmission spectra shifts toward the shorter wavelength side (blue shift).     

c-BN含量对(Ti,W)C/WC/Co金属陶瓷刀具材料力学性能的影响

采用真空热压烧结工艺制备了(Ti,W)C/WC/c-BN/Co金属陶瓷刀具材料,分析了(Ti,W)C/WC/c-BN/Co金属陶瓷刀具材料的微观结构、元素成分和物相组成,研究了不同含量c-BN对(Ti,W)C/WC/c-BN/Co金属陶瓷刀具材料微观结构和力学性能的影响.研究结果表明:适量添加c-BN 能有效细化颗粒,减少气孔等缺陷,提高材料的相对密度,(Ti,W)C/WC/c-BN/Co金属陶瓷刀具材料的断裂模式为穿/沿晶混合断裂模式;当c-BN含量为1wt;时,(Ti,W)C/WC/c-BN/Co金属陶瓷刀具的综合力学性能最优,其抗弯强度、断裂韧性和维氏硬度分别为769.32±10.21 MPa、6.69±0.18 MPa·m1/2和22.83±0.46 GPa.     

Influence of growth temperature on the selective area MOVPE of InAs nanowires on GaAs (1 1 1) B using N2 carrier gas

The influence of temperature on selective area (SA) InAs nanowire growth was investigated for metal-organic vapor phase epitaxy (MOVPE) using N₂ as the carrier gas and (1 1 1) B GaAs substrates. In contrast to the growth temperature range – below 600 °C – reported for hydrogen ambient, the optimal growth temperature between 650 and 700 °C was 100 K higher than the optimal ones for H₂ carrier gas. At these temperatures, nanowires with aspect ratios of about 80 and a symmetric hexagonal shape were obtained. The results found are attributed to the physical and chemical properties of the carrier gas.     

In-situ doping of and trench-refill with LPCVD-poly-silicon (I). (PH3/SiH4) ratio as a process-controlling parameter

The ratio of phosphine- to silane concentration in the reaction gas mixture is a processcontrolling parameter in LPCVD-polysilicon deposition not only with respect to doping level of the layer and layer growth rate on planar wafer surface, but also with respect to the degree of growth rate depression occurring by change-over from wafer surface to sidewall area within trenches in the region of the upper rim of a trench. Trench refill behaviour deteriorates in consequence of growth rate depression within trench the more the higher the doping level of poly-silicon will be chosen. Yet below a lower limit of doping poly-silicon growth rate equals that of undoped poly-silicon, and, as for trench-refill, there is no difference in layer growth within trench and beyond.     

Hydrogen-Bonding Interactions in the Crystal Structure of Bis( N -propyl- N -(2-hydroxyethyl)dithiocarbamato- S , S ′)nickel(II): Ni[S2CN(nPr)(CH2CH2OH)]2

Two independent molecules of Ni(S₂CN(Pr)CH₂CH₂OH)₂, each located about a center of inversion, comprise the asymmetric unit. The molecules differ from each other in terms of the relative orientation of the terminal hydroxyl groups. A square planar geometry is found for each nickel atom defined by four sulfur atoms derived from two symmetrically chelating dithiocarbamate ligands. The crystal packing is dominated by O–H···O interactions that lead to extensive cross linking in all directions. The compound crystallizes in the triclinic space group P-1 with a = 6.4008(11) ?, b = 11.480(2) ?, c = 12.517(2) ?, α = 88.021(2)°, β = 82.491(2)°, γ = 89.986(2)°, and Z = 2.     

Identification of a new family of diphosphate compounds, AI2BII3(P2O7)2: Structures of Ag2Co3(P2O7)2, Ag2Mn3(P2O7)2, and Na2Cd3(P2O7)2

Syntheses and single-crystal X-ray structural results are reported for three new mixed diphosphates of the family A^I ₂B^II ₃(P₂O₇)₂; Ag₂Co₃(P₂O₇)₂ (I), Ag₂Mn₃(P₂O₇)₂ (II), and Na₂Cd₃(P₂O₇)₂ (III). All crystallize in the triclinic system, space group P1 bar: (I) a = 5.351(4), b = 6.375(4), c = 16.532(4) Å, = 80.83(6) = 81.45(4), = 72.87(5)°, V = 528.9(6) ų, Z = 2, D _calc = 4.649 mg/m³, R/Rw = 0.0428/0.0548 for 3949 obs. reflns; (II) a = 5.432(7), b = 6.619(6), c = 16.51(3) Å, = 80.78(8) = 82.43(9), = 72.82(7)°, V = 557.7(13) ų, Z = 2, D _calc = 4.338 mg/m³, R/Rw = 0.0679/0.1303 for 2100 obs. reflns and (III) a = 5.67(3), b = 7.08(4), c = 7.90(4) Å, = 77.0(2), = 82.5(2), = 67.8(2)°, V = 286(3) ų, Z = 2, D _calc = 4.249 mg/m³, R/Rw = 0.0307/0.0342 for 1945 obs. reflns. (I) and (II) are isostructural but (III) is of a different type. All three structures are characterized by layers of P₂O₇ groups alternating with layers of mixed metal atoms. Differences are seen in the conglomerate bonding patterns of B atoms and in the irregular geometry of Ag in (I) and (II) compared to the octahedral bonding seen for Na in (III). The differences in structure may be understood in terms of the ratios of the ionic radii of A and B atoms.     

