Jožef Stefan Institute

About: Jožef Stefan Institute is a facility organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Liquid crystal & Dielectric. The organization has 3828 authors who have published 12614 publications receiving 291025 citations.

Reactive oxygen plasma-enabled synthesis of nanostructured CdO: tailoring nanostructures through plasma–surface interactions

Abstract: Plasma-assisted synthesis of nanostructures is one of the most precise and effective approaches used in nanodevice fabrication. Here we report on the innovative approach of synthesizing nanostructured cadmium oxide films on Cd substrates using a reactive oxygen plasma-based process. Under certain conditions, the surface morphology features arrays of crystalline CdO nano/micropyramids. These nanostructures grow via unconventional plasma-assisted oxidation of a cadmium foil exposed to inductively coupled plasmas with a narrow range of process parameters. The growth of the CdO pyramidal nanostructures takes place in the solid-liquid-solid phase, with the rates determined by the interaction of plasma-produced oxygen atoms and ions with the surface. It is shown that the size of the pyramidal structures can be effectively controlled by the fluxes of oxygen atoms and ions impinging on the cadmium surface. The unique role of the reactive plasma environment in the controlled synthesis of CdO nanopyramidal structures is discussed as well.

Microstructural and electrical characteristics of Y2O3-doped ZnO–Bi2O3-based varistor ceramics

Abstract: The microstructural and electrical characteristics of ZnO–Bi 2 O 3 -based varistor ceramics doped with Y 2 O 3 in the range from 0 to 0.9 mol% have been investigated. The addition of Y 2 O 3 resulted in the formation of a fine-grained Bi–Zn–Sb–Y–O phase along the grain boundaries of the ZnO grains which inhibits the grain growth. The mean ZnO grain size decreased from 11.3 to 5.4 μm with increasing amounts of Y 2 O 3 . The threshold voltage ( V T ) of the ceramics increased from 150 to 274 V/mm, the non-linear coefficient α was not influenced and remained at approximately 40, and the leakage current also increased with the amount of Y 2 O 3 added. On the basis of the Mukae et al. (Mukae, K., Tsuda, K. and Nagasawa, I., Capacitance-vs-voltage characteristics of ZnO varistors. J. Appl. Phys ., 1979, 50 , 4475–4476) Schottky barrier model of ZnO varistors, the addition of Y 2 O 3 resulted in a slight increase in the density of interface states ( N S ) and a more pronounced increase in the donor density ( N D ), causing a decrease of the barrier height ( Φ B ) and the depletion layer width (t). The increase of the leakage current ( I L ) with higher amounts of Y 2 O 3 added can be ascribed to the increase in donor density (N D ) as well as to the increased amount of Y 2 O 3 -containing phase at the grain boundaries of ZnO.