Mixture Of CaCO3 Research Articles

ChemInform Abstract: Ca3Si2O4N2:Ce3+,Li + Phosphor for the Generation of White‐Light‐Emitting Diodes with Excellent Color Rendering Index Values.

AbstractThe blue‐emitting phosphor (Ca0.94Ce0.03Li0.03) 3Si2O4N2 is synthesized by solid state reaction of a stoichiometric mixture of CaCO3, α‐Si3N4, SiO2, Li2CO3, and CeO2 (15%H2/85%N2, 1400 °C, 8 h).

ChemInform Abstract: Alternating Misfit Layered Transition/Alkaline Earth Metal Chalcogenide Ca3Co4O9 as a New Class of Chalcogenide Materials for Hydrogen Evolution.

AbstractThe misfit layered mixed oxide Ca3Co4O9 is prepared by calcining a mixture of CaCO3 and Co2O3 (850 and 900 °C, 1 d each) followed by epicyclic milling and final sintering in O2 (Pt crucible, 940 °C, 100 h).

Synthesis and characterization of high-pressure and high-temperature sphene (CaTiSiO5)

Sphene (CaTiSiO5), a calcium titanosilicate ceramic has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization and activation of precursors. During the high-pressure and high-temperature synthesis (HPS) process at 4 GPa and 1,200 °C, sphene undergoes into phase transition, from room-temperature phase P21/a to high-temperature phase A2/a. Evidence of that structural phase transition is given in this paper using infrared, Raman spectroscopy and X-ray powder diffraction. Rietveld refinement was employed to get the structural information of the synthesized powder. The most important structural change due to phase transition, the disappearance of the characteristic out-of-center distortion of the Ti atom and moving to the center of octahedra, was confirmed. HPS is an effective method for producing full-dense ceramics without any additives. Reduction of particle size occurred during high-pressure compaction. Microstructure and particle size of both phases were analyzed by scanning electron microscopy.

ChemInform Abstract: Local Melting of Charge Ordering in CaBaCo4O7 by Sr‐Doping.

AbstractCaBa1‐xSrxCo4O7 (x: 0, 0.06, 0.08, 0.1) are prepared by solid state reaction of stoichiometric mixtures of CaCO3, BaCO3, SrCO3, and Co3O4 (1.

Biocompatible nanocrystalline natural bonelike carbonated hydroxyapatite synthesized by mechanical alloying in a record minimum time

Single phase nanocrystalline biocompatible A-type carbonated hydroxyapatite (A-cHAp) powder has been synthesized by mechanical alloying the stoichiometric mixture of CaCO3 and CaHPO4.2H2O powders in open air at room temperature within 2h of milling. The A-type carbonation in HAp is confirmed by FTIR analysis. Structural and microstructure parameters of as-milled powders are obtained from both Rietveld's powder structure refinement analysis and transmission electron microscopy. Size and lattice strain of nanocrystalline HAp particles are found to be anisotropic in nature. Mechanical alloying causes amorphization of a part of crystalline A-cHAp which is analogous to native bone mineral. Some primary bond lengths of as-milled samples are critically measured. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay test reveals high percentage of cell viability and hence confirms the biocompatibility of the sample. The overall results indicate that the processed A-cHAp has a chemical composition very close to that of biological apatite.

ChemInform Abstract: A Novel White Emission in Ca8MgBi(PO4)7:Dy3+ Single‐Phase Full‐Color Phosphor.

AbstractCa8MgBi(PO4)7:xDy3+ (0.02 ≤ x ≤ 0.30) phosphors are synthesized by solid state reactions of stoichiometric mixtures of CaCO3, MgCO3, (NH4)2HPO4, Bi2O3, and Dy2O3 (750 °C for 3 h in air and 1200 °C for 4 h).

Milling assisted synthesis of calcium zirconate СаZrО3

Monophase calcium zirconate (CaZrO3) has been prepared from the equimolar ZrO2 + CaCO3 mixture by two-step synthesis process. In the first step, mechanical treatment of the mixture is performed in an AGO-2 planetary ball mill. In the second step, the milled mixture is annealed to form calcium zirconate. High-energy ball milling of the (ZrO2+CaCO3) mixture results in decrease in the temperature of CaZrO3 formation during annealing at 950 °C. The enhancement of CaZrO3 synthesis is due to accumulation of excess energy by the reagents, decreasing the particle size and notable increase in the interphase area because of “smearing” of CaCO3 on ZrO2 particles during milling. Nanocrystalline calcium zirconate has been produced by controlling the annealing temperature and time.

ChemInform Abstract: Improvement of the Energy Transfer from Ca3SnSi2O9 Host to Rare‐Earth Ions with the Assistance of Oxygen Vacancies.

