TY - JOUR
T1 - Enthalpy of formation of rare-earth silicates Y2SiO5 and Yb2SiO5 and N-containing silicate Y10(SiO4)6N2
AU - Liang, Jian Jie
AU - Navrotsky, Alexandra
AU - Ludwig, Thomas
AU - Seifert, Hans J.
AU - Aldinger, Fritz
N1 - Funding Information:
This work was supported as follows: The U.S. Department of Energy supported the calorimetric work
PY - 1999/4
Y1 - 1999/4
N2 - The enthalpies of formation of two rare-earth silicates (Y2SiO5 and Yb2SiO5) and a N-containing rare-earth silicate Y10(SiO4)6N2 have been determined using high-temperature drop solution calorimetry. Alkali borate (52 wt% LiBO2·48 wt% NaBO2) solvent was used at 800°C, and oxygen gas was bubbled through the melt. The nitrogen-containing silicate was oxidized during dissolution. The standard enthalpies of formation are for Y2SiO5, Yb2SiO5, and Y10(SiO4)6N2, respectively, -2868.54 ± 5.34, -2774.75 ± 8.21, and -14145.20 ± 16.48 kJ/mol from elements, and -52.53 ± 4.83, -49.45 ± 8.35, and -94.53 ± 11.66 kJ/mol from oxides (Y2O3 or Yb2O3, SiO2) and nitride (Si3N4). The silicates and N-containing silicate are energetically stable with respect to binary oxides and Si3N4, but the N-containing silicate may be metastable with respect to assemblages containing Y2SiO5, Si3N4, and SiO2. A linear relationship was found between the enthalpy of formation of a series of M2SiO5 silicates from binary oxides and the ionic potential (z/r) of the metal cation.
AB - The enthalpies of formation of two rare-earth silicates (Y2SiO5 and Yb2SiO5) and a N-containing rare-earth silicate Y10(SiO4)6N2 have been determined using high-temperature drop solution calorimetry. Alkali borate (52 wt% LiBO2·48 wt% NaBO2) solvent was used at 800°C, and oxygen gas was bubbled through the melt. The nitrogen-containing silicate was oxidized during dissolution. The standard enthalpies of formation are for Y2SiO5, Yb2SiO5, and Y10(SiO4)6N2, respectively, -2868.54 ± 5.34, -2774.75 ± 8.21, and -14145.20 ± 16.48 kJ/mol from elements, and -52.53 ± 4.83, -49.45 ± 8.35, and -94.53 ± 11.66 kJ/mol from oxides (Y2O3 or Yb2O3, SiO2) and nitride (Si3N4). The silicates and N-containing silicate are energetically stable with respect to binary oxides and Si3N4, but the N-containing silicate may be metastable with respect to assemblages containing Y2SiO5, Si3N4, and SiO2. A linear relationship was found between the enthalpy of formation of a series of M2SiO5 silicates from binary oxides and the ionic potential (z/r) of the metal cation.
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U2 - 10.1557/JMR.1999.0158
DO - 10.1557/JMR.1999.0158
M3 - Article
AN - SCOPUS:0032636155
SN - 0884-2914
VL - 14
SP - 1181
EP - 1185
JO - Journal of Materials Research
JF - Journal of Materials Research
IS - 4
ER -