首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 336 毫秒
1.
The sarkinite, Mn2(OH)AsO4, mineral has been synthesized in laboratory as pure phase under mild hydrothermal conditions. The decomposition process of the hydroxiarsenate compound is strongly dependent on the atmospheric conditions. The results of the thermal treatment in air or argon are quite different. In this way, a new black phase appears in air atmosphere in the 400‐630 °C temperature range whereas under inert atmosphere the structure of Mn2(OH)AsO4 at room temperature is maintained up to 560 °C. The weight loss is attributed to the partial decomposition of Mn2(OH)AsO4 above 400 °C with removal of OH groups and the oxidation of MnII to MnIII that occur simultaneously. Above 650 °C, the structures of the intermediate compounds are broken and the evolution of the inorganic residues gives rise to the formation of arsenates and oxides of MnII and MnIII in inert and air atmospheres.  相似文献   

2.
The basic copper arsenate mineral strashimirite Cu8(AsO4)4(OH)4·5H2O from two different localities has been studied by Raman spectroscopy and complemented by infrared spectroscopy. Two strashimirite mineral samples were obtained from the Czech (sample A) and Slovak (sample B) Republics. Two Raman bands for sample A are identified at 839 and 856 cm−1 and for sample B at 843 and 891 cm−1 are assigned to the ν1 (AsO43−) symmetric and the ν3 (AsO43−) antisymmetric stretching modes, respectively. The broad band for sample A centred upon 500 cm−1, resolved into component bands at 467, 497, 526 and 554 cm−1 and for sample B at 507 and 560 cm−1 include bands which are attributable to the ν4 (AsO43−) bending mode. In the Raman spectra, two bands (sample A) at 337 and 393 cm−1 and at 343 and 374 cm−1 for sample B are attributed to the ν2 (AsO43−) bending mode. The Raman spectrum of strashimirite sample A shows three resolved bands at 3450, 3488 and 3585 cm−1. The first two bands are attributed to water stretching vibrations whereas the band at 3585 cm−1 to OH stretching vibrations of the hydroxyl units. Two bands (3497 and 3444 cm−1) are observed in the Raman spectrum of B. A comparison is made of the Raman spectrum of strashimirite with the Raman spectra of other selected basic copper arsenates including olivenite, cornwallite, cornubite and clinoclase.  相似文献   

3.
The phosphate mineral series eosphorite–childrenite–(Mn,Fe)Al(PO4)(OH)2·(H2O) has been studied using a combination of electron probe analysis and vibrational spectroscopy. Eosphorite is the manganese rich mineral with lower iron content in comparison with the childrenite which has higher iron and lower manganese content. The determined formulae of the two studied minerals are: (Mn0.72,Fe0.13,Ca0.01)(Al)1.04(PO4, OHPO3)1.07(OH1.89,F0.02)·0.94(H2O) for SAA-090 and (Fe0.49,Mn0.35,Mg0.06,Ca0.04)(Al)1.03(PO4, OHPO3)1.05(OH)1.90·0.95(H2O) for SAA-072. Raman spectroscopy enabled the observation of bands at 970 cm−1 and 1011 cm−1 assigned to monohydrogen phosphate, phosphate and dihydrogen phosphate units. Differences are observed in the area of the peaks between the two eosphorite minerals. Raman bands at 562 cm−1, 595 cm−1, and 608 cm−1 are assigned to the ν4 bending modes of the PO4, HPO4 and H2PO4 units; Raman bands at 405 cm−1, 427 cm−1 and 466 cm−1 are attributed to the ν2 modes of these units. Raman bands of the hydroxyl and water stretching modes are observed. Vibrational spectroscopy enabled details of the molecular structure of the eosphorite mineral series to be determined.  相似文献   

4.
Indium arsenate(V) monohydrate, InAsO4·H2O, (I), crystallizes in the structure type of MnMoO4·H2O. The structure is built of In2O8(H2O)2 dimers (mean In—O = 2.150 Å) corner‐linked to slightly distorted AsO4 tetra­hedra (mean As—O = 1.686 Å). The linkage results in a three‐dimensional framework, with small voids into which the apical water ligand of the InO5(H2O) octa­hedron points. The hydrogen bonds in (I) are of medium strength. Lead(II) indium arsenate(V) hydrogen arsenate(V), PbIn(AsO4)(AsO3OH), (II), represents the first reported lead indium arsenate. It is characterized by a framework structure of InO6 octa­hedra corner‐linked to AsO4 and AsO3OH tetra­hedra. The resulting voids are occupied by Pb2O10(OH)2 dimers built of two edge‐sharing highly distorted PbO6(OH) polyhedra (mean Pb—O = 2.623 Å). The compound is isotypic with PbFeIII(AsO4)(AsO3OH). The average In—O bond length in (II) is 2.157 Å. In both arsenates, all atoms are in general positions.  相似文献   

