Preparation, characterization and thermal decomposition of praseodymium, terbium and neodymium carbonates

Sastry, R.L.N.; Yoganarasimhan, S. R.; Mehrotra, P.N.; Rao, C. N. R.

doi:10.1016/0022-1902(66)80442-6

Cited by 82 publications

(10 citation statements)

References 11 publications

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“…The oxide is first dissolved in an excess of the trichloroacetic acid and then heated under CO 2 bubbling until the excess trichloroacetic acid has been decomposed, after which precipitation can occur. Follow up studies on the normal rare earth carbonates by others such as Charles [83], Head [84,85], Sastry [86], Wakita [87], Shinn [88], and Eyring and coworkers [89,90] have utilized rare earth trichloroacetate decomposition to synthesize phase pure normal rare earth carbonates. For the purposes of characterizing the normal carbonates, such as diffraction analysis and thermal decomposition analysis, trichloroacetate decomposition has been the choice synthesis method.…”

Section: Decompositionmentioning

confidence: 99%

“…Other organic compounds such as gelatin, formic acid [79,80], acetic acid [81], and propionic acid [81] have been used to create the rare earth carbonates, but have only been utilized on a very limited scale, if at all. The most popular trichloroacetate and/or urea decompositions have been successfully used to synthesize the entire gamut of rare earth carbonates [59,61,68,71,72,74,75,[82][83][84][85][86][87][88][89][90][94][95][96][97][98]. In laboratory settings where chemical purity is of utmost importance, they have been considered as choice precursor materials as the alkali precipitants will create double carbonate contaminants given sufficient contact time.…”

Section: Decompositionmentioning

confidence: 99%

“…Based upon the general chemical formula of RE 2 (CO 3 ) 3 ·xH 2 O, the RE 2 O 3 :CO 2 ratio should be as close to 1:3 as possible, with the amount of water being released upon decomposition dependent upon the exact rare earth. The RE 2 O 3 :CO 2 ratio is affected by the hydrolysis of the carbonates, of which those of cerium through europium tend to hydrolyze into the hydroxycarbonate, and degrees of hydration are sensitive to drying conditions [86]. Further deviations can be attributed to contamination by precipitation agents, such as sodium/potassium carbonates, where prolonged exposure of the rare earth carbonates to aqueous solutions of alkali carbonates will create the double carbonate [36][37][38][39][40][41][42].…”

Section: Thermochemical Properties Of the Rare Earth Carbonatesmentioning

confidence: 99%

“…In general, the decomposition temperature for all rare earth carbonates and all intermediate phases (anhydrous and oxycarbonate) trends downwards with increasing atomic number. It should be noted that the thermal decomposition of the rare earth oxycarbonates have been previously characterized [86,[135][136][137].…”

Section: Thermal Behavior Of the Rare Earth Carbonatesmentioning

confidence: 99%

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Trends in Structure and Thermodynamic Properties of Normal Rare Earth Carbonates and Rare Earth Hydroxycarbonates

et al. 2018

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A general overview of the trends in structural and thermodynamic properties that have been identified within the hydrated normal rare earth carbonates and the rare earth hydroxycarbonates is presented. Based upon available literature, we demonstrate the trends in crystallographic unit cell parameters, thermal stability, aqueous solubility, and thermochemical properties. These trends can be attributed to both the unique chemistry and strong similarity of the rare earth elements. There are also inconsistent trends that signal research needs to better understand the structure-energy relationships of the rare earth carbonates.

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Section: Decompositionmentioning

confidence: 99%

Section: Decompositionmentioning

confidence: 99%

Section: Thermochemical Properties Of the Rare Earth Carbonatesmentioning

confidence: 99%

Section: Thermal Behavior Of the Rare Earth Carbonatesmentioning

confidence: 99%

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Trends in Structure and Thermodynamic Properties of Normal Rare Earth Carbonates and Rare Earth Hydroxycarbonates

et al. 2018

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“…Solid state reactions in the bulk and on the surface of rare earth sesquioxides induce morphological modifications in addition to compositional changes [47,87,90]. To characterize evolution of particle morphology during thermal decomposition, SEM images were collected for Pr 6 O 11 , Pr 2 O 3 , Pr(OH 3 ), and Pr 2 (CO 3 ) 3 •xH 2 O powders in the as received condition ( Figure 19) and following thermal treatment at 1300° C ( Figure 20).…”

Section: Thermal Decomposition Behavior Of Praseodymium Oxides Hydromentioning

confidence: 99%

Corrosion Protection Mechanisms of Rare-Earth Compounds Based on Cerium and Praseodymium

