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dc.contributor.advisor Margrave, John L.
dc.creatorSampson, Madeline P.
dc.date.accessioned 2009-06-04T00:21:15Z
dc.date.available 2009-06-04T00:21:15Z
dc.date.issued 1993
dc.identifier.urihttps://hdl.handle.net/1911/16662
dc.description.abstract A quadrupole mass spectrometer system was redesigned with pulse counting electronics and a resistively heated, high-temperature furnace. This system was employed in Knudsen effusion experiments to investigate the high temperature thermodynamics of strontium oxide, strontium metazirconate, strontium metahafnate, and three phases in the Ir-Al phase diagram. The strontium oxides were vaporized from thoria Knudsen cells and no container-sample reactions were observed. The enthalpy of formation of SrO$\sb{\rm(g)}$ and the dissociation energy of this molecule were calculated from the measured third law enthalpy of the congruent vaporization reaction. These values were $\rm\Delta\sb{f}H\sb{298}\lbrack SrO\sb{(g)}\rbrack = 1.8 \pm 0.9$ kcal/mol and D$\sb0\sp\circ = 96.2 \pm 0.9$ kcal/mol. The enthalpy of formation of SrZrO$\sb{\rm 3(s)}$ was also determined from a congruent vaporization reaction. The third law enthalpy of formation was calculated to be $\rm\Delta\sb{f}H\sb{298}\lbrack SrZrO\sb{3(s)}\rbrack\ =$ $-$405.7 $\pm$ 4.5 kcal/mol. Strontium metahafnate vaporized noncongruently in the temperature range 2280-2380 K. The third law heat of formation calculated from the measured vaporization enthalpy was $\rm\Delta\sb{f}H\sb{298}\lbrack SrHfO\sb{3(s)}\rbrack =$ $-$426.8 $\pm$ 1.6 kcal/mol. The three phases in the Ir-Al phase diagram which were investigated may be represented as IrAl$\sb3$ + IrAl$\sb{2.7},$ IrAl$\sb{2.7}$ + IrAl, and Ir$\sb{0.5}$Al$\sb{0.5}.$ Aluminum vaporized noncongruently from these phases. The Al vaporization reactions in the two-phase regions may be written 3 IrAl$\sb{\rm 3(s)} \to$ Ir$\sb3$Al$\sb{\rm 8(s)}$ + Al$\sb{\rm(g)}$ and Ir$\sb3$Al$\sb{\rm 8(s)} \to 3$ IrAl$\sb{\rm(s)} + 5$ Al$\sb{\rm(g)},$ respectively. The second law reaction enthalpies for these reactions were determined to be $\rm\Delta\sb{r}H\sb{298} = 60.7$ kcal/mol and $\rm\Delta\sb{r}H\sb{298} = 224.5$ kcal/mol, respectively. From the lines drawn through the ln a$\sb{\rm Al}$ vs 1/T plots, the activities of aluminum at 1500 K were calculated to be 0.36, 0.11, and 0.0061, respectively.
dc.format.extent 116 p.
dc.format.mimetype application/pdf
dc.language.iso eng
dc.subjectPhysical chemistry
Inorganic chemistry
dc.title Thermochemical investigations of selected ternary strontium oxides and iridium-aluminum alloys by high temperature mass spectrometry
dc.type.genre Thesis
dc.type.material Text
thesis.degree.department Chemistry
thesis.degree.discipline Natural Sciences
thesis.degree.grantor Rice University
thesis.degree.level Doctoral
thesis.degree.name Doctor of Philosophy
dc.identifier.citation Sampson, Madeline P.. "Thermochemical investigations of selected ternary strontium oxides and iridium-aluminum alloys by high temperature mass spectrometry." (1993) Diss., Rice University. https://hdl.handle.net/1911/16662.


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