5.
Raman spectroscopy has been sued to study the antimony containing mineral roméite Ca2Sb2O6(OH,F,O) from three different origins. Roméite is a calcium antimonate mineral of the pyrochlore group. An intense Raman band at ~518 cm?1 for roméite is assigned to the SbO ν1 symmetric stretching mode and the band at 466 cm?1 to the SbO ν3 antisymmetric stretching mode. The Raman band at 303 cm?1 is attributed to the OSbO bending mode. Some variation in band positions is observed and is attributed to the variation in composition between the three mineral samples.  相似文献   

6.
One μ‐alkoxo‐μ‐carboxylato bridged dinuclear copper(II) complex, [Cu2(L1)(μ‐C6H5CO2)] ( 1 )(H3L1 = 1,3‐bis(salicylideneamino)‐2‐propanol)), and two μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear copper(II) complexes, [Cu4(L1)2(μ‐C8H10O4)(DMF)2]·H2O ( 2 ) and [Cu4(L2)2(μ‐C5H6O4]·2H2O·2CH3CN ( 3 ) (H3L2 = 1,3‐bis(5‐bromo‐salicylideneamino)‐2‐propanol)) have been prepared and characterized. The single crystal X‐ray analysis shows that the structure of complex 1 is dimeric with two adjacent copper(II) atoms bridged by μ‐alkoxo‐μ‐carboxylato ligands where the Cu···Cu distances and Cu‐O(alkoxo)‐Cu angles are 3.5 11 Å and 132.8°, respectively. Complexes 2 and 3 consist of a μ‐alkoxo‐μ‐dicarboxylato doubly‐bridged tetranuclear Cu(II) complex with mean Cu‐Cu distances and Cu‐O‐Cu angles of 3.092 Å and 104.2° for 2 and 3.486 Å and 129.9° for 3 , respectively. Magnetic measurements reveal that 1 is strong antiferromagnetically coupled with 2J =‐210 cm?1 while 2 and 3 exhibit ferromagnetic coupling with 2J = 126 cm?1 and 82 cm?1 (averaged), respectively. The 2J values of 1–3 are correlated to dihedral angles and the Cu‐O‐Cu angles. Dependence of the pH at 25 °C on the reaction rate of oxidation of 3,5‐di‐tert‐butylcatechol (3,5‐DTBC) to the corresponding quinone (3,5‐DTBQ) catalyzed by 1–3 was studied. Complexes 1–3 exhibit catecholase‐like active at above pH 8 and 25 °C for oxidation of 3,5‐di‐tert‐butylcatechol.  相似文献   

7.
Raman spectra of coquandite Sb6O8(SO4)·(H2O) were studied, and related to the structure of the mineral. Raman bands observed at 970, 990 and 1007 cm?1 and a series of overlapping bands are observed at 1072, 1100, 1151 and 1217 cm?1 are assigned to the SO42? ν1 symmetric and ν3 antisymmetric stretching modes respectively. Raman bands at 629, 638, 690, 751 and 787 cm?1 are attributed to the SbO stretching vibrations. Raman bands at 600 and 610 cm?1 and at 429 and 459 cm?1 are assigned to the SO42? ν4 and ν2 bending modes. Raman bands at 359 and 375 cm?1 are assigned to O–Sb–O bending modes. Multiple Raman bands for both SO42? and SbO stretching vibrations support the concept of the non-equivalence of these units in the coquandite structure.  相似文献   

8.
Polarized specular reflection infrared spectra of crystalline NaNO3 were measured in the ν3 region at angles of incidence from 75° to 10°. In addition to the LO component, the TO component of ν3 appeared in the 65° spectrum, and the intensity of ν3(TO) increased relative to ν3(LO) with decreasing angle. The frequency of ν3(LO) shifted from 1460 cm?1 at 75° to 1448 cm?1 at 10° angle of incidence.  相似文献   

