Examinando por Autor "Groschner, C."

Mostrando 1 - 2 de 2

Restringido
Phase Identification and Temperature-Dependent Magnetization of Ti-Rich Titanomagnetite (0.5 <= x <= 1) in Different Atmospheres
(Institute of Electrical and Electronics Engineers, 2013-07-15) Lan, S.; Groschner, C.; Runco, J. N.; Wise, A.; Díaz Michelena, M.; Laughlin, D.; McHenry, M. E.
Reduced titanomagnetite solid solutions, xFe 2 TiO 4 - (1 - x)Fe 3 O 4 , with 0.5 ≤ × ≤ 1, were synthesized by sintering in 99.996% pure flowing argon. Samples showed a systematic variation in the second phase amount as a function of x. A wustite second phase primarily forms near the surface of titanomagnetite pellets. The amount of wustite decreases with increasing Ti concentration. XRD data confirms that samples with x > 0.8 have less than 1% wustite. M(T) curves were measured by vibrating sample magnetometer (VSM). A magnetization hump is observed in M(T) during heating and explained by ferrimagnetic phases formed by exsolution and precipitation processes. These phases were identified as titanomaghemite and magnetite by fitting M(T) cooling curves with a multi-phase Brillouin function.
Restringido
The Role of Atmosphere on Phase Transformations and Magnetic Properties of Ulvospinel
(Institute of Electrical and Electronics Engineers, 2013-07-12) Groschner, C.; Lan, S.; Wise, A.; Leary, A.; Lucas, M. S.; Park, C.; Laughlin, D. E.; Díaz Michelena, M.; McHenry, M. E.; National Science Foundation (NSF)
We have synthesized the antiferromagnetic mineral ulvospinel, Fe 2 TiO 4, in Ar to assess the role of inert atmosphere on phase formation and magnetic properties. We report the role of atmosphere on a possible phase transition and the magnetic properties of this mineral. Atmosphere dependent transformations of ulvospinel are observed with increasing temperature. Oxidation of ulvospinel to form metastable titanomaghemite is shown to occur at 300° in atmospheric conditions. Only slight titanomaghematitzation was observed in samples transformed under pressure in in situ temperature dependent X-ray experiments. Formation of ilmenite and hematite from ulvospinel was observed under high temperature, high pressure, and low oxygen atmosphere conditions.