Thermal stability and X-ray luminescent properties of cesium fluorophosphatozirconates

Crystalline cesium fluorophosphatozirconates (CFPZs) CsZr₂F₆PO₄ · 4H₂O, CsZrF₂PO₄ · 0.5H₂O, CsH₂Zr₂F₂(PO₄)₃ · 2H₂O, and amorphous Cs₂Zr₃OF₆(PO₄)₂ · 3H₂O were synthesized, and their thermal stability and luminescence ability were studied. The compositions of initial CsH₂Zr₂F₂(PO₄)₃ · 2H₂O and Cs₂Zr₃OF₆(PO₄)₂ · 3H₂O were refined. CsZr₂O_0.5F₅PO₄, CsHZr₂F(PO₄)₃, CsZr₂(PO₄)₃, and Cs₂Zr₃OF₆(PO₄)₂ crystalline intermediates, which are comparable with BaSO₄ and CaF₂ luminophors in the context of their X-ray luminescence intensity, were recognized by thermal analysis and X-ray powder diffraction under heating.     

Phase formation in the ZrO(NO3)2-H3PO4-RbF-H2O system: the PO 43? /Zr = 0.5 section

We studied phase formation in the ZrO(NO₃)₂-H₃PO₄-RbF-H₂O system along PO₄³⁻/Zr = 0.5 (mol/mol) and RbF/Zr = 1–5 (mol/mol) sections with 2–10 wt % ZrO₂ in the starting solution. We recovered amorphous rubidium oxofluorophosphatozirconate Rb₂Zr₃OF₆(PO₄)₂ · 2H₂O and the following fluorophosphatonitratozirconates: Rb₂ZrF₄(PO₄)_0.33NO₃, which forms large cubic system crystals; weakly crystallized RbZr₃OF₃(PO₄)₂(NO₃)₂ · 5H₂O; and amorphous Zr₃OF₃(PO₄)₂NO₃ · (7–8) H₂O. A shown by its IR spectrum, Rb₂ZrF₄(PO₄)_0.33NO₃ contains NO₃- and PO₄ groups that are not coordinated to zirconium, meaning that this is a triple salt ZrF₄ · Rb(PO₄)_0.33 · RbNO₃. The formula units of the RbZr₃OF₃(PO₄)₂(NO₃)₂ · 5H₂O and Zr₃OF₃(PO₄)₂NO₃ · (7–8)H₂O phases are only conventional. All compounds have been recovered for the first time.     

Synthesis of zirconium (hafnium) fluoride compounds and their X-ray luminescence properties

Twenty-five zirconium (hafnium) fluoride compounds have been synthesized at room temperature in the systems MO₂-H₂SO₄-M′_nA(HF)-H₂O (M = Zr (Hf); M′ = Na, K, Rb, Cs, NH₄; A = F, SO₄) and their X-ray luminescence spectra (luminescence wavelengths and relative intensities) have been measured. The X-ray luminescence of the compounds has been considered as a function of the composition (cations, anions, water content) and different structural factors (CNs, polyhedra, H-bonds). Ammonium compounds do not luminesce, and sodium fluorozirconates and heptafluorozirconates are weakly luminescing. Hexafluorozirconates M₂Zr(Hf)F₆ (M= K, Rb, Cs) and M₅Zr₄F₂₁ · 3H₂O (M = Rb, Cs), as well as oxofluorozirconate Rb₂Zr₃OF₁₂, are strongly luminescing compounds.     

Synthesis of rubidium fluorophosphatozirconates in the ZrO2-H3PO4-RbF-H2O system and their luminescent properties

Rubidium fluorophosphatozirconates (RFPZs) were synthesized along sections of the ZrO₂-H₃PO₄-RbF-H₂O system where PO ₄ ^3? /Zr = 1–2 (mol/mol) and RbF/Zr = 1–5 (mol/mol) and the initial solution contains 2–5 wt % ZrO₂. The following RFPZs have been isolated for the first time: RbZrF₂PO₄ · 0.5H₂O, Rb₃H₃Zr₃F₃(PO₄)₅, and RbZr₃F₄(PO₄)₃ · 1.5H₂O. Their formation fields were determined. The compounds were characterized using powder X-ray diffraction, crystal-optical analysis, chemical analysis, electron probe microanalysis, thermal analysis, and IR spectroscopy. Luminescent properties of the compounds were measured. All RFPZs are orthophosphates, have high thermal durability, and X-ray luminescence (XRL). Rb₃H₃Zr₃F₃(PO₄)₅ has the highest XRL intensity.     

