低化学稳定性复杂组分含磷铝硅酸盐玻璃体结构——含磷铝硅酸盐玻璃体结构模型与肥料开发

基于玻璃体无规则网络学说,建立了包含P2O5,K2O,CaO,MgO,SiO2,Fe2O3,FeO,Al2O3,B2O3,MnO,CuO,ZnO,NiO,MoO2,CoO和TiO2低化学稳定性复杂组分的玻璃体结构模型,推导出扩展的玻璃结构因子(Ob/Yb)ex及其计算式.对高效利用低品位磷矿、磷矿选矿尾矿、难溶性钾矿和低品位磷钾矿制造能为农作物吸收的玻璃体肥料具有一定的理论意义和应用价值.     

CsB3GeO7 and K2B2Ge3O10: explorations of new second-order nonlinear optical materials in the borogermanate systems

Two novel alkali(I) borogermanates with noncentrosymmetric structures, namely, CsB 3GeO 7 and K 2B 2Ge 3O 10, have been synthesized by high-temperature solid-state reactions in a platinum crucible. The structure of CsB 3GeO 7 features a novel three-dimensional (3D) framework composed of cyclic B 3O 7 (5-) groups that are interconnected by Ge(IV) cations, whereas the structure of K 2B 2Ge 3O 10 is a new 3D network based on cap-shaped [Ge 3B 2O 14] (10-) clusters that are interconnected via Ge-O-B bridges. CsB 3GeO 7 exhibits a second-harmonic generation (SHG) response that is about 1.5 times that of KDP (KH 2PO 4), whereas the SHG signal of K 2B 2Ge 3O 10 is very weak. Both compounds are insulators and transparent in the range of 300-5000 nm. The electronic structure calculations for both compounds also have been performed.     

Volatile magnesium octahydrotriborate complexes as potential CVD precursors to MgB2. Synthesis and characterization of Mg(B3H8)2 and its etherates

The solid-state reaction of MgBr2 and NaB3H8 at 20 degrees C, followed by sublimation at 80 degrees C and 0.05 Torr, affords Mg(B3H8)2 as a white solid. Similar reactions with MgBr2(Et2O) and MgBr2(Me2O)1.5 afford the crystalline ether adducts Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2, respectively. In contrast, reactions of MgBr2 with NaB3H8, the presence of excess solvent result in the formation of nonvolatile, probably ionic, magnesium compounds of the type [MgLx][B3H8]2. The adducts Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2 are the first crystallographically characterized magnesium complexes of the B3H8- ligand; in both structures, the magnesium center adopts a distorted cis-octahedral geometry with two bidentate B3H8 groups and two Et2O ligands. Owing to their volatility, Mg(B3H8)2(Et2O)2 and Mg(B3H8)2(Me2O)2 are potential precursors for the deposition of MgB2 thin films, although preliminary efforts to employ them as chemical vapor deposition sources produce boron-rich MgBx films instead, with x approximately 7. Finally, the synthesis and structure of Cp2Mg(thf) are described: this mono-thf adduct of Cp2Mg bears two eta5-Cp groups, unlike other Lewis base adducts of Cp2Mg, which contain one eta5-Cp group and one eta1- or eta2-Cp group.     

Ligand field modification around Cu2+ ions in sodium borate glass by codoping

Understanding the effect of codoping on the properties of photonic glasses is important for improving their properties. The effect of codoping on the ligand field around Cu(2+) ions in a sodium borate glass is examined using optical absorption spectroscopy, continuous-wave electron paramagnetic resonance, and three-pulse electron-spin-echo envelope-modulation. Glass with a composition of 0.1CuO·5Na(2)O·95B(2)O(3) was codoped with 2 mol % of Al(3+), Si(4+), P(5+), Zr(4+), or La(3+) oxide. Three codoping effects are found: strengthening the ligand field, as observed for Zr-codoping, which induces a large blue shift of the optical absorption peak of Cu(2+); weakening the ligand field, as observed for P-codoping, which causes a red shift of the Cu(2+) absorption peak; and almost no effect on the ligand field, which is observed for Al-, Si-, and La-codoping. Coordination structure models based on local charge neutrality are proposed for the codoped glasses. The mechanism of the codoping effect is revealed by elucidating the local structure around Cu(2+).     

