scholarly journals Hydrothermal synthesis of perovskite and pyrochlore powders of potassium tantalate

2002 ◽  
Vol 17 (12) ◽  
pp. 3168-3176 ◽  
Author(s):  
Gregory K. L. Goh ◽  
Sossina M. Haile ◽  
Carlos G. Levi ◽  
Fred F. Lange
Keyword(s):  
Hydrothermal Synthesis ◽  
Perovskite Structure ◽  
Charge Compensation ◽  
Stable Phase ◽  
Water Molecules ◽  
Potassium Tantalate ◽  
Defect Pyrochlore

Potassium tantalate powders were hydrothermally synthesized at 100 to 200 °C in 4 to 15 M aqueous KOH solutions. A defect pyrochlore, Kta2O5(OH). nH2O (n ≈ 1.4), was obtained at 4 M KOH, but at 7–12 M KOH, this pyrochlore was gradually replaced by a defect perovskite as the stable phase. At 15 M KOH, there was no intermediate pyrochlore, only a defect perovskite, 0.85Ta0.92O2.43(OH)0.57 0.15H2O. Synthesis at higher KOH concentrations led to greater incorporation of protons in the perovskite structures. The potassium vacancies required for charge compensation of incorporated protons could accommodate water molecules in the perovskite structure.

Charge compensation on the luminescence properties of ZnWO4:Tb3+ phosphors via hydrothermal synthesis

Optik ◽  
2013 ◽  
Vol 124 (21) ◽  
pp. 5057-5060 ◽  
Author(s):  
Jinsheng Liao ◽  
Dan Zhou ◽  
Xin Qiu ◽  
Shaohua Liu ◽  
He-Rui Wen
Keyword(s):  
Hydrothermal Synthesis ◽  
Charge Compensation ◽  
Luminescence Properties

Facile hydrothermal synthesis of NaTaO3 with high photocatalytic activity

2019 ◽  
Vol 33 (14n15) ◽  
pp. 1940046 ◽  
Author(s):  
Min Yen Yeh ◽  
Jun Hong Li ◽  
Shun Hsyung Chang ◽  
Shiow Yueh Lee ◽  
Huichun Huang
Keyword(s):  
Photocatalytic Activity ◽  
Hydrothermal Synthesis ◽  
Visible Light ◽  
Visible Light Irradiation ◽  
Perovskite Structure ◽  
Hydrothermal Reaction ◽  
High Photocatalytic Activity ◽  
Light Irradiation ◽  
Orthorhombic Perovskite

Orthorhombic perovskite structure NaTaO3 with cube shape was successfully synthesized by hydrothermal reaction. The as-prepared NaTaO3 behaves a great photocatalystic activity on degradation of MB solution not only under UV but also visible light irradiation.

scholarly journals Hydrothermal synthesis of KNbO3 and NaNbO3 powders

2003 ◽  
Vol 18 (2) ◽  
pp. 338-345 ◽  
Author(s):  
Gregory K.L. Goh ◽  
Fred F. Lange ◽  
Sossina M. Haile ◽  
Carlos G. Levi
Keyword(s):  
Hydrothermal Synthesis ◽  
Perovskite Phase ◽  
Processing Parameters ◽  
Water Molecules ◽  
Induction Periods ◽  
The Stability

Orthorhombic KNbO3 and NaNbO3 powders were hydrothermally synthesized in KOH and NaOH solutions (6.7–15 M) at 150 and 200 °C. An intermediate hexaniobate species formed first before eventually converting to the perovskite phase. For synthesis in KOH solutions, the stability of the intermediate hexaniobate ion increased with decreasing KOH concentrations and temperatures. This led to significant variations in the induction periods and accounted for the large disparity in the mass of recovered powder for different processing parameters. It is also believed that protons were incorporated in the lattice of the as-synthesized KNbO3 powders as water molecules and hydroxyl ions.

