Synthesis and Investigation of Double Condensed Phosphates of Scandium and Alkali Metals

Abstract

The present data are the result of experiments on synthesis and investigation of structure of an earlier unknown class of compounds: double condensed phosphates of scandium and alkali metals. The method of synthesis of double phosphates from solution-melts of phosphoric acids at 150–500°C was applied. At lower temperatures (150–240°) double acid di-phosphates MSc(H₂P₂O₇)₂ (where M-Li, Na, K) were crystallized. At 240–410° depending on initial relationship of the components, a number of double compounds (triphosphates of sodium-scandium and potassium-scandium, polyphosphate [LiSc(PO₃)₄]_x, ultraphosphate Na₃SCP₈O₂₃ and cyclophosphate K₂Sc₂P₈O₂₄) was obtained. Double ultraphosphate of sodium-scandium belongs to a rare type of double compounds. Up to now only one ultraphosphate of sodium-iron was known. At 415–500° double medium diphosphates MScP₂O₇ were synthesized. Comparing the results of double phosphates of scandium, gallium, and indium with literary data, we conclude that condensed compounds of scandium, according to their composition and structure, coincide with phosphates of light trivalent metals (Ga, Fe, Cr, Al) and are not similar to corresponding compounds of rare earth elements.     

Phosphates with Two Kinds of Condensed Anions

Abstract

Up to now a dozen of inorganic condensed phosphates containing two anions with different degrees of condensation have been reported.     

Complex Iron Phosphate Anions and Their Salts as Products of Chemisorption of Phosphates by Crystalline Iron Oxides

Chemisorption of phosphate anions by crystalline iron oxides is confined to those sites of the sorbent surface where substitution of silicate (in hydrohematite) or hydroxo and aqua (in hydrogoethite) ligands by phosphate ions is possible. In these sites, new crystalline spherical entities were detected, which were able to pass into the liquid phase. The new formations were identified as ammonium salts of сomplex iron-phosphoric acids. Binding of ammonium cations from solution indicates that the primary phosphate chemisorption products are complex iron phosphate anions capable of being transferred to solution and destructuring iron oxides.     

Hydrogen Isotope Absorption in Unary Oxides and Nitrides with Anion Vacancies and Substitution

The absorption states of hydrogen isotopes in various ceramic materials were investigated by density functional theory. For pristine ceramic materials, main-group oxides do not form any bond with a hydrogen atom. However, transition metal oxides form hydroxyl groups and absorb hydrogen atoms. Main-group and transition metal nitrides form ionic bonds between a hydrogen atom and the surrounded cation. For anion-deficient ceramic materials, hydrogen atoms are negatively charged because of excess electrons induced by anion vacancies, and ionic bonds form with the surrounded cation, which stabilizes the hydrogen absorption state. N substitutional doping into oxides introduces an electron hole, while O substitutional doping into the nitrides introduces an excess of electrons. Therefore, hydrogen isotopes form covalent bonds in N-substituted oxides, and form hydride ions in O-substituted nitrides. Thus, Al₂O₃, SiO₂, CrN, and TiN are promising materials as hydrogen permeation barriers.     

The Synthesis and Crystal Structures of New Condensed Phosphates of Manganese

Abstract

This work deals with the synthesis of condensed phosphates of Mn(II), Mn(III), and also their combinations with Na, Cs. The reaction of MnO₂ with molten polyphosphoric acids, partially neutralized with carbonates of Na and Cs is used. In the course of reaction of MnO₂ with molten polyphosphoric acids, Mn(IV) is reduced to Mn(III) or/and Mn(II). The ratio Mn(III)/Mn(II) depends on the conditions of synthesis (temperature, time, presence of oxidants or reductants etc.). By varying these parameters we obtained 7 new manganese phosphates and determined their structures.     

Phase Transformations in Mixtures of Calcite and Dolomite with Condensed Phosphates of Calcium during Heating

The thermal interactions of dolomite and calcite with calcium polyphosphates up to 1000°C were studied by thermal (dynamic heating and isobaric conditions) and X-ray diffraction methods. It was found that in mixtures with Ca-polyphosphates less than half of the carbonates reacted before decomposition to oxides with the phosphates. The rates of the reactions of phosphates with MgO were much lower than those with CaO. The scheme of the main crystalline phase transformations was constructed. This revised version was published online in July 2006 with corrections to the Cover Date.     

