{"id":{"repo_id":"mississippi","oai_identifier":"oai:egrove.olemiss.edu:etd-1775"},"canonical_url":"https://search.dev.ndltd.org/etd/mississippi/oai:egrove.olemiss.edu:etd-1775","repository":{"repo_id":"mississippi","name":"University of Mississippi","base_url":"https://egrove.olemiss.edu/do/oai/"},"display":{"title":"Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study","abstract":"Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic attenuation of PMN-PT is observed at temperatures below 400 K. A strong stiffening is observed in the temperature range of 400 K - 673 K, folloby a gradual softening at higher temperatures. With varying pressure, an increased pressure sensitivity of the elastic properties of PMN-PT is observed at the temperatures in the stiffening phase. Elastic behavior at elevated temperatures and pressures were studied for correlations with the ferroelectric domains at temperatures below the Curie temperature (TC), the locally polarized nano-regions, and an existence of pseudo-cubic crystalline at higher temperatures between (TC and TB). Thermoelectric lanthanum tellurides and skutterudites are being investigated by NASA's Jet Propulsion Laboratory for advanced thermoelectric generates (TEGs). Effects of nickel (Ni) doping on elastic properties of lanthanum tellurides at elevated temperatures were investigated in the temperature range of 293 K - 800 K. A linear stiffening was observed with increasing the Ni content in the material. Elastic properties of p-type and n-type bismuth-based skutterudites were investigated in the temperature range of 293 K - 723 K. Elastic properties of rare-earth doped strontium titanate were also investigated in the temperature range of 293 K - 750 K.","abstract_html":"Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic attenuation of PMN-PT is observed at temperatures below 400 K. A strong stiffening is observed in the temperature range of 400 K - 673 K, folloby a gradual softening at higher temperatures. With varying pressure, an increased pressure sensitivity of the elastic properties of PMN-PT is observed at the temperatures in the stiffening phase. Elastic behavior at elevated temperatures and pressures were studied for correlations with the ferroelectric domains at temperatures below the Curie temperature (TC), the locally polarized nano-regions, and an existence of pseudo-cubic crystalline at higher temperatures between (TC and TB). Thermoelectric lanthanum tellurides and skutterudites are being investigated by NASA's Jet Propulsion Laboratory for advanced thermoelectric generates (TEGs). Effects of nickel (Ni) doping on elastic properties of lanthanum tellurides at elevated temperatures were investigated in the temperature range of 293 K - 800 K. A linear stiffening was observed with increasing the Ni content in the material. Elastic properties of p-type and n-type bismuth-based skutterudites were investigated in the temperature range of 293 K - 723 K. Elastic properties of rare-earth doped strontium titanate were also investigated in the temperature range of 293 K - 750 K.","abstract_has_math":false,"creators":["Tennakoon, Sumudu"],"institution":null,"degree_name":"Ph.D. in Physics","degree_level":"Dissertation","degree_discipline":"Physics and Astronomy","degree_department":null,"school":null,"contributors":["Joseph R. Gladden","P. Raju Mantena","Kevin Beach"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2016,"date_issued":"2016-01-01T08:00:00Z","date_published":"2016-01-01T08:00:00Z","updated_at":"2026-07-24T03:05:59Z","subjects":["Elastic Properties","High Temperature And Pressure","Phase Transition","Relaxor Ferroelectrics","Resonant Ultrasound Spectroscopy","Thermoelectric","Physics"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://egrove.olemiss.edu/etd/776","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Joseph R. Gladden","P. Raju Mantena","Kevin Beach"]},{"key":"dc:creator","label":"Author","values":["Tennakoon, Sumudu"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2019-06-27T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics and Astronomy"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D. in Physics"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Elastic Properties","High Temperature And Pressure","Phase Transition","Relaxor Ferroelectrics","Resonant