Studies of Phase Transitions in Chain Compounds
{'Code': '03090005', 'Directorate': {'Abbreviation': 'MPS', 'LongName': 'Direct For Mathematical & Physical Scien'}, 'Division': {'Abbreviation': 'CHE', 'LongName': 'Division Of Chemistry'}}
{'SignBlockName': 'Margaret A. Cavanaugh', 'PO_EMAI': None, 'PO_PHON': None}
This project is jointly supported by the Inorganic,                             Bioinorganic and Organometallic Chemistry Program and the Solid                 State Chemistry Program.  The focus of the project is the                       chemistry of quasi-one-dimenional chain-like compounds, which                   are of interest in the materials area because of unusual                        magnetic properties and electrical conductivity.                                                                                                                The properties of chain compounds which exhibit phase                           transitions or which have unusual structures will be                            investigated by structural, magnetic, and theoretical studies.                  Magnetic susceptibility and preliminary magnetization studies                   on aqua(N-(salicylaldiminato)glycinato)copper(II) hemihydrate,                  CuNSG, have revealed a discontinuity in the magnetic                            susceptibility versus temperature plot at 2.1 K.  This                          discontinuity was initially identified as a spin-Peierls                        transition.  Analysis of the available magnetization data by                    10-spin cluster calculations now suggest that this                              discontinuity is the temperature at which the progressive,                      temperature-dependent dimerization of the chain is terminated.                  New magnetization and EPR studies will be performed to                          determine whether this explanation is correct. The available                    and new magnetization data will be analyzed with 14-spin                        cluster calculations, and EPR studies on single crystals will                   be carried out to determine the temperature dependence of the                   dimensionality of the system.  The phase transitions which have                 been identified in related carboxylato- or carbonato-bridged                    chain compounds will be investigated by low-field magnetic                      susceptibility studies and EPR using single crystals.  The                      next-nearest neighbor chain hydrazinium copper chloride is an                   example of a system with frustration, and a phase transition                    was predicted and observed.  The mechanism by which the system                  relieves the frustration will be determined.  Spin ladder                       chains which may exhibit frustration, and integer spin chains                   which may exhibit Haldane gaps will be investigated by                          structural, magnetic, and EPR studies.
{'FirstName': 'William', 'LastName': 'Hatfield', 'PI_MID_INIT': 'E', 'PI_SUFX_NAME': None, 'PI_FULL_NAME': 'William E Hatfield', 'EmailAddress': None, 'NSF_ID': '000342808', 'StartDate': '08/01/1988', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'University of North Carolina at Chapel Hill', 'CityName': 'CHAPEL HILL', 'ZipCode': '275995023', 'PhoneNumber': '9199663411', 'StreetAddress': '104 AIRPORT DR STE 2200', 'StreetAddress2': None, 'CountryName': 'United States', 'StateName': 'North Carolina', 'StateCode': 'NC', 'CONGRESSDISTRICT': '04', 'CONGRESS_DISTRICT_ORG': 'NC04', 'ORG_UEI_NUM': 'D3LHU66KBLD5', 'ORG_LGL_BUS_NAME': 'UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL', 'ORG_PRNT_UEI_NUM': 'N8DMK1K4C2K5'}
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[{'Code': '1762', 'Text': 'SOLID STATE & MATERIALS CHEMIS'}, {'Code': '1968', 'Text': 'PHYSICAL INORGANIC'}]
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1988&All=true', 'xml': '8807498.xml'}