胆盐与磷酸钙的相互作用

胆汁的pH条件下(pH=6～8)，应该生成无定形磷酸钙(ACP)，而在胆结石中磷酸钙通常以羟基磷灰石的形式出现.利用谱学方法研究了ACP与胆盐的作用.结果表明，胆盐以胶团的形式与ACP作用，在溶液中形成复合胶团，使其溶解度增加.不同类型胆盐与ACP的作用能力不同：脱氧胆酸钠(NaDC) > 牛磺胆酸钠(NaTC) > 胆酸钠(NaC).胆盐与ACP中结合钙的亲和能力大于结合钙的亲和能力，使ACP在胆汁的环境下容易转化为羟基磷灰石.     

Estimation Of Metals As Sulphides : Estimation of rhenium. silver and mercury

1. It has been shown that under proper conditions rhenium, mercury and silver can be precipitated quantitatively as pure sulphides and the precipitate weighed directly for the estimation of the metal. 2. in the case of rhenium the solution containing perrhenate is treated with excess of alkali sulphide and the resulting solution containing the thiohalt is treated with excess of concentrated hydrochloric acid and ammonium sulphate. The precipitate is weighed directly as Re₂S₇. 3. In the case of silver the metal in ammoniacal solution is treated with excess of alkali sulphide and the precipitate weighed directly as Ag₂S. 4. In the case of mercury, the solution containing the metal is treated with excess of alkali sulphide solution in the cold followed by excess of hydrochloric acid. The precipitate obtained under these conditions is completely free from sulphuur and can be weighed directly as HgS. 5. Although germanium forms a thiosalt which decomposes with excess of hydrochloric acid, it was found that the metal cannot be estimated as sulphide owing to the pephization of the precipitate on washing and its decomposition on heating.     

五种含氧酸盐对L-丙氨酸迁移焓的影响

本文以带疏水侧链的丙氨酸为研究对象, 在298.15 K下测定其在LiNO3, NaNO3, KNO3, NaClO4及Na2SO4水溶液中的溶解焓, 探讨了不同种类的阳离子和阴离子对迁移焓的影响, 为揭示蛋白质与含氧酸盐水溶液的相互作用提供了有用信息.     

Low-Temperature Chemical Approaches for Synthesizing Sulfides and Nitrides of Reactive Transition Metals

The advent of the sol–gel technique over the past several decades and the recognition of its excellent flexibility for synthesizing a large variety of oxide ceramics and glasses in both bulk and thin-film forms has generated considerable interest in using solution-based processes to prepare ceramic materials. Because of the success of the sol–gel technique, a number of other chemical processes have been developed utilizing metalorganic/organometallic starting materials to create molecularly architectured precursors, which have proven effective in synthesizing both oxide and non-oxide materials. In the present study, two different chemical approaches have been implemented to synthesize non-oxides (sulfides and nitrides) of reactive transition-metal elements. Accordingly, a novel thio-sol–gel process for preparing TiS₂ and NbS₂ powders has been studied. In the case of TiS₂ synthesis, the chemical reaction has been examined in detail using Fourier-transform infrared spectroscopy (FTIR) and gas chromatography (GC). The effects of modification of the titanium precursor on the morphology of the final sulfide have also been investigated and are discussed. A second, more generalized process has been developed for synthesizing homogeneous precursors in multicomponent systems. Its utilization in preparing ternary nitrides has been demonstrated, and is also presented. © 1997 by John Wiley & Sons, Ltd.     

Atomic Absorption Spectrophotometric Analysis of Condensed Phosphates by a Flow Detector Connected with a Gel Chromatographic Column

Abstract

An atomic absorption flow detector combined with a gel chromatographic column (Sephadex G-25) gives a sensitive and quantitative method of determining various condensed phosphates such as diphosphate, tri-phosphate, tetraphosphate and Kurrol's salt. This method is based on the automatic recording of atomic absorption at the resonance line of magnesium due to magnesium complexes of condensed phosphates which are produced during the elution of condensed phosphate anions through the column pre-equilibrated with a magnesium chloride solution.     

