Phase Equilibria in the System K2CO3-Nb2O5 by the Method of Differential Thermal Analysis

Reisman, Arnold; Holtzberg, F.

doi:10.1021/ja01613a025

Cited by 130 publications

(67 citation statements)

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“…The System Nb^O^-KNbO2 5 3 A phase equilibrium diagram for this system was previously reported by Reisman and Holtzberg [20] . Additional information on compound formation, crystal growth, and unit cell dimensions has been p\iblished by Guerchais [21], Whiston and Smith [22], and Nassau et_ al_ [23].…”

Section: Discussion Of Resultsmentioning

confidence: 76%

Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

Roth¹,

Parker²,

Brower³

et al. 1974

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Section: Discussion Of Resultsmentioning

confidence: 76%

Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

Roth¹,

Parker²,

Brower³

et al. 1974

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“…Both the water content in the hygroscopic alkali carbonate precursors and alkali evaporation during processing must be compensated for by the introduction of excess alkali. 15,[19][20][21][22] Solid state processing of KNN (especially Li and Ta codoped KNN) can also result in inhomogeneity unless a pre-reaction of the B-site oxides through the "precursor method" is performed. 23,24 Wet chemical methods generally produce homogeneous ceramic powders of small particle size with good stoichiometry control.…”

Section: Introductionmentioning

confidence: 99%

Sintering of sub-micron K 0.5 Na 0.5 NbO 3 powders fabricated by spray pyrolysis

Haugen

Madaro

Bjørkeng

et al. 2015

Journal of the European Ceramic Society

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K0.5Na0.5NbO3 (KNN)-based ceramics are promising lead-free piezoelectrics, but processing of these materials is an ongoing challenge. Here, we present a spray pyrolysis route to highquality KNN-based powders. Fine-grained (<100 nm as-prepared, ~130 nm calcined at 800 °C) and phase-pure KNN and Li0.03K0.485Na0.485Nb0.8Ta0.2O3 (KNNLT) powders were obtained from aqueous precursor solutions. Ceramics with 95 % of theoretical density and with normalized strain of 333 pm/V were obtained by conventional sintering. The sintering of KNN remained challenging even for the fine grained powders, and the origins of these processing challenges were investigated by dilatometry and electron microscopy. Coarsening into cuboidal grains, which strongly reduced the sinterability, was observed in alkali-oxide excess KNN, caused by the formation of a liquid phase at ~650 °C. We propose that the reactivity of alkali oxide with moisture and carbon dioxide at lower temperatures cause the formation of the liquid phase at the surface even for stoichiometric KNN powders.Evaporation, mainly of potassium oxide, at high temperatures was shown to cause the formation of a Nb-rich secondary phase. The segregation of a secondary phase and inhomogeneous distribution of K/Na are discussed in relation to sintering above the solidus temperature of KNN.

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“…20,21) In addition, slight changes in stoichiometry (both on the Na-rich and the K-rich side) easily lead to the formation of second phases. 22) NKN films with different compositions had similar dense microstructures with particulates, showing little dependence on composition.…”

Section: Methodsmentioning

confidence: 97%

Characterization of Ferroelectric NaxK1−xNbO3 System Films Prepared by Pulsed Laser Deposition

Lai

Goto

et al. 2008

Mater. Trans.

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Ferroelectric Na x K 1Àx NbO 3 (NKN) films were prepared on quartz and Pt/SrTiO 3 (100) substrates by pulsed laser deposition. The effects of composition and preparation conditions on the crystal structure and ferroelectricity of the NKN films were investigated by changing the Na content (x), substrate temperature (T sub ), oxygen partial pressure (P O2 ), target-to-substrate distance (D t-s ) and laser energy density (E L ). The permittivity values of the NKN films were 390 to 520 at room temperature and 100 kHz, showing a maximum at x ¼ 0:5. The maximum remnant polarization value was 8:2 Â 10 À2 C m À2 at x ¼ 0:5.

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Phase Equilibria in the System K₂CO₃-Nb₂O₅ by the Method of Differential Thermal Analysis

Cited by 130 publications

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Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

Sintering of sub-micron K 0.5 Na 0.5 NbO 3 powders fabricated by spray pyrolysis

Characterization of Ferroelectric Na<I><SUB>x</SUB></I>K<SUB>1−<I>x</I></SUB>NbO<SUB>3</SUB> System Films Prepared by Pulsed Laser Deposition

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Phase Equilibria in the System K2CO3-Nb2O5 by the Method of Differential Thermal Analysis

Cited by 130 publications

References 0 publications

Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

Alkali oxide-tantalum oxide and alkali oxide-niobium oxide ionic conductors

Sintering of sub-micron K 0.5 Na 0.5 NbO 3 powders fabricated by spray pyrolysis

Characterization of Ferroelectric Na<I><SUB>x</SUB></I>K<SUB>1&minus;<I>x</I></SUB>NbO<SUB>3</SUB> System Films Prepared by Pulsed Laser Deposition

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Phase Equilibria in the System K₂CO₃-Nb₂O₅ by the Method of Differential Thermal Analysis

Characterization of Ferroelectric Na<I><SUB>x</SUB></I>K<SUB>1−<I>x</I></SUB>NbO<SUB>3</SUB> System Films Prepared by Pulsed Laser Deposition