Y2O3:Eu phosphor particles prepared by spray pyrolysis from a solution containing citric acid and polyethylene glycol

Y₂O₃:Eu phosphor particles were prepared by large-scale spray pyrolysis. The morphological control of Y₂O₃:Eu particles in spray pyrolysis was attempted by adding polymeric precursors to the spray solution. The effect of composition and amount of polymeric precursors on the morphology, crystallinity and photoluminescence characteristics of Y₂O₃:Eu particles was investigated. Particles prepared from a solution containing polyethylene glycol (PEG) with an average molecular weight of 200 had a hollow structure, while those prepared from solutions containing adequate amounts of citric acid (CA) and PEG had a spherical shape, filled morphology and clean surfaces after post-treatment at high temperature. Y₂O₃:Eu particles prepared from an aqueous solution with no polymeric precursors had a hollow structure and rough surfaces after post-treatment. The phosphor particles prepared from solutions with inadequate amounts of CA and/or PEG also had hollow and/or fragmented structures. The particles prepared from the solution containing 0.3 M  CA and 0.3 M  PEG had the highest photoluminescence emission intensity, which was 56% higher than that of the particles prepared from aqueous solution without polymeric precursors. Received: 22 March 2002 / Accepted: 26 March 2002 / Published online: 5 July 2002 RID="*" ID="*"Corresponding author. Fax: +82-42/861-4245, E-mail: yckang@pado.krict.re.kr     

Resonant Auger Raman effect for adsorbates

Accepted: 6 March 1997     

Screening effects in the decay process of autoionizing and shake-up states

Summary Screening effects due to the presence of an excited electron, acting as spectator during the decay process of autoionizing and shake-up states, are analysed in the specific case of the Auger spectrum of LiF molecule. Decreasing of total decay probability and enhancement of the energy of the emitted electrons results as the major effects that can be ascribed to electronic relaxation processes. Our analysis confirms experimental observations made in photoemission experiments on semiconductors and previous theoretical predictions.     

Physical properties of superhard and ultrahard fullerites created from solid C60 by high-pressure-high-temperature treatment

60 in the pressure range and the temperature range were studied. These properties are the specific gravity, specific heat in the range , sound velocities, elastic moduli, electrical properties, resistance to uniaxial stress and stability against oxidation. These properties are different from those of diamond and other carbon forms. The hardness of ultrahard fullerites exceed the hardness of diamond. The structures of the samples are described on the basis of X-ray data. Received: 27 September 1996/Accepted: 19 December 1996     

Growth characteristics of chloride‐based SiC epitaxial growth

In this study some aspects of the chloride‐based CVD growth process have been investigated by using both the approach to add HCl to the standard precursors and by using the single molecule precursor methyltrichlorosilane (MTS). The efficiency of the process for different precursors, the growth rate stability and the effect that the C/Si and Cl/Si ratios have on the growth are studied. It is found that MTS is the most efficient precursor and that the growth becomes carbon limited at C/Si < 1. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Short‐circuit current improvement of CuGaSe2 solar cells with a ZnS/(Zn,Mg)O buffer combination

CuGaSe₂ (CGS) thin‐film solar cells were prepared with an in‐line co‐evaporation process and the established buffer combination CdS/i‐ZnO was replaced by ZnS/(Zn,Mg)O. We obtained functional CGS solar cells with a strong gain in the short‐circuit current density as compared to the CdS/i‐ZnO buffer reference cells. The enhanced current density is a result of improved transmission in the wavelength region between 330 nm and 550 nm of the ZnS/(Zn,Mg)O buffer combination as compared to CdS/i‐ZnO. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)