TY - JOUR
T1 - Unique crystallization and formation of nonlinear optical (Na,K)NbO 3 phases in (Na,K)NbGeO5 glasses
AU - Narita, K.
AU - Takahashi, Y.
AU - Benino, Y.
AU - Fujiwara, T.
AU - Komatsu, T.
N1 - Funding Information:
This work was supported with a Grant of Nippon Sheet Glass Foundation for Materials Science and Engineering, and a Grant-in-Aid for Scientific Research from the Ministry of Education, Science, Sports and Culture, Japan, and the 21st Century Center of Excellence (COE) Program in Nagaoka University of Technology.
PY - 2004/5
Y1 - 2004/5
N2 - 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.
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.
KW - (Na,K)NbO
KW - Nanocrystallization
KW - Optical basicity
KW - Second harmonic generation
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U2 - 10.1016/j.optmat.2003.10.003
DO - 10.1016/j.optmat.2003.10.003
M3 - Article
AN - SCOPUS:1842833384
SN - 0925-3467
VL - 25
SP - 393
EP - 400
JO - Optical Materials
JF - Optical Materials
IS - 4
ER -