Porous Phosphates of Trivalent Metals: Problems of Their Synthesis and Application

Abstract

Porous phosphates are compounds with a branched system of pores, such as X-ray amorphous xerogels of metalphosphates and crystalline phosphates of zeolite type. Having generalized extensive experimental data about the conditions of Al-, Fe-, Cr-, Ga-, In-, Y-phosphate hydrogels synthesis we found the influence of a number of factors on the rates of their formation, stability of structures and the porosity character of xerogels. The mechanism of porous structure formation of xerogels of metalphosphates has been proposed. The problems connected with the regulation of porous structure of xerogels have been discussed. The formation of porous crystalline aluminophosphates of zeolite type has been accomplished through a number of stages. The nature of alkyl ammonium bases influences the direction of the crystallization process and the type of the structure. It was noted that the stoppind of crystallization on different stages of synthesis gives the possibility to obtain new molecular sieves. Thermal changes and sorption properties of aluminopnosphates of zeolite type have been studied. During the process of removing organic cations the formation of secondary porosity was established. The effectiveness of applying porous metalphosphates in catalysis and adsorption processes has been showed.     

The Synthesis,Structure and Properties of Phosphire-Nium Halogenides

Abstract

In the study of electrophilic addition of organoelement halogenides to alkoxyacetylensl it has been found that in the absence of catalysts dialkyl(pheny1)halogenphosphines add to internal alkoxyacetylenes, which results in the formation of stable phosphirenes (I) of a new type.     

Thermochemical Study of Gaseous Salts of Oxygen-containing Acids: XIV. Barium and Chromium Phosphates

Gas-phase equilibria involving barium and chromium(II) phosphates were studied by high-temperature mass spectrometry. Standard enthalpies of formation and atomization of gaseous BaPO₂, BaPO₃, CrPO₂, and CrPO₃ were determined.     

Reactions of 2-Pyridyl Substituted Phosphine Oxides and Phosphonium Salts with Organometallic Reagents and in Aqueous Media

Phosphine oxides bearing two or three 2-pyridyl groups react with organometallic reagents affording 2,2′-bipyridyl, 2-substituted pyridines and pyridine in good yields. Phosphonium salts and phosphine oxides, bearing at least two 2-pyridyl or substituted 2-pyridyl groups also give the corresponding 2,2′-bipyridyls and pyridines upon treatment with acid or neutral solvents such as water and alcohols in substantial yields. The 2,2′-bipyridyls are considered to be formed by ligand coupling within the pentacoordinated phosphorus intermediate formed incipiently during the reaction.     

Phosphorus-Containing Salts of Polyhexamethyleneguanidinium for Protection of Metals from Corrosion,Biological Overgrowing,and Salt Deposition

The procedure for preparing polyhexamethyleneguanidinium phosphate and polyhexamethyleneguanidinium hydroxyethylidenediphosphonate, protecting metals from corrosion and biological overgrowing, was optimized.     

Strontium Tantalates with a Perovskite Structure: Their Conductivity and High-Temperature Interaction with Water

The interaction of perovskite-like solid solutions Sr_{6 – 2x} Ta_{2 + 2x} O_{11 + 3x} (x= 0–0.28) with water is studied, along with dependences of the solutions' conductivity on their composition and the atmosphere's temperature and humidity. The Sr_{6 – 2x} Ta_{2 + 2x} O_{11 + 3x} phases with high concentrations of structural oxygen vacancies are high-temperature mixed oxygen–hydrogen ionic conductors whose conduction is sensitive to the presence of water vapor up to 900°C. According to a thermogravimetric study, the amount of water incorporated into the complex-oxide matrix is proportional to the concentration of structural oxygen vacancies. The process of water incorporation is considered in terms of crystalline and chemical properties of the structure. The oxygen-deficient perovskites containing coordination-unsaturated metalatoms can reconstruct their coordination polyhedron by adding water molecules, with subsequent partial dissociation of water to hydroxyl groups. The proposed mechanism explains different states of water in the oxide and a two-stage nature of its removal: water molecules coordinating the metal atom and those surrounding OH^–leave the core in the first and second stages, respectively.     

Ternary Nitrides,Phosphides, and Arsenides of Lithium

Ternary phases have been prepared from lithium, another metal, and nitrogen, phosphorus, or arsenic. The ternary compounds, in particular the nitrides, are thermally more stable than the binary compounds. The lithium gives rise to a relatively high polar bonding component. At high temperatures, lithium and the second metal are often randomly distributed among the interstices of the metalloid lattice. The ordering processes that take place with decreasing temperature are investigated by X-ray and magnetic methods and by differential thermal analysis. The phases are classified on a structural basis into seven groups.