{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/19069"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/19069","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Effect of minor phase additions on the microstructure and dielectric properties of barium titanate ceramics","abstract":"Grain growth in BaTiO$\\sb3$ can be significantly inhibited by insoluble or slightly soluble second phase additions such as ZrO$\\sb2$, or by fluxes in the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ system. SEM and TEM observations revealed enhanced microstructural uniformity in these specimens. For the ZrO$\\sb2$ modified BaTiO$\\sb3$ system, Zr diffused into the BaTiO$\\sb3$ lattice when sintered above 1320$\\sp\\circ$C, resulting in a chemical modification of the tetragonal structure and the development of core-shell grains. TEM analysis of ZrO$\\sb2$ modified BaTiO$\\sb3$ sintered at temperatures less than 1320$\\sp\\circ$C, revealed the presence of ZrO$\\sb2$ at the grain boundaries as discrete particles ($\\approx$0.03 $\\mu$m). Modification of BaTiO$\\sb3$ with organically derived ZrO$\\sb2$ resulted in the formation of substantial chemical inhomogeneities in the microstructure. These inhomogeneities were observed by TEM as large ZrO$\\sb2$ particles ($>$75nm) and as a Ti and Zr rich phase, Ba$\\sb2$(ZrTi)$\\sb5$O$\\sb{12}$. In the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ modified BaTiO$\\sb3$, fluxed samples had an amorphous grain boundary phase, which became microcrystalline upon addition of ZrO$\\sb2$. For these samples core-shell grains were observed in specimens sintered at 1175$\\sp\\circ$C for 2h. More noticeable in the samples were regions near the grain boundaries where significant diffusion of the flux constituents into the BaTiO$\\sb3$ occurred, resulting in the formation of a fine domain structure. These fine-grained samples were accompanied by an increase in the internal stress level with decreasing grain size and increasing concentration of core-shell grains. The core-shell grains are comprised of a core of unmodified BaTiO$\\sb3$ and a shell of Zr modified BaTiO$\\sb3$, Ba(Zr$\\sb{\\rm x}$Ti$\\sb{\\rm 1-x}$)O$\\sb3$. This condition leads to high internal stress levels, arising from the thermal expansion mismatch between the core and the shell. The stress was found to be compressive in nature and dependent on temperature, time and grain size. The combination of internal stress and core-shell grains resulted in a decrease in the axial ratio $(c/a)$ with decreasing grain size and an essentially flat permittivity response with temperature, a condition consistent with a distribution of Curie points within the ceramic. These modified dielectrics also show a decrease in the aging rate with increasing temperature, resulting from the internal stress condition.","abstract_html":"Grain growth in BaTiO$\\sb3$ can be significantly inhibited by insoluble or slightly soluble second phase additions such as ZrO$\\sb2$, or by fluxes in the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ system. SEM and TEM observations revealed enhanced microstructural uniformity in these specimens. For the ZrO$\\sb2$ modified BaTiO$\\sb3$ system, Zr diffused into the BaTiO$\\sb3$ lattice when sintered above 1320$\\sp\\circ$C, resulting in a chemical modification of the tetragonal structure and the development of core-shell grains. TEM analysis of ZrO$\\sb2$ modified BaTiO$\\sb3$ sintered at temperatures less than 1320$\\sp\\circ$C, revealed the presence of ZrO$\\sb2$ at the grain boundaries as discrete particles ($\\approx$0.03 <span class=\"etd-inline-math\">&mu;</span>m). Modification of BaTiO$\\sb3$ with organically derived ZrO$\\sb2$ resulted in the formation of substantial chemical inhomogeneities in the microstructure. These inhomogeneities were observed by TEM as large ZrO$\\sb2$ particles ($&gt;$75nm) and as a Ti and Zr rich phase, Ba$\\sb2$(ZrTi)$\\sb5$O$\\sb{12}$. In the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ modified BaTiO$\\sb3$, fluxed samples had an amorphous grain boundary phase, which became microcrystalline upon addition of ZrO$\\sb2$. For these samples core-shell grains were observed in specimens sintered at 1175$\\sp\\circ$C for 2h. More noticeable in the samples were regions near the grain boundaries where significant diffusion of the flux constituents into the BaTiO$\\sb3$ occurred, resulting in the