Hydrothermal Synthesis and Structure of a Potassium Tantalum Defect Pyrochlore

1998 ◽  
Vol 37 (18) ◽  
pp. 4697-4701 ◽  
Author(s):  
Niangao Duan ◽  
Zheng-Rong Tian ◽  
William S. Willis ◽  
Steven L. Suib ◽  
John M. Newsam ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Defect Pyrochlore

Facile hydrothermal synthesis and pulsed laser deposition of Ca0.5Y1−x(WO4)2:xEu3+ phosphors: investigations on the luminescence, Judd–Ofelt analysis and charge compensation mechanism

2017 ◽  
Vol 41 (2) ◽  
pp. 493-502 ◽  
Author(s):  
Venkatakrishnan Mahalingam ◽  
Jagannathan Thirumalai
Keyword(s):  
Thin Film ◽  
Hydrothermal Synthesis ◽  
Pulsed Laser ◽  
Emission Spectra ◽  
Charge Compensation ◽  
Laser Deposition ◽  
Alkali Metal Ions ◽  
Compensation Mechanism ◽  
Pl Emission ◽  
Co Doped

PL emission spectra of Ca0.5Y1−x(WO4)2:xEu3+ for powder and thin film phosphors, and PL spectra of Ca0.5Y1−x(WO4)2:xEu3+ co-doped with alkali metal ions.

La(OH)2I(H2O): Closing a Gap in Rare Earth Hydroxide Halide Structural Chemistry

2006 ◽  
Vol 61 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Tom Nilges
Keyword(s):  
Hydrogen Bonding ◽  
Rare Earth ◽  
Hydrothermal Synthesis ◽  
Related Structure ◽  
Water Molecules ◽  
Space Group ◽  
Iodide Ions ◽  
Hydroiodic Acid ◽  
Additional Water ◽  
Edx Analyses

AbstractUCl3 type La(OH)2I can be stabilized by additional water molecules during a hydrothermal synthesis from hydroiodic acid and lanthanum carbonate hydrate at 453 K to form La(OH)2I(H2O). The new rare earth (RE) hydroxide halide hydrate crystallizes monoclinically, space group C2/m with lattice parameters of a = 19.691(3), b = 4.136(1), c = 6.286(1) Å, β = 108.45(1)° and V = 485.6(2) Å3, wR2 = 0.0695, 648 F2 values and 32 variables. La centered, distorted, tricapped, trigonal prisms formed by iodide, (OH−)- and (H2O) groups are connected via common edges in [001]-direction and common faces in [010]-direction to built up a zigzag like layered arrangement. Hydrogen bonding between the water molecules and iodide ions of adjacent La(OH)2I layers stabilize the UCl3 related structure, which was only observed for the lighter homologues La(OH)2X (X = Cl, Br) so far. DTA/TG and IR measurements substantiated the occurrence of (H2O)- and (OH−)-groups and semiquantitative EDX analyses proved a 1:1 composition for La:I in La(OH)2I(H2O).

scholarly journals A novel crystal polymorph of volborthite, Cu3V2O7(OH)2·2H2O

2012 ◽  
Vol 68 (7) ◽  
pp. i41-i44 ◽  
Author(s):  
Hajime Ishikawa ◽  
Jun-ichi Yamaura ◽  
Yoshihiko Okamoto ◽  
Hiroyuki Yoshida ◽  
Gøran J. Nilsen ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Single Crystal ◽  
Room Temperature ◽  
Magnetic Interactions ◽  
Water Molecules ◽  
Monoclinic Structure ◽  
Space Group ◽  
X Ray

A new polymorph of volborthite [tricopper(II) divanadium(V) heptaoxide dihydroxide dihydrate], Cu3V2O7(OH)2·2H2O, has been discovered in a single crystal prepared by hydrothermal synthesis. X-ray analysis reveals that the monoclinic structure has the space groupC2/cat room temperature, which is different from that of the previously reportedC2/mstructure. Both structures have Cu3O6(OH)2layers composed of edge-sharing CuO4(OH)2octahedra, with V2O7pillars and water molecules between the layers. The Cu atoms occupy two and three independent crystallographic sites in theC2/mandC2/cstructures, respectively, likely giving rise to different magnetic interactions between CuIIspins in the kagome lattices embedded in the Cu3O6(OH)2layers.

Sign in / Sign up

Export Citation Format

Share Document