9.
The minerals mimetite Pb5(AsO4)3Cl, arsenian pyromorphite Pb5(PO4,AsO4)3Cl and hedyphane Pb3Ca2(AsO4)3Cl have been studied by Raman spectroscopy complimented with infrared spectroscopy. Mimetite is characterised by a band at 812–3 cm−1 attributed to the Ag mode. For the arsenian pyromorphite this band is observed at 818 cm−1 and for hedyphane at 819 cm−1. For mimetite and hedyphane bands at 788 and 765 cm−1 are attributed to Au and E1u vibrational modes and are both Raman and infrared active. For the arsenian pyromorphite, Raman bands at 917–1014 cm−1 are attributed to phosphate stretching vibrations. Raman spectroscopy clearly identifies bands attributable to isomorphous substitution of arsenate by phosphate. The observation of low intensity bands in the 3200–3550 cm−1 region are assigned to adsorbed water and OH units, thus indicating some replacement of chloride ions with hydroxyl ions.  相似文献   

10.
Neodymium(III) peroxotitanate is used as a precursor for obtaining Nd2TiO5. The last one possesses numerous valuable electrophysical properties. TiCl4, Nd(NO3)3·6H2O and H2O2 in mol ratio 1:2:10 were used as starting materials. The reaction ambience was alkalized to pH = 9 with a solution of NH3. The obtained neodymium(III) peroxotitanate and intermediate compounds of the isothermal heating were proved by the help of quantitative analysis and infrared spectroscopy (IRS). It has Nd4[Ti2(O2)4(OH)12]·7H2O composition. The absorption band observed in IRS at 831 cm?1 relates to a triangular bonding of the peroxo group of Ti, at 1062 cm?1—terminal groups Ti–OH and at 1491 and 1384 cm?1—the bridging OH?-groups Ti–O(H)–Ti. Nd2TiO5 was obtained by thermal decomposition of neodymium(III) peroxotitanate. The isothermal conditions for decomposition were determined on the base of differential thermal analysis, thermogravimetric and differential scanning calorimetry results in the temperature range of 20–1000 °C. The mechanism of thermal decomposition of Nd4[Ti2(O2)4(OH)12]·7H2O to Nd2TiO5 was studied. In the temperature range of 20–208 °C, a simultaneous decomposition of the peroxo groups by the separation of oxygen and hydrate water is conducted and Nd4[Ti2O4(OH)12] is obtained. From 208 to 390 °C, the terminal OH?-groups are separated and Nd4[Ti2O7(OH)6] is formed. In the range of 390–824 °C, the bridging OH?-groups are completely decomposed to Nd2TiO5. The optimal conditions for obtaining nanocrystalline Nd2TiO5 are 900 °C for 6 h and 20–80 nm.  相似文献   

11.
The crystal structures of caesium dihydrogen arsenate(V) bis[trihydrogen arsenate(V)], Cs(H2AsO4)(H3AsO4)2, ammonium dihydrogen arsenate(V) trihydrogen arsenate(V), NH4(H2AsO4)(H3AsO4), and dilithium bis(dihydrogen phosphate), Li2(H2PO4)2, were solved from single‐crystal X‐ray diffraction data. NH4(H2AsO4)(H3AsO4), which was hydrothermally synthesized (T = 493 K), is homeotypic with Rb(H2AsO4)(H3AsO4), while Cs(H2AsO4)(H3AsO4)2 crystallizes in a novel structure type and Li2(H2PO4)2 represents a new polymorph of this composition. The Cs and Li compounds grew at room temperature from highly acidic aqueous solutions. Li2(H2PO4)2 forms a three‐dimensional (3D) framework of PO4 tetrahedra sharing corners with Li2O6 dimers built of edge‐sharing LiO4 groups, which is reinforced by hydrogen bonds. The two arsenate compounds are characterized by a 3D network of AsO4 groups that are connected solely via multiple strong hydrogen bonds. A statistical evaluation of the As—O bond lengths in singly, doubly and triply protonated AsO4 groups gave average values of 1.70 (2) Å for 199 As—OH bonds, 1.728 (19) Å for As—OH bonds in HAsO4 groups, 1.714 (12) Å for As—OH bonds in H2AsO4 groups and 1.694 (16) Å for As—OH bonds in H3AsO4 groups, and a grand mean value of 1.667 (18) Å for As—O bonds to nonprotonated O atoms.  相似文献   

