The influence of a seed crystal on the texture of a bulk YBaCuO specimen

Die ordnende Wirkung eines Saat-Kristalles auf die Textur einer massiven YBaCuO-Probe Um die Abhängigkeit der lokalen Textur von Teilen einer zylindrischen YBaCuO-Probe vom Abstand zum Saatkristall zu untersuchen, wurde eine sehr gut texturierte YBaCuO-Probe in 9 rechteckige und in 12 Randstücke zerschnitten. Von den einzelnen Teilen der YBaCuO-Probe wurden die Texturen mit Hilfe der Neutronen-Beugung am Reaktor in Geesthacht gemessen und zwar mit einem "equal-area"-Raster. Die Maschenweite betrug 1° bis zu einer Achsabweichung der Zylinderachse der originären YBaCuO-Probe von 10° und von 10° Achsabweichung bis zu 20° Achsabweichung betrug die Maschenweite 2°. Aus der Summe der gezählten Neutronen auf Kleinkreisen der Polkugel wurden die einzelnen Werte der Verteilung der Achsabweichungen der c-Achsen der kristallinen Domänen von der Zylinderachse berechnet. Die mittlere Achsabweichung der c-Achsen der kristallinen Domänen von der Zylinderachse der unzerschnittenen YBaCuO-Probe wächst vom inneren Stück mit dem Saatkristall zu den Randstücken der zylindrischen Probe hin an

The influence of a seed crystal on the texture of a bulk YBaCuO specimen

To investigate the dependence of the local texture of parts of an YBaCuO specimen on the distance of the seed crystal from the position of the part of the specimen, a very good textured YBaCuO specimen was cut into 9 rectangular pieces and into 12 boundary pieces of the cylindric original specimen. From the individual parts of the YBaCuO specimen the texture was measured by neutron diffraction at the Geesthacht reactor with an equal area raster. The grid width was 1 up to 10 deviation from the cylinder axis of the original YBaCuO cylinder and 2 from 10 deviation until 20 deviation. From the sum of the counted neutrons on small circles on the pole sphere the individual values of the distributions of the angular deviations of the c-axes of the crystalline domains from the cylinder axis have been calculated. The mean deviation of the c-axes from the axis of the original cylinder increases from the inner part with the seed crystal to the boundary parts of the cylindric YBaCuO specimen. (orig.)4 refs.Available from TIB Hannover: ZA 5141(6072) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Texture of superconducting YBaCuO-cylinders and their levitation force repulsing an inducting permanent magnet

To investigate the relationship between the maximum possible magnetic levitation force of YBaCuO cylinders, with which they repel an inducting permanent magnet, and the texture quality of these YBaCuO cylinders, the textures of several YBaCuO specimens were measured in a number of series using the neutron texture diffractometer of the TUC/GKSS group. A first relationship between levitation force and texture could be presented. However, the measurement results were found to be scattered considerably around the tendency curve. A YBaCuO specimen of 94.5 N levitation force exhibited the best texture. A specimen of the same FWHM of the orientation distribution of the c-axes of the crystallites, but with a 94% limit of the distribution of the c-axis deviations from the cylinder axis of the specimen increased by 7 , reached a levitation force of 75.3 N only. This tendency - smaller levitation force at tilted distribution - is also confirmed by specimens, whose measurement values are far from the tendency curve, but which show the same tendency when connected to pairs. (orig.)10 refs.Available from TIB Hannover: ZA 5141(5961) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman