Exchange of SO42? ions with F? ions in mineral celestite under hydrothermal conditions

Suárez-Orduña, R.

doi:10.1016/j.ssi.2004.03.022

Cited by 10 publications

(3 citation statements)

References 7 publications

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“…30Therefore, we surmise that the formation of SrTiO3 from the conversion of the BC plate occurred according to the chemical reaction described by reaction 4, but this chemical equilibrium resulted from the simultaneous dissolution of the solid phases that is described by the chemical reactions given in reactions 2 and 3. The present transformation mechanism is different from that proposed for various single-step chemical reactions applied to prepare strontium and barium inorganic compounds using SrSO4 (28,30) and BaSO4(41) in highly concentrated alkaline hydrothermal media.…”

Section: 4bc Polycrystalline Plate Single-step Hydrothermal Converscontrasting

confidence: 78%

“…Therefore, we surmise that the formation of SrTiO 3 from the conversion of the BC plate occurred according to the chemical reaction described by reaction , but this chemical equilibrium resulted from the simultaneous dissolution of the solid phases that is described by the chemical reactions given in reactions and . The present transformation mechanism is different from that proposed for various single-step chemical reactions applied to prepare strontium and barium inorganic compounds using SrSO 4 , and BaSO 4 in highly concentrated alkaline hydrothermal media. The reaction pathway associated with the synthesis of SrTiO 3 via the hydrothermal conversion of BC crystal plates was derived from SEM observations (see Figure ). The SEM observation conducted on the raw BC polycrystalline plate shows a clear boundary between the two composing phases Sr 0.75 Ba 0.25 SO 4 and Sr 0.97 Ba 0.03 SO 4 (see Figure a).…”

Section: Resultsmentioning

confidence: 64%

“…Similarly, the use of different precursors (e.g., Ti-gel, TiO 2 powders, , and strontium (Sr(NO 3 ) 2 salt) influences control of the crystallization process of cubic perovskite titanates. Some of the present authors have previously explored the use of high-purity sulfate mineral ores (i.e., SrSO 4 as precursor mineral) for preparing inorganic compounds (i.e., SrCO 3 and SrF 2 ) via a single-step conversion. The solubility of SrSO 4 mineral plays an important role to complete the conversion under alkaline fluids under hydrothermal conditions, because the solubility of the mineral hinders its dissolution, even in mild alkaline hydrothermal media (<1 M KOH) .…”

Section: Introductionmentioning

confidence: 99%

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Facile Synthesis of Perovskite-Structured Powders Using Barite–Celestite Ore under Hydrothermal Alkaline Conditions

Rendón-Ángeles¹,

Matamoros-Veloza

Veloza

et al. 2017

Ind. Eng. Chem. Res.

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Barite-celestite (BC) crystals were treated in highly concentrated alkaline hydrothermal fluid (5 M KOH) coexisting with a Ti(OH)4•4.5H2O gel to produce SrTiO3 particles between 150 and 250 °C for several intervals between 6 h and 96 h. The BC transformation was initiated at a lower temperature (150 °C) and the total precursors consumption was completed at 250 °C for 96 h, resulting only in the crystallization of SrTiO3 particles. Different temperatures of reaction (≤200 °C) lead to variations in morphology and particle size of the SrTiO 3. The crystal growth of faceted cubic agglomerates was achieved at 250 °C, and it is provoked by the Oswald ripening mechanism. The release of barium to the hydrothermal fluid from the precursor occurred simultaneously with the transformation process. A low value of activation energy required for the single-step transformation of the BC plates into SrTiO3 particles was observed (26.33 kJ mol-1), under static hydrothermal conditions.

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Section: 4bc Polycrystalline Plate Single-step Hydrothermal Converscontrasting

confidence: 78%