Melt Crystallization of the Metaphosphates of Mono and Divalent Oxides: A Review on Structural and Kinetic Aspects

The devitrification and structure of RE(PO3)3 (RE = La, Pr, Nd, Gd, Dy,Y) glasses are studied by infrared spectroscopy, X-ay diffraction and differential thermal analysis. The results from devitrification experiments show that RE(PO3)3 glasses (regardless of the size of RE3+) crystallize first to give monoclinic Yb(PO3)3 type crystals. The IR spectra of devitrified. La, Pr, and Nd samples differ, however, from those of Gd, Dy and Y in the range of symmetric POP stretching frequencies. To unravel the differences demonstrated in the IR spectra of devitrified RE(PO3)3 we performed preliminary Rietveld refinement on the crystal structure of the "metastable" Nd(PO3)3 [monoclinic, P21/c a = 11.468 (4)

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STRUCTURE AND DEVITRIFICATION CHEMISTRY OF RE(PO3)3 (RE=La, Pr, Nd, Gd, Dy, Y) METAPHOSPHATE GLASSES

Ilieva¹,

Kovacheva

Cole

et al. 2002

Phosphorus Research Bulletin

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Fragility of a Calcium Metaphosphate Melt and Relaxation of Its Glass Fibres

Yue

2002

Phosphorus Research Bulletin

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With regard to fragility and workability, the calcium metaphosphate-like melt (CMP) with the composition 51.4Ca048.6P205 in mol% is compared with the soda-lime-silicate melt (NCS) with the composition 16Na2O-10CaO-74SiO2 in mol%. The fragility of the two melts is characterised by determining the fragility index F1/2, the difference in heat capacity between glass and melt, and configurational entropy. The difference of heat capacity between the CMP glass and crystal is measured. The intense crystallisation takes place at the temperature T = 1.20Tg, where Tg is the glass transition temperature. The fibres are drawn from the CMP melt. The ratio of the fictive temperature Tf to Tg of these fibres is found to be 1.053 by estimating the excess energy stored during fibre forming. Relaxation features of the CMP fibres are examined by doing systematic thermal ageing experiments and calorimetric measurements. The endotherm and exotherm simultaneously occur in a certain range of ageing temperatures. The dependence of the endotherm and extherms on the ageing temperature is discussed.

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Melt Crystallization of the Metaphosphates of Mono and Divalent Oxides: A Review on Structural and Kinetic Aspects

Abstract: The anionicpolymer structure of metaphosphate melts and glasses determines their crystallization as a typical case of an anionic reconstruction.

Cited by 2 publications

References 13 publications

STRUCTURE AND DEVITRIFICATION CHEMISTRY OF RE(PO<SUB>3</SUB>)<SUB>3</SUB> (RE=La, Pr, Nd, Gd, Dy, Y) METAPHOSPHATE GLASSES

STRUCTURE AND DEVITRIFICATION CHEMISTRY OF RE(PO<SUB>3</SUB>)<SUB>3</SUB> (RE=La, Pr, Nd, Gd, Dy, Y) METAPHOSPHATE GLASSES

Fragility of a Calcium Metaphosphate Melt and Relaxation of Its Glass Fibres

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