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The various Ni(1) species formed by thermal reduction and by hydrogen reduction in Ni(I1)-exchanged silicoaluminophosphate-5 (NiH-SAPOJ) were studied by electron spin resonance and electron spin echo modulation spectroscopies. Four distinct Ni(1) species are observed in NiH-SAPO-5 heated to 873 K under vacuum: Ni(I)(OZ),(H2O)2 at room temperature where 0, is a zeolitic framework oxygen, Ni(I)(Oz), between room temperature and 473 K, Ni(I)(0,)3 near the center of a 6-ring window (site SII) at temperatures between 473 K and 573 K, and Ni(I)(O,)6 inside a hexagonal prism (site SI) at temperatures above 773 K. Nickel metal clusters Ni(O), are also observed by thermal reduction above 673 K. Two distinct Ni(1) species are observed in NiH-SAPO-5 after hydrogen reduction at 573 K: Ni(I)(O,)6 at site SI and Ni(I)(Hz),. A Ni-(I)(02)n species is produced in NiH-SAPO-5 after hydrogen reduction, evacuation, and adsorption of water, indicating water decomposition. On adsorption of methanol, Ni(1) in site SI migrates near a 6-ring window and directly coordinates to two methanol molecules and indirectly to one methanol molecule at a greater distance. Ni(1) coordinates to one ethylene by a n-bonding interaction.

The various Ni(1) species formed by reduction and adsorbate interactions in silicoaluminophosphate-1 1, synthesized by incorporation of Ni(I1) in the synthesis mixture (NiAPSO-11) and formed by partial ion exchange of H(1) by Ni(I1) (NiHSAPO-1 l), were studied by electron spin resonance. After dehydration at temperatures above 773 K one Ni(1) species is observed in NiAPSO-11, while this treatment does not generate any Ni(1) species in NiHSAPO-11. Two distinct Ni(1) species, assigned as isolated Ni (1) and Ni(I)-(H2),,, are observed in both NiAPSO-11 and NiH-SAPO-11 after reduction in hydrogen at 573 K. Ni(I)-(Oz),, species are produced both in hydrogen-reduced NiAPSO-11 and in NiH-SAPO-11 after adsorption of water, indicating water decomposition on the Ni-containing oxide surface. Ni(1) complexes with methanol show some differences in the g parameters between NiAPSO-1 1 and NiH-SAPO-1 1. A more significant difference between NiAPSO-1 1 and NiH-SAPO-1 1 in nickel ion coordination to adsorbates is seen with nonpolar adsorbates. The adsorption of carbon monoxide onto NiAPSO-11 and NiHSAPO-11 produces Ni(1)-(CO),, with n = 1-3. The Ni(I)-(CO)I species is not observed in NiH-SAPO-11. The rate of ethylene adsorption onto NiAPSO-11 is 1000-fold more rapid than onto NiHSAPO-11. The contrasting ESR characteristics of Ni(1) in suggest that Ni(1) in NiAPSO-11 is in a framework site.

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Fine‐particle Y2O2S:normalEu red phosphor (∼1 μm) with spherical shapes was synthesized from a submicron‐size yttrium (europium) oxide, obtained by controlled hydrolysis of yttrium alkoxide‐europium chloride, employing sodium thiosulfate as a sulfurizing agent. Various preparative parameters, such as activator concentration, firing temperature, and duration, were optimized for the maximum luminance at low‐voltage excitation (<1000 V), and the best phosphor was compared with a commercial phosphor. The best phosphor with an improved luminance can be obtained for the phosphor prepared at 1000°C for 6 h and doped with 4 mol % europium. The fine‐grained phosphor showed increased luminance at low current densities false(<120 μA/cm2false) and decreased luminance at high current densities. The improvement in luminance is attributed to the small particle size of the phosphors and uniform distribution of the activator. Synthesized phosphors were analyzed using X‐ray diffraction and scanning electron microscopy to interpret the observed luminescent properties. © 2000 The Electrochemical Society. All rights reserved.