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1.
The investigation of europium(III) sulphate hydrate and samarium(III) sulphate hydrate was performed by thermal analysis (TG-DTG) and simultaneous infrared evolved gas analysis-Fourier transformed infrared (EGA-FTIR) spectroscopy. The TG, DTG and DTA curves were recorded at the 25–1400 °C in the dynamic air atmosphere by TG/DTA analyser. The infrared evolved gas analysis was obtained on the FTIR spectrometer. Eu2(SO4)3·nH2O (n = 3.97) and Sm2(SO4)3·nH2O (n = 8.11) were analysed, the dehydration and decomposition steps were investigated and the water content was calculated. The formation of different oxysulphates was studied.
The trace rare earth elements in Eu and Sm sulphates were determined by ICP-MS. The concentration of trace Eu, Sm, La, Gd, Y and Ce ranged from 3.9 × 10−6 to 1.5 × 10−4% (m/m). 相似文献
2.
The modification of the triple helical structure in aqueous gelatin solutions by changing pH and adding alkyl sulphates at 298 K and after rechilling the solution to 283 K was investigated by CD-measurement. At 298 K the triple helical content at the IEP of the gelatin has its maximum value. It is only weakly affected by adding sodium dodecyl sulphate (SDDS) at concentrations <10–4 M/dm3. The unfolding of the triple helix affected by pH and SDDS is reversible by rechilling the solution. The triple helical content of gelatin solutions decreases at SDDS concentrations higher than 10–4 M/dm3. In all cases the decrease of the amount of triple helical structure is connected with an increase of the cis-configuration in single chains and leads to chain reversals. At sufficiently high SDDS concentrations-sheets are formed. These changes are thermally irreversible. Sodium decyl sulphate (SDS) has a more minor influence than SDDS except in the range of the c.m.c. of SDS. At sufficiently high SDS concentrations,-turns appear. 相似文献
3.
Agudelo A. C. Marco J. F. Gancedo J. R. Pérez-Alcázar G. A. 《Hyperfine Interactions》2002,139(1-4):141-152
The corrosion reaction of four Fe–Mn–Al alloys exposed to a cycling, dry–humid, SO2 (0.001% by volume) polluted atmosphere was studied. ICEMS, XPS, AES-SAM and transmission Mössbauer spectroscopy at different temperatures were employed to characterize the corrosion products. The analytical results indicate that (i) ferrihydrite is the main component of the rust; (ii) there is an abundant presence of Mn2+ and SO3
2–/SO4
2– on the top of the corrosion layer, the concentration of SO4
2– increasing with the number of cycles; and (iii) the magnetic hyperfine pattern exhibited by the series of low-temperature spectra of the rust is quite different from that observed in the rust formed under similar corrosive environments on iron and weathering steel. This latter finding is correlated with a slow rate of transformation of the Fe3+ species formed at the early stages of corrosion into -FeOOH, the usual final product of this type of corrosion processes. The sulphate anions, abundant inside the electrolyte during the wet periods, could be incorporated to the ferrihydrite structure being responsible for the Mössbauer spectral pattern recorded from the corrosion products at low temperatures. 相似文献
4.
The X-band EPR studies of Cr3+-doped LCS have been performed. The values of the spin-Hamiltonian parameters for Cr3+ ions have been estimated at room temperature. The effect of crystal twinning on the EPR spectra has also been described. The temperature behaviour of EPR lines originated from two structurally different chromium complexes has been studied close to the ferroelastic phase transition. From the temperature dependence of positions of the split resonance lines a value of the critical exponent β of the order parameter was found to be β = 0.25. 相似文献
5.
Frost RL Wills RA Martens W Weier M 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):869-874
Near-infrared (NIR) spectroscopy has been used to analyse a suite of synthesised jarosites of formula Mn(Fe3+)6(SO4)4(OH)12 where M is K, Na, Ag, Pb, NH4+ and H3O+. Whilst the spectra of the jarosites show a common pattern, differences in the spectra are observed which enable the minerals to be distinguished. The NIR bands in the 6300-7000 cm-1 region are attributed to the first fundamental overtone of the infrared and Raman hydroxyl stretching vibrations. The NIR spectrum of the ammonium-jarosite shows additional bands at 6460 and 6143 cm-1, attributed to the first fundamental overtones of NH stretching vibrations. A set of bands are observed in the 4700-5500 cm-1 region which are assigned to combination bands of the hydroxyl stretching and deformation vibrations. The ammonium-jarosite shows additional bands at 4730 and 4621 cm-1, attributed to the combination of NH stretching and bending vibrations. NIR spectroscopy has the ability to distinguish between the jarosite minerals even when the formula of the minerals is closely related. The NIR spectroscopic technique has great potential as a mineral exploratory tool on planets and in particular Mars. 相似文献
6.
