Transparent glasses having molar composition (23x)K2O xNa2O 27Nb2O5 50SiO2 (x = 0, 5, 10, 15 and 23) have been synthesized by the melt-quenching technique and their devitrification behaviour has been investigated by DTA and XRD. Depending on the composition, the glasses showed a glass transition temperature in the range 660–680 °C and devitrified in several steps. XRD measurements showed that the replacement of K2O byNa2O strongly affects the crystallization behaviour. Particularly, in the glasses with only potassium or low sodium content the first devitrification step is related to the crystallization of an unidentified phase, while in the glass containing only sodium, NaNbO3 crystallizes. For an intermediate sodium content (x = 10 and 15) a potassium sodium niobate crystalline phase, belonging to the tungsten-bronze family, is formed by bulk nucleation. This system looks promising to produce active nanostructured glasses as the tungsten-bronze type crystals have ferroelectric, electro-optical and non-linear optical properties. Preliminary measurements evidenced SHG activity in the crystallized glasses containing this phase.
Crystallization and second harmonic generation in potassium–sodium niobiosilicate glasses / Aronne, Antonio; Fanelli, Esther; Pernice, Pasquale; S., Peli; C., Giannetti; G., Ferrini. - In: JOURNAL OF SOLID STATE CHEMISTRY. - ISSN 0022-4596. - STAMPA. - 182:(2009), pp. 2796-2800. [doi:10.1016/j.jssc.2009.07.052]
Crystallization and second harmonic generation in potassium–sodium niobiosilicate glasses
ARONNE, ANTONIO;FANELLI, Esther;PERNICE, PASQUALE;
2009
Abstract
Transparent glasses having molar composition (23x)K2O xNa2O 27Nb2O5 50SiO2 (x = 0, 5, 10, 15 and 23) have been synthesized by the melt-quenching technique and their devitrification behaviour has been investigated by DTA and XRD. Depending on the composition, the glasses showed a glass transition temperature in the range 660–680 °C and devitrified in several steps. XRD measurements showed that the replacement of K2O byNa2O strongly affects the crystallization behaviour. Particularly, in the glasses with only potassium or low sodium content the first devitrification step is related to the crystallization of an unidentified phase, while in the glass containing only sodium, NaNbO3 crystallizes. For an intermediate sodium content (x = 10 and 15) a potassium sodium niobate crystalline phase, belonging to the tungsten-bronze family, is formed by bulk nucleation. This system looks promising to produce active nanostructured glasses as the tungsten-bronze type crystals have ferroelectric, electro-optical and non-linear optical properties. Preliminary measurements evidenced SHG activity in the crystallized glasses containing this phase.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
