Beiträge zum thermischen Verhalten von Übergangsmetallniobaten III. Darstellung und Struktur von orthorhombischem CuNb2O6

Kratzheller, B.; Gruehn, R.

doi:10.1016/0925-8388(92)90732-o

Cited by 13 publications

(5 citation statements)

References 14 publications

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“…For this compound, two polymorphs, orthorhombic (O-) and monoclinic (M-) phases have been found. Kratzheller and Gruehn reported that CuNb 2 O 6 can be prepared in either the monoclinic (680-740 • C) or orthorhombic (>740 • C) modification by heating equimolecular mixtures of CuO and Nb 2 O 5 in air, and in most cases, the two phases are found side by side [13]. In fact, the columbite-type phase (orthorhombic phase) is formed preferentially at temperature above 900 • C. In order to determine the crystal structure type of CuNb 2 O 6 , Langbein investigated the preparation of copper niobates by thermal decomposition of freeze-dried complex oxalate solutions, and found that thermal treatment at 600 • C for the precursor lead to the pure monoclinic form of CuNb 2 O 6 , and subsequent annealing at 800 • C or 900 • C brought about a partial conversion into orthorhombic columbite structure, while the direct decomposition of the freeze-dried precursor at 900 • C lead to the pure orthorhombic phase [8].…”

Section: Resultsmentioning

confidence: 98%

Preparation of CuNb2O6 nanocrystalline powders by sol–gel method

Zhang

Liu

2009

Journal of Alloys and Compounds

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Section: Resultsmentioning

confidence: 98%

Preparation of CuNb2O6 nanocrystalline powders by sol–gel method

Zhang

Liu

2009

Journal of Alloys and Compounds

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“…Copper niobate (CuNb 2 O 6 ) exhibits two polymorphs: monoclinic ( P 2/ c ) and an orthorhombic form. , A literature survey reveals the formation of these two CuNb 2 O 6 polymorphs at different reaction temperatures; i.e., the monoclinic polymorph can be obtained at temperatures <740 °C, while the orthorhombic form is formed at temperatures >740 °C. − Zinc niobate (ZnNb 2 O 6 ) commonly crystallizes in an orthorhombic structure with space group Pbcn / Pnab …”

Section: Resultsmentioning

confidence: 99%

“…For both these compounds, studies oriented toward the tuning of bandgap energies (or “band engineering”) have served to open up further avenues for heterogeneous photocatalysis and PEC applications. ,− …”

Section: Resultsmentioning

confidence: 99%

Solution Combustion Synthesis, Characterization, and Photoelectrochemistry of CuNb₂O₆ and ZnNb₂O₆ Nanoparticles

et al. 2016

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This study reports on the solution combustion synthesis of two different ternary niobium oxides, namely, p-CuNb 2 O 6 and n-ZnNb 2 O 6. Such ternary oxides are attractive candidates in the "Holy Grail" search for efficient and stable semiconductors for solar energy conversion and environmental remediation. We demonstrate how this time-and energy-efficient method is capable of synthesizing high surface area and crystalline nanoparticles of the above compounds with enhanced optoelectronic properties. The synthesized crystalline samples were characterized by powder X-ray diffraction (with Rietveld refinement for phase purity), diffuse reflectance UV−visible and Raman spectroscopy, electron microscopy, and photoelectrochemical (PEC) techniques. The band structure of these oxides was probed by linear sweep voltammetry and by measuring their photoaction spectra (internal photon to electron conversion efficiency vs wavelength). The obtained bandgap energy values (1.9 and 3.2 eV for the Cu-and Zn-containing compounds, respectively) were in reasonable agreement with those obtained via electronic structure calculations (2.07 and 3.53 eV). Finally, p-CuNb 2 O 6 showed promising activity for the PEC reduction of CO 2 , while n-ZnNb 2 O 6 was active for sulfite and water photooxidation. HCOOH, CH 3 OH, etc., produced by the photochemical or PEC conversion of CO 2. 4,8,9 The most extensively studied n-type metal oxide semiconductor is TiO 2 , mostly because of its robustness, outstanding stability in aqueous media, coupled with nontoxicity and earth abundance of its constituent elements. 10,11 However, the wide bandgap (3.0−3.2 eV) of this material limits its application in solar energy utilization processes. A plethora of other n-type oxide semiconductors (binary or even ternary oxides) have been applied as photoanodes (e.g., ZnO, WO 3 , Nb 2 O 5 , SrTiO 3). 12 On the other hand, p-type semiconductors Special Issue: Kohei Uosaki Festschrift

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“…[150,151] Very extensive experimental investigations (Table 6) and a critical comparison of the detailed thermodynamic model calculations were performed for the systems M/Nb/O (M Sc, [152] Hf, Zr, [111] V, Cr, Mn, [153] Fe, Co, [154] Ni, [155] Cu, [156,157] Zn, Cd [158] ) at a later date. [159] A very unfavorable influence on the transport of niobates was shown for the unavoidable traces of moisture (ca.…”

Section: Transition Metal Niobatesmentioning

confidence: 99%

New Results of Chemical Transport as a Method for the Preparation and Thermochemical Investigation of Solids

Gruehn

Glaum

2000

Angew. Chem. Int. Ed.

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Chemical transport experiments are a valuable aid of great potential in the synthesis and thermochemical characterization of solids. Compounds of interest can often only be crystallized by this method. The use of a transport balance allows very detailed observations, particularly of the course of the experiment over time (simultaneous or sequential deposition of multiple-phase solids). The computer program CVTRANS enables a quantitative thermochemical description of the experiment based on the cooperative transport model. A compilation of recent results illustrates the development and efficiency of the method. The transport of phosphides, anhydrous phosphates and sulfates, and rare-earth oxide and oxohalide compounds are treated in detail.

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Beiträge zum thermischen Verhalten von Übergangsmetallniobaten III. Darstellung und Struktur von orthorhombischem CuNb2O6

Cited by 13 publications

References 14 publications

Preparation of CuNb2O6 nanocrystalline powders by sol–gel method

Preparation of CuNb2O6 nanocrystalline powders by sol–gel method

Solution Combustion Synthesis, Characterization, and Photoelectrochemistry of CuNb₂O₆ and ZnNb₂O₆ Nanoparticles

New Results of Chemical Transport as a Method for the Preparation and Thermochemical Investigation of Solids

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Beiträge zum thermischen Verhalten von Übergangsmetallniobaten III. Darstellung und Struktur von orthorhombischem CuNb2O6

Cited by 13 publications

References 14 publications

Preparation of CuNb2O6 nanocrystalline powders by sol–gel method

Preparation of CuNb2O6 nanocrystalline powders by sol–gel method

Solution Combustion Synthesis, Characterization, and Photoelectrochemistry of CuNb2O6 and ZnNb2O6 Nanoparticles

New Results of Chemical Transport as a Method for the Preparation and Thermochemical Investigation of Solids

Contact Info

Product

Resources

About

Solution Combustion Synthesis, Characterization, and Photoelectrochemistry of CuNb₂O₆ and ZnNb₂O₆ Nanoparticles