Lanthanum oxide, deposition

The production of endohedral fullerene complexes in visible amounts was first accomplished by a pulsed laser vaporization of a lanthanum oxide-graphite composite rod in a flow of argon gas at 1200 °C [66]. In this procedure, the newly formed endohedrals, together with empty fullerenes, sublime readily and are carried away in the flowing gas, depositing on the cool surfaces of the apparatus. This sublimate contains the complexes La CgQ, La C74 and La Cg2 (Figure 1.9). Among these, the endohedral molecule La Cg2 exhibits an extra stability. It can... 

Eecent work by L. M. Dermis2 and his co-workers has shown that electrolysis may be of considerable value in effecting a complete or partial separation of the oxides of the rare earth metals. Prom a neutral solution of the nitrates of neodymium, praseodymium, lanthanum, and samarium, nearly all the lanthanum is deposited as hydroxide in the last fractions discharged on the cathode. The hydroxides are deposited fractionally in order of their basicity, and the deposition is not dependent upon the... 

FIGURE 18. Influence of deposition and annealing temperature on lanthanum oxide film composi-tion . Reproduced from Reference 280 by permission of Elsevier... 

In order to evaluate the interaction between platinum and rhodium deposited on the alumina-lanthanum oxide, the different catalysts were characterized by temperature programmed reduction and measure of the activity for the reaction of propane-propene oxidation. 

Specific surface area of the catalysts before (Sg) and after the reaction (Sg ) and their activity (a), activity per area (a/Sg), selectivity (S) and coke deposited on the catalysts (C) in the dehydrogenation of ethylbenzene. LFAW, LFA, ALF and LF samples prepared by the Methods 1, 2 and 3 and by the mechanical mixture of the iron and lanthanum oxide, respectively. 

Lanthanum oxide thin film was grown on Si substrates by the metall-organic chemical vapor deposition (MOCVD) method (400-650°C) [27]. Thin silicon oxynitride layer on the Si substrate functions well to suppress the interfacial reaction between lanthanum oxide and Si and results in the increase in the dielectric constant of deposited lanthanum oxide. The formed oxynitride layer is also effective in decreasing the leakage current. 

The final step, vaporization of calcium, does not work for metals with high vapor pressure, as the metal itself would vaporize with the calcium. Instead the oxide is reduced with metallic lanthanum, which has a very low vapor pressure. Lanthanum oxide and a melt of the actual RE metal are formed. The reduction reaction occurs in a tantalum container. The reduced RE metals e.g. samarium, are vaporized and deposit on the walls of the tantalum container. This method is used for [boiling point (°C) in parenthesis] Sm (1794), Eu (1529), Tm (1950), Yb (1196). 

Figure 2.1. Illustration of two kinds of sample preparation procedures. One is the mositure desorbed La203 film (Type-A) which was annealed at 400 °C in high vacuum (HV) chamber (10-6Pa) to make lanthanum hydroxide decompose into lanthanum oxide and H2O[10]. The other is the moisture absorbed sample (Type-B) which was exposed to the air (the temperature is 24 °C and the relative humidity is around 55%) with different time (zero,6 and 12 hours). Both samples were followed by 6nm Si02 layer deposition. Type A sample was processed without any exposure to the air to prevent the moisture absorption...

Kale SS, Jadhav KR, Patil PS. Characterizations of spray-deposited lanthanum oxide (La203) thin films. Mater. Lett. 2005 59 3007-3009. DOI 10.1016/j.matlet.2005.02.091. 

M. Ichikawa. Catalysis by supported metal crystallites from carbonyl clusters. II. Catalytic ethanol synthesis from carbon monoxide and hydrogen under atmospheric pressure over supported rhodium crystaUites prepared from Rh carbonyl clusters deposited on titanium dioxide, zirconium oxide, and lanthanum oxide. Bull. Chem. Soc. Jpn. 51, 1978, 2273-2277. 

The result is the formation of a dense and uniform metal oxide layer in which the deposition rate is controlled by the diffusion rate of ionic species and the concentration of electronic charge carriers. This procedure is used to fabricate the thin layer of soHd electrolyte (yttria-stabilized 2irconia) and the interconnection (Mg-doped lanthanum chromite). 

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