Neutron powder diffraction studies of sulfuric acid hydrates. I. The structure of sulfuric acid hemitriskaidekahydrate D2SO4.6(1/2)D2O

We report the first neutron diffraction data from D2SO4.6(1/2)D2O. The crystal is monoclinic, space group Cm, with four formula units per unit cell. At 4.2 K the unit cell dimensions are a = 6.253 26(4) A, b = 26.813 62(10) A, c = 5.908 45(2) A, and beta = 112.1939(3) degrees [V = 917.286(6) A3 and rho(deuterated) = 1664.14(2) kg m(-3)]. The deuteron positions refined from the neutron data are in agreement with those established by single crystal x-ray analysis [D. Mootz and A. Merschenz-Quack, Z. Naturforsch. B 42, 1231 (1987)], but not with those found from the ab initio simulation of Hirsch and Ojamae [Acta Crystallogr, Sect. B: Struct. Sci. 60, 179 (2004)]. The crystal consists of SO4(2-), D3O+ ions, and D2O molecules hydrogen bonded to form a layered structure in which sheets of "icelike" D3O+ and D2O are separated by layers of opposing SO4(2-) tetrahedra.     

Raman spectrum, quantum mechanical calculations and vibrational assignments of (95% alpha-TeO2/5% Sm2O3) glass

Chozen system of tellurite glasses doped with rare earth oxides (95% alpha-TeO(2)+5% Sm2O3) was prepared by melt quenching. Consequently, the Raman spectrum (150-1250 cm(-1)) of the modified tellurite have been recorded. As a continuation to our normal coordinate analysis, force constants and quantum mechanical (QM) calculations for tbp TeO4(4-) (triagonal bipyramid, C(2v)) and TeO(3+1); Te2O7(6-) (bridged tetrahedral), we have carried out ab initio frequency calculations for tpy TeO3(2-) (triagonal pyramidal, C(3v) and C(s)) and tp TeO3(2-) (triagonal planar, D(3h)) ions. The quantum mechanical calculations at the levels of RHF, B3LYP and MP2 allow confident vibrational assignments and structural identification in the binary oxide glass (95% alpha-TeO2 +5% Sm2O3). The dominant three-dimensional network structures in the modified glass are triagonal pyramidal TeO3 with minor features of short range distorted tbp TeO4 and bridged tetrahedral unit of TeO(3+1), leading to a structure of infinite chain. Therefore, alpha-TeO2/Sm2O3 (95/5%) glass experience structural changes from TeO4 (tbp); Te2O7 (TeO(3+1))-->TeO3 (tpy).     

Ba3[Ge2B7O16(OH)2](OH)(H2O) and Ba3Ge2B6O16: novel alkaline-earth borogermanates based on two types of polymeric borate units and GeO4 tetrahedra

Two new barium borogermanates with two types of novel structures, namely, Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) and Ba(3)Ge(2)B(6)O(16), have been synthesized by hydrothermal or high-temperature solid-state reactions. They represent the first examples of alkaline-earth borogermanates. Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) crystallized in a polar space group Cc. Its structure features a novel three-dimensional anionic framework composed of [B(7)O(16)(OH)(2)](13-) polyanions that are bridged by Ge atoms with one-dimensional (1D) 10-membered-ring (MR) tunnels along the b axis. The Ba(II) cations, hydroxide ions, and water molecules are located at the above tunnels. Ba(3)Ge(2)B(6)O(16) crystallizes in centrosymmetric space group P1. Its structure exhibits a thick layer composed of circular B(6)O(16) units connected by GeO(4) tetrahedra via corner sharing, forming 1D 4- and 6-MR tunnels along the c axis. Ba1 ions reside in the tunnels of the 6-MRs, whereas Ba2 ions are located at the interlayer space. Both compounds feature new types of topological structures. Second-harmonic-generation (SHG) measurements indicate that Ba(3)[Ge(2)B(7)O(16)(OH)(2)](OH)(H(2)O) displays a weak SHG response of about 0.3 times that of KH(2)PO(4). Optical, thermal stability, and ferroelectric properties as well as theoretical calculations have also been performed.     

