1633-05-2Relevant articles and documents
Hydrogen Bonding in Amorphous Alkaline Earth Carbonates
Leukel, Sebastian,Mondeshki, Mihail,Tremel, Wolfgang
, p. 11289 - 11298 (2018)
Amorphous intermediates play a crucial role during the crystallization of alkaline earth carbonates. We synthesized amorphous carbonates of magnesium, calcium, strontium, and barium from methanolic solution. The local environment of water and the strength of hydrogen bonding in these hydrated modifications were probed with Fourier transform IR spectroscopy, 1H NMR spectroscopy, and heteronuclear correlation experiments. Temperature-dependent spin-lattice (T1) relaxation experiments provided information about the water motion in the amorphous materials. The Pearson hardness of the respective divalent metal cation predominantly determines the strength of the internal hydrogen-bonding network. Amorphous magnesium carbonate deviates from the remaining carbonates, as it contains additional hydroxide ions, which act as strong hydrogen-bond acceptors. Amorphous calcium carbonate exhibits the weakest hydrogen bonds of all alkaline earth carbonates. Our study provides a coherent picture of the hydrogen bonding situation in these transient species and thereby contributes to a deeper understanding of the crystallization process of carbonates.
Syntheses, structure and properties of Alkaline-earth metal salts of 4-Nitrophenylacetic acid
Srinivasan, Bikshandarkoil R,Dhavskar, Kiran T,N?ther, Christian
, p. 1765 - 1774 (2016)
The synthesis, crystal structure, spectral characteristics and thermal properties of alkaline-earth metal salts of 4-nitrophenylacetic acid (4-npaH) namely, [Mg(H2O)6](4-npa)2?4H 2O (4-npa = 4-nitrophenyl-acetate) (1), [Ca(H 2O) 2(4-npa) 2] (2) and [Sr(H 2O) 3(4-npa) 2] ?4.5H 2O(3) are reported. In 1, the 4-npa ion functions as a charge balancing counter anion for the octahedral [Mg(H 2O) 6] 2+ unit with the Mg(II) ion situated on a centre of inversion. The two unique lattice water molecules link the [Mg(H 2O) 6] 2+ cations and 4-npa anions with the aid of O-H ?O interactions. Compounds 2 and 3 are one-dimensional (1-D) coordination polymers containing an eight coordinated Ca(II) situated in a general position and a nine coordinated Sr(II) located on a twofold axis. The μ2-bridging tridentate binding modes of the crystallographically independent 4-npa ligands in 2 and the unique 4-npa ligand in 3 link the bivalent metal ions into an infinite chain with alternating Ca ?Ca separations of 3.989 and 4.009 ?, respectively, and a single Sr ?Sr separation of 4.194 ? in the 1-D chain. [Figure not available: see fulltext.]
Synthesis and characterization of strontium carbonate nanowires with a axis orientation and dendritic nanocrystals
Huang, Qing,Gao, Lian,Cai, Ye,Aldinger, Fritz
, p. 290 - 291 (2004)
Strontium carbonate nanowires that grow along the a axis were synthesized in large scale through simple hydrothermal approach for the first time. The aspect ratio of the product is more than 1000. Dendritic nanocrystals were also generated at low temperatures. Moreover, this method is feasible to be applied in the synthesis of barium carbonate nanowires.
Direct synthesis of Sr3Al2(OH)12 from solution for preparation of fine-grained Sr3Al2O6 phosphors at low temperature
Qi, Jianquan,Zhang, Xinyi,Han, Xiumei,Li, Yuanyuan,Wu, Xueyang,Zhong, Ruixia,Guo, Rui
, p. 421 - 426 (2016)
The precursors Sr3Al2(OH)12 can be directly precipitated from solution near room temperature under the normal pressure. The cubic Sr3Al2O6 with fine grain size can be synthesized from Sr3Al2(OH)12 at the temperature as low as 600 °C. Especially, the rare earth element, such as Eu3+ etc., as luminescent center, has been simultaneously integrated into the lattices of Sr3Al2O6. The luminescent intensities of the samples annealed at a temperature over 800 °C are strong enough for phosphors, and increase with the annealing temperatures, reach a maximum at 1200 °C and then drop down at 1300 °C. The grain sizes of all the samples annealed below 1200 °C are smaller than 1 μm and suitable for mixing with other phosphors in the applications. The photoluminescent spectra of the Sr3Al2O6:Eu3+ reveal that the intensities of both emission and excitation peaks increase with the dose of Eu3+, and reach maxima at the dose level about 1.2%, then decrease due to concentration quenching. A new excitation band at 230 nm has been observed in heavier doped samples due to the complex point defects produced by association.
Electrical characterization of strontium tartrate single crystals
Arora,Patel, Vipul,Patel,Amin, Brijesh,Kothari, Anjana
, p. 965 - 973 (2004)
The a.c. and d.c. conductivity of SrC4H4O 6·3H2O are measured and are found to lie between usual conductivities of semiconductor and insulator. Temperature dependence of d.c. conductivity shows intrinsic conduction, which is confirmed by the slope of lnσ versus lnf data. Due to application of thermal energy, noticeable conductivity peaks imply liberation of water molecules during dehydration and the formation of strontium oxalate. The conductivity plot has a nature similar to the intrinsic-to-extrinsic transition found in normal semiconductors. There occurs Efros hopping conduction in our samples.
