Yaohua Xu

Hydrothermal synthesis and characterization of NH4Sn2(PO4)3

Abstract NH 4 Sn 2 (PO 4 ) 3 has been synthesized hydrothermally from the NH 3 SnO 2 P 2 O 5 H 2 O system, and characterized by X-ray powder diffraction, differential thermal analysis—thermogravimetric analysis, and Raman and IR spectroscopy.

Hydrothermal synthesis and characterization of K2Ce(PO4)2 · H2O

Abstract A new compound in the system K2OCeO2P2O5H2O (K2Ce(PO4)2 · H2O) has been hydrothermally synthesized and characterized by X-ray powder diffraction, differential thermal analysis, thermogravimetric analysis, composition analysis, IR, Raman and impedance spectra. The product crystallized as an orthorhombic phase with a = 12.79(3) A , b = 14.01(5) A , c = 15.94(3) A and v = 2854 A 3 . The compound is a proton conductor at temperatures below 180 °C, an insulator between 180 °C and 320 °C, and a potassium-ion conductor above 340 °C. The proton conductivities of the compound were 1.70 × 108 S cm−1 at 40 °C and 1.95 × 10−7 S cm−1 at 160 °C, and the K-ion conductivity 1.62 × 10−9 S cm−1 at 340 °C.

Hydrothermal synthesis and characterization of (NH4)Ce(PO4)2·H2O

A new monohydrated ammonium cerium phosphate (NH4)2Ce(PO4)2·H2O is hydrothermally synthesized from the system NH3–CeO2–P2O5–H2O and characterized by powder X-ray diffraction, differential thermal analysis–thermogravimetric analysis, elemental chemical analysis, IR, Raman and impedance spectroscopy.

Hydrothermal synthesis and characterization of β-Na3Ce(PO4)2

Abstract β-Na 3 Ce(PO 4 ) 2 has been hydrothermally synthesized in the system Na 2 OCe 2 O 3 P 2 O 5 H 2 O (CePO 4 Na 3 PO 4 ). The product was characterized by X-ray powder diffraction, differential thermal and thermogravimetric analyses, Raman and IR spectroscopy.

The luminescence of ion-exchangeable defect pyrochlore KNbWO6·H2O:xEu3+

KNbWO6·H2O:xEu3+ is prepared by ion exchange under hydrothermal conditions. Three K+ ions of KNbWO6·H2O are exchanged for one Eu3+ ion and KNbWO6·H2O:xEu3+ keeps its defect pyrochlore structure. Thermal analysis results indicate that the Eu3+ ion incorporates into the channels of the defect pyrochlore structure in the form of the aqueous ion [Eu(H2O)n]3+. [Eu(H2O)n]3+ in the channel looses water at 450 °C, which is much higher than that of KNbWO6·H2O. The hydration of the Eu3+ ion in the pyrochlore structure has significant influence on the luminescence properties of KNbWO6·H2O:xEu3+. The emission intensity increases 10 times when the as-prepared KNbWO6·H2O:xEu3+ is annealed at 450 °C for 2 h.

Preparation and characterization of AlAsO4-3 and AlAsO4-4, two new aluminoarsenates with occluded 1,2-diaminopropane

Abstract Two new amine-occluding aluminoarsenates (designated AlAsO 4 -3 and AlAsO 4 -4) with compositions AlAsO 4 · 0.3C 3 H 10 N 2 · 0.2H 2 O and AlAsO 4 · 0.2C 3 H 10 N 2 · 0.4H 2 O were prepared hydrothermally by using 1,2-diaminopropane as a template. The former is indexable on the basis of a cubic cell with a = 7.722 A and the latter, a monoclinic one with a = 19.255, b = 12.013, c = 10.356 A, and β = 127.58°. AlAsO 4 -3 contains octahedrally coordinated Al atoms whereas AlAsO 4 -4 contains not only octahedrally coordinated Al atoms but also tetrahedrally coordinated ones. In AlOAs bond force, these two compounds are different to a great extent from each other as well as from α-quartz-type AlAsO 4 which contains AlO 4 and AsO 4 coordination units. When calcined at high temperature (e.g., 800°C), both lose the template completely and the framework arsenic partially.

Hydrothermal synthesis and characterization of KSn2(PO4)3

KSn2(PO4)3 is synthesized hydrothermally from the K2O–SnO2–P2O5–H2O system, and characterized by X-ray powder diffraction, Raman and IR spectroscopy.