Influence of processing conditions on dielectric properties of CaCu3Ti 4O12 thin films
CaCu3Ti4O12 possesses one of the largest values of the effecti ve dielectric permittivity in a large frequency and temperature range ever reported for a ce amic material, and is thus a very promising materi l for various electronic and electromechanical applic ations. The origin of such high permittivity has be en attributed to ‘electrical’ heterogeneities in the m icrostructure [1-3]. By Chemical Solution Depositio n, we have prepared CaCu 3Ti4O12 ceramic thin films under different conditions, try ing to establish the influence of microstructure on their dielectric properties.
Separation of grain boundary effects and intrinsic properties in perovskite-like Gd 0.6 Y 0.4 BaCo 2 O 5.5 using high-frequency dielectric spectroscopy
The dielectric response of ${\mathrm{Gd}}_{0.6}{\mathrm{Y}}_{0.4}{\mathrm{BaCo}}_{2}{\mathrm{O}}_{5.5},$ which undergoes a sequence of magnetic and electronic phase transitions, has been investigated in the radio-frequency range from 1 MHz to 1.8 GHz in order to separate the intrinsic properties from grain boundary and sample-electrode interface effects. Analysis of the measured response, showing the characteristics of a damped resonator, reveals the intrinsic dc resistivity, which cannot be detected using the standard four-point measurement method. From the skin-effect-governed dielectric response the temperature dependence of the magnetic permeability was determined.
Synthesis, crystal structure, and mössbauer study of a series of perovskite-like compounds [ACu3] (M, Fe)4O12
A series of cubic perovskite-like compounds with the general formula [ACu3](M, Fe)4O12 is synthesized. The A-sites are occupied by large cations such as Th4+ or rare earths R3+. The B-sites are statistically occupied by Fe3+ cations and by tetravalent M4+ cations such as Mn4+ or Ti4+ The structure of [NdCu3](Ti3Fe)O12 (space group Im3) is refined from room temperature neutron diffraction data. Mossbauer spectroscopy data performed on [NdCu3](Ti3Fe)O12 and on [ThCu3] · (Mn2Fe2)O12 show that a magnetic order takes place below 14 K for the first compound and below 200 K for the second one. 
 
 
 
Es wurde eine Reihe von kubischen perovskit-ahnlichen Verbindungen mit der allgemeinen Formel [ACu3](M, Fe)4O12 hergestellt. Die A-Platze werden von grosen Kationen wie Th4+ oder Seltenen Erden R3+ besetzt. Die B-Platze werden statistisch besetzt durch Fe3+-Kationen und durch tetravalente M4+-Kationen wie Mn4+ oder Ti4+. Die Struktur von [NdCu3](Ti3Fe)O12 (Raumgruppe Im3) wird aus Neutronenbeugungswerten bei Zimmertemperatur gewonnen. Mosbauer-spektroskopiewerte an [NdCu3](Ti3Fe)O12 und an [ThCu3](Mn2Fe2)O12 zeigen, das eine magnetische Ordnung unterhalb 14 K fur die erste Verbindung und unterhalb 200 K fur die zweite Verbindung stattfindet.