formation of a fine domain structure. These fine-grained samples were accompanied by an increase in the internal stress level with decreasing grain size and increasing concentration of core-shell grains. The core-shell grains are comprised of a core of unmodified BaTiO$\\sb3$ and a shell of Zr modified BaTiO$\\sb3$, Ba(Zr$\\sb{\\rm x}$Ti$\\sb{\\rm 1-x}$)O$\\sb3$. This condition leads to high internal stress levels, arising from the thermal expansion mismatch between the core and the shell. The stress was found to be compressive in nature and dependent on temperature, time and grain size. The combination of internal stress and core-shell grains resulted in a decrease in the axial ratio $(c/a)$ with decreasing grain size and an essentially flat permittivity response with temperature, a condition consistent with a distribution of Curie points within the ceramic. These modified dielectrics also show a decrease in the aging rate with increasing temperature, resulting from the internal stress condition.","abstract_has_math":true,"creators":["Armstrong, Timothy Robert"],"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":["Buchanan, Relva C."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2011,"date_issued":"2011-05-07T11:56:01Z","date_published":"2011-05-07T11:56:01Z","updated_at":"2026-07-22T22:25:12Z","subjects":["Materials Science and Engineering"],"languages":["eng"],"rights":["Copyright 1989 Armstrong, Timothy Robert"],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9010797","(UMI)AAI9010797"],"render_values":[{"text":"AAI9010797","href":null,"code":true},{"text":"(UMI)AAI9010797","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/2142/19069","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Buchanan, Relva C."]},{"key":"dc:creator","label":"Author","values":["Armstrong, Timothy Robert"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2011-05-07T11:56:01Z","10000-01-01","1989"]},{"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":["Materials Science and Engineering"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["Copyright 1989 Armstrong, Timothy Robert"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["AAI9010797","(UMI)AAI9010797","http://hdl.handle.net/2142/19069"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Grain growth in BaTiO$\\sb3$ can be significantly inhibited by insoluble or slightly soluble second phase additions such as ZrO$\\sb2$, or by fluxes in the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ system. SEM and TEM observations revealed enhanced microstructural uniformity in these specimens. For the ZrO$\\sb2$ modified BaTiO$\\sb3$ system, Zr diffused into the BaTiO$\\sb3$ lattice when sintered above 1320$\\sp\\circ$C, resulting in a chemical modification of the tetragonal structure and the development of core-shell grains. TEM analysis of ZrO$\\sb2$ modified BaTiO$\\sb3$ sintered at temperatures less than 1320$\\sp\\circ$C, revealed the presence of ZrO$\\sb2$ at the grain boundaries as discrete particles ($\\approx$0.03 $\\mu$m). Modification of BaTiO$\\sb3$ with organically derived ZrO$\\sb2$ resulted in the formation of substantial chemical inhomogeneities in the microstructure. These inhomogeneities were observed by TEM as large ZrO$\\sb2$ particles ($>$75nm) and as a Ti and Zr rich phase, Ba$\\sb2$(ZrTi)$\\sb5$O$\\sb{12}$. In the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ modified BaTiO$\\sb3$, fluxed samples had an amorphous grain boundary phase, which became microcrystalline upon addition of ZrO$\\sb2$. For these samples core-shell grains were observed in specimens sintered at 1175$\\sp\\circ$C for 2h. More noticeable in the samples were regions near the grain boundaries where significant diffusion of the flux constituents into the BaTiO$\\sb3$ occurred, resulting in the formation of a fine domain structure. These fine-grained samples were accompanied by an increase in the internal stress level with decreasing grain size and increasing concentration of core-shell grains. The core-shell grains are comprised of a core of unmodified BaTiO$\\sb3$ and a shell of Zr modified BaTiO$\\sb3$, Ba(Zr$\\sb{\\rm x}$Ti$\\sb{\\rm 1-x}$)O$\\sb3$. This condition leads to high internal stress levels, arising from the thermal expansion mismatch between the core and the shell. The stress was found to be compressive in nature and dependent on temperature, time and grain size. The