Synthese und Struktur von RbHfF5, Rb2Zr3F12O und Rb2Hf3F12O — zwei Oxidfluoride mit zentraler trigonal‐planarer [M3O]‐Gruppe

Synthesis and Structure of RbHfF₅, Rb₂Zr₃F₁₂O and Rb₂Hf₃F₁₂O — two Oxydefluorides with Central Trigonal‐plane [M₃O] Group Colorless RbHfF₅ crystallizes isotypic with (NH₄)ZrF₅ and TlHfF₅ monoclinic, space group P2₁/c ‐ C_2h (No. 14) with a = 776.6, b = 789.6, c = 789.8 pm, and β = 120.52°. Also colorless Rb₂Zr₃F₁₂O crystallizes trigonal, space group R3¯m — D₃d (No. 166), with a = 771.9 and c = 2963.0 pm, isotypic is Rb₂Hf₃F₁₂O with a = 769.2 pm and c = 2986.1 pm. Both compounds are isotypic with Tl₂Zr₃F₁₂O.     

Phase formation in the ZrO(NO<Subscript>3</Subscript>)<Subscript>2</Subscript>-H<Subscript>3</Subscript>PO<Subscript>4</Subscript>-CsF-H<Subscript>2</Subscript>O system at low concentration of the phosphorus-containing component

The ZrO(NO₃)₂-H₃PO₄-CsF-H₂O system was studied at 20°C along the section at a molar ratio of PO₄³⁻/Zr = 0.5 (which is of the greatest interest in the context of phase formation) at ZrO₂ concentrations in the initial solutions of 2–14 wt % and molar ratios of CsF: Zr = 1−6. The following compounds were isolated for the first time: crystalline fluorophosphates CsZrF₂PO₄ · H₂O, amorphous oxofluorophosphate Cs₂Zr₃O₂F₄(PO₄)₂ · 3H₂O, and amorphous oxofluorophosphate nitrate CsZr₃O_1.25F₄(PO₄)₂(NO₃)_0.5 · 4.5H₂O. The compound Cs₃Zr₃O_1.5F₆(PO₄)₂ · 3H₂O was also isolated, which forms in a crystalline or glassy form, depending on conditions. The formation of the following new compounds was established: Cs₂Zr₃O_1.5F₅(PO₄)₂ · 2H₂O, Cs₂Zr₃F₂(PO₄)₄ · 4.5H₂O, and Zr₃O₄(PO₄)_1.33 · 6H₂O, which crystallize only in a mixture with known phases. All the compounds were studied by X-ray powder diffraction, crystal-optical, thermal, and IR spectroscopic analyses.     

Solid-state decomposition studies on fluoroperoxo species of transition metals. Part VI. Kinetics of isothermal decomposition of M2Zr2(O2)2F6 · 2 H2O (M = Rb+, or Cs+)

The decomposition of solid fluoroperoxozirconates of alkali metals, M₂Zr₂(O₂)₂F₆ · 2 H₂O (M = Rb⁺, Cs⁺), is carried out in vacuum under isothermal conditions. The stoichiometry of the reaction may be represented by the equation, M₂Zr₂(O₂)₂F₆ · 2 H₂O(S) — M₂Zr₂O₂F₆(s) + O₂(g) + 2 H₂ O(g) (condensed). The fractional decomposition α is determined by measuring the pressure of oxygen evolved during pyrolysis with a McLeod gauge. The α values range from 0.06 to 0.70 for the rubidium and from 0.06 to 0.79 for the caesium species in the temperature ranges 107–202°C and 101–219°C, respectively. The α—time data for both compounds show that the kinetics are deceleratory throughout the course of the decomposition reaction. In both compounds, the initial stages of decomposition are described by a unimolecular decay law, while the later stages obey a contracting volume equation at all temperatures. The activation energies from Arrhenius plots are 14.0 and 10.9 kcal mole^?1 for the rubidium and 12.9 and 11.2 kcal mole^?1 for the caesium compound.     