Localization of Co2- anion radicals in strontium carbonate obtained by thermal decomposition of strontium oxalate
Stoyanova, R.,Angelov, S.,Bozhilov, K.
, p. 1163 - 1170 (1990)
Mn2+ EPR probes and transmission electron microscopy are used to study the influence of the thermal decomposition rate of strontium oxalate monohydrate on the morphology and the extended defects in the SrCO3 formed. The correlations
Single-step synthesis of SrMoO4 particles from SrSO4 and their anti-corrosive activity
Diaz-Algara,Rendón-Angeles,Matamoros-Veloza,Yanagisawa,Rodriguez-Galicia,Rivera-Cobo
, p. 73 - 84 (2014)
The transformation of three different sizes (4 mineral powder into SrMoO4 scheelite-type tetragonal particles was investigated via conventional hydrothermal treatments under both static and stirring conditions (20 rpm) at 100-250 °C and varying reaction intervals (0.08-48 h) in alkaline solutions saturated with MoO42-. A partial SrSO4 transformation was found to proceed in mild to concentrated alkaline NaOH solutions (0.1-2.5 M), the complete transformation of SrSO4 to SrMoO4 was observed to proceed at temperatures lower than 200 °C over 48 h in a static 5 M NaOH solution, but this process was accelerated when the autoclave was stirred at 20 rpm during the treatment, which led to the production of uncontaminated SrMoO4 particles at 200 °C within 6 h. The resultant SrMoO4 particles had octahedral bipyramidal morphology and particle sizes between 1 and 5 μm; these particles exhibited a noticeable agglomeration at the intermediate and final stages of the reaction due to the formation of agglomerates with an average size of 60 μm. However, stirring of the mixture in the autoclave markedly reduced the growth of the bulky agglomerations of SrMoO4 particles. A coupled process involving the bulk dissolution of the SrSO4 powder and, subsequently, the massive precipitation of SrMoO4 in an alkaline solution (5 M NaOH) saturated with MoO42- ions was utilised to crystallise the SrMoO4 particles. Kinetic studies demonstrated that the activation energy required for the formation of the octahedral shaped SrMoO4 particles was 25.8 kJ mol-1 in the system without agitation; in contrast, the activation energy decreased to 12.8 kJ mol-1 when the transformation was stirred. In a subsequent investigation, the ionic permeability resistance of a commercial paint applied to a AISI 1020 steel substrate was improved by adding a 2.0 wt.% of the transformed SrMoO4 particles to the paint.
Ca(II), Sr(II) and Ba(II) ion interaction with the rheumatoid arthritis drug tenoxicam: Structural, thermal, and biological characterization
Adam, Abdel Majid A.
, (2018)
Recently, one of the most common conditions that manifests as joint and muscle inflammation is rheumatoid arthritis. One of the treatments for this arthritis includes non-steroidal anti-inflammatory drugs (NSAIDs) of the oxicam family, and the widest used drug in this family is tenoxicam (Tenox). In this study, the complexation properties of the drug Tenox with Ca(II), Sr(II) and Ba(II) ions in a (dichloromethane + water) binary solvent system are reported. The formed metal complexes were characterized structurally, thermally, and biologically. Tenox was found to act as a chelate monoanionic ligand towards all metal ions with complexation stoichiometry of 1:2 (Metal: Tenox) for Ca(II) and Sr(II) ions, and 1:1 for Ba(II) ions. The Tenox ligand behaves as a bidentate ligand when coordinated with Sr(II) or Ba(II) ions and as a tridentate ligand when coordinated with Ca(II) ions. The Sr(II) and Ba(II) complex of the Tenox ligand exhibited marked inhibitory effect on the cell growth of the C. albicans species.
Solvothermal synthesis of fusiform hexagonal prism SrCO3 microrods via ethylene glycol solution
Shi, Liange,Du, Fanglin
, p. 1550 - 1555 (2007)
Fusiform hexagonal prism SrCO3 microrods were prepared by a simple solvothermal route at 120 °C, and characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) and Fourier transform infrared (FT-IR) spectroscopy. By controlling the content of ethylene glycol (EG), it was found that ethylene glycol (EG) played an important role in the formation of such SrCO3 microrods. Finally, effects of other solvents on the products, including 1,2-propanediol and glycerin, were also investigated.
Room temperature syntheses and thermal behaviors of hydrogarnets Sr3M2(OH)12 (M = Al, Cr and Fe)
Chen, Yun-Feng,Yang, Zhi,Li, Yong-Ming,Guo, Jing,Fu, Wen-Fu,Wang, Ying-Xia,Liao, Fu-Hui,Li, Jianye
, p. 248 - 252 (2015)
Hydrogarnets Sr3M2(OH)12 (M = Al, Cr and Fe) were synthesized through a solid state reaction at room temperature with Al(NO3)3·9H2O, CrCl3·6H2O, FeCl3·6H2O, Sr(NO3)2 and NaOH as the starting materials. All X-ray diffraction (XRD) data of Sr3M2(OH)12 were indexed by the cubic system with the space group of Ia-3d. XRD, differential thermal analysis and thermogravimetric (DTA-TG), and scanning electron microscopy (SEM) were employed to investigate the structural stability, thermal properties and morphologies of Sr based hydrogarnets. The cause of room temperature synthesis and the thermal decomposition behaviors of Sr-based hydrogarnets Sr3M2(OH)12 (M = Al, Cr and Fe) are discussed.
