678 research outputs found
A Study of Dug-standing Pillar Building in Middle Ages TOSA Port Site 3―Consideration of Vassal area―
Magnetic-field-induced insulator-metal transition in W-doped VO2 at 500 T
Metal-insulator (MI) transitions in correlated electron systems have long
been a central and controversial issue in material science. Vanadium dioxide
(VO2) exhibits a first-order MI transition at 340 K. For more than half a
century, it has been debated whether electronic correlation or the structural
instability due to dimerised V ions is the more essential driving force behind
this MI transition. Here, we show that an ultrahigh magnetic field of 500 T
renders the insulator phase of tungsten (W)-doped VO2 metallic. The spin Zeeman
effect on the d electrons of the V ions dissociates the dimers in the
insulating phase, resulting in the delocalisation of electrons. Because the
Mott-Hubbard gap essentially does not depend on the spin degree of freedom, the
structural instability is likely to be the more essential driving force behind
the MI transition.Comment: 9 pages, 9 figures (including the supplementary information
Low-Temperature Luminescence Spectroscopy of Violet Sr-Al-O:Eu2+ Phosphor Particles
Violet Sr–Al–O:Eu2+ phosphor particles were synthesized from a metal–ethylenediaminetetraacetic acid (EDTA) solution of Sr, Al, Eu, and particulate alumina via spray drying and sintering in a reducing atmosphere. The crystal structures and emission properties at 85–300 K were investigated. The composition of the violet Sr–Al–O:Eu2+ phosphor particles was determined from various Sr–Al–O:Eu2+ phosphors by their emission properties' dependence on temperature. The highly crystalline SrAl12O19:Eu2+ emission phases were confirmed by their crystallite sizes and the activation energies for the 4f5d–8S7/2 transition of the Eu2+ ion. These results showed that the material identification for the violet Sr–Al–O:Eu2+ phosphor was accomplished by the low-temperature luminescence measurements
- …