Structure, stability and vibrational spectrum of the hydrogen-bonded complex between HNO3 and H2O. Ab initio and DFT studies

The structure, stability and vibrational spectrum of the binary complex between HONO2 and H2O have been investigated using ab initio calculations at SCF and MP2 levels with different basis sets and B3LYP/6-31G(d,p) calculations. Full geometry optimization was made for the complex studied. It was established that the hydrogen-bonded H2O...HONO2 complex has a planar structure. The corrected values of the dissociation energy at the SCF and MP2 levels and B3LYP calculations are indicative of relatively strong OH...O hydrogen-bonded interaction. The changes in the vibrational characteristics (vibrational frequencies and infrared intensities) arising from the hydrogen bonding between HONO2 and H2O have been estimated by using the ab initio calculations at SCF and MP2 levels and B3LYP/6-31G(d,p) calculations. It was established that the most sensitive to the complexation is the stretching O-H vibration from HONO2. In agreement with the experiment, its vibrational frequency in the complex is shifted to lower wavenumbers. The predicted frequency shift with the B3LYP/6-31G(d,p) calculations (-439 cm(-1)) is in the best agreement with the experimentally measured (-498 cm(-1)). The intensity of this vibration increases dramatically upon hydrogen bonding. The ab initio calculations at the SCF level predict an increase up to five times; at the MP2 level up to 10 times and the B3LYP/6-31G(d,p) predicted increase is up to 17 times. The good agreement between the predicted values of the frequency shifts and those experimentally observed show that the structure of the hydrogen-bonded complex H2O...HONO2 is reliable.     

Nature of the bottom t2g-block bands of layered perovskites. Implications for the transport properties of phases where these bands are partially filled

The electronic structure of a series of double layer (Sr(3)V(2)O(7), KLaNb(2)O(7), Li(2)SrNb(2)O(7), RbLaNb(2)O(7), Rb(2)LaNb(2)O(7)) as well as triple layer (Ca(4)Ti(3)O(10), K(2)La(2)Ti(3)O(10), Sr(4)V(3)O(9.7), CsCa(2)Nb(3)O(10)) Dion-Jacobson and Ruddlesden-Popper phases and quadruple layer A(n)()B(n)(O(3)(n)(+2) phases (Sr(2)Nb(2)O(7) as well as the low-temperature and room-temperature structures of Sr(2)Ta(2)O(7)) has been studied by means of a first-principles density functional theory approach. The results are rationalized on the basis of a simple tight-binding scheme, which provides a simple yet precise scheme allowing the correlation of the crystal structure details and the nature of the bottom t(2g)-block band levels. Both the quantitative and the qualitative approaches are used to analyze the nature of the carriers in intercalated samples of the d(0) semiconducting phases as well as those of the metallic d(x) (0 < x < or = 1) systems. The Ruddlesden-Popper and Dion-Jacobson materials with partially filled t(2g)-block bands must be genuine two-dimensional metals except when the M-O(ap) distances of the outer layer octahedra are similar and the band filling is not low. The conducting electrons in these phases are almost equally distributed among the different layers. It is shown that the A(n)()B(n)O(3)(n)(+2) phases with partially filled bands are potentially interesting materials because they are structurally two-dimensional materials exhibiting one-dimensional band structure features. Finally, the possible application of the simple scheme to related materials such as layered perovskite oxynitrides and the effect of disorder are briefly discussed.     

Raman scattering properties of a protonic titanate HxTi2-x/4[symbol: see text]x/4O4.H2O ([symbol: see text], vacancy; x=0.7) with lepidocrocite-type layered structure

Raman scattering spectroscopy is employed to characterize a layered titanate HxTi2-x/4[symbol: see text]x/4O4.H2O ([symbol: see text]: vacancy; x=0.7) with lepidocrocite (gamma-FeOOH)-type layered structure. Nine Raman lines corresponding to (3Ag+3B1g+3B3g) Raman-active modes expected from this orthorhombic structure (space group D2h25-Immm) are recorded at 183, 270, 387, 449, 558, 658, 704, 803, and 908 cm(-1), which are assigned to Ti-O lattice vibrations within the two-dimensional (2D) lepidocrocite-type TiO6 octahedral host layers. These intrinsic Raman bands present a clear signature that can be used for probing the protonic titanate HxTi2-x/4[symbol: see text]x/4O4.H2O and the 2D titanate nanosheets, as well as their corresponding derivates.     

