Oxidation Characteristics of the Lanthanide Metals

Abstract

Oxidation rates and rate equations off La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu„ Y were determined in dry and moist air in the temperature range 100–800 C (212–1472 F) by precision weight gain measurements Oxide structures were examined by both metallographie and x-ray analyses. Observed oxidation characteristics are related to oxide structures and the physico-chemical properties of the rare earth metals.

Oxidation resistance of B2 rare earth–magnesium intermetallic compounds

“…Above 40 • C, however, Loriers concluded that the oxidation progresses beyond the formation of Ce 2 O 3 , with the oxidation becoming linear due to the initial oxide reacting further to form CeO 2 . This paralinear oxidation was also observed by Greene and Hodge [6] and Cubicciotti [12]. Love and Kleber [4] observed Ce to have the highest oxidation rate of the rare earth metals tested, followed by Pr and Tb.…”

“…The calculations resulted in average values of c p = 4.18 × 10 3 mg 2 /dm 4 s and Q = 104 kJ/mol. Although a value for the activation energy for the oxidation of pure Y could not be found in the literature, a literature value for the parabolic rate constant of Y oxidation at 700 • C was found to be k p = 30 mg 2 /dm 4 s [6]. The parabolic rate constant for the oxidation of YMg at 700 • C was calculated to be k p = 1.0 × 10 −2 mg 2 /dm 4 s. A large disparity was also observed between the oxidation of CeMg and pure Ce.…”

“…Unlike Y, a direct comparison of activation energies could be made with Ce. Again using the same technique, data from Greene and Hodge [6] were used to calculate the activation energy for the oxidation of pure Ce to be Q = 58.9 kJ/mol, which is less than half that observed for CeMg. Thus we conclude that alloying of Y and Ce with Mg to form the B2 phases greatly increased the oxidation resistance of the rare earth metals.…”

“…The heavy trivalent lanthanides (Gd to Lu), Sc, and Y are the most oxidation-resistant rare earth metals [1,4]. For rare earth metals that form protective oxide layers, most investigators report that diffusion of O atoms through the oxide layer is the rate-limiting factor in their elevated temperature oxidation [5][6][7]. * Corresponding author.…”

High temperature oxidation kinetics of dysprosium particles

“…Although a few manuscripts and reports were published in the late 1950s and 1960s on the oxidation behavior of dysprosium [19][20][21][22], the experiments were performed on monolithic samples (rather than powders or particles) and the results appeared to be contradictory. Of particular interest in this study is the high temperature oxidation kinetics of elemental dysprosium in the temperature range of 450-1000°C in N 2 -(2%, 20%, and 50%) O 2 and Ar-20% O 2 range of implications ranging from semiconductor and electronics applications, to ''green'' energy and electric motor (magnetic) applications, to nuclear power generation applications.…”