combination of internal stress and core-shell grains resulted in a decrease in the axial ratio $(c/a)$ with decreasing grain size and an essentially flat permittivity response with temperature, a condition consistent with a distribution of Curie points within the ceramic. These modified dielectrics also show a decrease in the aging rate with increasing temperature, resulting from the internal stress condition.","Made available in DSpace on 2011-05-07T11:56:01Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9010797.pdf: 6961092 bytes, checksum: 1abb8d4746683a664e0e00490945eb97 (MD5) Previous issue date: 1989","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:34:27Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:13:09-05:00 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":["Effect of minor phase additions on the microstructure and dielectric properties of barium titanate ceramics"]}]}],"canonical_facts":{"dc:contributor":["Buchanan, Relva C."],"dc:creator":["Armstrong, Timothy Robert"],"dc:date":["2011-05-07T11:56:01Z","10000-01-01","1989"],"dc:description":["Grain growth in BaTiO$\\sb3$ can be significantly inhibited by insoluble or slightly soluble second phase additions such as ZrO$\\sb2$, or by fluxes in the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ system. SEM and TEM observations revealed enhanced microstructural uniformity in these specimens. For the ZrO$\\sb2$ modified BaTiO$\\sb3$ system, Zr diffused into the BaTiO$\\sb3$ lattice when sintered above 1320$\\sp\\circ$C, resulting in a chemical modification of the tetragonal structure and the development of core-shell grains. TEM analysis of ZrO$\\sb2$ modified BaTiO$\\sb3$ sintered at temperatures less than 1320$\\sp\\circ$C, revealed the presence of ZrO$\\sb2$ at the grain boundaries as discrete particles ($\\approx$0.03 $\\mu$m). Modification of BaTiO$\\sb3$ with organically derived ZrO$\\sb2$ resulted in the formation of substantial chemical inhomogeneities in the microstructure. These inhomogeneities were observed by TEM as large ZrO$\\sb2$ particles ($>$75nm) and as a Ti and Zr rich phase, Ba$\\sb2$(ZrTi)$\\sb5$O$\\sb{12}$. In the CaO$\\cdot$Al$\\sb2$O$\\sb3\\cdot$B$\\sb2$O$\\sb3$ modified BaTiO$\\sb3$, fluxed samples had an amorphous grain boundary phase, which became microcrystalline upon addition of ZrO$\\sb2$. For these samples core-shell grains were observed in specimens sintered at 1175$\\sp\\circ$C for 2h. More noticeable in the samples were regions near the grain boundaries where significant diffusion of the flux constituents into the BaTiO$\\sb3$ occurred, resulting in the formation of a fine domain structure. These fine-grained samples were accompanied by an increase in the internal stress level with decreasing grain size and increasing concentration of core-shell grains. The core-shell grains are comprised of a core of unmodified BaTiO$\\sb3$ and a shell of Zr modified BaTiO$\\sb3$, Ba(Zr$\\sb{\\rm x}$Ti$\\sb{\\rm 1-x}$)O$\\sb3$. This condition leads to high internal stress levels, arising from the thermal expansion mismatch between the core and the shell. The stress was found to be compressive in nature and dependent on temperature, time and grain size. The combination of internal stress and core-shell grains resulted in a decrease in the axial ratio $(c/a)$ with decreasing grain size and an essentially flat permittivity response with temperature, a condition consistent with a distribution of Curie points within the ceramic. These modified dielectrics also show a decrease in the aging rate with increasing temperature, resulting from the internal stress condition.","Made available in DSpace on 2011-05-07T11:56:01Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9010797.pdf: 6961092 bytes, checksum: 1abb8d4746683a664e0e00490945eb97 (MD5) Previous issue date: 1989","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:34:27Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:13:09-05:00 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":["AAI9010797","(UMI)AAI9010797","http://hdl.handle.net/2142/19069"],"dc:language":["eng"],"dc:rights":["Copyright 1989 Armstrong, Timothy Robert"],"dc:subject":["Materials Science and Engineering"],"dc:title":["Effect of minor phase additions on the microstructure and dielectric properties of barium titanate ceramics"],"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":"2026-07-22T22:25:12Z"}