Titanium(IV) oxide phase stability in alkaline sodium phosphate solutions at elevated temperatures
Titanium(IV) oxide is shown to transform to a sodium titanium hydroxphosphate compound in concentrated sodium phosphate solutions at elevated temperatures via TiO{sub 2}(s) + 4Na{sup +} + 2HPO{sub 4}{sup =} {r_reversible} Na{sub 4}T(OH){sub 2}(PO{sub 4}){sub 2}(S). The thermodynamic equilibrium for this reaction was investigated in the system TiO{sub 2}Na{sub 2}O-P{sub 2}O{sub 5}-H{sub 2}O for Na/P atom ratios between 2 and 3. Based on observed reaction threshold values for sodium phosphate concentration and temperature, the respective standard entropy and free energy of formation for Na{sub 4}Ti(OH){sub 2}(PO{sub 4}){sub 2} were calculated to be 823. 1 J/mol-K and -4025.1 kJ/mol at 298 K.
- Research Organization:
- Knolls Atomic Power Lab., Schenectady, NY (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC12-76SN00052
- OSTI ID:
- 10121701
- Report Number(s):
- KAPL--4740; ON: DE93006254
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360202
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201
AQUEOUS SOLUTIONS
CHEMICAL AND PHYSICOCHEMICAL PROPERTIES
CHEMICAL REACTIONS
FORMATION FREE ENERGY
HYDROXIDES
PHASE STABILITY
RUTILE
SODIUM COMPOUNDS
SODIUM PHOSPHATES
STRUCTURE AND PHASE STUDIES
TEMPERATURE RANGE 0400-1000 K
TITANIUM COMPOUNDS
TITANIUM OXIDES