ОПРЕДЕЛЕНИЕ ВИДА ХИМИЧЕСКИХ СВЯЗЕЙ В СУЛЬФАТАХ И ФТОРОСУЛЬФАТО-ЦИРКОНАТАХ НЕОДИМА МЕТОДОМ ИК СПЕКТРОСКОПИИЗалкинд О.А., Годнева М

The heating behavior in air of pentafluorozirconates NiZr2F10 center dot 7H(2)O and NiZr2F10 center dot 9H(2)O for the first time isolated from the ZrO2-H2SO4-HF-NiCl2-H2O system is studied by differential thermal, X-ray diffraction, and chemical analyses. Thermal treatment is shown to transform nonahydrate NiZr2F10 center dot 9H(2)O into heptahydrate NiZr2F10 center dot 7H(2)O, which is followed by the formation of hydrated oxofluorozirconates NiZr2O1.5F7 center dot 5H(2)O and NiZr2O1.5F7 center dot 3H(2)O and anhydrous NiZr2O3.25F3.5. The unit cell parameters of the isolated compounds are determined. The chemical bonds and structural fragments of the compounds are studied by IR spectroscopy.

Phase formation in the ZrO2-H2SO4-HF-Zn(NO3)(2)-H2O system has been investigated along the sections with molar ratios SO3/Zr = 2 and 5; Zn/Zr = 0.5 and 1; and F/Zr = 1-6 and with 10-17 wt % ZrO2 in the solutions as well as during concentrating of unsaturated solutions at 50degreesC. The following phases crystallize in the system: fluorozirconates ZnZrF.6H(2)O, ZnZrF6.5H(2)O, and ZnZr2F10.7H(2)O, and a supposed composition ZnZr2F10.nH(2)O (n much less than 7); fluorides alpha-ZrF4.3H(2)O, ZrF4.H2O, and ZrF4.HF.3H(2)O; and fluoride sulfates alpha-, beta-, and gamma-ZrF2SO4.2.5H(2)O, On keeping, due to internal hydrolysis, pentafluorozirconate ZnZr2F10.7H(2)O transforms into oxofluorozirconate ZnZr2O1.5F7.5H(2)O. All fluorozirconates, excluding ZnZrF6.6H(2)O, have been isolated for the first time. The compounds have been investigated by chemical analysis, crystal-optical analysis, X-ray powder diffraction, and thermogravimetry.

Data on the optical properties and densities of fluorozirconates and fluorosulfatozirconates of univalent metals (MFZs and MFSZs) are tabulated. The symmetry of the crystals is shown to depend on the F/Zr molar ratio in the compound, and the outer-sphere cation was shown to affect the refractive index. For coarse-crystalline compounds, the molar refraction R is determined and a correlation is found between R-obs and R-calc. For fine-crystalline compounds, the molar refraction is calculated taking into account its bond increments, as well as the density. The coordination number of zirconium(IV) in 18 polymorphs is considered.

Fluorosulfatotitanates have been synthesized from sulfuric acid solutions containing 6-14 wt % of TiO2 in sections of the TiO2-H2SO4-MF-H2O system (M = NH4, Na, K, Rb, Cs) at SO3/Ti molar ratios (MRs) of 2 and 5 by adding MF up to the MF/Ti MRs of 4 and 2. The crystalline (NH4)(2)TiF4SO4, and Rb2TiF4SO4 fluorosulfatotitanates and the M2TiF2(SO4)(2) . nH(2)O (M = NH4, Rb, Cs) and Cs4Ti3O2F4(SO4)(4) . 14H(2)O compounds amorphous to X-rays have been obtained for the first time. The compounds are characterized by chemical analysis, crystal-optical analysis, X-ray powder diffraction, thermal analysis, and IR spectroscopy. The M2TiF2(SO4)(2) . nH(2)O (M = NH4, K, Rb) compounds convert in storage into crystalline MTiO(SO4)(2) . nH(2)O oxofluorosulfatotitanates. Cesium fluorosulfatotitanate remained unchanged in storage.

Phase formation along the sections of the ZrO2-H2SO-HF-NiCl2-H2O system is investigated at 5-15 wt % ZrO2 and molar ratios SO3: Zr = 2 or 5, F : Zr = 1-6, and Ni : Zr = I or 2. The following compounds crystallize in the system: fluorozirconates NiZrF6 . 6H(2)O, NiZr2F10 . 7H(2)O, and NiZr2F10 . 9H(2)O; fluorides alpha- and beta-ZrF4 . 3H(2)O, and fluorosulfates alpha-, beta-, and gamma-ZrF2SO4 . 2.5H(2)O. Fluorozirconates NiZr2F10 . 7H(2)O and NiZr2F10 . 9H(2)O, fluoride beta-ZrF4 . 3H(2)O, and fluorosulfate of a conventional composition gamma-ZrF2SO4 . 2.5H(2)O are isolated for the first time. Compounds are investigated by chemical, crystal-optical, X-ray powder diffraction, and thermogravimetry analyses.

Phase formation at 2-15 wt % ZrO 2 for various molar ratios was investigated in comparison with the Zr(SO 4 ) 2 -NaF-H 2 O system. The following compositions were investigated: in the absence of HF, SO 3 /Zr = 5 and NaF/Zr = 1-7; and in the presence of HF, SO 3 /Zr = 2, F/Zr = 2-6, and NaF/Zr = 1. The fields of formation of crystalline sodium fluorozirconates Na 5 Zr 2 F 1 3 , β-Na 2 ZrF 6 , α-Na 7 Zr 6 F 3 1 , and Na 7 Zr 6 F 3 1 . 12H 2 O; sodium fluorosulfate zirconates Na 2 ZrF 4 SO 4 and β-Na 2 ZrF 2 (SO 4 ) 2 . 2.5H 2 O; and on X-ray amorphous phase Zr 2 O 2 F 2 SO 4 . 6H 2 O are drawn. The Na 7 Zr 6 F 3 1 . 12H 2 O compound and sodium fluorosulfate zirconate β-Na 2 ZrF 2 (SO 4 ) 2 . 2.5H 2 O are obtained for the first time. Na 7 Zr 6 F 3 1 , which was earlier isolated from melts, is obtained from solutions. The compounds are characterized by crystal optics, X-ray diffraction, and thermal analyses, and IR spectroscopy. The unit cell parameters of sodium fluorozirconate Na 2 ZrF 4 SO 4 are determined.

Phase formation at 15 and 50 degrees C in solutions containing 2.5-10.0 wt % ZrO(2) was studied for molar ratios SO(4)(2-) : Zr = 5 and KF : KCl = 4. Fluorosulfatozirconates and fluorozirconates, anew poly morph of KZrF(5) among them, were isolated. The phase fields were outlined, and a comparison of the systems was done.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The compound is monoclinic, space group C2/m, with a=12.257, b=10.187, c=12.033A, β=117.02°, final R value of 0.017. The structure consists of layers of {[Zr 2 F 9 (H 2 O) 2 ] - }∞ ∞, SO 4 2- anions and NH 4 + cations. The eight pointed Zr polyhedra, joined by pairs of fluorine atoms, form tetramerous rings. These rings are joined in a layer via common fluorine atoms.The SO 4 2- group does not occur in the coordination polyhedron of Zr.