スプレーICP法により調製したLa_<1-x>Sr_xMnO_3配向薄膜

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Oriented thin films of La_<1-x>Sr_xMnO_3 were prepared by spray-ICP (inductively coupled plasma) technique. An aqueous solution of metal nitrates, as starting material, was partially decomposed to the constituent atoms and ions in the plasma. Different reactivity of these species with oxygen resulted in a deviation of the composition of the film from that of the mother solution. The composition of the mother solution was adjusted to obtain films with a desired composition. (001) oriented films (based on the orthorhombic system) with flat surface were obtained on (100) MgO substrates. The film consisted of particles, coalesced together so close that the grain boudaries were not resolvable. The temperature dependence of the electrical conductivity of the films exhibited semiconductor-semiconductor transitions for the films with x≨0.25, semiconductor-metal transitions for the films with x=0.28 and 0.3, and a metal-metal transition for the film with x=0.5. However, the transition temperatures were different from those reported for the single crystals. The transition phenomena changed drastically by heat treatment in air, suggesting that oxygen stoichiometry (total metal/oxygen ratio) critically influences the electrical properties. The semiconductor-metal transition took place at x=0.27 for the low temperature phase of the (001) oriented film and randomly oriented film. The transition composition is different from the composition (x= 0.17) reported for the single crystal low-temperature phase, but close to that for the single crystal high-temperature phase. The grain boundaries as well as the oxygen stoichiometry appear to influence the electrical properties.
社団法人日本セラミックス協会の論文
1999-07-01

スプレーICP法により調製したLa_<1-x>Sr_xMnO_3配向薄膜

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