{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/18930"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/18930","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Grain size effect on structure and properties for chemically-prepared barium titanate","abstract":"Many reports exist in the literature which indicate that BaTiO$\\sb3,$ when prepared as a powder with small particle size $({<}1\\mu$m) or as a polycrystalline ceramic with small grain size, displays dramatic deviations in crystal structure and electrical properties, compared with forms involving larger crystallite sizes. Specifically, ceramists have been concerned for decades primarily with three characteristics for BaTiO$\\sb3$ which have been reported with decreasing crystallite size to the nano scale: (i) a progression at room temperature from the normally tetragonal structure to one of apparent cubic symmetry, when examined by conventional x-ray diffraction (XRD), (ii) substantially decreasing values of the dielectric constant (K$\\sp\\prime$) for grain sizes below 0.5$\\mu$m, and (iii) the concept that ferroelectricity should become unstable below a limiting critical crystallite size. This thesis reports an experimental investigation which substantially clarifies and leads to a plausible explanation of these phenomena for chemically prepared BaTiO$\\sb3.$","abstract_html":"Many reports exist in the literature which indicate that BaTiO$\\sb3,$ when prepared as a powder with small particle size <span class=\"etd-inline-math\">({&lt;}1&mu;</span>m) or as a polycrystalline ceramic with small grain size, displays dramatic deviations in crystal structure and electrical properties, compared with forms involving larger crystallite sizes. Specifically, ceramists have been concerned for decades primarily with three characteristics for BaTiO$\\sb3$ which have been reported with decreasing crystallite size to the nano scale: (i) a progression at room temperature from the normally tetragonal structure to one of apparent cubic symmetry, when examined by conventional x-ray diffraction (XRD), (ii) substantially decreasing values of the dielectric constant (K$\\sp\\prime$) for grain sizes below 0.5<span class=\"etd-inline-math\">&mu;</span>m, and (iii) the concept that ferroelectricity should become unstable below a limiting critical crystallite size. This thesis reports an experimental investigation which substantially clarifies and leads to a plausible explanation of these phenomena for chemically prepared BaTiO$\\sb3.$","abstract_has_math":true,"creators":["Frey, Matthew Henry"],"institution":"University of Illinois at Urbana-Champaign","degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Materials Science and Engineering","degree_department":null,"school":null,"contributors":["Payne, David A."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T11:51:37Z","date_published":"2011-05-07T11:51:37Z","updated_at":"2026-07-22T22:25:11Z","subjects":["Physics, Electricity and Magnetism","Physics, Condensed Matter","Engineering, Materials Science"],"languages":["eng"],"rights":["Copyright 1996 Frey, Matthew Henry"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["9780591198126","AAI9712272","(UMI)AAI9712272"],"render_values":[{"text":"9780591198126","href":null,"code":true},{"text":"AAI9712272","href":null,"code":true},{"text":"(UMI)AAI9712272","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/18930","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Payne, David A."]},{"key":"dc:creator","label":"Author","values":["Frey, Matthew Henry"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T11:51:37Z","10000-01-01","1996"]},{"key":"dc:type","label":"Dc Type","values":["text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Materials Science and Engineering"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Illinois at Urbana-Champaign"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Physics, Electricity and Magnetism","Physics, Condensed Matter","Engineering, Materials Science"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1996 Frey, Matthew Henry"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["9780591198126","AAI9712272","(UMI)AAI9712272","http://hdl.handle.net/2142/18930"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Many reports exist in the literature which indicate that BaTiO$\\sb3,$ when prepared as a powder with small particle size $({<}1\\mu$m) or as a polycrystalline ceramic with small grain size, displays dramatic deviations in crystal structure and electrical properties, compared with forms involving larger crystallite sizes. Specifically, ceramists have been concerned for decades primarily with three characteristics for BaTiO$\\sb3$ which have been reported with decreasing crystallite size to the nano scale: (i) a progression at room temperature from the normally tetragonal structure to one of apparent cubic symmetry, when examined by conventional x-ray diffraction (XRD), (ii) substantially decreasing values of the dielectric constant (K$\\sp\\prime$) for grain sizes below 0.5$\\mu$m, and (iii) the concept that ferroelectricity should become unstable below a limiting critical crystallite size. This thesis reports an experimental investigation which substantially clarifies and leads to a plausible explanation of these phenomena for chemically prepared BaTiO$\\sb3.