Methods of investigation transformation kinetics of yttrium carbonate hydroxide in citric acid solution into yttrium citrate dihydrate (original) (raw)
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Preparation of yttrium citrate by the reaction of yttrium hydroxide with sodium citrate
2020
A method of obtaining yttrium citrate by transformation of freshly precipitated yttrium hydroxide in the solutions of sodium citrate under hydrothermal conditions has been proposed. To determine the synthesis time, transformation kinetics consisted in by taking the solid samples for the C and H contents analysis after 6, 12, 24, 48 and 72 hours of synthesis. Simultaneously these samples were subjected to the thermogravimetric analysis. As follows from the thermogravimetric analysis adsorption of citrate dihydrate on yttrium hydroxide is observed in the initial period up to 24 hours. Later the yttrium citrate dihydrate is formed. The thermogravimetric analysis of the final product i.e. amorphous yttrium citrate showed that the decomposition/oxidation of the sample occurs in six stages the particle size analysis method of static light scattering showed that 45% of the particles had a diameter of 0.1-0.9μm and 55% of particles with sizes from 0.9 to 5 μm.
Synthesis and thermogravimetric analysis of monoclinic yttrium citrate dihydrate
Journal of Thermal Analysis and Calorimetry
The yttrium citrate was synthesized using freshly precipitated yttrium hydroxide and citric acid (or monosodium citrate) in the aqueous environment by the hydrothermal treatment at 80 °C or 100 °C. The properties of the samples were investigated using the CHN, XRD, TGA and static light scattering. Crystalline yttrium citrate dihydrate is formed by the reaction of citric acid with freshly precipitated yttrium hydroxide after 14 days of reaction at 80 or 100 °C. The thermogravimetric analysis of the crystalline sample of yttrium citrate dihydrate, thermal decomposition of the compound in the synthetic air occurs in four stages with the release of mainly water and carbon dioxide. Methane and propyne are formed in smaller amounts.
Russian Journal of Inorganic Chemistry, 2007
The effect of hydrothermal and ultrasonic/hydrothermal treatment on the phase composition and micromorphology of yttrium hydroxocarbonates has been studied. The hydrothermal treatment of a suspension of amorphous yttrium hydroxocarbonate hydrate, Y(OH)CO3 · 1.25H2O, does not significantly alter the composition of the powder, while ultrasonication directly in the course of hydrothermal treatment under the same conditions yields crystalline yttrium hydroxocarbonate Y(OH)CO3. The thermolysis of yttrium hydroxocarbonates Y(OH)CO3 · xH2O and Y(OH)CO3 has been studied.
Carbochlorination of yttrium oxide
Thermochimica Acta, 2010
The reaction of chlorination of a mixture composed by Y 2 O 3 and sucrose carbon was studied by thermogravimetry over a temperature range of 550-950 • C. The reaction proceeds through several successive stages. The first of them is the formation of solid yttrium oxychloride (YOCl) and subsequently the YOCl is carbochlorinated to produce YCl 3 (solid or liquid, depending on the temperature) in two stages. The stoichiometries of the first stage and the global reaction were estimated by mass balances, taking into account the chlorine adsorbed by the remainder carbon. The results showed that the reactions involved progress with the formation of CO 2 and CO in the temperature range of 600-775 • C. The interaction between sucrose carbon and chlorine was analyzed by thermogravimetry in order to quantify the amount of chlorine which is adsorbed on its surface. It was studied the effect of the temperature and initial mass of carbon. The morphological analysis performed by SEM of partially reacted samples showed that the formation of YOCl proceeds through a mechanism of nucleation and growth. For temperatures above 715 • C the final product of the carbochlorination is liquid YCl 3 , whose evaporation is observed in the thermogravimetry. The evaporation kinetics was analyzed in argon atmosphere and from the thermogravimetric curves was determined a value of 250 kJ/mol for the heat of evaporation of YCl 3. This value is consistent with a partial dimerization of the gaseous chloride.
Ceramics
A study of the morphology and evolution of the microstructure during thermal decomposition of Y2(C2O4)3·10H2O was conducted, and the stages and factors having the greatest impact on particle size and specific surface area were identified. The effect of the yttrium oxalate hexahydrate phases on the course of decomposition was also investigated. The evolution of the morphology and microstructure of decomposition products was explained from the analysis of volume shrinkage at various stages of the reaction. The formation of oxycarbonate is accompanied by the largest shrinkage during the reaction. At this stage, there is a significant increase in the specific surface area to 60–90 m2/g. Conversely, the morphology and microstructure of the particles during the transformation of oxycarbonate into yttrium oxide change insignificantly. Yttrium oxide powders obtained from the monoclinic and triclinic hexahydrate phases have the same specific surface area, but different morphology and bulk de...