AbstractEu3+‐doped Ca3SnSi2O9 is prepared via solid state synthesis using stoichiometric mixtures of CaCO3, CaF2, SnO2, SiO2, Eu2O3, and Dy2O3 with small amounts of H3BO3 as flux (1400 °C, 4 h, ambient atmosphere).

ChemInform Abstract: Crystal Growth, Nonlinear Frequency‐Doubling and Spectral Characteristic of Nd:Ca9La(VO4)7 Crystal.

AbstractPure and Nd‐doped Ca9La(VO4)7 crystals with various Nd3+ levels (3.2, 18.9, 31.4, and 32 at.%) are grown by the Czochralski method at 1430 °C from powders prepared by solid state reaction of a stoichiometric mixture of CaCO3, V2O5, La2O3, and Nd2O3 (alumina crucible, 1000 °C, 8 h).

Effects of desalted duck egg white peptides and their products on calcium absorption in rats

The effects of desalted duck egg white peptides (DPs), phosphorylated DPs (PDPs) and DPs–calcium complexes (DPs-Ca) on calcium absorption in vivo were investigated. Ninety fast-growing male rats were divided into 10 groups and treated with different dosages of CaCO3, calcium gluconate, DPs-Ca as well as CPPs, DPs and PDPs supplemented with CaCO3. Eight-week oral administration results indicated that the high dosage PDPs+CaCO3 group was significantly higher than the high dosage DPs+CaCO3 group in calcium absorption, bone calcium content, BMD and maximum stress, but lower in ALP activity (P < 0.05). Additionally, the high dosage DPs-Ca group showed higher bone indices than the high dosage DPs+CaCO3, calcium gluconate and CaCO3 groups (P < 0.05). These results suggest that in vivo, phosphorylated DPs are more effective than DPs in improving calcium absorption and bone strength, and DPs–calcium complexes are more beneficial to bone tissues than the DPs and CaCO3 mixture.

ChemInform Abstract: Preparation and Luminescence Characteristics of Eu‐Doped Calcium Chloride Silicate Ca7Si2O8Cl6.

AbstractEu‐activated Ca7Si2O8Cl6 phosphors are prepared by calcination of a stoichiometric mixture of CaCO3 and SiO2 in the presence of 0.1—5.0 mol% Eu2O3 (air, 850 °C, 5—10 h) before fluxing the resulting powder with CaCl2 (N2/5%H2 atmosphere, corundum boat, 1100 °C, 5—10 h).

ChemInform Abstract: Cationic Disorder and Mn3+/Mn4+ Charge Ordering in the B′ and B′′ Sites of Ca3Mn2NbO9 Perovskite: A Comparison with Ca3Mn2WO9.

AbstractPolycrystalline Ca3MnIII2WO9 (I) and Ca3MnIII/IV2NbO9 (II) are prepared by calcination in air of stoichiometric mixtures of CaCO3, MnCO3, and WO3 (or Nb2O5) (Pt crucible, 800 °C, 12 h).

The Influence of Hydrothermal Temperature on CaO-based Adsorbents Synthesized by Sol-Gel-Hydrothermal Method

To capture carbon dioxide (CO2), a major green house gas from flue gas, several kinds of adsorbents have been synthesized, characterized and tested. In this study, CaO-based adsorbents were synthesized via sol-gel-hydrothermal method and different hydrothermal temperatures (100, 120, 140 and 160°C) have been investigated in order to verify their influence on the CaO-based adsorbents. Experimental results showed that the Ca(OH)2 adsorbent with a mixture of CaCO3 synthesized at 120°C hydrothermal treatment possesses high CO2 adsorption capacity (0.52 g-CO2/g-sorbent) and at 160°C hydrothermal treatment, CaC2O4.H2O adsorbent was observed and its CO2 adsorption capacity was 0.46 g-CO2/g-sorbent for first carbonation/calcination cycle.

Metal Glycerolates as Catalysts in the Transesterification of Refined Soybean Oil with Methanol under Reflux Conditions

Divalent metal glycerolates were synthesized and investigated in the methyl transesterification of refined soybean oil. Higher conversions to monoacylesters were obtained for strontium and barium monoglycerolates and calcium diglycerolate. Calcium diglycerolate was shown to be stable up to a third reuse cycle, decomposing to an inactive mixture of CaCO3 and Ca(OH)2.

ChemInform Abstract: Preparation and Dielectric Properties of Unfilled Tungsten Bronze Ferroelectrics Ba4RETiNb9O30.

AbstractNovel Ba4LnTiNb9O30 compounds with Ln: La, Pr, Nd, Sm, Eu, and Gd are prepared by solid state reaction of stoichiometric mixtures of CaCO3, Ln2O3, TiO2, and Nb2O5 (1300 °C, 8 h, followed by sintering at 1290—1380 °C for 8 h).

