We demonstrate a new pathway for the synthesis of carbon nanohorns (CNHs) in a reactor by using inductively coupled plasma (ICP) and gaseous precursors. Thermal plasma synthesis allows the formation of different carbon allotropes such as carbon nanoflakes, hybrid forms of flakes and nanotubules, CNHs embryos, seed-like CNHs and onion-like polyhedral graphitic nanocapsules. In this study, pressure has the greatest impact on the selectivity of carbon nanostructures: pressure below 53.3 kPa favors the growth of carbon nanoflakes and higher pressures, 66.7 kPa and above, promotes the formation of CNHs. The ratio between methane and hydrogen as well as the global concentration of CH4?+?H2 inside the plasma flame are also crucial to the reaction. CNHs are formed preferentially by injection of a 1:2 ratio of H2 to CH4 at 82.7 kPa with a production rate of 20 g/h. The synthesis pathway is easily scalable and could be made continuous, which offers an interesting alternative compared to methods based on laser-, arc- or induction-based vaporization of graphite rods.
CF parameters have been calculated from the splitting of some of the manifolds of Tm3+ in Yttrium Aluminum Garnet (YAlG). Values of these parameters are: A20
=270 cm–1, A22
=± 95 cm–1, A40
=–170 cm–1, A42
=± 410 cm–1, A44
=–1020 cm–1, A60
=30 cm–1, A62
=± 115 cm–1, and A64
=–475 cm–1. There are indications that these parameters do not describe the splitting patterns of excited states with higher energy.
Zusammenfassung Aus der Aufspaltung entarteter Zustände von Tm3+ in YAlG sind Kristallfeldparameter berechnet worden. Die Werte dieser Parameter sind: A20
=270 cm–1, A22
=± 95 cm–1, A40
=–170 cm–1, A42
=± 410 cm–1, A44
=–1020 cm–1, A60
=30 cm–1, A62
=± 115 cm–1, und A64
=–475 cm–1. Es gibt Anzeichen dafür, daß diese Parameter nicht das Aufspaltungsmuster angeregter Zustände höherer Energie beschreiben.
Résumé On a calculé les paramètres du champ cristallin à partir de la séparation obtenue par levée de dégénerescence pour les niveaux de Tm3+ dans le grenat d'yttrium aluminium (YAlG). Les valeurs de ces paramètres sont: A20
=270 cm–1, A22
=±95 cm–1, A40
=–170 cm–1, A42
= ± 410 cm–1, A44
=–1020 cm–1, A60
=30 cm–1, A62
=± 115 cm–1 et A64
=–475 cm–1. Il existe des indications selon lesquelles ces paramètres ne décrivent pas l'aspect des séparations des états excités d'énergies plus élevées.
Three compounds exist in the system Al2O3-Y2O3:yttrium aluminum garnet (YAG, Y3Al5O12), yttrium aluminum perovskite (YAP, YAlO3), and yttrium aluminum monoclinic (YAM, Y4Al2O9)[1]. Among these compounds, YAG has received the most attention due to its good optical properties. Single crystal YAG is best known as a solid-state laser host material. 相似文献
Carbon material was produced using an inductively coupled thermal plasma torch system of 35 kW and a conical shape reactor.
The carbon nanopowders were obtained by plasma decomposition of methane at various flow rates and show a uniform microstructure
throughout the reactor. The product has a crystalline graphitic structure, with a stacking of between 6 and 16 planes and
a nano-flake morphology with particles dimensions of approximately 100 nm long, 50 nm wide and 5 nm thick. Nitrogen was also
introduced in some synthesis experiments along with the methane precursor using flow rates of 0.1 and 0.2 slpm. The resulting
product has the same structural properties and the nitrogen is incorporated into the graphitic structure through pyridinic
type bonds. 相似文献
The paper presents a multi-element analysis of europium, yttrium and lanthanum compounds by atomic emission spectrometry with inductively coupled plasma (ICP-AES). The plasma power was optimized, the choice of analytical lines of the impurities to be determined and the concentration of matrix element were substantiated. The method allows to determine up to 40 trace elements with the limits of detection (LODs) ranging from 10–6 to 10–3 wt %. 相似文献
Experimental and theoretical works on the efficiency of M2+ ion formation, which reduces the analytical signals of M+ ions and cause spectral interferences in inductively coupled plasma mass spectrometry, are discussed. Disagreements in the published data are analyzed. Problems for future investigations are formulated. 相似文献