Synthesis and characterization of Al-and Y-Al-citrates as potential precursors for YAlO3
Central European Journal of Chemistry, 2006
Al-and Y-Al-citric complexes have been synthesized in ethylene glycol medium at conditions close to the ones used in polymerized complex method and their composition and spectral characteristics have been studied. Proofs have been found for the formation in the bimetallic system of a mixed-metal Al-Y-complex. Doubly ionized and esterified ligands take place in the Al-complex. All of the ligands forming Y-Al-complex are mono-or doubly esterified. Deprotonation of the alcoholic group takes place in the formation of the mixed-metal complex. Both complexes contain adduct-bonded ethylene glycol. Heating of the bimetallic complex or of the polyester resin formed leads to not phase-homogeneous YAlO3-along with cubic YAlO3, its orthorhombic modification as well as Y4All2O9 are found by X-ray diffractometry.
On the influence of K 2CO 3 additives in obtaining HTSC materials of the YBCO system
Applied Superconductivity, 1995
The concentration dependence of the transition temperature Tc and microstructure has been studied in the high-Tc compounds Y1−2xBa2−0.2xKxCu3O7−y, Y1Ba2Cu3.5−xKxO7−y, Y1Ba2−xCu3KxO7−y, where x = 0–1.50. Only traces of K (1 × 10−2 wt%) were observed in all samples after the final baking and no proof could be found for alkali metal cations participating in the Perovskite crystal cell. Between x = 0.40–0.75 a homogeneous grain-size ceramic structure was observed. This behaviour permits the obtaining of monophase Y1Ba2Cu3Oy with values of Tc = 93.6 K and ΔT = 1.5 K using simplified technological process and baking in air atmosphere.
Synthesis and properties of Y2O3 powder obtained by different methods
Journal of the European Ceramic Society, 1992
Three different wet chemical methods for the preparation of fine yttrium oxide powders from chloride solutions were compared: (a) precipitation with ammonia, (b) precipitation with urea, and (c) precipitation from an Y-organometallic complex. Powders with widely different morphological characteristics resulted. Ammonia precipitated powder was strongly agglomerated. Urea precipitated powder consisted of spherical particles with narrow size distribution (mean size ~ 0"4 I~m), whereas powder obtained from the Y-organometallic complex had a foamy structure' and consisted of soft agglomerates very sensitive to mechanical treatment. Powders were characterized by SEM and TEM techniques, and it was observed that agglomerates consist of randomly oriented crystallites with nearly spherical shape. On compare trois diffkrentes mkthodes de prkparation de poudres .fines d'oxyde d'yttrium, ~ partir de solutions de chlorures, par voie chimique humide: (a) prbcipitation avec de l'ammoniaque, (b) prbcipitation avec de l'urke et (c) prbcipitation ~ partir d'un complexe organo-mktallique d'yttrium. II en rbsulte des poudres posskdant des caractOristiques morphologiques trks diffbrentes. La voie (a) donne une poudre trOs agglomkrke, la voie (b) une poudre formOe de particules sphkriques prksentant une granulombtrie resserrbe (taille moyenne d'environ 0"41tm), tandis que la voie (c) produit une poudre ?~ la structure 'en mousse', formke d'agglombrats mous, trks sensibles h un traitement mkcanique. Les poudres ont ktb caractkriskes par une ktude MEB et MET, montrant que les agglomkrats consistent en des cristallites, de forme pratiquemment sphkrique, orientbes de fa¢on alkatoire. Drei verschiedene naflchemische Verfahren zur Herstellung feinkOrniger Y203-Pulver aus chloridischen Ausgangsl6sungen wurden miteinander verglichen: (a) Fiillung mit Ammoniak, (b) Fiillung mit Harnstoff und (c) Fiillung aus einer Y-organometallischen Verbindung. Die erhaltenen Pulver wiesen iiuJ3erst unterschiedliche Morphologien auf Das mit Ammoniak gefiillte Pulver zeigte einen hohen Agglomerationsgrad. Die mit Harnstoff gejgillten Pulver bestanden aus kugelf6rmigen Teilchen mit einer engen Korngrb'flenverteilung (mittlerer Durch-messer~ 0"41~m). Das Pulver aus der Y-organometallischen Verbindung hatte eine 'schwammige Struktur' und wies weiche, durch mechanische Behandlung leicht zerst6rbare, Agglomerate auf Die Pulver wurden mittels REM und TEM charakterisiert. Dabei zeigte sich, daft die Agglomerate aus nahezu kugelf6rmigen Kristalliten mit statistischer Orientierung bestehen.