Titanium(IV) oxide phase stability in alkaline sodium phosphate solutions at elevated temperatures

Technical Report · Tue Sep 01 00:00:00 EDT 1992

OSTI ID:7001082

Ziemniak, S E; Opalka, E P

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: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC12-76SN00052
• OSTI ID: 7001082
• Report Number(s): KAPL-4740; ON: DE93006254
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202 -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKALI METAL COMPOUNDS
AQUEOUS SOLUTIONS
CHALCOGENIDES
CHEMICAL REACTIONS
DISPERSIONS
ENERGY
FORMATION FREE ENERGY
FREE ENERGY
HYDROGEN COMPOUNDS
HYDROXIDES
MATERIALS
MINERALS
MIXTURES
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE STABILITY
PHOSPHATES
PHOSPHORUS COMPOUNDS
PHYSICAL PROPERTIES
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RUTILE
SODIUM COMPOUNDS
SODIUM PHOSPHATES
SOLUTIONS
STABILITY
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
THERMODYNAMIC PROPERTIES
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS