TY  - THES
A1  - Mahler, Willy
T1  - Thermisch induzierte Strukturumwandlungen von Langmuir-Blodgett-Multischichten aus Fettsäuresalzen
Y1  - 1996
ER  - 
TY  - JOUR
A1  - Mahler, Willy
A1  - Bodenstein, G.
A1  - Pietsch, Ullrich
T1  - Phasentransformationen in Cd-Stearat-Multischichten bei unterschiedlichen Metallionenkonzentrationen
Y1  - 1995
ER  - 
TY  - JOUR
A1  - Neumann, Werner
A1  - Buchsteiner, Alexandra
A1  - Mahler, Willy
A1  - Geue, Thomas
A1  - Pietsch, Ullrich
T1  - Dielectric loss spectroscopy at fatty acid salt multilayers
N2  - Dielectric loss spectroscopy (DLS) was performed at compact samples and lamellary organized Langmuir-Blodgett (LB) films from various fatty acid salts. Previous thermoanalytical measurements at compact samples revealed the appearance of two different phase transition temperatures; the lower one is related to the acid the second one to the acid salt molecules. In spite of ill defined electrical contacts with the film the characteristic DLS frequencies obtained from about 100nm thick multilayer films are similar to those recorded from bulk samples. No significant variations of frequencies were found changing the counter ions. Besides conductivity influence at low frequncies we found two relaxations related to the mobility of the dipolar carboxylat-metal group at about 100 and 10000Hz. One of these frequencies is related to the rotation around the chain axis. The strength of this relaxation increases significantly with increasing the sample temperature above 105°C. This temperature is connected with a structural phase transition observed by X-ray reflectometry. In case of Pb-stearate the results of the dielectric measurements help to interprete this structural change as a transition from an orthorhombic into a free-rotator phase. The uncorrelated rotation of molecules around their molecular axes initiates a much increased relaxation strength at the carboxylat-metal sites.
Y1  - 2000
ER  -