Thermodynamic studies on lithium ferrites

Journal Article · Sun May 15 00:00:00 EDT 2011 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2011.03.033· OSTI ID:21494274

Parida, S C; Naik, Y P; Chaudhary, Ziley Singh ^[1]; Venugopal, V ^[2]

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1. Product Development Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)
2. Radiochemistry and Isotope Group, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

Thermodynamic studies on ternary oxides of Li-Fe-O systems were carried out using differential scanning calorimetry, Knudsen effusion mass spectrometry, and solid-state electrochemical technique based on fluoride electrolyte. Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined in the temperature range 127-861 K using differential scanning calorimetry. Gibbs energies of formation of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using Knudsen effusion mass spectrometry and solid-state galvanic cell technique. The combined least squares fits can be represented as {Delta}{sub f}G{sub m}{sup o}(LiFe{sub 5}O{sub 8},s,T)/kJ mol{sup -1} ({+-}6)=-2341+0.6764(T/K) (588{<=}T/K{<=}971) {Delta}{sub f}G{sub m}{sup o}(LiFeO{sub 2},s,T)/kJ mol{sup -1} ({+-}3)=-708+0.1656(T/K) (569{<=}T/K{<=}1021) The temperature independent term of the above equations represents {Delta}{sub f}H{sup o}{sub m}(T{sub av}) and temperature dependent term represents negative change in entropy of the respective compounds. Thermodynamic analysis shows that LiFe{sub 5}O{sub 8}(s) is more stable compared to LiFeO{sub 2}(s). -- Graphical abstract: Comparison of {Delta}{sub f}G{sub m}{sup o}(T) of lithium ferrites determined using different techniques. Display Omitted Highlights: {yields} Thermodynamic studies on Li-Fe-O system using DSC, KEQMS and galvanic cell. {yields} Heat capacities of LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were determined using DSC 127-861 K. {yields} {Delta}{sub f}G{sup o}{sub m} of these compounds were determined and compared. {yields} Thermodynamic tables for LiFe{sub 5}O{sub 8}(s) and LiFeO{sub 2}(s) were constructed.

• OSTI ID: 21494274
• Journal Information: Journal of Solid State Chemistry, Vol. 184, Issue 5; Other Information: DOI: 10.1016/j.jssc.2011.03.033; PII: S0022-4596(11)00130-7; Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CALORIMETRY
ELECTROCHEMISTRY
ELECTROLYTES
ENTROPY
FERRITES
FLUORIDES
KNUDSEN FLOW
LEAST SQUARE FIT
LITHIUM COMPOUNDS
MASS SPECTROSCOPY
SPECIFIC HEAT
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
ALKALI METAL COMPOUNDS
CHEMISTRY
FERRIMAGNETIC MATERIALS
FLUID FLOW
FLUORINE COMPOUNDS
GAS FLOW
HALIDES
HALOGEN COMPOUNDS
IRON COMPOUNDS
MAGNETIC MATERIALS
MATERIALS
MATHEMATICAL SOLUTIONS
MAXIMUM-LIKELIHOOD FIT
NUMERICAL SOLUTION
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SPECTROSCOPY
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENT COMPOUNDS