Classification of heavy metal fluorides. Fluorides with high water contents

Five fluoride structures differing in the character of linkage of cationic polyhedra and in relative water contents are considered. The cationic sublattice is four-layered (ABAC) in K₂Cu(ZrF₆)₂·6H₂O, face-centered (F-type, ABC) in CuZrF₆·4H₂O primitive cubic (P-type) in Cu₃(ZrF₇)₂·16H₂O, hexagonal one-layered (AA) in Cu₂ZrF₈·12H₂O and hexagonal two-layered (AB) in Zr₂F₈·6H₂O. Some structures have considerably distorted symmetries of cationic sublattices compared to anhydrous structures because of the anisotropy of cation surroundings in the first, second, and third spheres, but al characteristic close-packed cation planes of the corresponding structural types are retained. In structures with cation-cation distances of ～3.5 Å, dimeric cations are arranged as single fragments for planes with d_hkl>3.5 Å or as separate fragments for planes with smaller d_hkl.     

ZrONO3)2-H3PO4-KF(HF)-H2O system at molar ratios of PO 43? /Zr = 0.5?1.6 as the basis for phase formation

The system ZrO(NO₃)₂-H₃PO₄-KF(HF)-H₂O was studied at ∼20°C along sections at molar ratios of PO₄³⁻ = 0.5, 1.0, and 1.6; KF: Zr = 1−5; and HF: Zr = 2−6. Phases in precipitates were identified by X-ray powder diffraction; IR spectroscopy; and crystal-optical, chemical, X-ray fluorescence and thermal analyses. The following crystalline phases were isolated: potassium fluorozirconates K₃ZrF₇, K₂ZrF₆, δ-KZrF₅, and KZrF₅ · H₂O; zirconium hydrophosphate Zr(HPO₄)₂ · 0.5H₂O; and potassium fluorophosphate zirconate K₃Zr₃F₃(HPO₄)₃(PO₄)₂. The following amorphous basic oxo(hydroxo)fluorohydrophosphate nitrates were isolated: K₄Zr₄O_2.5F₈(HPO₄)₂(NO₃)₃ · 6H₂O, K₂Zr₃O₃F₂(HPO₄)₂(NO₃)₂ · H₂O, and KZr₃O_1.5F₃(HPO₄)₂(NO₃)₃ · 2H₂O. Fields of solid phases were constructed, and the roles of anions and cations in the phase formation were considered.     

Carbonat‐Hydrate der schweren Alkalimetalle: Darstellung und Struktur von Rb2CO3 · 1,5 H2O und Cs2CO3 · 3 H2O

Carbonate Hydrates of the Heavy Alkali Metals: Preparation and Structure of Rb₂CO₃ · 1.5 H₂O und Cs₂CO₃ · 3 H₂O Rb₂CO₃ · 1.5 H₂O and Cs₂CO₃ · 3 H₂O were prepared from aqueous solution and by means of the reaction of dialkylcarbonates with RbOH and CsOH resp. in hydrous alcoholes. Based on four‐circle diffractometer data, the crystal structures were determined (Rb₂CO₃ · 1.5 H₂O: C2/c (no. 15), Z = 8, a = 1237.7(2) pm, b = 1385.94(7) pm, c = 747.7(4) pm, β = 120.133(8)°, V_EZ = 1109.3(6) · 10⁶ pm³; Cs₂CO₃ · 3 H₂O: P2/c (no. 13), Z = 2, a = 654.5(2) pm, b = 679.06(6) pm, c = 886.4(2) pm, β = 90.708(14)°, V_EZ = 393.9(2) · 10⁶ pm³). Rb₂CO₃ · 1.5 H₂O is isostructural with K₂CO₃ · 1.5 H₂O. In case of Cs₂CO₃ · 3 H₂O no comparable structure is known. Both structures show [(CO₃^2–)(H₂O)]‐chains, being connected via additional H₂O forming columns (Rb₂CO₃ · 1.5 H₂O) and layers (Cs₂CO₃ · 3 H₂O), respectively.     

