caa a22 4500 378877038 CHVBK 20180305123423.0 cr unu---uuuuu 161128e20030201xx s 000 0 eng 10.1524/ract.91.2.93.19992 doi (NATIONALLICENCE)gruyter-10.1524/ract.91.2.93.19992 Stability of U(VI) solid phases in the U(VI)-Ca2+-SiO2-OH system [Elektronische Daten] [B. Ritherdon, C. Phelps, H. Neff, A.G. Sowder, S.B. Clark] Synthetic metaschoepite was altered at 70°C, for 30days in silicate solutions of varying compositions to study alteration reactions and to compare experimental observations with a thermodynamic model of stability of the uranyl minerals metaschoepite ([(UO2)8O2(OH)12](H2O)10), becquerelite (Ca[(UO2)3O2(OH)3]2(H2O)8), α-uranophane (Ca[(UO2)(SiO3OH)]2(H2O)5) and soddyite ((UO2)2(SiO4)· (H2O)2). Powder X-ray diffraction analysis, scanning electron microscopy and solution chemistry were used to monitor the alteration of the initial metaschoepite. In general, the secondary phases predicted by the thermodynamic model formed. However, an unexpected mineral (a calcium uranate) was observed above pH 8. Also, within the timeframe of these experiments, U(VI) silicate phases only formed at Si concentrations much higher than the lower field boundaries for uranophane and soddyite. © 2003 Oldenbourg Wissenschaftsverlag GmbH Laboratory techniques, experiments nationallicence Analytical chemistry nationallicence Inorganic chemistry nationallicence Ritherdon B. aut Phelps C. aut Neff H. aut Sowder A.G. aut Clark S.B. aut Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 91/2/2003(2003-02-01), 93-96 0033-8230 91:2/2003<93 2003 91 ract https://doi.org/10.1524/ract.91.2.93.19992 text/html Onlinezugriff via DOI 1 research article jats NATIONALLICENCE 856 40 https://doi.org/10.1524/ract.91.2.93.19992 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Ritherdon B. aut NATIONALLICENCE 700 1- Phelps C. aut NATIONALLICENCE 700 1- Neff H. aut NATIONALLICENCE 700 1- Sowder A.G. aut NATIONALLICENCE 700 1- Clark S.B. aut NATIONALLICENCE 773 0- Radiochimica Acta/International journal for chemical aspects of nuclear science and technology Oldenbourg Wissenschaftsverlag GmbH 91/2/2003(2003-02-01), 93-96 0033-8230 91:2/2003<93 2003 91 ract CC0 http://creativecommons.org/publicdomain/zero/1.0 nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-gruyter