{"id":{"repo_id":"uiuc","oai_identifier":"oai:www.ideals.illinois.edu:2142/28682"},"canonical_url":"https://search.dev.ndltd.org/etd/uiuc/oai:www.ideals.illinois.edu:2142/28682","repository":{"repo_id":"uiuc","name":"University of Illinois - Urbana-Champaign","base_url":"https://www.ideals.illinois.edu/oai-pmh"},"display":{"title":"Phonon scattering by ferroelectric domain walls in potassium dihydrogen phosphate","abstract":"I have studied phonon scattering by ferroelectric domain walls in KH2P04 (KDP) using thermal conductivity and phonon imaging measurements of samples in both single-domain (poled) and multidomain states. Domains were eliminated by applying a 2- 3kV /em field using evaporated electrodes. Phonon images of a poled (001) sample (at 1.7K) show two-fold symmetric focusing patterns that clearly show the small orthorhombic distortion of the lattice. Poled images are qualitatively reproduced by calculations using continuum acoustics with room temperature tetragonal elastic moduli split to orthorhombic symmetry; a rough set of low temperature orthorhombic moduli is thereby determined. The presence of domains causes a large change in ST focusing structures but little change in L and FT patterns. There is an apparent decrease in overall intensity for all modes. The images show strongly mode and polarization dependent phonon scattering. Monte Carlo simulations using acoustic mismatch (phonon reflection) to model phonon/domain wall interactions accurately reproduce the changes seen in the domained images. The low temperature (0.03-3K) thermal conductivity, K, of [100], [110], and [001] (tetragonal basis) oriented samples was measured. K in poled samples shows typical surface-limited behavior which is predicted to 13% by calculations including finite length and anisotropy and using elastic constants from the imaging simulations. Domain walls produce a 40% conductivity decrease in a [110] sample and a 30% decrease in [100) samples which is nearly independent of sample size, suggesting strong scattering of only a subset of phonons. Domain wall scattering is nearly temperature independent between 0.3K and 1K, but decreases at lower temperatures, and increases above 1K. The [001] sample couldn't be poled, but the domained K is higher than that expected from sample surface scattering. Domains parallel to the heat flow may be channeling phonons and increasing K. Acoustic mismatch calculations applied to K predict the right order of scattering, but do not reproduce the sample size effects. Orientation effects can be partially explained. The probability of diffuse scattering at the domain boundaries (often seen in Kapitza resistance studies) is at most 1%.","abstract_html":"I have studied phonon scattering by ferroelectric domain walls in KH2P04 (KDP) using thermal conductivity and phonon imaging measurements of samples in both single-domain (poled) and multidomain states. Domains were eliminated by applying a 2- 3kV /em field using evaporated electrodes. Phonon images of a poled (001) sample (at 1.7K) show two-fold symmetric focusing patterns that clearly show the small orthorhombic distortion of the lattice. Poled images are qualitatively reproduced by calculations using continuum acoustics with room temperature tetragonal elastic moduli split to orthorhombic symmetry; a rough set of low temperature orthorhombic moduli is thereby determined. The presence of domains causes a large change in ST focusing structures but little change in L and FT patterns. There is an apparent decrease in overall intensity for all modes. The images show strongly mode and polarization dependent phonon scattering. Monte Carlo simulations using acoustic mismatch (phonon reflection) to model phonon/domain wall interactions accurately reproduce the changes seen in the domained images. The low temperature (0.03-3K) thermal conductivity, K, of [100], [110], and [001] (tetragonal basis) oriented samples was measured. K in poled samples shows typical surface-limited behavior which is predicted to 13% by calculations including finite length and anisotropy and using elastic constants from the imaging simulations. Domain walls produce a 40% conductivity decrease in a [110] sample and a 30% decrease in [100) samples which is nearly independent of sample size, suggesting strong scattering of only a subset of phonons. Domain wall scattering is nearly temperature independent between 0.3K and 1K, but decreases at lower temperatures, and increases above 1K. The [001] sample couldn't be poled, but the domained K is higher than that expected from sample surface scattering. Domains parallel to the heat flow may be channeling phonons and increasing K. Acoustic mismatch calculations applied to K predict the right order of scattering, but do not reproduce the sample size effects. Orientation effects can be partially explained. The probability of diffuse scattering at the domain boundaries (often seen in Kapitza resistance studies) is at most 1%.","abstract_has_math":false,"creators":["Weilert, Mark Anthony"],"institution":null,"degree_name":"Ph.D.","degree_level":"Dissertation","degree_discipline":"Physics","degree_department":null,"school":null,"contributors":["Anderson, A.C."],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012-01-23T18:08:00Z","date_published":"2012-01-23T18:08:00Z","updated_at":"2026-07-22T22:25:27Z","subjects":["phonon scattering","ferroelectric domain walls","potassium dihydrogen phosphate"],"languages":["en"],"rights":["1993 Mark Anthony Weilert"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2142/28682","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Anderson, A.C."]},{"key":"dc:creator","label":"Author","values":["Weilert, Mark Anthony"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012-01-23T18:08:00Z","10000-01-01","1993"]},{"key":"dc:type","label":"Dc Type","values":["Dissertation / Thesis","text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Physics"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Dissertation"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Ph.D."]