University of Electro-Communications

About: University of Electro-Communications is a education organization based out in Tokyo, Japan. It is known for research contribution in the topics: Laser & Robot. The organization has 8041 authors who have published 16950 publications receiving 235832 citations. The organization is also known as: UEC & Denki-Tsūshin Daigaku.

Yb3+-doped Y3Al5O12 ceramics – A new solid-state laser material

Abstract: We have succeeded in the fabrication of Yb3+ : Y3Al5O12 ceramics by the nanocrystalline technology and a vacuum sintering method. The first diode end-pumped ceramic laser with this novel solid-state material was demonstrated. The 345-mW cw output power was obtained with the slope efficiency of 26%. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Magnetic properties of REMe0.5Mn0.5O3 (RE = Rare Earth Element, Me = Ni, Co)

Abstract: Magnetic properties of REMe 0.5 Mn 0.5 O 3 with Me = Ni and Co are investigated for a series of rare earth (RE) elements. In both systems with Me = Ni and Co, the Curie temperature ( T C ), below which the magnetic moments of Me 2+ and Mn 4+ allign ferromagnetically, decreases remarkably as RE goes from La to heavier elements; from 295 K for RE = La to 50 K for Lu with Me = Ni, and from 250 K for La to 95 K for Ho with Me = Co. The decrease of T C is interpreted as due to the bond angle (θ) dependence of the superexchange interactions between Me 2+ and Mn 4+ through O 2- ; T C is roughly linear to cos 2 θ as predicted by a simple theory [C. Boekema et al. : Int. J. Mag. 3 (1972) 341], but a distinct deviation from the linear relation is observed for the late RE elements. The magnetic moments of RE ions appears only in a low temperature region, typically below 30 K. Qualitative discussion on the exchange interactions involving RE is presented.

Effect of pressing temperature on fine-grained structure formation in 7475 aluminum alloy during ECAP

Abstract: The effect of pressing temperature on microstructural development under ECAP conditions was studied in an as-cast 7475 aluminum alloy at temperatures from 523 to 673 K. The samples were pressed by using route A up to strains of 12. New equiaxial grains with high angle boundaries (HABS) start to be formed after three passes and then gradually developed with repeated ECAP, finally, followed by fully development of a new fine-grained structure. The average (sub)grain size tends to increase and the aspect ratio decreases with increasing pressing temperature. The misorientation distribution of strain-induced dislocation boundaries shows a single peak type at low angle misorientations until second pass and then gradually shifts to higher angles with increasing of strain. Increase in pressing temperature retards the transformation kinetics from low angle boundaries to high angle ones, while the fraction of the latter as well as the average misorientation approach a same saturation value irrespective temperature in high strain. The mechanism of ultra-fine grain formation during ECAP is discussed.