نتایج جستجو برای: سیلیکات silicate

تعداد نتایج: 11306  

2015
Kazuki Yamaoka Yoshihiro Takahashi Yoshiki Yamazaki Nobuaki Terakado Takamichi Miyazaki Takumi Fujiwara

Silicate glass has been used for long time because of its advantages from material's viewpoint. In this paper, we report the observation of Pockels effect by Mach-Zehnder interferometer in polycrystalline ceramics made from a ternary silicate glass via crystallization due to heat-treatment, i.e., glass-ceramics. Since the silicate system is employed as the precursor, merits of glass material ar...

2002
KAZUO ABE YASUNORI WATANABE

Inductively Coupled Plasma Atomic Emission Spectrometry (ICP) was adopted for direct analysis of silicate in seawater, eliminating necessity for pre-treatment. Via this method, the determination of silicate is rapid and easy compared with conventional methods of colorimetry. In seawater analysis, a decrease of sensitivity of about 24% was observed due to interference by coexisting elements, mai...

2010
María Teresa Sánchez Joaquín Pérez-Pariente Carlos Márquez-Alvarez

The use of the attenuated total reflectance (ATR) technique to perform time-resolved FTIR spectroscopy analysis of the synthesis of SBA-15 silicate is reported. This spectroscopy is a powerful technique to investigate the assembly of surfactants and silicate species as well as surfactant micellization, as infrared bands are sensitive to local polarity and conformation of the surfactant chains. ...

2002
Po-tsun Liu

Thermal stability of a porous low-k film is a critical issue for application consideration in the back-end-of-line. In this study, thermal stability of the porous silicate has been investigated by changing the thermal processing temperatures. Experimental results have shown that the dielectric constant of the porous silicate still remains below 2.0 after thermal processing at 500 8C for 1 h. A ...

2007
M. P. Li G. Zhao Aigen Li

An accurate knowledge of the mineralogy (chemical composition and crystal structure) of the silicate dust in the interstellar medium (ISM) is crucial for understanding its origin in evolved stars, the physical and chemical processing in the ISM, and its subsequent incorporation into protostellar nebulae, protoplanetary disks and cometary nuclei where it is subjected to further processing. While...

2001
David E. Harker Steven J. Desch

Silicate dust grains in the interstellar medium are known to be mostly amorphous, yet crystalline silicate grains have been observed in many long-period comets and in protoplanetary disks. Annealing of amorphous silicate grains into crystalline grains requires temperatures > ∼ 1000K, but exposure of dust grains in comets to such high temperatures is incompatible with the generally low temperatu...

2015
Jonas Bremer

To get en enhanced understanding of water in the planet forming region of protoplanetary disks, it is important to understand how dust, which is the main source of opacity affects the mid-IR emission of water. Therefore, this thesis presents a comprehensive study of the connection between the mid-IR water emission and the peak strength of the 10 μm silicate feature. Besides the investigation of...

2015
Robert J Friederichs Helen F Chappell David V Shepherd Serena M Best

Experimental chemistry and atomic modelling studies were performed here to investigate a novel ionic co-substitution in hydroxyapatite (HA). Zinc, silicate co-substituted HA (ZnSiHA) remained phase pure after heating to 1100 °C with Zn and Si amounts of 0.6 wt% and 1.2 wt%, respectively. Unique lattice expansions in ZnSiHA, silicate Fourier transform infrared peaks and changes to the hydroxyl I...

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2010
Frederic Moynier Qing-Zhu Yin Keita Irisawa Maud Boyet Benjamin Jacobsen Minik T Rosing

Recent high precision (142)Nd isotope measurements showed that global silicate differentiation may have occurred as early as 30-75 Myr after the Solar System formation [Bennett V, et al. (2007) Science 318:1907-1910]. This time scale is almost contemporaneous with Earth's core formation at approximately 30 Myr [Yin Q, et al. (2002) Nature 418:949-952]. The (182)Hf-(182)W system provides a power...

2016
Yifeng Wang Carlos F. Jove-Colon Kristopher L. Kuhlman

Aqueous dissolution of silicate glasses and minerals plays a critical role in global biogeochemical cycles and climate evolution. The reactivity of these materials is also important to numerous engineering applications including nuclear waste disposal. The dissolution process has long been considered to be controlled by a leached surface layer in which cations in the silicate framework are grad...

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