Ca(1)(-)(x)Na(2)(x)Al(2)B(2)O(7): a structure with tunable density of Na(+) vacancies

A series of samples with the composition Ca(1)(-)(x)Na(2)(x)Al(2)B(2)O(7) (0 < x < or = 1) was investigated and a hexagonal structure with unusually large range of homogeneity (at least from x = 0.01 to 0.95) was revealed. The hexagonal phase consists of [Al(2)B(2)O(7)](infinity)(2)(-) lamellae stacked along the c axis, as in CaAl(2)B(2)O(7) and Na(2)Al(2)B(2)O(7). Nevertheless, the configuration and stacking sequence of the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae are different in these three structures. In the hexagonal structure of Ca(1)(-)(x)()Na(2)(x)()Al(2)B(2)O(7), Ca and half Na cations (Na1) statistically occupy the same crystallographic site which is located between the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae, the other half Na cations (Na2) distribute in the planes bisecting the [Al(2)B(2)O(7)](infinity)(2)(-) lamellae. Depending on the composition, the site occupation factor of Na2 site can vary in the same range as x, leading to a tunable density of Na(+) vacancies in the structure. The AlO(4) tetrahedra and BO(3) triangles in the structure tilt in appropriate ways to improve the bond valence sum of Na2 cations which are not sufficiently bonded to the anions.     

水热条件硼酸镁盐过饱和水溶液的相转化

针对中国盐湖硼资源特点,模拟合成MgO•3B2O3-H2O过饱和溶液,在120 ℃水热条件下对固相析出的过程进行跟踪.析出固相采用化学分析方法、X射线衍射、红外光谱进行物相鉴定.对析出固相的相转化反应机理进行了探讨,结合有关实验分析了MgSO4对固相析出的影响.     

Two novel acentric borate fluorides: M3B6O11F2 (M = Sr, Ba)

Two novel, noncentrosymmetric borate fluorides, Sr(3)B(6)O(11)F(2) and Ba(3)B(6)O(11)F(2), have been synthesized hydrothermally and their structures determined. The compounds are isostructural, crystallizing in space group P2(1), having lattice parameters of a = 6.4093 (13) ?, b = 8.2898 (17) ?, c = 9.3656 (19) ?, and β = 101.51 (3)° for Sr(3)B(6)O(11)F(2) and a = 6.5572 (13) ?, b = 8.5107 (17) ?, c = 9.6726 (19) ?, and β = 101.21 (3)° for Ba(3)B(6)O(11)F(2). The structure consists of a complex triple-ring borate framework having aligned triangular [BO(3)] groups that impart polarity. Fluorine atoms are bound only to the alkaline-earth metals and are not part of the borate framework, resulting in a vastly different structure from those of the hydrated borates Sr(3)B(6)O(11)(OH)(2) and Ba(3)B(6)O(11)(OH)(2) with similar formulas. The title compounds are transparent to nearly 200 nm, making them potentially useful for deep-ultraviolet nonlinear-optical applications.     

B2O3/ZrO2催化剂的11B MAS NMR表征

 用11B MAS NMR技术研究了B2O3/ZrO2催化剂中B2O3活性组分的存在形式及作用状态. 结果表明,B2O3在ZrO2表面以三配位BO3与四配位BO4结构单元存在. ZrO2载体的预焙烧温度和硼含量对B2O3的作用状态具有重要的影响,并改变BO3与BO4结构单元之间的比例. 催化剂表面吸附水的存在对BO4与BO3之间的分布有很大的影响,催化剂焙烧脱水至少可使部分BO4转化为BO3. BO4结构形式容易在无定形的微孔大比表面积的ZrO2表面形成; BO3结构形式却倾向于在结晶形的中孔小比表面积的ZrO2上存在.     

Tautomeric and conformational properties of malonamide, NH2C(O)-CH2-C(O)NH2: electron diffraction and quantum chemical study

The geometric structure of malonamide, NH2C(O)-CH2-C(O)NH2, has been investigated by gas electron diffraction (GED) and quantum chemical calculations (B3LYP and MP2 approximations with 6-311++G(3df,pd) basis sets). Both GED and quantum chemistry result in the existence of a single diketo conformer in the gas phase. According to GED refinement this conformer possesses (sc,ac) conformation with one C=O bond in synclinal orientation (dihedral angle tau(O=C-C-C)=49.0(3.0) degrees) and the other C=O bond in anticlinal orientation (dihedral angle tau(O=C-C-C)=139.5(3.3) degrees). The experimental geometric parameters are reproduced very closely by the B3LYP method.     