Phase formation in the ZrO(NO3)2-H3PO4-CsF(HF)-H2O system

The phase formation in the system ZrO(NO₃)₂-H₃PO₄-CsF(HF)-H₂O was studied at the molar ratio CsF/Zr = 1 along the sections PO ₄ ^3? /Zr = 0.5 and 1.5 at a ZrO₂ concentration in the initial solution of 2?C14 wt %. The following compounds were isolated: Cs₅Zr₄F₂₁ · 3H₂O, CsZr₂(PO₄)₃ · 2HF · 2H₂O, CsZrF₂PO₄ · H₂O, CsZr₂F₆PO₄ · 4H₂O (for the first time), CsHZrF₃PO₄ (for the first time), Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(P_O4)_2.66 · nH₂O. The compositions of CsZrF₂PO₄ · H₂O, Cs_0.70ZrF(PO₄)_1.23 · nH₂O, and CsHZr₂F₂(PO₄)_2.66 · nH₂O are conditional. All the compounds were characterized by crystal-optical, X-ray powder diffraction, thermal analyses, and IR spectroscopy. The formula CsHZrF₃PO₄ was established by energy-dispersive analysis with a LEO-1450 scanning electron microscope and an MS-46 CAMECA X-ray microanalyzer.     

Synthese und Struktur von Zr4ON3F5, einer Verbindung mit fluorit-verwandter Überstruktur vom Vernier-Typ

Synthesis and Structure of Zr₄ON₃F₅, a Compound with a Fluorite Related Superstructure of the Vernier Type Ammonolysis of β? ZrF₄ or ZrF₄ · NH₃ yields zirconium nitride fluoride ZrNF and zirconium oxide nitride fluoride Zr₄ON₃F₅. Electron diffraction and electron energy loss spectroscopy were used to distinguish these two ammonolysis products by structure and composition. ZrNF crystallizes isotypically to baddeleyite ZrO₂ in the space group P2₁/c with the lattice constants a = 522.7(3), b = 502.6(2), c = 519.1(3) pm, β = 98.98(7)°, Z = 4, while Zr₄ON₃F₅ forms an anion-excess fluorite-related structure of the vernier type. The structure of Zr₄ON₃F₅ was refined from neutron powder diffraction data. It crystallizes monoclinic in space group P112₁/b with lattice constants a = 512.17(3), b = 2 151.3(1), c = 536.69(3) pm, γ = 90.128(6)°, Z = 4. Within the homologous series M_nX_2n+1 of the vernier phases Zr₄ON₃F₅ is a member with n = 4.     

Spectrophotometric and thermal analytical studies on the dehydration of copper(II) sulfate and its double salts

Spectrophotometric (diffuse reflection) and TG-DTA data on the dehydration of CuSO₄ · 5H₂O, Na₂Cu(SO₄)₂ · 2H₂O, M₂Cu(SO₄)₂ · 6H₂O(M⁺ = K⁺, Rb⁺, Cs⁺ and NH⁺₄) and Co₂Cu(SO₄)₃ · 18H₂O are given. Although complete dehydration of CuSO₄ · 5H₂O brings about a striking color change from blue to white, it was found that there is only a slight decrease in the v?_max. of its d-d band in the course of this change, and the total light absorption in the visible-UV region increases at the same time. The dehydration of the alkali metal and ammonium double salts, most of which contain [Cu(OH₂)₆]²⁺ aquo ions (in contrast to the [Cu(OH₂)₄]²⁺ in CuSO₄ · 5H₂O), occurs generally more easily than that of CuSO₄ - 5H₂O, and their v?_max. increases slightly in the change, leading to blue or green anhydrous products, although the formation of a white modification was observed with the potassium salt. It was also found that the v?_max. of the Cu²⁺ ion in the dehydrated cobalt(II) double salt is still lower than that in anhydrous CuSO₄, i.e., the ligand field and/or tetragonality around it is decreased by the presence of Co²⁺ ions.     

