The regularities of the solid solutions between the scheelite-type compounds and rare earth molybdates or tungstates were investigated by the atomic parameter-support vector machine method and the intelligent database...The regularities of the solid solutions between the scheelite-type compounds and rare earth molybdates or tungstates were investigated by the atomic parameter-support vector machine method and the intelligent database of phase diagrams of molten salt systems. The crystal structure of scheelite-type compounds having M^1M^′Ⅲ （XO4）2（X = Mo, W） as common formula and the formability of the continuous solid solution between these compounds and rare earth molybdates or tungstates were also investigated. Besides, the cell constants of these compounds can be calculated by some semi-empirical equations. Based on the obtained relationships, the results of computerized prediction of the solid solubility of T1Pr （MoO4）2-Pr2 （MoO4）3 system have good agreement with experimental results.展开更多
The new scheelite form of SmCrO4 oxide was obtained by heating the zircon-type SmCrO4 oxide at 4 GPa and 803 K. X-ray diffraction revealed that this scheelite SmCrO4 phase crystallized with tetragonal symmetry, S.G. I...The new scheelite form of SmCrO4 oxide was obtained by heating the zircon-type SmCrO4 oxide at 4 GPa and 803 K. X-ray diffraction revealed that this scheelite SmCrO4 phase crystallized with tetragonal symmetry, S.G. I41/a and lattice parameters: a=0.50776(3) nm and c=1.15606(2) nm. This structural phase transition from zircon to scheelite involved a decreasing of around 10% in the unit cell volume. Although the Cr-O and Sm-O distances did not change very much in both zircon and scheelite polymorphs, the changes occurred in the bond angles were remarkable that appear to support the proposed reconstructive model to explain this structural zircon-scheelite phase transition. Magnetic susceptibility and magnetization measurements revealed that the scheelite SmCrO4 oxide behaved an antiferromagnetic material, where the Sm3+ and Cr5+ were simultaneously ordered. The estimated Néel temperature, TN, was 16 K and the critical field at 12 K associated with the metamagnetic transition was 3.2 T.展开更多
The efficient new red emitting scheelite-type compounds, Eu3＋-doped （5 tool.%） Y（Zro.5Wo.5）O4, Lu（Zro.sWo,5）O4 and Y（Y1/3W2/3）O4, were successfully prepared. The crystal structure, photoluminescence and decay...The efficient new red emitting scheelite-type compounds, Eu3＋-doped （5 tool.%） Y（Zro.5Wo.5）O4, Lu（Zro.sWo,5）O4 and Y（Y1/3W2/3）O4, were successfully prepared. The crystal structure, photoluminescence and decay properties of the obtained phosphors were investigated. Shifts of the peaks in the XRD patterns were observed when y3＋ sites in the host were occupied by Lu3＋ or Zr/W sites were occupied by Y/W, As a result of the crystallographic occupancy of Eu3＋ located at the cation positions without inversion symmetry, under O---Zr/W and O---.Eu3＋ ligand-to-metal charge-transfer states （LMCT） excitation at 300 nm, the emission spectra of these compounds presented 5Do---7F2 transition for EH3＋ at 612 nm. The diagram of EU3＋ energy levels in these new scheelite-type compounds and the energy transfer processes were discussed.展开更多
文摘The regularities of the solid solutions between the scheelite-type compounds and rare earth molybdates or tungstates were investigated by the atomic parameter-support vector machine method and the intelligent database of phase diagrams of molten salt systems. The crystal structure of scheelite-type compounds having M^1M^′Ⅲ （XO4）2（X = Mo, W） as common formula and the formability of the continuous solid solution between these compounds and rare earth molybdates or tungstates were also investigated. Besides, the cell constants of these compounds can be calculated by some semi-empirical equations. Based on the obtained relationships, the results of computerized prediction of the solid solubility of T1Pr （MoO4）2-Pr2 （MoO4）3 system have good agreement with experimental results.
基金Project supported by the Spanish MICINN and FEDER under Research Project No. MAT200763497SOPRANO Project Under Marie Curie Actions (FP7)
文摘The new scheelite form of SmCrO4 oxide was obtained by heating the zircon-type SmCrO4 oxide at 4 GPa and 803 K. X-ray diffraction revealed that this scheelite SmCrO4 phase crystallized with tetragonal symmetry, S.G. I41/a and lattice parameters: a=0.50776(3) nm and c=1.15606(2) nm. This structural phase transition from zircon to scheelite involved a decreasing of around 10% in the unit cell volume. Although the Cr-O and Sm-O distances did not change very much in both zircon and scheelite polymorphs, the changes occurred in the bond angles were remarkable that appear to support the proposed reconstructive model to explain this structural zircon-scheelite phase transition. Magnetic susceptibility and magnetization measurements revealed that the scheelite SmCrO4 oxide behaved an antiferromagnetic material, where the Sm3+ and Cr5+ were simultaneously ordered. The estimated Néel temperature, TN, was 16 K and the critical field at 12 K associated with the metamagnetic transition was 3.2 T.
基金supported by National Natural Science Foundation of China(11104298U133220251302039)
文摘The efficient new red emitting scheelite-type compounds, Eu3＋-doped （5 tool.%） Y（Zro.5Wo.5）O4, Lu（Zro.sWo,5）O4 and Y（Y1/3W2/3）O4, were successfully prepared. The crystal structure, photoluminescence and decay properties of the obtained phosphors were investigated. Shifts of the peaks in the XRD patterns were observed when y3＋ sites in the host were occupied by Lu3＋ or Zr/W sites were occupied by Y/W, As a result of the crystallographic occupancy of Eu3＋ located at the cation positions without inversion symmetry, under O---Zr/W and O---.Eu3＋ ligand-to-metal charge-transfer states （LMCT） excitation at 300 nm, the emission spectra of these compounds presented 5Do---7F2 transition for EH3＋ at 612 nm. The diagram of EU3＋ energy levels in these new scheelite-type compounds and the energy transfer processes were discussed.