$","Research in this thesis determined that the evolution of structure from tetragonal to apparent cubic crystal symmetry for polycrystals does not result from a shift of the normal cubic-tetragonal transformation $\\rm (T\\sb{c} = 130\\sp\\circ C)$ below room temperature. A more complete characterization of the size effect, including XRD, Raman and infrared spectroscopy, differential scanning calorimetry, and hot-stage transmission electron microscopy, revealed that $\\rm T\\sb{c}$ shifts only by ${\\approx}5\\sp\\circ C,$ while the orthorhombic-tetragonal transformation shifts above room temperature, before ferroelectric transformation characteristics (spontaneous strain, enthalpy) become suppressed. Also, it was found that ultrafine-grain materials, which appear cubic when examined by XRD, exhibit light scattering characteristics of lower symmetry acentric phases. With regard to the second issue above, this thesis reports a new explanation for original electrical data measured for BaTiO$\\sb3$ ceramics with grain sizes as small as 40nm, prepared by a special high pressure (8GPa) forming method. A microstructure model is developed which considers the dielectric behavior of bulk ceramics in terms of grain interiors and series limiting boundary regions. Curie-Weiss characteristics, in addition to dielectric properties measured in the temperature range of stability for the tetragonal phase, are fully described by dielectric mixing of the transforming primary phase and grain boundary regions with a value of $\\rm K\\sp{\\prime}=130$ and a thickness of 8 A. These findings underscore the importance of interfaces in determining the properties for materials of ultrafine microstructure. Finally, with regard to a critical size for ferroelectricity for BaTiO$\\sb3,$ it is reported in this thesis that ceramic specimens with grain size of 40nm exhibit Raman scattering characteristics of the acentric orthorhombic phase, thermal depolarization consistent with Curie-Weiss behavior, and polarization-reversal characteristics indicative of ferroelectricity. Thus, the conclusion is made that such a critical size, if it exists, must be less than 40nm.","Made available in DSpace on 2011-05-07T11:51:37Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9712272.pdf: 8405199 bytes, checksum: 7a0d80c3f1c55fbffae6119b313c777d (MD5) Previous issue date: 1996","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:33:30Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:12:23-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"]},{"key":"dc:title","label":"Title","values":["Grain size effect on structure and properties for chemically-prepared barium titanate"]}]}],"canonical_facts":{"dc:contributor":["Payne, David A."],"dc:creator":["Frey, Matthew Henry"],"dc:date":["2011-05-07T11:51:37Z","10000-01-01","1996"],"dc:description":["Many reports exist in the literature which indicate that BaTiO$\\sb3,$ when prepared as a powder with small particle size $({<}1\\mu$m) or as a polycrystalline ceramic with small grain size, displays dramatic deviations in crystal structure and electrical properties, compared with forms involving larger crystallite sizes. Specifically, ceramists have been concerned for decades primarily with three characteristics for BaTiO$\\sb3$ which have been reported with decreasing crystallite size to the nano scale: (i) a progression at room temperature from the normally tetragonal structure to one of apparent cubic symmetry, when examined by conventional x-ray diffraction (XRD), (ii) substantially decreasing values of the dielectric constant (K$\\sp\\prime$) for grain sizes below 0.5$\\mu$m, and (iii) the concept that ferroelectricity should become unstable below a limiting critical crystallite size. This thesis reports an experimental investigation which substantially clarifies and leads to a plausible explanation of these phenomena for chemically prepared BaTiO$\\sb3.$","Research in this thesis determined that the evolution of structure from tetragonal to apparent cubic crystal symmetry for polycrystals does not result from a shift of the normal cubic-tetragonal transformation $\\rm (T\\sb{c} = 130\\sp\\circ C)$ below room temperature. A more complete characterization of the size effect, including XRD, Raman and infrared spectroscopy, differential scanning calorimetry, and hot-stage transmission electron microscopy, revealed that $\\rm T\\sb{c}$ shifts only by ${\\approx}5\\sp\\circ C,$ while the orthorhombic-tetragonal transformation shifts above room temperature, before ferroelectric transformation characteristics (spontaneous strain, enthalpy) become suppressed. Also, it was found that ultrafine-grain materials, which appear cubic when examined by XRD, exhibit light scattering characteristics of lower symmetry acentric phases. With regard to the second issue above, this thesis reports a new explanation for original electrical data measured for BaTiO$\\sb3$ ceramics with grain sizes as small as 40nm, prepared by a special high pressure (8GPa) forming method. A microstructure model is developed which considers the dielectric behavior of bulk ceramics in terms of grain interiors and series limiting boundary regions. Curie-Weiss characteristics, in addition to dielectric properties measured in the temperature range of stability for the tetragonal phase, are fully described by dielectric mixing of the transforming primary phase and grain boundary regions with a value of $\\rm K\\sp{\\prime}=130$ and a thickness of 8 A. These findings underscore the importance of interfaces in determining the properties for materials of ultrafine microstructure. Finally, with regard to a critical size for ferroelectricity for BaTiO$\\sb3,$ it is reported in this thesis that ceramic specimens with grain size of 40nm exhibit Raman scattering characteristics of the acentric orthorhombic phase, thermal depolarization consistent with Curie-Weiss behavior, and polarization-reversal characteristics indicative of ferroelectricity. Thus, the conclusion is made that such a critical size, if it exists, must be less than 40nm.","Made available in DSpace on 2011-05-07T11:51:37Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9712272.pdf: 8405199 bytes, checksum: 7a0d80c3f1c55fbffae6119b313c777d (MD5) Previous issue date: 1996","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:33:30Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:12:23-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission","ETDs are only available to UIUC Users without author permission","U of I Only"],"dc:identifier":["9780591198126","AAI9712272","(UMI)AAI9712272","http://hdl.handle.net/2142/18930"],"dc:language":["eng"],"dc:rights":["Copyright 1996 Frey, Matthew Henry"],"dc:subject":["Physics, Electricity and Magnetism","Physics, Condensed Matter","Engineering, Materials Science"],"dc:title":["Grain size effect on structure and properties for chemically-prepared barium titanate"],"dc:type":["text"],"thesis:degree_discipline":["Materials Science and Engineering"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."],"thesis:institution_name":["University of Illinois at Urbana-Champaign"]},"updated_at":"2026-07-22T22:25:11Z"}