Ultrasound Spectroscopy","Thermoelectric","Physics"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://egrove.olemiss.edu/etd/776"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic attenuation of PMN-PT is observed at temperatures below 400 K. A strong stiffening is observed in the temperature range of 400 K - 673 K, folloby a gradual softening at higher temperatures. With varying pressure, an increased pressure sensitivity of the elastic properties of PMN-PT is observed at the temperatures in the stiffening phase. Elastic behavior at elevated temperatures and pressures were studied for correlations with the ferroelectric domains at temperatures below the Curie temperature (TC), the locally polarized nano-regions, and an existence of pseudo-cubic crystalline at higher temperatures between (TC and TB). Thermoelectric lanthanum tellurides and skutterudites are being investigated by NASA's Jet Propulsion Laboratory for advanced thermoelectric generates (TEGs). Effects of nickel (Ni) doping on elastic properties of lanthanum tellurides at elevated temperatures were investigated in the temperature range of 293 K - 800 K. A linear stiffening was observed with increasing the Ni content in the material. Elastic properties of p-type and n-type bismuth-based skutterudites were investigated in the temperature range of 293 K - 723 K. Elastic properties of rare-earth doped strontium titanate were also investigated in the temperature range of 293 K - 750 K."]},{"key":"dc:title","label":"Title","values":["Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study"]}]}],"canonical_facts":{"dc:contributor":["Joseph R. Gladden","P. Raju Mantena","Kevin Beach"],"dc:creator":["Tennakoon, Sumudu"],"dc:date.available":["2019-06-27T07:00:00Z"],"dc:description.abstract":["Relaxor ferroelectric lead magnesium niobate-lead titanate (PMN-PT) material exhibits exceptional electromechanical properties. The material undergoes a series of structural phase transitions with changes in temperature and the chemical composition. The work covered in this dissertation seek to gain insight into the phase diagram of PMN-PT using temperature and pressure dependence of the elastic properties. Single crystal PMN-PT with a composition near morphotropic phase boundary (MPB) was investigated using a resonant ultrasound spectroscopy (RUS) methodologies in the temperature range of 293 K - 800 K and the pressure range from near vacuum to 3.4 MPa. At atmospheric pressure, significantly high acoustic attenuation of PMN-PT is observed at temperatures below 400 K. A strong stiffening is observed in the temperature range of 400 K - 673 K, folloby a gradual softening at higher temperatures. With varying pressure, an increased pressure sensitivity of the elastic properties of PMN-PT is observed at the temperatures in the stiffening phase. Elastic behavior at elevated temperatures and pressures were studied for correlations with the ferroelectric domains at temperatures below the Curie temperature (TC), the locally polarized nano-regions, and an existence of pseudo-cubic crystalline at higher temperatures between (TC and TB). Thermoelectric lanthanum tellurides and skutterudites are being investigated by NASA's Jet Propulsion Laboratory for advanced thermoelectric generates (TEGs). Effects of nickel (Ni) doping on elastic properties of lanthanum tellurides at elevated temperatures were investigated in the temperature range of 293 K - 800 K. A linear stiffening was observed with increasing the Ni content in the material. Elastic properties of p-type and n-type bismuth-based skutterudites were investigated in the temperature range of 293 K - 723 K. Elastic properties of rare-earth doped strontium titanate were also investigated in the temperature range of 293 K - 750 K."],"dc:identifier":["https://egrove.olemiss.edu/etd/776"],"dc:subject":["Elastic Properties","High Temperature And Pressure","Phase Transition","Relaxor Ferroelectrics","Resonant Ultrasound Spectroscopy","Thermoelectric","Physics"],"dc:title":["Temperature And Pressure Effects On Elastic Properties Of Relaxor Ferroelectrics And Thermoelectrics: A Resonant Ultrasound Spectroscopy Study"],"thesis:degree_discipline":["Physics and Astronomy"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D. in Physics"]},"updated_at":"2026-07-24T03:05:59Z"}