Phase Diagram of the Quaternary System KCl–MgCl<Subscript>2</Subscript>–NH<Subscript>4</Subscript>Cl–H<Subscript>2</Subscript>O at <Emphasis Type="Italic">t</Emphasis> = 60.00 °C and Their Application

Based on the requirement for the comprehensive exploitation and utilization of the salt lake resources magnesium chloride and potassium chloride, a new technology to produce KCl and ammonium carnallite (NH₄Cl·MgCl₂·6H₂O) by using NH₄Cl as salting-out agent to separate carnallite is proposed. The solubilities of quaternary system KCl–MgCl₂–NH₄Cl–H₂O were measured by the isothermal method at t = 60.00 °C and the corresponding phase diagram was plotted and analyzed. The analysis of this phase diagram shows that there are seven saturation points and eight regions of crystallization. These eight regions of crystallization represent salts corresponding to KCl, NH₄Cl, MgCl₂·6H₂O, (K_1?n (NH₄) _n )Cl, ((NH₄) _n K_1?n )Cl, (K_1?n (NH₄) _n )Cl·MgCl₂·6H₂O, KCl·MgCl₂·6H₂O and NH₄Cl·MgCl₂·6H₂O. According to the phase diagram analysis and calculations, ammonium carnallite (NH₄Cl·MgCl₂·6H₂O) and KCl can be obtained using carnallite as raw materials and ammonium chloride as salting-out agent at t = 60.00 °C. The new technology shows the advantages of being easy to operate and having low energy consumption. The research on this quaternary phase diagram is the foundation for reasonable development of carnallite resources and comprehensive utilization of the salt lake brines.     

铵光卤石气固反应法制备无水氯化镁

铵光卤石气固反应法制备无水氯化镁;ouig     

Temperature dependent control of the solubility of gallium nitride in supercritical ammonia using mixed mineralizer

Using a mass-loss method, we investigated the solubility change of gallium nitride (GaN) in supercritical ammonia with mixed mineralizers [ammonium chloride (NH₄Cl)?+?ammonium bromide (NH₄Br) and NH₄Cl?+?ammonium iodide (NH₄I)]. The solubilities were measured over the temperature range 450–550 °C, at 100 MPa. The solubility increased with NH₄Cl mole fraction at 450 °C and 100 MPa. The temperature dependence of the solubility curve was then measured at an equal mole ratio of the two mineralizers. The slope of the solubility–temperature relationship in the mixed mineralizer was between those of the individual mineralizers. These results show that the temperature dependence of the solubility of GaN can be controlled by the mineralizer mixture ratio. The results of the van’t Hoff plot suggest that the solubility species were unchanged over the investigated temperature range. Our approach might pave the way to realizing large, high-quality GaN crystals for future gallium-nitride electronic devices, which are increasingly on demand in the information-based age.     

Investigation of the Reaction of Roasted Serpentine Ore with Some Ammonium Salts

The reaction between roasted serpentine ore and ammonium sulfate was studied at the range of temperature 250–1000°C using different molar ratios to determine the maximum extraction of magnesia and also to characterize the different reaction products. The maximum extraction of MgO from the roasted ore reached 92.4% at 400°C. It was found from XRD that ammonium magnesium sulfate [(NH₄)₂Mg₂(SO₄)₃] was produced as the main product at 400°C, which decomposes to magnesium sulfate at 500–600°C. The last compound decomposes to magnesium oxide at 900–1000°C. Thermal analysis of the reaction mixture confirmed the results obtained by XRD. Extraction of magnesia by ammonium chloride at 300–400°C showed low percentage of extraction (7.8%). Comparison was made between using ammonium chloride instead of sulfate taking into consideration the thermal decomposition products of both ammonium salts. Extraction of magnesia from the roasted ore by aqueous ammonium sulfate or ammonium chloride showed good results.     

Variations in the Electrokinetic Potential of Magnesium Hydrosilicate Fibers upon Treatment with Ammonium Chloride

The effect of the treatment of magnesium hydrosilicate (Mg₃Si₂O₅(OH)₄) fibers with an aqueous 5% ammonium chloride solution at 37?40 and 57?60°C on their electrokinetic potential (ζ potential) is studied. The maximum time of exposure in the NH₄Cl solution was 100 min, while the ζ potential was measured every 20 min. It is shown that the treatment of the initial magnesium hydrosilicate fibers with the NH₄Cl solution leads to a reversal of their surface charge and a rise in the absolute value of the negative charge, which is explained by magnesium leaching out of the surface layer of the fibers. Washing of the treated fibers with distilled water leads again to the sign reversal of the ζ potential. Therewith, the character of the dependences of the fiber ζ potential on the time of the treatment with the 5% NH₄Cl solution at T = 37?40°C is the same before and after washing.     

