The enthalpies of crystallization of gallium garnets Y{sub 3}Ga{sub 5}O{sub 12} and Er{sub 3}Ga{sub 5}O{sub 12} from amorphous coprecipitated hydroxides
- Moscow State Univ. (Russian Federation)
This work continues the investigations on determination of the temperatures and enthalpies of crystallization for oxide compounds and solid solutions. The authors measured the enthalpies of crystallization from amorphous coprecipitated hydroxides for gallium garnets Y{sub 3}Ga{sub 5}O{sub 12} and Er{sub 3}Ga{sub 5}O{sub 12}. These experimental data were used in calculating the enthalpy of crystallization {Delta}{sub cr}H(Ga{sub 2}O{sub 3}, am.). The calculated enthalpies of crystallization of amorphous Ga{sub 2}O{sub 3} strongly differ from the value of -81 kJ/mol reported previously, based on the assumption of isomorphous miscibility. Apparently, this discrepancy arises from the fact that the calculated enthalpies of mixing upon the formation of solid solutions are strongly dependent on the metal-oxygen bond ionicity assumed in calculations. The determined value of -22.8 kJ/mol is more consistent with the enthalpies of crystallization of other amorphous substances, which usually constitute 20-50% of the enthalpies of solidification (melting).
- OSTI ID:
- 98722
- Journal Information:
- Inorganic Materials, Vol. 30, Issue 8; Other Information: PBD: Aug 1994; TN: Translated from Neorganicheskie Materialy; 30: No. 8, 1103-1104(1994)
- Country of Publication:
- United States
- Language:
- English
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