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91.
The structure factors of Mg2SiO4 glass have been measured using high energy x-ray diffraction up to pressures of 30.2 GPa, and the equation of state measured up to 12.8 GPa. The average Mg-O coordination numbers were extracted from the experimental pair distribution functions assuming two cases (i) there is no change in Si-O coordination number with pressure and (ii) the average Si-O coordination number increases the same as for pure SiO2 glass. Both analyses give similar results and show a gradual increase in the average Mg-O coordination number from 5.0 at ambient pressure to ~ 6.6(6) at 30.2 GPa. There is good qualitative agreement between the experimental structure and equation of state data for the glass compared to several recent molecular dynamics simulations carried out on liquid Mg2SiO4. 相似文献
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A study of energy transfer was performed in dysprosium-terbium-doped silicate glasses at room temperature. Enhancement of the Tb3+ emission and a decrease in the Dy3+ emission are observed as a result of energy transfer from Dy3+ ions to Tb3+ ions. The energy transfer efficiencies, transfer probabilities, as well as average donor-acceptor distances were also calculated. It is concluded that the energy transfer mechanism between Dy3+ and Tb3+ ion is mainly electric dipole-dipole in nature. 相似文献
98.
Liliane G. Hubert-Pfalzgraf Nadia Touati Sergej V. Pasko J. Vaissermann Adulfas Abrutis 《Polyhedron》2005,24(18):3066-3073
Hafnium β-diketonatochlorides HfCl2(thd)2 (1), HfCl(thd)3 (2) as well as β-diketonato-silylamide and/or siloxide derivatives of 1 namely Hf(thd)2[N(SiMe3)2]2 (3), Hf(thd)2(OSiMe3)2 (4) and Hf(thd)2(OSitBuMe2)2 (5) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) were synthesized and characterized by elemental analysis, FT-IR, 1H NMR and TGA. 2 and 5 were also characterized by single-crystal X-ray diffraction. The siloxide ligands are in cis position for 5 and exert a strong trans effect. The new volatile compounds were tested as single-source precursors for the deposition of HfSixOy films by pulsed liquid injection MOCVD on Si(1 0 0) and R plane sapphire. The as-deposited at 600–800 °C films were essentially amorphous, Hf-rich (Hf/Hf + Si = 0.7–0.85) and smooth. 相似文献
99.
Edith Bertling-Kampf Michael Heimann Rainer Kleibrink Heinrich C. Marsmann 《无机化学与普通化学杂志》1993,619(9):1639-1645
Silicate Anions in Alkali Silicate Melts Melts of alkali silicates with molar ratios of alkali (Li, Na, K, Cs) to silicon between R = 4.0 and ca. 2.0 were prepared, quenched and worked up to the trimethylsilyl silicic acid esters. These were identified by comparison to the GC and silicon-29 NMR data of trimethylsilyl silicic acid esters from other sources. It was found that with cations of Li and Na mostly linear silicates were formed. But with the cations of K and Cs a considerable amount of the cyclic species Si6O96? was present. Branched silicates were of minor importance only. Besides the alkali silicon ratio, the temperature of the melt before quenching influences the composition of the silicate mixture. 相似文献