Determination of the optimum conditions for the synthesis of praseodymium(III) chloride

In the present work, we have synthesized praseodymium(III) chloride, PrCl₃, from the praseodymium oxide, Pr₆O₁₁, by dry method in the presence of ammonium chloride, NH₄Cl. This study includes the establishment of an assembly synthesis under inert gas. The thermal decomposing process of pure NH₄Cl was investigated by TG–DTG. The results showed that NH₄Cl begins to lose weight at 188 °C, large loss of weight ending at 302 °C when NH₄Cl is heated at the rate of 10 °C/min under N₂ atmosphere. For chlorination, NH₄Cl participates directly in the reaction, and HCl decomposed from NH₄Cl also contributes to the chlorination reaction. The influence of various synthesis parameters (temperature, contact time and chemical composition) on the reaction yield was studied, and the optimum conditions for synthesis were, thus, determined and discussed.     

有机溶剂法无水氯化镁的制备与表征

Ammonium carnallite was synthesized by hydrated magnesium chloride in salt lake and ammonium chloride solution. Dehydrated ammonium carnallite was dissolved in methanol under low temperature by feeding ammonia, to prepare anhydrous magnesium chloride. The results show that anhydrous magnesium chloride contains magnesium oxide in an amount less than 0.1% by weight, the yield of magnesium chloride was above 99.5%. Ammonium carnallite, ammoniation magnesium chloride and anhydrous magnesium chloride were characterized by thermoanalysis, X-ray powder diffraction and scanning electron microscopy.     

Crystallization of metastable monoclinic carnallite,KCl·MgCl2·6H2O: missing structural link in the carnallite family

During evaporation of natural and synthetic K–Mg–Cl brines, the formation of almost square plate‐like crystals of potassium carnallite (potassium chloride magnesium dichloride hexahydrate) was observed. A single‐crystal structure analysis revealed a monoclinic cell [a = 9.251 (2), b = 9.516 (2), c = 13.217 (4) Å, β = 90.06 (2)° and space group C2/c]. The structure is isomorphous with other carnallite‐type compounds, such as NH₄Cl·MgCl₂·6H₂O. Until now, natural and synthetic carnallite, KCl·MgCl₂·6H₂O, was only known in its orthorhombic form [a = 16.0780 (3), b = 22.3850 (5), c = 9.5422 (2) Å and space group Pnna].     

Luminescence studies of the thermal dehydration of europium trifluoride

The thermal dehydration of hydrated europium trifluoride has been followed by high-resolution luminescence spectroscopy and thermogravimetric analysis. For EuF₃ precipitated by aqueous HF, it was determined that the bound water of hydration actually existed in two forms, which were removable at low (100–250°C) and high (350–550°C) temperatures. Calcination of this material at still higher temperatures produced anhydrous EuF₃ contaminated by EuOF. Precipitation of EuF₃ by NH₄F resulted in the occlusion of variable amounts of ammonium fluoride, but in these materials only the low-temperature water was contained. Extensive ethanol washing of the NH₄F-precipitated EuF₃ led to removal of the ammonium fluoride, but this hydrated material was not found to contain the high-temperature water. Neither material prepared by NH₄F precipitation exhibited any tendency towards EuOF formation. It would thus appear that the EuOF compound is formed only during the loss of the high-temperature water, and if this water is not present in the sample then one may form anhydrous EuF₃ free from EuOF contamination.     

Penta‐Ammoniates of Aluminium Halides: The Crystal Structures of AlX3·5NH3 with X = Cl,Br, I

Colourless crystals grow in the colder part of a glass ampoule when AlX₃·5NH₃ with X = Cl, Br, I is heated for 3—6 d to 330 °C (Cl), 350 °C (Br) and 400 °C (I), respectively. The chloride forms hexagonal prisms while the bromide and iodide were obtained as a bunch of lancet‐like crystals. The chloride and bromide crystallize isotypic whereas the iodide has an own structure type. All three are related to the motif of the K₂PtCl₆ type. So the formula of the ammoniates may be written as X₂[Al(NH₃)₅X] ≙ [Al(NH₃)₅X]X₂. The compounds are characterized by the following crystallographic data AlCl₃·5NH₃: Pnma, Z = 4, a = 13.405 (1)Å, b = 10.458 (1)Å, c = 6.740 (2)Å AlBr₃·5NH₃: Pnma, Z = 4, a = 13.808 (2)Å, b = 10.827 (1)Å, c = 6.938 (1)Å AlI₃·5NH₃: Cmcm, Z = 4, a = 9.106 (2)Å, b = 11.370 (2)Å, c = 11.470 (2)Å For the chloride and the bromide the structure determinations were successful including hydrogen positions. All three compounds contain octahedral molecular cations [Al(NH₃)₅X]²⁺ located in distorted cubes formed by the remaining 2X^— ions. The orientation of the octahedra to each other is clearly different for those with X = Cl, Br in comparison to the one with X = I.     