12.
Synthesis and Structure of a High Temperature Cobaltarsenate: H? Co3(AsO4)2 Single crystals of the high temperature compound H? Co3(AsO4)4 were prepared at 1800°C with a CO2-Laser technique. X-ray single crystal work shows monoclinic symmetry (space group C-P21/c; a = 6.457, b = 8.510, c = 11.187 Å; ß = 90.73°). In opposition to monoclinic m-CO3(AsO4)2 H? Co3(AsO4)2 has a different coordination of Co2+ including a different connection of the distorted polyhedra. There exists a significant similarity to Cu3(AsO4)2.  相似文献   

13.
The objective of this research is to determine the molecular structure of the mineral leogangite. The formation of the types of arsenosulphate minerals offers a mechanism for arsenate removal from soils and mine dumps. Raman and infrared spectroscopy have been used to characterise the mineral. Observed bands are assigned to the stretching and bending vibrations of (SO4)2− and (AsO4)3− units, stretching and bending vibrations of hydrogen bonded (OH) ions and Cu2+-(O,OH) units. The approximate range of O–H?O hydrogen bond lengths is inferred from the Raman spectra. Raman spectra of leogangite from different origins differ in that some spectra are more complex, where bands are sharp and the degenerate bands of (SO4)2− and (AsO4)3− are split and more intense. Lower wavenumbers of δ H2O bending vibration in the spectrum may indicate the presence of weaker hydrogen bonds compared with those in different leogangite samples. The formation of leogangite offers a mechanism for the removal of arsenic from the environment.  相似文献   

14.
On the Crystal Structure of Barium-Copper-Orthoarsenate BaCu2(AsO4)2 Single crystals of BaCu2(AsO4)2 were prepared above 1 000°C by CO2-LASER technique and investigated by X-ray structure determination. The light blue crystals show monoclinic symmetry, space group C? P21/n, a = 4.752; b = 8.506; c = 8.945 Å; β = 93.49°, Z = 2. BaCu2(AsO4)2 represents a hitherto unknown structure type with Cu2+ in trigonal bipyramidal coordination. Ba2+ shows an 8 + 2 surrounding by O2? and As5+ is tetrahedrally coordinated. The crystal structure is discussed with respect to related orthophosphates and vanadates.  相似文献   

15.
This research was done on hureaulite samples from the Cigana claim, a lithium bearing pegmatite with triphylite and spodumene. The mine is located in Conselheiro Pena, east of Minas Gerais. Chemical analysis was carried out by Electron Microprobe analysis and indicated a manganese rich phase with partial substitution of iron. The calculated chemical formula of the studied sample is: (Mn3.23, Fe1.04, Ca0.19, Mg0.13)(PO4)2.7(HPO4)2.6(OH)4.78. The Raman spectrum of hureaulite is dominated by an intense sharp band at 959 cm−1 assigned to PO stretching vibrations of HPO42− units. The Raman band at 989 cm−1 is assigned to the PO43− stretching vibration. Raman bands at 1007, 1024, 1047, and 1083 cm−1 are attributed to both the HOP and PO antisymmetric stretching vibrations of HPO42− and PO43− units. A set of Raman bands at 531, 543, 564 and 582 cm−1 are assigned to the ν4 bending modes of the HPO42− and PO43− units. Raman bands observed at 414, and 455 cm−1 are attributed to the ν2 HPO42− and PO43− units. The intense A series of Raman and infrared bands in the OH stretching region are assigned to water stretching vibrations. Based upon the position of these bands hydrogen bond distances are calculated. Hydrogen bond distances are short indicating very strong hydrogen bonding in the hureaulite structure. A combination of Raman and infrared spectroscopy enabled aspects of the molecular structure of the mineral hureaulite to be understood.  相似文献   

16.
An organic-inorganic compound of tetraethylammonium dihydrogenarsenate bis(arsenic acid) salts of formula (NEt4)(H2AsO4)(H3AsO4)2, a potential new nonlinear optical material, was prepared by a slow evaporation technique and characterized by IR and Raman spectroscopy accomplished with DFT calculation and electrical-dielectrical measurements. The structure has been solved using direct method and refined by least-squares analysis. In this case, the structure consists of infinite parallel two-dimensional planes built of mutually H2AsO4?, H3AsO4 tetrahedra connected by strong O–H?O hydrogen bonding giving birth to trimers. The geometry, first hyperpolarizability and harmonic vibrational wavenumbers were calculated by means of density functional theory (DFT) with the B3LYP/6-31G(d) level of theory. Good consistency was found between the calculated and the experimental structure, IR, and Raman results. The first hyperpolarizability βtot of the title compound is about 1.75 times more than that of the reference crystal KDP. The complex impedance has been investigated in relation to the temperature and frequency ranges 297 and 373 K and 1 to 100 KHz, respectively. The conductivity temperature variation shows a typical Arrhenius-type behavior with a linear dependence on logarithm of conductivity. Transport properties in this material appear to be due to proton hopping mechanism.  相似文献   