Phase formation in the ZrO(NO3)2-NaF(HF)-H3PO4-H2O system at 20°C

Phase formation in the ZrO(NO₃)₂-NaF(HF)-H₃PO₄-H₂O system was studied at 20°C and 2.0–14.5 wt % ZrO₂ in the initial solution along sections with molar ratios PO ₄ ^3? /Zr = 0.5 and 1.5 and also in the presence of hydrogen fluoride at Na/Zr = 1 and PO ₄ ^3? /Zr = 0.5, 1.0, and 1.5. Crystalline zirconium hydrophosphate Zr(HPO₄)₂ · H₂O, fluorozirconates Na₅Zr₂F₁₃ and Na₇Zr₆F₃₁ · 12H₂O, fluorophosphatozirconates NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O, and amorphous NaZrO_0.5F(PO₄) · 4H₂O (provisional composition) were separated at room temperature. NaH₂Zr₃F₃(PO₄)₄ · 3H₂O and NaZr₂F₆(PO₄) · 4H₂O were prepared for the first time and were studied by crystal-optical, elemental, and thermal analyses, X-ray powder diffraction, IR spectroscopy, scanning electron microscopy (SEM), and X-ray microanalysis. Na₇Hf₆F₃₁ · 12H₂O was found to exist in a mixture with the hydrophosphate.     

Crystal structure of monoclinic modifications of zirconium and hafnium tetrafluoride trihydrates

The monoclinic modification of ZrF₄·3H₂O, isostructural to HfF₄·3H₂O, is synthesized and structurally studied for the first time. Unlike the triclinic modification of ZrF₄·3H₂O with a dimeric structure, the synthesized compound has a polymer structure formed from infinite chains composed of ZrF₆(H₂O)₂ groups sharing F…F edges. The crystal structure of HfF₄·3H₂O, previously determined by the photo method, is refined. The refined data on the geometric characteristics of the coordination polyhedron of the Hf atom and the system of hydrogen bonds in the structure are obtained.     

Cyclohexaphosphates of Alcaline Metals

Abstract

The fast progress of chemistry of condensed phosphates resulted in a great attention to this kind of inorganic polymers all over the world. This paper reports preparation by ion exchange with lithium salt (1), solubility in water, some structural data and thermal transformation of alcaline metals cyclohexaphosphates (CHP). The crystal structures of all the compounds (table) were determined (Na₆P₆O₁₈·6H₂O one has been described previously (2)). The crystals are built up of CHP-rings and alcaline metal (M^I) polyhedra, so that during the transition from Li to Cs coordination number (c.n.) of M^I increases from 4 to 9. In crystal Li₆P₆O₁₈ · 5H₂O only 4 water molecules are coordinated by metal, moreover, there are channels where 2 additional water molecules may be placed. Rb₆P₆O₁₈·6H₂O and Cs₆P₆O₁₈·6H₂O were found to be isomorphous, as well as anhydrous K₆P₆O 18 and Rb₆P₆O₁₈.     

Solubility in the systems Rb2SO4-H2SO4-H2O and Cs2SO4-H2SO4-H2O at 25°

Conclusions The solubility of rubidium and cesium sulfates in aqueous solutions of sulfuric acid was studied at 25°. Rubidium sulfate forms the compounds 3Rb₂SO₄· H₂SO₄, Rb₂SO₄ · H₂SO₄, Rb₂SO₄·3H₂SO₄ and Rb₂SO₄·7H₂SO₄ with sulfuric acid, while cesium sulfate forms the compounds Cs₂SO₄·H₂SO₄; Cs₂SO₄·3H₂SO₄ and Cs₂SO₄ · 7H₂SO₄.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1166–1170, June, 1968.     

