Lux-Flood theory

Since Arrhenius, definitions have extended the scope of what we mean by acids and bases. These theories include the proton transfer definition of Bronsted-Lowry (Bronsted, 1923 Lowry, 1923a,b), the solvent system concept (Day Selbin, 1969), the Lux-Flood theory for oxide melts, the electron pair donor and acceptor definition of Lewis (1923, 1938) and the broad theory of Usanovich (1939). These theories are described in more detail below. 

The Lux-Flood theory relates to oxide melts. Geologists have often used acid-base concepts for the empirical classification of igneous silicate rocks (Read, 1948). Silica is implicitly assumed to be responsible for acidity, and the silica content of a rock is used as a measure of its acid-base balance ... 

From this discussion it can be seen that there is no ideal acid-base theory for AB cements and a pragmatic approach has to be adopted. Since the matrix is a salt, an AB cement can be defined quite simply as the product of the reaction of a powder and liquid component to yield a salt-like gel. The Bronsted-Lowry theory suffices to define all the bases and the protonic acids, and the Lewis theory to define the aprotic acids. The subject of acid-base balance in aluminosilicate glasses is covered by the Lux-Flood theory. 

Lux—Flood Definition In contrast to the BrpnstedLowry theory, which emphasizes the proton as the principal species in acid-base reactions, the definition proposed by Lux and extended by Flood describes add-base behavior in terms of the oxide ion. This add-base concept was advanced to treat non protonic systems which were not amenable to the Bipnsted-Lowry definition. For example, in high-temperature inorganic melts, reactions such as the following take place ... 

According to the Lux-Flood / V I acid-base theory, an acid is an oxide ion acceptor, and a base is an oxide ion donor. This theory is useful in the steel and ceramic industries, where oxides are commonly employed. 

There were some attempts to estimate acid-base properties for oxide compounds, both solids and melts. The most popular of them is Lux-Flood s acid-base theory.2,3 This concept seems to be more effective for estimating the acid-base characteristics of anhydrous borates and of some promising solvents for the flux growth of borate crystals. According to Lewis-Lux s equation,... 

Lux—Flood Definition In contrast to the Brpnsted-Lowiy theory, which emphasizes the proton as the... 

Acid-base concepts share some features with seemingly different types of interactions complexing, precipitation, and even redox. Comparison of these through theories of Bronsted, Lewis, Usanovich, and Lux-Flood extends our use of the electronic interpretations of... 

Lux (1939) developed an acid-base theory for oxide melts where the oxide ion plays an analogous but opposite role to that of the hydrogen ion in the Bronsted theory. A base is an oxide donor and an acid is an oxide acceptor (Lux, 1939 Flood Forland, 1947a,b Flood, Forland Roald, 1947) ... 

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