Nanocrystalline Si particles of 10 nm size, doped with traces (1 at. %) of Sn, are prepared by mechanical attrition in an inert ambient. After stain-etching, the particles photoluminesce at room temperature. 119Sn Mössbauer spectroscopy, Raman scattering, photoluminesce, and Fourier transform infrared spectroscopy measurements performed as a function of stain-etching time reveal systematic changes, and suggest that the molecular structure of porous Si consists of nanocrystalline Si particles with surfaces passivated by H and/or O atoms.

3.4889-4899[lo] Mass spectrometric analysis of N 2 0 produced from 99.9% "N and 96.2% " 0 nitric oxide indicated -85% "N,'*O, -10% 'sN2'60, and -5 % l4 "N,"O. Attempts to obtain a parent ion of [TpMe2Cu(N0,)] using mass spectrometry (El. CI, and FAB) were unsuccessful. However, the product WAS determined to contain predominantly sN'80, on the basis of two new intense bands in the IR spectrum at 1143 and 831 cm-' that %ere not present in the spectra of independently synthesized [TpM'2C~('5N'h02)] and [ I l l Lead references-F. [13] Crystal data for 5 (C,jH22N,0,BCu): green prism, size 0.600 x 0.500 x 0.450 mm, M , = 406.74, space group Pnma (No. 62). a = 18.192(6) A, h = 13.504(6) A. t' =7.970(3) A, V = 1Y58(3) A', 2 = 4, ( i c n l r d = 1.380 g c m -' . For a total of 2050 unique, observed reflections with I > 2.00 u(I) and 134 variable parameters. the discrepancy indices are R = 0.048 and R, = 0.053. Further details of the crystal structure investigation are available on request from the

Stoichiometric Ca2CuO3, having square-planar Cu-chains [C. L. Teske and H. Müller-Buschbaum, Z. Anorg. Allg. Chem. 379, 234 (1970); M. Hjorth and J. Hyldtoft, Acta Chem. Scand. 44, 516 (1990)], is expectedly antiferromagnetic due to 1D intrachain superexchange [K. Okuda, S. Noguchi, K. Konishi, H. Deguchi, and K. Takeda, J. Magn. Magn. Mater. 104–107, 817 (1992)]. Nonetheless, we report remarkable spontaneous ferromagnetism at 293 K after sintering, prominently in oxygen. This apparently introduced excess oxygen at vacant quasioctahedral sites, promoting spin-flip and ferromagnetic interchain coupling. Thermogravimetry (TGA) revealed excess oxygen, ≈0.17 O/Cu. X-ray diffraction (XRD) yielded a comparatively smaller unit cell. Ferromagnetism disappeared by oxygen depletion, mimicking reported nonmagnetism of Ca2CuO3−δ [Okuda et al. (1992)]. Elemental analysis showed insignificant magnetic impurity traces. Tc ranged between 680 K and 723 K, depending on freshness and purity. Saturation magnetization varied with processing, optimally 0.30 A · m2/kg at 1.0 T applied field. Coercivity and remanence varied with purity.

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Eine tetragonale Phase SrCuO2 bewirkt möglicherweise das supraleitende Verhalten von im Sol‐Gel‐Verfahren hergestellten Proben der nominalen Zusammensetzung Bi2Sr2CuO6. Die Meßergebnisse weisen auf eine Sprungtemperatur bis 70°C hin, wobei die Supraleitung auf eine zu weniger als 0.1% in der Probe vorhandene Phase zurückzuführen ist. Acht Proben zeigten Anzeichen von Raumtemperatursupraleitung, bei vierzehn weiteren lagen die Tc‐Werte zwischen 25 und 110 K.