Youhyuk Kim

Photoluminescence of GdVO4:Eu3+, Al 3+ Phosphors under VUV Excitation

The microstructure and photoluminescence properties of Gd0.94-xAlxEu0.06VO4 (0≤x≤0.04) phosphors with various Al3+ contents were investigated. The phosphors showed a nanocrystalline nature and a high-quality powder characteristic. The crystallite sizes of the phosphors were calculated to be 46-48 nm. The annealed Gd0.94-xAlxEu0.06VO4 phosphors crystallized in the tetragonal structure. In the emission spectra, several emission peaks were observed over the measured wavelength range (500-750 nm), which were caused by the difference in the transitions of Eu3+ ions, depending on the local symmetry (5D0 → 7Fj, j = 1, 2, 3, and 4). The strongest emission peak was located at 619 nm, providing a high-purity red emission. The doped Al3+ yielded significantly enhanced the emission intensity. The most intense high-purity red emission was obtained for Gd0.93Al0.01Eu0.06VO4.

Solid state structure of WCl2(OCH2CH2CH2CH2PPh2)2 and π-bonding ability of alkoxide in chelating PO ligand

Abstract The solid state structure of the WCl2(OCH2CH2CH2CH2PPh2)2 (1) is determined by X-ray crystallography. Compound 1 crystallizes in the space group C2 with the following unit cell parameters: a=16.474(3) A, b=11.001(2) A, c=10.741(2) A, β=127.21(3)°, and Z=2. The molecule is described as a distorted octahedral structure with two oxygen atoms trans, two chlorine atoms cis and two phosphorus atoms cis. Substantial π-bonding from alkoxide to tungsten is suggested by the relatively short distance of WO with 1.816(11) A. Stereochemistry of alkoxide ligand and substantial π-bonding is consistent with the fact that in octahedral d2 systems, two π donors seek a mutual trans arrangement, regardless of the chelating OCH2CH2CH2CH2PPh2 ligand.