Abstract
Lanthanides “Ln” (rare earths) are critical elements found in natural minerals such as calcium phosphate apatites, in sedimentary and igneous settings as well as in skeletal diagenesis. From a medical point of view, nanoparticles of lanthanide-doped apatites can be produced for conferring luminescence properties of interest in cancer cells detection. However, the impact of the substitution of Ln for Ca on the stability and solubility of related apatite phases is still essentially unknown. To investigate the thermochemical effects of such lanthanide substitution for calcium in apatite, we prepared and analyzed four series of apatites with up to 10% lanthanide substitution for calcium. After thorough physicochemical characterization via complementary techniques (XRD, FTIR, TG/DSC, and IPCAES), high-temperature oxide melt solution calorimetry in molten sodium molybdate at 973 K was performed to determine their enthalpies of formation from constituent oxides and from the elements, at 298 K. Our results indicate that although enthalpies of formation are strongly exothermic in all cases, Ln-doping has a destabilizing effect, which increases with dopant concentration and with the size of the incorporated Ln3+ ion. After estimating standard entropies, Gibbs free energies of formation and equilibrium constants for Ca2+/Ln3+ exchange reactions in apatite were then evaluated, for the first time allowing access to quantitative thermodynamic data that may be used in various fields for stability calculations or partitioning estimates between fluids and solids.
© 2014 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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Articles in the same Issue
- Highlights and Breakthroughs Merrillite and apatite as recorders of planetary magmatic processes
- Highlights and Breakthroughs Comparing clays from Mars and Earth: Implications for martian habitability
- Data-driven abductive discovery in mineralogy
- Thermal expansion of fluorapatite-hydroxylapatite crystalline solutions
- Synthesis and structure of carbonated barium and lead fluorapatites: Effect of cation size on A-type carbonate substitution
- Optical absorption spectroscopy study of the causes for color variations in natural Fe-bearing gahnite: Insights from iron valency and site distribution data
- Si-magnetite nano-precipitates in silician magnetite from banded iron formation: Z-contrast imaging and ab initio study
- Ordering kinetics in synthetic Mg(Al,Fe3+)2O4 spinels: Quantitative elucidation of the whole Al-Mg-Fe partitioning, rate constants, activation energies
- Experimental study of phlogopite reaction rim formation on olivine in phonolite melts: Kinetics, reaction rates, and residence times
- Etch-pit size, dissolution rate, and time in the experimental dissolution of olivine: Implications for estimating olivine lifetime at the surface of Mars
- Ferrian saponite from the Santa Monica Mountains (California, U.S.A., Earth): Characterization as an analog for clay minerals on Mars with application to Yellowknife Bay in Gale Crater
- A large spectral survey of small lunar craters: Implications for the composition of the lunar mantle
- In-situ characterization of oxalic acid breakdown at elevated P and T: Implications for organic C-O-H fluid sources in petrologic experiments
- Slawsonite-celsian-hyalophane assemblage from a picrite sill (Prague Basin, Czech Republic)
- Determining hematite content from NUV/Vis/NIR spectra: Limits of detection
- The role of water in generation of group II kimberlite magmas: Constraints from multiple saturation experiments
- Quantum mechanical modeling of hydrolysis and H2O-exchange in Mg-, Ca-, and Nisilicate clusters: Implications for dissolution mechanisms of olivine minerals
- Redox-driven exsolution of iron-titanium oxides in magnetite in Miller Range (MIL) 03346 nakhlite: Evidence for post crystallization oxidation in the nakhlite cumulate pile?
- Energetics of lanthanide-doped calcium phosphate apatite
- Thermal conductivity of molten and glassy NaAlSi3O8, CaMgSi2O6, and Mg2SiO4 by non-equilibrium molecular dynamics at elevated temperature and pressure
- Energetics of heterometal substitution in ε-Keggin [MO4Al12(OH)24(OH2)12]6/7/8+ ions
- Ab initio calculations of elastic constants of plagioclase feldspars
- Diagenetic formation of interlayer-deficient fluorophlogopite as a clay mineral in Early Cambrian phosphorite (Lesser Himalaya, India): The trioctahedral analog of illite
- Natural sepiolite: Enthalpies of dehydration, dehydroxylation, and formation derived from thermochemical studies
- A new interpretation of decomposition products of serpentine under shock compression
- model for calculating the viscosity of natural iron-bearing silicate melts over a wide range of temperatures, pressures, oxygen fugacites, and compositions
- The replacement of chalcopyrite by bornite under hydrothermal conditions
- Characterization of porosity in sulfide ore minerals: A USANS/SANS study
- Synthesis of a quenchable high-pressure form of magnetite (h-Fe3O4) with composition Fel(Fe2+0.75Mg0.26)Fe2(Fe3+ 0.70Cr0.15Al0.11Si0.04)2O4
- High-pressure elasticity of sodium majorite garnet, Na2MgSi5O12
- Armstrongite from Khan Bogdo (Mongolia): Crystal structure determination and implications for zeolite-like cation exchange properties
- Steinhardtite, a new body-centered-cubic allotropic form of aluminum from the Khatyrka CV3 carbonaceous chondrite
- New Mineral Names
- Book Review