分子动力学模拟研究β-BAB2O4熔体的结构

The local structure of β-BaB2O4 melt at 1400 K has been studied by using the method of molecular dynamics simulation. The radial functions simulated show agreement with the recent experimental results of X-ray diffraction. The calculation of bond order parameters indicates that the local structure of the melt can be described by the model of linear combination of 0.11 tetrahedrons BO4 and 0.89 planar triangles BO3. In the process of crystal growth the existing of many planar triangles BO3 in the melt maybe favorable for the forming of planar boroxol rings B3O6 near the crystal interface. The statistics of rings and chains have been done and some isolated BO3, pyroborate B2O5,chain（－B－O－）n and isolated B3O6 rings are found in the melt which is in agreement with HTRS experimental results. A large (－B－O－)n network is also found and it is suggested that the planar BO3 units are mainly existed in the network but isolated.     

Correlation effects on the structure and dynamics of the H3O+ hydrate: B3LYP/MM and MP2/MM MD simulations

Two combined quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) simulations, namely B3LYP/MM and MP2/MM, have been performed to investigate the possible influence of electron correlation on the structure and dynamics of the H(3)O(+) hydrate. In comparison to the previously published HF/MM results, both B3LYP/MM and MP2/MM simulations clearly reveal stronger H(3)O(+)-water hydrogen bond interactions, which are reflected in a slightly greater compactness of the H(3)O(+) hydrate. However, the B3LYP/MM simulation, although providing structural details very close to the MP2/MM data, shows an artificially slow dynamic nature of some first shell water molecules as a consequence of the formation of a long-lived H(3)O(+)···H(2)O hydrogen bonding structure.     

NaRuO2 and NaxRuO2.yH2O: new oxide and oxyhydrate with two dimensional RuO2 layers

The new oxide and oxyhydrate NaRuO2 and NaxRuO2.yH2O (x = 0.22, y = 0.45) have been characterized. NaRuO2 is isostructural with alpha-NaFeO2. The symmetry is rhombohedral (R3m space group) with lattice parameters of a = 3.018(2) A and c = 16.493(3) A. The structure has been refined by the Rietveld method. The oxyhydrate NaxRuO2.yH2O has been prepared by stirring a sample of NaRuO2 in water at ambient temperature. NaxRuO2.yH2O crystallizes in the space group R3m with lattice parameters of a = 2.930(2) A and c = 21.913(5) A. The structure is related to the CuFeO2 3R polytype structure with the AABBCC sequence of the oxygen close packed layers along the c-axis. Analogies with the related cobalt phases are discussed. The susceptibilities of NaRuO2 and NaxRuO2.yH2O are small and constant in a large temperature range.     

(C4N3H15)[(BO2)2(GeO2)4]: the first organically templated 3D borogermanate showing 1D 12-rings, large channels, and a novel zeolite-type framework topology constructed from Ge8O24 and B2O7 cluster units

The first organically templated 3D borogermanate with a novel zeolite-type topology, (C4N3H15)[(BO2)2(GeO2)4] FJ-17, has been solvothermally synthesized and characterized by IR spectroscopy, powder X-ray diffraction (PXRD), TGA, and single-crystal X-ray diffraction. The compound crystallized in the monoclinic space group P2(1)/c with a = 6.967(1) A, b = 10.500(1) A, c = 20.501(1) A, beta = 90.500(3) degrees , V = 1499.68(8) A3, and Z = 4. The framework topology of this compound is the previously unknown topology with the vertex symbols 3.4.3.9.3.8(2) (vertex 1), 3.8.3.4.6(2).9(2) (vertex 2), 3.8(2).4.6(2).6(2).8 (vertex 3), 4.8.4.8.8(3).12 (vertex 4), 4.8.4.8.8(2).12 (vertex 5), and 3.8.4.6(2).6.8(2) (vertex 6). The structure is constructed from Ge8O24 and B2O7 clusters. The Ge8O24 cluster contains eight GeO4 tetrahedra that share vertices; the B2O7 unit is composed of two BO4 tetrahedra sharing a vertex. The cyclic Ge8O24 clusters connect to each other through vertices to form a 2D layer with 8,12-nets. The adjacent layers are further linked by the dimeric B2O7 cluster units, resulting in a 3D framework with 12- and 8-ring channels along the a and b axes, respectively. In addition, there is a unique B2GeO9 3-ring in the structure.