Unique crystallization and formation of nonlinear optical (Na,K)NbO 3 phases in (Na,K)NbGeO5 glasses

K. Narita, Y. Takahashi, Yasuhiko Benino, T. Fujiwara, T. Komatsu

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

Crystalline phases and second-order optical nonlinearities in crystallized glasses of (Na,K)NbGeO5 (i.e., xNa2O·(25-x)K 2O·25Nb2O5·50GeO2) are examined. The molar volume of the glasses decreases with increasing Na 2O content, indicating that the glass structure of NaNbGeO 5 glass is more compact compared with KNbGeO5 glass. The optical basicity of the glasses is 0.94-0.95, implying that chemical bonds among constituents ions are basically very ionic. (Na,K)NbGeO5 glasses exhibit a unique crystallization depending on the Na2O/K2O ratio. The main crystalline phase in crystallized NaNbGeO5 glass is the NaNbGeO5 phase. KNbGeO5 glass shows a prominent bulk nanocrystallization giving nanocrystals of the K3.8Nb 5Ge3O20.4 phase. A glass with the composition of K3.8Nb5Ge3O20.4 also shows a bulk nanocrystallization. The crystallized glasses with K3.8Nb 5Ge3O20.4 and NaNbGeO5 crystalline phases do not show a second harmonic generation (SHG) at room temperature. The nonlinear optical (Na,K)NbO3 phases showing a SHG are formed at the surface (∼5 μm) of crystallized glasses with x=15 and 20, giving an orientation of the (110) plane. The present study suggests the presence of mixed-alkali effect in the crystallization behavior of (Na,K)NbGeO5 glasses.

Original languageEnglish
Pages (from-to)393-400
Number of pages8
JournalOptical Materials
Volume25
Issue number4
DOIs
Publication statusPublished - May 2004
Externally publishedYes

Fingerprint

Crystallization
crystallization
Glass
glass
Nanocrystallization
Harmonic generation
Crystalline materials
harmonic generations
Chemical bonds
Alkalies
Alkalinity
chemical bonds
Density (specific gravity)
Nanocrystals
alkalies
nanocrystals
nonlinearity
Ions

Keywords

  • (Na,K)NbO
  • Nanocrystallization
  • Optical basicity
  • Second harmonic generation

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

Cite this

Unique crystallization and formation of nonlinear optical (Na,K)NbO 3 phases in (Na,K)NbGeO5 glasses. / Narita, K.; Takahashi, Y.; Benino, Yasuhiko; Fujiwara, T.; Komatsu, T.

In: Optical Materials, Vol. 25, No. 4, 05.2004, p. 393-400.

Research output: Contribution to journalArticle

Narita, K. ; Takahashi, Y. ; Benino, Yasuhiko ; Fujiwara, T. ; Komatsu, T. / Unique crystallization and formation of nonlinear optical (Na,K)NbO 3 phases in (Na,K)NbGeO5 glasses. In: Optical Materials. 2004 ; Vol. 25, No. 4. pp. 393-400.
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AB - Crystalline phases and second-order optical nonlinearities in crystallized glasses of (Na,K)NbGeO5 (i.e., xNa2O·(25-x)K 2O·25Nb2O5·50GeO2) are examined. The molar volume of the glasses decreases with increasing Na 2O content, indicating that the glass structure of NaNbGeO 5 glass is more compact compared with KNbGeO5 glass. The optical basicity of the glasses is 0.94-0.95, implying that chemical bonds among constituents ions are basically very ionic. (Na,K)NbGeO5 glasses exhibit a unique crystallization depending on the Na2O/K2O ratio. The main crystalline phase in crystallized NaNbGeO5 glass is the NaNbGeO5 phase. KNbGeO5 glass shows a prominent bulk nanocrystallization giving nanocrystals of the K3.8Nb 5Ge3O20.4 phase. A glass with the composition of K3.8Nb5Ge3O20.4 also shows a bulk nanocrystallization. The crystallized glasses with K3.8Nb 5Ge3O20.4 and NaNbGeO5 crystalline phases do not show a second harmonic generation (SHG) at room temperature. The nonlinear optical (Na,K)NbO3 phases showing a SHG are formed at the surface (∼5 μm) of crystallized glasses with x=15 and 20, giving an orientation of the (110) plane. The present study suggests the presence of mixed-alkali effect in the crystallization behavior of (Na,K)NbGeO5 glasses.

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