Synthesis of high aspect ratio platelike Ba1−xCaxTiO3 particles by topochemical microcrystal conversion method

A-site complex perovskite Ba1−xCaxTiO3 (x≤0.25) platelike particles with high aspect ratio (edge length to thickness) of 8–10 and micron sizes (6–8μm) were synthesized via a topochemical microcrystal conversion reaction between the platelet Bi4Ti3O12 and the powdered BaCO3–CaCO3 mixture at 950°C in KCl flux. The morphology and A-site elemental composition of the resulting particles has been studied with reference to the effect of the concentration and molar ratio of the Ca2+ and Ba2+ in molten salt. The A-site elemental composition of the resultant particles was correspond linearly to the molar ratio of the Ca2+ and Ba2+ in molten salt. The morphology and size distribution of the synthetic Ba1−xCaxTiO3 particles was inherited from that of the precursor phase Bi4Ti3O12. The designed synthesis routine has potential to synthesize other A-site complex perovskite platelike particles with high aspect ratio and micron sizes, which serving as a suitable template and seeded crystals can be employed to produce highly textured ceramics via TGG/RTGG method and single crystals by SPC technique.

ChemInform Abstract: Triple‐Layered Perovskite Niobates CaRNb3O10 (R: La, Sm, Eu, Gd, Dy, Er, Yb, or Y): New Self‐Activated Oxides.

AbstractThe title compounds are synthesized by solid state reactions of stoichiometric mixtures of CaCO3, Nb2O5, and Ln2O3 (Ln: La, Sm, Eu, Gd, Dy, Er, Yb, Y) at 1300—1350 °C for 20—48 h twice.

Relação Ca: Mg do corretivo da acidez do solo e as características agronômicas de plantas forrageiras

A variação na relação Ca:Mg em corretivos da acidez do solo é a principal forma de alterar a disponibilidade desses nutrientes para as espécies forrageiras. O objetivo com o trabalho foi avaliar o efeito de diferentes proporções entre cálcio e magnésio na forma de CaCO3 e MgCO3 sobre as propriedades químicas do solo e as características agronômicas de espécies forrageiras em Araguaína, TO. O estudo foi sobre Neossolo Quartzarênico Órtico típico, com 5% de argila, com fatorial 3 x 5, sendo três as espécies forrageiras (Brachiaria brizantha cv. Xaraés, Panicum maximum cv: Mombaça e estilosante Campo Grande - Stylosanthes capitata e S. macrocephala) e cinco as relações de Ca:Mg no calcário (1:1; 2:1; 4:1, 6:1 e 8:1). Os tratamentos foram dispostos em delineamento em blocos ao acaso, com quatro repetições. Todos os tratamentos receberam dose equivalente de 4t/ha de calcário. As diferentes relações Ca:Mg influenciaram no desenvolvimento e produtividade das forrageiras entretanto, não se obteve comportamento coerente que indicasse a tendência de resposta das plantas ao aumento ou redução da relação Ca:Mg. Além disto, as diferentes forrageiras foram semelhantes em relação a química do solo, porém as relações Ca:Mg alteraram as propriedades químicas do solo.

Synthesis of micron-scale platelet Ba1−xCaxTiO3 microcrystals by the topochemical microcrystal conversion method

A-site complex perovskite Ba1−xCaxTiO3 microcrystals with platelike shape and micron sizes were synthesized successfully via a designed one-step topochemical microcrystal conversion reaction method. In the process of synthesis, platelet Bi4Ti3O12 were used as precursor and powdered carbonates BaCO3–CaCO3 mixture were employed as reactants in KCl flux at 950°C. The designed one-step TMC synthesis routine has potential to synthesize other A-site complex perovskite microcrystals with platelike shape and micron sizes. The synthetic platelike Ba1−xCaxTiO3 microcrystals with an edge length of about 6–10μm and a thickness is less than 0.5μm. These microcrystals serving as a suitable template seed can be employed to produce highly textured ceramics using the reactive templated grain growth (RTGG) method and single crystals via seeded polycrystal conversion (SPC) technique.

Preparation and characterization of chrome doped sphene pigments prepared via precursor mechanochemical activation

Mechanical activation of precursors has been used for the preparation of Cr-doped sphene ceramic pigments (CaTi1yCrySiO5). Ceramic material has been prepared from a powder mixture of CaCO3, TiO2, SiO2 and Cr(NO3)9H2O using vibro-milling for homogenization and activation of precursors. The mechanochemical process initially yielded amorphous powders, which on further calcination, crystallized to yield Cr-doped sphene ceramic pigment. Phase evolution in CaTi1yCrySiO5 composition with thermal treatment was investigated by X-ray powder diffraction (XRPD). Texture properties and particle size distribution were analyzed by scanning electron microscopy (SEM) and laser diffraction, respectively. UV/Vis reflectance spectra are used to determinate the behavior of the chromium ion. The color efficiency of pigments was evaluated by colorimetric analysis (CIE L a b system). Photoluminescence measurements were also performed.