Synthesis,Structure, and Decomposition of (NH4)2[Mo6Cl14] · H2O

(NH₄)₂[Mo₆Cl₁₄] · H₂O ( 1 ) was prepared from reactions of MoCl₂ in ethanol with aqueous NH₄Cl solution. It crystallizes in the monoclinic space group I2/a (no. 15), Z = 4 with a = 912.3(1), b = 1491.2(2), c = 1724.8(2) pm, β = 92.25(1)°; R1 = 0.023 (based on F values) and wR2 = 0.059 (based on F² values), for all measured X‐ray reflections. The structure of the cluster anion can be given as [(Mo₆Cl)Cl]^2– (i = inner, a = outer ligands). Thermal stability studies show that 1 loses crystal water followed by the loss of NH₄Cl above 350 °C to yield MoCl₂. The water‐free compound (NH₄)₂[Mo₆Cl₁₄] ( 2 ) was synthesized by solid state reaction of MoCl₂ and NH₄Cl in a sealed quartz ampoule at 270 °C. No single‐crystals could be obtained. Decompositions of 1 and 2 under nitrogen and argon exhibited the loss of NH₄Cl at about 350 °C. Decomposition under NH₃ resulted in the formation of MoN and Mo₂N at 540 °C and 720 °C, respectively.     

Metallochlorophosphates-Perspective Binders for Heat Resistive Compositions

Abstract

New ways of synthesizing aluminium, magnesium and chromium phosphate binders with phosphorous metal ratio of 1:l were discovered. It was found that the viscous solution of met-allochlorophosphate binders and powdered chlorophosphate aluminium, magnesium and chromium can be used as a component for heat resistive materials. Viscous binders increase the mechanical strength, while powdered chlorophosphates ensure safe storage, usage and transportation. Investigation of formation conditions, constituent, pnysico-chemical properties and thermal treatment of liquid binders and precipitated from it aluminium, chromium and magnesium chlorophosphate showed the presence of MHPO₄ · nH₂O where M-Al, Cr and MgH₂PO₄Cl·nH₂O where n = 2–6. It was found that similar compounds are formed by the reaction of metallic chloride with phosphoric acid and metallic hydrooxide, the mixture of phosphoric and hydrochloric acids having M:P:Cl = 1:1:1.1–1.8 ratio. The latter method is more technological. It was stated that the viscosity, density and stability of liquid chlorophosphate binders depend on the nature of cations: viscosity increases, while density decreases from Cr-Mg-Al, precrystallization period increases from 1 to 3 days for magnesium up to 3–5 months for aluminium, and a year for chromium. As a result of thermal treatment metallic orthophosphate without water of crystallization is produced. Highly effective heat resistive materials with compressive strength of 70–106 MPa, refrectoriness 1300–1800°C oped. ?1800°C and hardening temperature of 150–350°C are developed.     

DTA-TG and XRD study on the reaction between ZrOCl2·8H2O and (NH4)2HPO4 for synthesis of ZrP2O7

In this paper, we report results of thermoanalytical investigation on the reaction between ZrOCl₂·8H₂O and (NH₄)₂HPO₄ in molar ratio 1:2. Differential thermal-thermogravimetric and X-ray diffraction analyses were performed in order to reveal the chemical transformations, which took place during heating of the individual compounds ZrOCl₂·8H₂O, (NH₄)₂HPO₄ and the mixture ZrOCl₂·8H₂O:2(NH₄)₂HPO₄. It was shown that the transformations in the mixture below 160 °C were connected with dehydration of ZrOCl₂·8H₂O and interaction between the components of the mixture, which resulted in the formation of NH₄Cl, NH₄H₂PO₄ and a mainly amorphous zirconium phase, most likely t-ZrO₂. The zirconium component subsequently reacted with ammonium dihydrophosphate (below 200 °C) or with dehydrated phosphate derivatives (above 200 °C), which in both cases yielded an amorphous product. The interaction between the components of the mixture resulting in the formation of ZrP₂O₇ was completed by its crystallisation at 610 °C. Our study indicates an alternative low-temperature approach for the synthesis of the technologically important ZrP₂O₇ material.     

Thermoanalytical study on the reactions of selected rare earth oxides with ammonium halides

A comparative study has been made on the reactions of RE oxides (RE = Y, La, Gd and Lu) with ammonium bromide, and of yttrium oxide with ammonium halides NH₄X (X = F, Cl, Br and I) at different temperatures. Most of the reactions take place in three stages, with formation of two intermediate compounds, REX₃ · 3 NH₃ and REX₃ · 1.5 NH₃. The endothermic reactions begin between 200 and 300°C and the formation of the RE oxyhalide is completed between 340 and 470°C. These temperatures were observed to rise with the increasing atomic number of RE in the series LaOBrLuOBr, and of halide in the series YOFYOI.     