Self-assembly and crystal structures of coordination polymers constructed by 4′-hydroxyisoflavone-3′-sulfonates with Cs(I) and Rb(I)

Four coordination polymers, [CsL1(H₂O)₂]·H₂O (1), [CsL2(H₂O)₂]·H₂O (2), [Rb₂(L2)₂(H₂O)₂]·2H₂O (3) and [RbL3(H₂O)] (4), were synthesized by Cs(I), Rb(I) and 4′-hydroxyisoflavone-3′-sulfonates L1–L3 [L1 = 7-methoxy-4′-hydroxyisoflavone-3′-sulfonate, L2 = 7-ethoxy-4′-hydroxyisoflavone-3′-sulfonate, L3 = 7-ethoxy-4′,5-dihydroxyisoflavone-3′-sulfonate]. The crystal structures of 1–4 were determined by single-crystal X-ray diffraction. The influences of 4′-hydroxyisoflavone-3′-sulfonate ligands and Cs⁺, Rb⁺ on their structural features and self-assembly were investigated. The sulfonates of L1–L3 not only coordinate with Cs⁺ or Rb⁺ directly, but also bridge the organic region and the inorganic region in 1–4. Non-covalent interactions such as coordination interaction, π–π stacking interaction and hydrogen bonding assembled 1–4 into 3-D networks together with the electrostatic interactions between Cs⁺, Rb⁺ and the sulfonate anions.     

Thermal stability and X-ray luminescence properties of cesium fluorophosphatohafnates

The thermal stability of cesium fluorophosphatohafnates (crystalline CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O, CsHfF₂PO₄ · 0.5H₂O, CsHf₂F₆PO₄ · 4H₂O and X-ray amorphous Cs₂Hf₃O_1.5F₅(PO₄)₂ · 5H₂O, Cs₅H₄Hf₃F₇(PO₄)_3.66(NO₃)₃ · 5H₂O) was determined. The weight ratios Cs⁺/Hf and PO ₄ ^3? /ZrHf in CsHf₂F₂(HPO₄)₂PO₄ · 2H₂O were confirmed by identifying the calcination production CsHf₂(PO₄)₃ (～1000°C). A new crystalline compound CsHf₂F(HPO₄)(PO₄)₂ was found by thermogravimetric and X-ray powder diffraction analysis during heating. A new method for hydrothermal synthesis of CsHf₂(PO₄)₃, which was different from the already known one, was proposed. It was ascertained that CsHf₂(PO₄)₃ possesses a significant X-ray luminescence; whereas in fluorophosphatehafnates show low luminescence intensity.     

The isotypic hydrogen phosphate and arsenate dihydrates M2HXO4·2H2O (M = Rb,Cs; X = P,As)

The four isotypic alkaline metal monohydrogen arsenate(V) and phosphate(V) dihydrates M₂HXO₄·2H₂O (M = Rb, Cs; X = P, As) [namely dicaesium monohydrogen arsenate(V) dihydrate, Cs₂HAsO₄·2H₂O, dicaesium monohydrogen phosphate(V) dihydrate, Cs₂HPO₄·2H₂O, dirubidium monohydrogen arsenate(V) dihydrate, Rb₂HAsO₄·2H₂O, and dirubidium monohydrogen phosphate(V) dihydrate, Rb₂HPO₄·2H₂O] were synthesized by reaction of an aqueous H₃XO₄ solution with one equivalent of aqueous M₂CO₃. Their crystal structures are made up of undulating chains extending along [001] of tetrahedral [XO₃(OH)]⁻ anions connected via strong O—H...O hydrogen bonds. These chains are in turn connected into a three‐dimensional network via medium‐strength hydrogen bonding involving the water molecules. Two crystallographically different M⁺ cations are located in channels running along [001] or in the free space of the [XO₃(OH)]⁻ chains, respectively. They are coordinated by eight and twelve O atoms forming irregular polyhedra. The structures possess pseudosymmetry. Due to the ordering of the protons in the [XO₃(OH)]⁻ chains in the actual structures, the symmetry is reduced from C2/c to P2₁/c. Nevertheless, the deviation from C2/c symmetry is minute.