MAS-NMR studies of glasses and glass-ceramics based on a clinopyroxene–fluorapatite system

Abstract

Glasses and glass-ceramics based on the ternary system CaMgSi 2 O 6 -NaAlSi 2 O 6 -Ca 5 (PO 4 ) 3 F (diopside(Di)-jadeite(Jd)-fluorapatite(FAp)) have been studied with magic angle spinning (MAS) NMR, powder x-ray diffraction (XRD) and thermal calorimetry. In this silicate system Na 2 O and Al 2 O 3 has been progressively substituted for CaO and MgO: (CaMgSi 2 O 6 ) 1-x -(NaAlSi 2 O 6 ) x -(Ca 5 (PO 4 ) 3 F) y where 0 ≤ x ≤ 30mol% and y = 7 mol%. 29Si MAS-NMR of the glasses showed a peak corresponding to a mixed Q

Elastic Properties of Clinopyroxene Based Glasses along Diopside (CaMgSi<sub>2</sub>O<sub>6</sub>)-Jadeite (NaAlSi<sub>2</sub>O<sub>6</sub>) Join

“…Similar results have also been reported on diopside-jadeite-fluorapatite glasses by Abo-Mosallam et al [12]. For the studied glasses, Table 5 gives the theoretically calculated packing density (V t ), the elastic moduli (E cal , S cal and B cal ) and the Poisson's ratio based on the model of Makishima and…”

“…Poisson's ratio exhibits a slight increase at low Al contents, However when we increases the mole % of Jd the network connectivity is increased [12] so the poison ratio decrease, because the higher connectivity of network decrease the Poisson's ratio.…”

Synthesis and characterization of clinopyroxene based glasses and glass-ceramics along diopside (CaMgSi2O6)–jadeite (NaAlSi2O6) join

“…He has reported that with increase in Jd content in the glasses, the polymerization in silicate glass network shifted from Q 2 to Q 3 (Q n : degree of polymerization; n: number of bridging oxygens) and Al exists predominantly as Al (IV) species. A complete solid solution has been reported to exist between Di-Jd glassceramics at 1 atm pressure for the first time in literature [2]. However, to the best of our knowledge, the structure and crystallization behavior in complete series of glasses along DiJd join have not been reported so far in open literature.…”

“…Wood et al [9] studied the thermo-chemistry of synthetic Di-Jd pyroxenes and found that the investigated synthetic clinopyroxenes have positive excess enthalpies of mixing. Also, it was reported that Di-Jd solid solutions are 'pseudo-ideal' near 1:1 composition at temperatures of 1000-1500 K. Recently, Abo-Mosallam et al [2] studied the structure and crystallization behavior of glasses www.elsevier.com/locate/ceramint and glass-ceramics along (CaMgSi 2 O 6 ) 1Àx -(NaAlSi 2 O 6 ) x -(Ca 5 (PO 4 ) 3 F) y where 0 x 30 mol.% and y = 7 mol.%. He has reported that with increase in Jd content in the glasses, the polymerization in silicate glass network shifted from Q 2 to Q 3 (Q n : degree of polymerization; n: number of bridging oxygens) and Al exists predominantly as Al (IV) species.…”

“…It is noteworthy that although Jd is metastable at one bar pressure and only forms at high pressure (!3 GPa), a stable solid solution exists between Di and Jd forming a C2/c monoclinic lattice and is one of the most important pseudo-binary chemical systems in petrology [2]. It is due to this reason that Di-Jd join has been an area under discussion among researchers for a considerable period of time.…”