A method for the identification and quantification of underivatised steryl sulphates in invertebrates by liquid chromatography
(LC) coupled with tandem mass spectrometry (MS) involving a single cleanup step has been developed. Negative electrospray
ionisation and positive and negative atmospheric-pressure chemical ionisation (APCI) spectra of steryl sulphate showed pseudomolecular
ions ([M+H–H2SO4]+or [M–H]−). Collision-induced dissociation (CID) was efficient only in positive APCI. LC-MS in negative APCI was least susceptible
to interference and possible differences in response factors. The detection limits (signal-to-noise ratio of 3) based on cholest-5-enyl-3-sulphate
in positive and negative APCI modes are 3.66 and 0.73 pmol μL−1, respectively. Calibration plots and response factors for cholest-5-enyl-3-sulphate relative to the internal standard, cholecalciferyl-3-sulphate,
in both positive and negative polarities, were linear in the concentration range from 1.22 to 16.4 pmol μL−1 with good coefficients of determination (R
2>0.98). It is suggested that the structure elucidation of steryl sulphates is best achieved in CID positive APCI mode, whereas
their quantification should be carried out using negative APCI. 相似文献
7.
Chr Christov S. Petrenko Chr Balarew Vl. Valyashko 《Journal of solution chemistry》1994,23(7):795-812
Pitzer's model has been applied to the thermodynamic study at 25°C of a series of systems of the type MeX-MeX-H2O, MeX-MeX-H2O (where Me, Me=K, NH4,Rb and Cs; X, X=Cl, Br and I), MeSO4-MeSO4-H2O (where Me, Me=Mg, Ni, Zn and Co). The integral Gibbs energy of mixing Gmix and the excess Gibbs energy of mixing GE(s) are calculated, and simplified correlation equations are proposed for their calculation. The results obtained are compared with experimental data from the literature and with values calculated using various theories. The rational activity coefficients of the mixed crystal components are estimated. The energy of phase transition of one structure into another has been estimated for the isodimorphous mixed crystals in the system MgSO4–CoSO4–H2O. 相似文献
8.
K C Patil S Govindarajan R Soundararajan V R Pai Verneker 《Journal of Chemical Sciences》1981,90(5):421-426
Thermal analysis of hydrazinium metal sulphates, (N2H5)2 M(SO4)-I, and their hydrazinates, (N2H5)2−M(SO4)23N2H4−II, whereM=Fe, Co and Ni have been investigated using thermogravimetry and differential thermal analysis. Type II compounds on heating
decompose through an intermediate I and metal suphlate to the respective metal oxides. 相似文献
9.
When reaction mixtures of rare earth(III) sulphates and tetramethylammonium sulphate in molar ratios of from 1∶4 to 1∶12 were evaporated at ambient temperature and the concentrated reaction mixture was treated with ethanol, double sulphates with general empirical formula (CH3)4NLn(SO4)2·2H2O (Ln=Ho?Lu and Y) were obtained as reaction products. The crystalline products were identified by quantitative analysis, X-ray powder diffraction patterns and TG, DTG and DTA analysis. They were found to be isostructural. Their thermal decomposition took place in three stages. The temperature range of the dehydration mainly decreased from Ho to Lu. The thermal decomposition in the second and third stages occurred with many thermal events. As final product, Ln2O(SO4)2 was obtained. 相似文献
10.
On evaporation at room temperature of an aqueous mixture of Ln(III) sulphate and ethanolammonium sulphate in a molar ratio
higher than 1:12, in the presence of sulphuric acid, double sulphates of Sm, Eu, Ho, Tm, Yb and Y with a waxy feel were obtained.
The stoichiometry of the obtained compounds was determined by means of elemental and TG analysis. On the basis of X-ray powder
diffraction patterns it was concluded that an isostructural group with a general formula: Ln2(HOCH2CH2NH3)8(SO4)7·8H2O was obtained. The above compounds have a stoichiometry and a crystal structure different from those of the double sulphates
of La, Ce, Pr and Nd with the same monovalent cation, as presented earlier.
The thermal decomposition of the investigated compounds in the temperature range from ambient temperature up to 1173 K occurred
in a similar way, mainly in three not well-differentiated steps. Lanthanide oxysulphates were obtained as final products.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献