Synthesis of ultrafine zirconia

Harrison, Darwin Anil; Stevens, R.; Milne, Steven J.

doi:10.1007/bf01770921

Cited by 6 publications

(4 citation statements)

References 6 publications

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“…7a,11 Combustion reactions can be used to produce metal oxides using reactive precursors based on citrate-nitrate gels 12 and other organic fuels. 13 Metathesis (exchange) reactions between solid precursors have also successfully produced metal oxides in moderate temperature reactions (v600 uC) along with alkali metal phosphate 14 or halide 15 byproducts. The above routes have advantages over precipitation routes in that they are performed in the solid-state, do not require any outside source of oxygen (e.g.…”

Section: Introductionmentioning

confidence: 99%

Rapid, energetic metathesis routes to crystalline metastable phases of zirconium and hafnium dioxide

Gillan

Kaner

2001

J. Mater. Chem.

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Rapid, exothermic metathesis (exchange) reactions between ZrCl 4 and Na 2 O result in crystalline ZrO 2 in seconds. Thermal analysis and in situ reaction temperature measurements show that the reaction initiates near the sublimation point of ZrCl 4 , rapidly reaches temperatures above 1350 uC, and generates a molten NaCl flux for a few seconds. Powder X-ray diffraction demonstrates that the product is a mixture of room-temperature monoclinic and high-temperature cubic ZrO 2 phases. The addition of cubic phase stabilizers such as Ca, Y, or Ce oxides or their chlorides to the reaction results in an increase in cubic phase formation up to nearly 70%. These partially stabilized products can withstand annealing to 1300 uC, unlike the unstabilized product, which reverts to the thermodynamic room-temperature monoclinic form on heating to 900 uC. The analogous reaction between HfCl 4 and Na 2 O results in crystalline HfO 2 . The addition of CaO to this reaction also enhances cubic phase formation.

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Section: Introductionmentioning

confidence: 99%

Rapid, energetic metathesis routes to crystalline metastable phases of zirconium and hafnium dioxide

Gillan

Kaner

2001

J. Mater. Chem.

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“…The average crystallite size of ZrO 2 prepared in the present experiment is well within this size as shown later. Hence stability of the t-ZrO 2 appears to be primarily due to the small crystallite size as also proposed by Harrison et al (1987).…”

Section: Phasesmentioning

confidence: 53%

“…The preparation method used here is essentially the same as described by Harrison et al (1987). A solid state reaction between Na2ZrO 3 and (NaPO3) 6 proceeds as follows Na2ZrO 3 + 1/6(NaPO3) ~ 5°°°c> ZrO 2 +Na3PO 4.…”

Section: Methodsmentioning

confidence: 99%

“…Ultrafine t-ZrO 2 powders have been successfully prepared by a variety of methods (Mazdiyasni et al 1967;Haberko et al 1975;Brook 1980;Rhodes 1981;Kagawa et al 1983;Jean 1991;Mottet et al 1992;Suzuki et al 1992;Maher et al 1993). Harrison et al (1987) briefly reported some years ago a rather simple method for preparation of t-ZrO 2 powders having a crystallite size of =13 nm by a solid state reaction between sodium metazirconate (Na2ZrO3) and sodium hexa metaphosphate (NaPO3) 6 at relatively low temperature (500°C). The method converts coarse m-ZrO z to fine t-ZrO 2 in a two-step process: first the precursor Na2ZrO 3 is prepared from coarse m-ZrO 2 and subsequently by a solid state reaction between Na2ZrO 3 and (NaPO3)6, fine t-ZrO 2 powder is obtained.…”

Section: Introductionmentioning

confidence: 99%

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Preparation of tetragonal zirconia powders by a solid state reaction: Kinetics, phases and morphology

1998

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Powders of tetragonal (t)ZrO 2 have been prepared by a solid state reaction between sodium metazirconate and sodium metaphosphate. The reaction temperatures and times have been varied between 450 and 550°C and 5 and 75 h, respectively. Zirconia powder, mostly in the t and t" phases, is obtained. The yield of ZrO 2 powder increases monotonically with time at all reaction temperatures according to a phase boundary controlled kinetics. The fraction of t phase also increases with time at 450°C and 500°C but goes through a maximum at 550°C, the highest temperature employed. A maximum of 55% of the precursor monoclinic zirconia (used to prepare sodium meta zirconate) is converted to t phase at 500°C/75 h. The ZrO z powder consists of crystallites of size 9-25 nm agglomerated into particles having average size between 2 and 4/zm. The agglomerates have a breaking strength of 100 MPa. A hydrothermal treatment is found to break the agglomerates into smaller sizes. Grinding the powder in a mortar and pestle converts only 12% of the t phase into monoclinic, indicating that substantial fraction of the tetragonal phase is the non transformable variety t'. Heating experiments also confirm this.

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Nanocrystalline ZrO2 by Crystallization of Amorphous Oxide

Chaim

1993

Mechanical Properties and Deformation Behavior of Materials Having Ultra-Fine Microstructures

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Synthesis of ultrafine zirconia

Cited by 6 publications

References 6 publications

Rapid, energetic metathesis routes to crystalline metastable phases of zirconium and hafnium dioxide

Rapid, energetic metathesis routes to crystalline metastable phases of zirconium and hafnium dioxide

Preparation of tetragonal zirconia powders by a solid state reaction: Kinetics, phases and morphology

Nanocrystalline ZrO2 by Crystallization of Amorphous Oxide

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