Thermal expansion and thermal conductivity of (Ca1-x,Mgx)Zr₄(PO₄)₆ where x = 0.0-0.4

dc.contributor.authorVan Aken, Stephen Marken
dc.contributor.departmentMaterials Engineeringen
dc.date.accessioned2014-03-14T21:34:14Zen
dc.date.adate2009-04-18en
dc.date.available2014-03-14T21:34:14Zen
dc.date.issued1990en
dc.date.rdate2009-04-18en
dc.date.sdate2009-04-18en
dc.description.abstractSolid-state reaction and sol-gel processing methods were used to prepare samples of (Ca<sub>1 - X,</sub>Mg<sub>X</sub>)Zr₄(PO₄)₆(CZP-CMZP) where x = 0.0-0.4. CMZP is a member of the NaZr₂(PO₄)₃ (NZP) class of ceramics and is being investigated for heat engine applications. Linear thermal expansion was determined with a dual push rod dilatometer and axial thermal expansion by high temperature X-ray diffraction and least squares refinement. Thermal diffusivity was determined with the laser flash method and specific heat by differential scanning calorimetry. Thermal conductivity was found by the product of the thermal diffusivity, specific heat, and bulk density of each sample. Results indicate that CMZP samples exhibit very low α̅<sub>L</sub> values which become more positive as Mg²⁺ content is increased. Thermal expansion anisotropy (from room temperature to 1000°C) is significantly reduced by the addition of Mg²⁺. Samples where x = 0.4 exhibit the lowest anisotropy with α<sub>a</sub> being essentially zero (hexagonal system). The thermal conductivity of CMZP samples is very low (0.56 W/m K at 200°C). Thermal conductivity values were observed to decrease with increasing Mg²⁺ content. The materials structure and cation site selection are discussed in relation to the observed properties.en
dc.description.degreeMaster of Scienceen
dc.format.extentxi, 91 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-04182009-041436en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-04182009-041436/en
dc.identifier.urihttp://hdl.handle.net/10919/42159en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1990.V362.pdfen
dc.relation.isformatofOCLC# 23612938en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1990.V362en
dc.subject.lcshCeramic materialsen
dc.subject.lcshThermal stressesen
dc.titleThermal expansion and thermal conductivity of (Ca<sub>1-x</sub>,Mg<sub>x</sub>)Zr₄(PO₄)₆ where x = 0.0-0.4en
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineMaterials Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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