Hydrolysis of magnesium hydride in the presence of ammonium salts

The influence of the nature of ammonium salts (NH₄Cl, (NH₄)₂SO₄, (NH₄)HSO₄, [(CH₃)NH₃]Cl) and their concentration in aqueous solutions on the hydrolysis of magnesium hydride has been studied. The highest degree and fastest rate of hydrolysis are observed at an ammonium salt concentration of ～7.5%. The most efficient activator among the ammonium salts under consideration is (NH₄)HSO₄.     

Two Mercury Chloro Thiocyanate Complexes: NH4[HgCl2(SCN)] and NH4[HgCl(SCN)2]

Single crystals of NH₄[HgCl₂(SCN)] ( 1 ) and NH₄[HgCl(SCN)₂] ( 2 ) are obtained by slow evaporation of ethanol solutions of HgCl₂ and NH₄SCN or Hg(SCN)₂ and NH₄Cl. 1 crystallizes in the monoclinic space group P2₁ (a = 9.297(1), b = 4.171(1), c = 9.198(1)Å, β = 92.827(5)°). The structure consists in HgCl₂(SCN) linear chains, extending along the twofold axis, connected through the ammonium ions. 2 crystallizes in the monoclinic space group C2/c (a = 7.088(1), b = 19.986(2), c = 5.958(1)Å, β = 100.718(5)°). The structure consists of HgCl(SCN)₂ molecules connected through the ammonium ions. The second order non linear optical properties of 1 are discussed.     

Reactivity of Ammonium Halides: Action of Ammonium Chloride and Bromide on Iron and Iron(III) Chloride and Bromide

Ammonium chloride and bromide, (NH₄)Cl and (NH₄)Br, act on elemental iron producing divalent iron in [Fe(NH₃)₂]Cl₂ and [Fe(NH₃)₂]Br₂, respectively, as single crystals at temperatures around 450 °C. Iron(III) chloride and bromide, FeCl₃ and FeBr₃, react with (NH₄)Cl and (NH₄)Br producing the erythrosiderites (NH₄)₂[Fe(NH₃)Cl₅] and (NH₄)₂[Fe(NH₃)Br₅], respectively, at fairly low temperatures (350 °C). At higher temperatures, 400 °C, iron(III) in (NH₄)₂[Fe(NH₃)Cl₅] is reduced to iron(II) forming (NH₄)FeCl₃ and, further, [Fe(NH₃)₂]Cl₂ in an ammonia atmosphere. The reaction (NH₄)Br + Fe (4:1) leads at 500 °C to the unexpected hitherto unknown [Fe(NH₃)₆]₃[Fe₈Br₁₄], a mixed‐valent Fe^II/Fe^I compound. Thermal analysis under ammonia and the conditions of DTA/TG and powder X‐ray diffractometry shows that, for example, FeCl₂ reacts with ammonia yielding in a strongly exothermic reaction [Fe(NH₃)₆]Cl₂ that at higher temperatures produces [Fe(NH₃)]Cl₂, FeCl₂ and, finally, Fe₃N.     

ChemInform Abstract: Pentacoordinate Phosphorus in a High-Pressure Polymorph of Phosphorus Nitride Imide P4N6(NH).

The title γ-P₄N₆(NH) polymorph is obtained by high-temperature high-pressure synthesis using P₃N₅ and NH₄Cl in the molar ratio of 4:1 (multianvil cell, 14 GPa, 1200 °C, 3 h).     

Anhydrous oxygen-free rare earth material preparation and characterization

The present paper addresses the preparation and characterization of anhydrous oxygen-free rare earth materials, such as terbium fluoride (TbF₃). The fluorination of terbium oxide (Tb₄O₇) by ammonium bifluoride (NH₄HF₂) to prepare anhydrous TbF₃ was reported in this work. The parameters affecting fluorination were studied, including the fluorination temperature, excess stoichiometric amount of NH₄HF₂, and time for fluorination. The temperatures of Tb₄O₇ fluorination by NH₄HF₂ determined by thermogravimetric analysis and differential thermal analysis ranged from 350°C to 500°C. The phase structure of the as-prepared products identified by the X-ray diffraction method was indexed to the orthorhombic phase of TbF₃ [space group: Pnma (no. 62)] that exhibited good accordance with the values in the standard cards JCPDS No. 37-1487 for TbF₃. Energy-dispersive X-ray spectroscopy (EDS) methods were used to analyze the elemental compositions in the as-prepared products; the fluorine (F) and terbium (Tb) elemental compositions calculated from the [TbF₃] formula are in good agreement with those calculated from the EDS pattern. The optimum parameters for fluorination were determined from the results, and anhydrous oxygen-free TbF₃ can be used to study the preparation of metallic terbium by the calcinothermic reduction method.