The formation of a Schiff base intermediate: a nickel(II) complex of an asymmetric tripodal ligand

Treatment of Ni(ClO₄)₂ · 6H₂O with the condensing product of 2-formylpyridine N-oxide and 1,5-diamino-3-(8-methylquinolyl)azapentane (dmqa) has resulted in the formation of an asymmetric tripodal nickel(II) complex, [C₂₈H₃₂N₆O₃Ni](ClO₄)₂ · H₂O, which has been crystallographically characterized. Crystal data: triclinic, space group p , a = 10.384(2), b = 10.911(3), c = 16.6101(11) Å, = 95.62(2), = 105.04(2), = 112.954(11)°, D _c = 1.581 g/cm³, Z = 2 and V = 1631.0(6) ų. A quinoline moiety is first introduced into an arm in the complex of a tripodal ligand in which an ethylcarbinoxyamine group, the intermediate of Schiff bases, exists.     

B位四价Sn4+, Zr4+取代对Ba(Zn1/3Nb2/3)O3系统微观结构的影响

采用传统的固相陶瓷烧结工艺,利用四价正离子Sn4+、Zr4+取代Ba(Zn1/3Nb2/3)O3陶瓷的B位Zn2+、Nb5+,研究其对Ba(Zn1/3Nb2/3)O3系统微观结构的影响.四价Sn4+、Zr4+取代B位Zn2+、Nb5+可以形成固溶体,系统的主晶相仍为立方相.系统晶格常数a随着Sn4+取代量的增加而呈线性增大,相同Sn4+取代量下随着烧结温度的增加,晶格常数a增大.BaZrO3(BZ)的加入可减少第二相的生成.Sn4+、Zr4+均可改善系统烧结特性,加快致密化形成.     

X-ray Crystal Structure of Trans -UO2(N(SiMe3)2)2(THF)2: One in a Series of Uranyl(VI) Complexes Supported by Bis(trimethylsilyl)amido Ligands

Abstract The title compound trans-UO₂(N(SiMe₃)₂)₂(THF)₂ (1) was synthesized and characterized by X-ray crystallography. The complex crystallizes in the monoclinic space group C2/c (#15) with lattice parameters a = 16.0771(5) ?, b = 13.1196(4) ?, c = 16.9391(6) ?, β = 116.853(1)°, V = 3187.61(18) ?³, Z = 4, D _calc = 1.532 g cm^-3. The six-coordinate uranium(VI) center adopts an all-trans octahedral geometry consisting of mutually trans oxo groups, silylamido ligands, and neutral THF donors. Structural comparisons of this uranyl(VI) bis(amido) complex with a related tris(amido) derivative within the series are made based on symmetry, charge, and coordination number. Graphical Abstract The X-ray crystal structure of the title complex is reported, providing comparisons based on symmetry, charge, and coordination number with a related uranyl(VI) amido derivative within this series.      

Reaction of bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) with PhCCo3(CO)9: synthesis and X-ray characterization of the dmpdmh-bridged polymorphs of PhCCo3(CO)7[(MeO)2PN(Me)N(Me)P(OMe)2]

The tricobalt cluster PhCCo₃(CO)₉ reacts with the bis(phosphanyl)hydrazine ligand bis(dimethoxyphosphino)dimethylhydrazine (dmpdmh) to give the monosubstituted cluster [PhCCo₃(CO)₈]₂(dmpdmh) and the disubstituted cluster PhCCo₃(CO)₇(dmpdmh) as the major products. This latter cluster contains a bridging dmpdmh ligand. Both IR and NMR spectroscopies (³¹P and ¹H) have been employed in the solution characterization of these two clusters. The solid-state structure of PhCCo₃(CO)₇(dmpdmh) was unequivocally established by X-ray diffraction analysis, which has revealed the presence of two different polymorphs for this particular cluster. The first polymorph crystallizes in the monoclinic space group P2₁/n, a = 9.7127(7) Å, b = 17.025(2) Å,c = 16.894(1) Å, = 96.245(5)°, V = 2777.0(4) ų, Z = 4, and d _calc = 1.689 g/cm³; while the second polymorph crystallizes in the orthorhombic space group Pbca, a = 16.925(2) Å, b = 16.208(2) Å, c = 20.541(3) Å, V = 5635(1) ų, Z = 8, and d _calc = 1.665 g/cm³.