An Ultrasonic Sensor for Process Modeling and Proces Control of Ceramic Superconductors
This research demonstrates the feasibility of utilizing nondestructive ultrasonic sensors to monitor the effects of oxygen content, processing time and temperature on the resultant mechanical, structural, and electrical properties of high temperature ceramic superconductors. Ultrasonic velocity changes, as a function of processing time and temperature, have clearly been shown to indicate the transformation between orthorhombic and tetragonal phases in Y-Ba-Cu-O.
On the Disorder of LiNbO3 Crystals
Results of investigations of the absorption, electrical conductivity, and photoconductivity of LiNbO3 are presented. They are explained by a model being similar to the anti-Frenkel disorder and by the formation of F2 centres during the reduction of the crystals. The model also illustrates the dependence of the Curie temperature on the Li:Nb ratio and optically induced refractive index inhomogeneities. 
 
 
 
Es werden Ergebnisse von Untersuchungen der Absorption, der elektrischen Leitfahigkeit und der Phtoleitfahigkeit von LiNbO3 vorgelegt. Sie werden mit einem der Anti-Frenkel-Fehlordnung ahnlichen Model und der Bildung von F2-Zentren bei der Reduktion der Kristalle erklart. Das Modell macht zugleich die Abhangigikeit der Curie-Temperatur vom Li:Nb-Verhaltnis und optisch induzierte Brechzahlinhomogenitaten verstandlich.
Submicron polymer structures with X-ray lithography and hot embossing
This article describes the process chain for replication of submicron structures with varying aspect ratios (AR) up to 6 in polymethylmethacrylate (PMMA) by hot embossing to show the capability of the entire LIGA process to fabricate structures with these dimensions. Therefore a 4.7 μm thick layer of MicroChem 950k PMMA A11 resist was spin-coated on a 2.3 μm Ti/TiOx membrane. It was patterned with X-ray lithography at the electron storage ring ANKA (2.5 GeV and λc ≈ 0.4 nm) at a dose of 4 kJ/cm3 using a Si3N4 membrane mask with 2 μm thick gold-absorbers. The samples were developed in GG/BDG and resulted in AR of 6–14. Subsequent nickel plating at 52°C resulted in a 200 μm thick nickel tool of 100 mm diameter, which was used to replicate slit-nozzles and columns in PMMA. Closely packed submicron cavities with AR 6 in the nickel shim were filled to 60% during hot embossing.