Fahrenholtz¹,

O’Keefe²,

Morris³

2012

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This report is approved for public release; distribution is unlimited The mechanisms by which rare-earth compounds provide corrosion protection were investigated. A variety of environmentally benign corrosion inhibitors, including rare-earth compounds, are potential replacements for carcinogenic chromate-based inhibitors in conversion coatings and primers. Chromates are robust inhibitors that provide protection to a multitude of metal alloys from a variety of different types of coatings, whereas most alternative inhibitors only protect a limited number of alloys or can only be used in a specific type of coating. Understanding protection mechanisms could allow for extension of protection to other alloys or coating types. For cerium-based conversion coatings, protection was accompanied by the formation of an interfacial reaction layer between the coating and the substrate. Praseodymium-based inhibitors in epoxy-polyamide primers provided protection by dissolving from the primer and forming precipitates in damaged areas. Both inhibitors are capable of providing corrosion protection on high strength aluminum alloys that is comparable to chromates when a suitable phase is incorporated into an appropriate coating. Corrosion protection mechanisms; non-chromate corrosion inhibitors; cerium; praseodymium; cerium-based conversion coatings, epoxy-polyamide primers;

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A Study of the Thermal Hysteresis in AgNO₃

et al. 1987

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A b s t r a c t . The reversible phase transformation of AgNO, is studied. Dielectric constant, d.c. resistivity, differential thermal analysis (DTA) and dilatometric measurements show the occurrence of a reversible phase transition II+I a t 160°C with heat of transformation H = 0.78 kcal/mol. The thermal hysteresis in this reversible transformation is examined, the magnitude of the temperature hysteresis does not exceed 12°C. An acceptable agreement is observed between the measured values of the transition temperature obtained by three different experimental techniques. The dilatometric analysis shows that this transition is accompanied by thermal shrinkage with relative shrinkage coefficient 8 x Thermal analysis are also used to get thermodynamic and kinetic data of this phase transition. The temperature dependence of the dielectric constant and d.c. resistivity for single crystals as well as polycrystalline samples of AgNO, have clearly located and confirm the phase transitions II+I+II with a strong support to its thermal hysteresis character. The conduction mechanism is found to be activated by energy 0.12 eV for phase I and 0.36 eV for phase 11. The observed thermal behaviour of the various measured parameters is attributed to orientations1 disorder of the nitrate group leading to an order-disorder phase transition which is reported here for first time in AgNO,. Studie zur thermalen Hysterese von AgNOSI n h a l t s u b e r s i c ht. Der reversible Phasenubergang in AgNO, wird untersucht. Messungen der Dielektrizitatskonstante und des Gleichstromwiderstands, Differentialthermoanalyse und Dilatometrie zeigen das Auftreten eines reversiblen Phaseniiberganges II+I bei 160°C mit einer Umwandlungswarme von 0,78 kcal/mol. Eine annehmbare ubereinstimmung der gemessenen Umwandlungstemperatur aus drei verschiedenen MeBverfahren wird beobachtet. Die Dilatometrie zeigt, da0 diese Phasenumwandlung von Schrumpfen mit einem relativen Schrumpfungskoeffizienten von 8 x begleitet wird. Die Temperaturabhangigkeit der Dielektrizititskonstante und des Gleichstromwiderstands fur einkristalline und polykristalline F'roben hat die Existenz und die ubergangstemperatur des Phasenubergangs II-+I+II bestitigt. Die Daten zeigen die Hysterese dieses nergangs. Die Aktivierungsenergien des Leitungsmechanismus liegen bei 0.12 eV fur Phase I und bei 0,36eV fur Phase 11. Das beobachtete Temperaturverhalten der verschiedenen gemessenen Parameter wird einer ungeordneten Orientierung der Nitratgruppen zugeordnet, was auf einen Ordnungs-Unordnnngsiibergang hinwcist, der hier zum ersten Ma1 fur AgNO, konstatiert wird.

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Preparation, characterization and thermal decomposition of praseodymium, terbium and neodymium carbonates

Cited by 82 publications

References 11 publications

Trends in Structure and Thermodynamic Properties of Normal Rare Earth Carbonates and Rare Earth Hydroxycarbonates

Trends in Structure and Thermodynamic Properties of Normal Rare Earth Carbonates and Rare Earth Hydroxycarbonates

Corrosion Protection Mechanisms of Rare-Earth Compounds Based on Cerium and Praseodymium

A Study of the Thermal Hysteresis in AgNO₃

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Preparation, characterization and thermal decomposition of praseodymium, terbium and neodymium carbonates

Cited by 82 publications

References 11 publications

Trends in Structure and Thermodynamic Properties of Normal Rare Earth Carbonates and Rare Earth Hydroxycarbonates

Trends in Structure and Thermodynamic Properties of Normal Rare Earth Carbonates and Rare Earth Hydroxycarbonates

Corrosion Protection Mechanisms of Rare-Earth Compounds Based on Cerium and Praseodymium

A Study of the Thermal Hysteresis in AgNO3

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A Study of the Thermal Hysteresis in AgNO₃