17.
《Chemical physics》1987,112(3):379-386
We have measured the νs(OH) band parameters of the IR absorption spectra for a wide variety of hydrogen-bonded (HB) complexes of CH3OH(D), CF3CH2OH, and (CF3)3COH(D) with some simplest representatives of various classes of bases in Xe and Kr in the temperature range 120–270 K. The νs(OH) absorption bands of the HB complexes in solution in atomic solvents have been demonstrated to be narrower by a factor of 2 to 4 than in molecular solvents at the same temperature. The fact that the νs(OH) bandwidths in Xe and in the gas phase at similar temperatures are practically the same indicates that these bandwidths are in both cases governed mainly by the contribution of “hot transitions” from a sequence of excited levels of the νβ low-frequency bending mode of the hydrogen bond. The other characteristic features revealed for the complexes under study in liquid Xe and Kr at νs(OH) frequency shifts up to 500 cm−1 include: (1) slight temperature dependence of the νs(OH) bandwidth (0.1–0.3 cm−1/K), (2) almost “normal” isotope frequency ratio νs(OH)/νs(OD) (1.34–1.36) and (3) low νs(OH) temperature shift values (0.1–0.4 cm−1/K).  相似文献   

18.
Investigation of aqueous solutions of polyborates LiB(OH)4, Li2B4O5(OH)4, and LiB5O6(OH)4 at different acidity has been performed by Raman spectroscopy at 25°C. The geometries and Raman vibrational frequencies of H3BO3 in aqueous phase were calculated at different basis sets, and verified the veracity. The calculated characteristic Raman shifts of B(OH)3, B(OH)4 ?, B3O3(OH)4 ?, B3O3(OH)5 2?, B4O5(OH)4 2?, and B5O6(OH)4 ? were assigned to 880.0, 735.33, 599.06, 740.16, 551.67, and 521.04 cm?1, respectively. Assignments of the bands were tentatively ascribed by comparing the calculated Raman spectrum. The chemical species distribution and the relevant molecular interaction mechanisms in the polyborates solutions were suggested.  相似文献   

19.
The infrared and Raman spectra of sodium α-, β- and γ-hydroxybutyrates and their deuterated analogues are examined in the 4000-100 cm−1 range and an assignment of the fundamental vibrations is given. Based on the localization of the asymmetric stretching vibrations νasOH and the out-of-plane vibration γOH, inter- and/or intramolecularly hydrogen-bonded forms are proposed: the low frequencies of νasOH (<3200 cm−1) and high frequencies of γOH (≈800 cm−1) argue in favour of the existence of intramolecular hydrogen bonding. Sodium α-hydroxybutyrate exhibits as a chelate ring with an intramolecular hydrogen bond between hydroxyl and carboxyl groups, whereas sodium, β-hydroxybutyrate has the two association forms with inter- and intramolecular hydrogen bonds. Sodium γ-hydroxybutyrate exists as a hydrogen-bonded polymer, with an intermolecular hydrogen bond between the hydroxyl groups and between the hydroxyl and carbonyl groups. At a crystallization temperature above 50°C, only the α- salt showed a structural change indicating the existence of intra- and intermolecular hydrogen bonds. This result is confirmed by differential scanning analysis.  相似文献   

20.
Two new compounds, (H2en)3(H2enMe)4(H3O){CuI[MoV 6O12(OH)3(HPO4)(PO4)3]2}?·?6H2O (1) and (H2enMe)4{CuICuII[MoV 6O12(OH)3(PO4)(HPO4)2(H2PO4)]2}?·?3H2O (2), were hydrothermally synthesized and characterized by elemental analysis, IR, TGA, and single-crystal X-ray diffraction analysis. Crystallographic analysis reveals that 1 is constructed from cluster anions {CuI[MoV 6O12(OH)3(HPO4)(PO4)3]2}15?, protonated organic amines, and water molecules. Each cluster is bridged through hydrogen bonds to form a 3-D supermolecular structure. For 2, {CuI[MoV 6O12(OH)3(PO4)(HPO4)2(H2PO4)]2}11? are connected by CuII cations to form an infinite chain. The formation of 1 and 2 reveals that organoamines influence the structures of the crystals.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号