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["phonon scattering","ferroelectric domain walls","potassium dihydrogen phosphate"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["1993 Mark Anthony Weilert"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2142/28682"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["I have studied phonon scattering by ferroelectric domain walls in KH2P04 (KDP) using thermal conductivity and phonon imaging measurements of samples in both single-domain (poled) and multidomain states. Domains were eliminated by applying a 2- 3kV /em field using evaporated electrodes. Phonon images of a poled (001) sample (at 1.7K) show two-fold symmetric focusing patterns that clearly show the small orthorhombic distortion of the lattice. Poled images are qualitatively reproduced by calculations using continuum acoustics with room temperature tetragonal elastic moduli split to orthorhombic symmetry; a rough set of low temperature orthorhombic moduli is thereby determined. The presence of domains causes a large change in ST focusing structures but little change in L and FT patterns. There is an apparent decrease in overall intensity for all modes. The images show strongly mode and polarization dependent phonon scattering. Monte Carlo simulations using acoustic mismatch (phonon reflection) to model phonon/domain wall interactions accurately reproduce the changes seen in the domained images. The low temperature (0.03-3K) thermal conductivity, K, of [100], [110], and [001] (tetragonal basis) oriented samples was measured. K in poled samples shows typical surface-limited behavior which is predicted to 13% by calculations including finite length and anisotropy and using elastic constants from the imaging simulations. Domain walls produce a 40% conductivity decrease in a [110] sample and a 30% decrease in [100) samples which is nearly independent of sample size, suggesting strong scattering of only a subset of phonons. Domain wall scattering is nearly temperature independent between 0.3K and 1K, but decreases at lower temperatures, and increases above 1K. The [001] sample couldn't be poled, but the domained K is higher than that expected from sample surface scattering. Domains parallel to the heat flow may be channeling phonons and increasing K. Acoustic mismatch calculations applied to K predict the right order of scattering, but do not reproduce the sample size effects. Orientation effects can be partially explained. The probability of diffuse scattering at the domain boundaries (often seen in Kapitza resistance studies) is at most 1%.","Submitted by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:08:00Z No. of bitstreams: 1 1993_weilert.pdf: 5529329 bytes, checksum: 4c7e430d96b65007057ec515b3b6e7aa (MD5)","Made available in DSpace on 2012-01-23T18:08:00Z (GMT). No. of bitstreams: 1 1993_weilert.pdf: 5529329 bytes, checksum: 4c7e430d96b65007057ec515b3b6e7aa (MD5) Previous issue date: 1993","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:08:00Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:10:14-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: dissertation","dissertation","U of I Only"]},{"key":"dc:title","label":"Title","values":["Phonon scattering by ferroelectric domain walls in potassium dihydrogen phosphate"]}]}],"canonical_facts":{"dc:contributor":["Anderson, A.C."],"dc:creator":["Weilert, Mark Anthony"],"dc:date":["2012-01-23T18:08:00Z","10000-01-01","1993"],"dc:description":["I have studied phonon scattering by ferroelectric domain walls in KH2P04 (KDP) using thermal conductivity and phonon imaging measurements of samples in both single-domain (poled) and multidomain states. Domains were eliminated by applying a 2- 3kV /em field using evaporated electrodes. Phonon images of a poled (001) sample (at 1.7K) show two-fold symmetric focusing patterns that clearly show the small orthorhombic distortion of the lattice. Poled images are qualitatively reproduced by calculations using continuum acoustics with room temperature tetragonal elastic moduli split to orthorhombic symmetry; a rough set of low temperature orthorhombic moduli is thereby determined. The presence of domains causes a large change in ST focusing structures but little change in L and FT patterns. There is an apparent decrease in overall intensity for all modes. The images show strongly mode and polarization dependent phonon scattering. Monte Carlo simulations using acoustic mismatch (phonon reflection) to model phonon/domain wall interactions accurately reproduce the changes seen in the domained images. The low temperature (0.03-3K) thermal conductivity, K, of [100], [110], and [001] (tetragonal basis) oriented samples was measured. K in poled samples shows typical surface-limited behavior which is predicted to 13% by calculations including finite length and anisotropy and using elastic constants from the imaging simulations. Domain walls produce a 40% conductivity decrease in a [110] sample and a 30% decrease in [100) samples which is nearly independent of sample size, suggesting strong scattering of only a subset of phonons. Domain wall scattering is nearly temperature independent between 0.3K and 1K, but decreases at lower temperatures, and increases above 1K. The [001] sample couldn't be poled, but the domained K is higher than that expected from sample surface scattering. Domains parallel to the heat flow may be channeling phonons and increasing K. Acoustic mismatch calculations applied to K predict the right order of scattering, but do not reproduce the sample size effects. Orientation effects can be partially explained. The probability of diffuse scattering at the domain boundaries (often seen in Kapitza resistance studies) is at most 1%.","Submitted by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:08:00Z No. of bitstreams: 1 1993_weilert.pdf: 5529329 bytes, checksum: 4c7e430d96b65007057ec515b3b6e7aa (MD5)","Made available in DSpace on 2012-01-23T18:08:00Z (GMT). No. of bitstreams: 1 1993_weilert.pdf: 5529329 bytes, checksum: 4c7e430d96b65007057ec515b3b6e7aa (MD5) Previous issue date: 1993","Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Carolyn Rauber (crauber2@illinois.edu) on 2012-01-23T18:08:00Z Item is restricted indefinitely.","Restriction data tranferred 2014-07-01T11:10:14-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: dissertation","dissertation","U of I Only"],"dc:identifier":["http://hdl.handle.net/2142/28682"],"dc:language":["en"],"dc:rights":["1993 Mark Anthony Weilert"],"dc:subject":["phonon scattering","ferroelectric domain walls","potassium dihydrogen phosphate"],"dc:title":["Phonon scattering by ferroelectric domain walls in potassium dihydrogen phosphate"],"dc:type":["Dissertation / Thesis","text"],"thesis:degree_discipline":["Physics"],"thesis:degree_level":["Dissertation"],"thesis:degree_name":["Ph.D."]},"updated_at":"2026-07-22T22:25:27Z"}