Effects of Nano-LiTaO(3) Crystallization on the Dielectric and Optical Properties in Er(3+)-Doped Li(2)O-Ta(2)O(5)-SiO(2)-Al(2)O(3) Glasses

The precursor glass of LiTaO(3) nanocrystals was prepared in a new Er(3+)-doped Li(2)O-Ta(2)O(5)-SiO(2)-Al(2)O(3) system by the melt-quench technique. They were isothermally crystallized at 680 degrees C for 3-100 h to obtain nanostructured glass-ceramics. The X-ray diffraction and transmission electron microscopy confirm the nanocrystallization of LiTaO(3) (16-34 nm) yielding transparent glass-ceramics. A steep rise in the dielectric constant with the heat-treatment time is attributed to ferroelectric LiTaO(3) crystallization. Photoluminescence spectra exhibit the (4)I(13/2) -> (4)I(15/2) emission transition of Er(3+) ions at 1570 nm when excited at 984 nm. Its intensity and lifetime decrease with an increase in heat-treatment time due to concentration quenching effect

Structure, dielectric and optical properties of Nd(3+)-doped LiTaO(3) transparent ferroelectric glass-ceramic nanocomposites

Here, we present the structural, dielectric and optical properties of neodymium ion (Nd(3+)) doped novel transparent glass-ceramics containing LiTaO(3) narrocrystals in the Li(2)O-Ta(2)O(5)-SiO(2)-Al(2)O(3) (LTSA) glass system prepared by the melt-quenching technique. The precursor glasses were isothermally crystallized at 680 degrees C for 3-100 h. following the differential thermal analysis (DTA) data, to obtain narrostructured glass-ceramics. They were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Fourier transform infrared reflection spectra (FTIRRS), optical absorption and luminescence spectroscopy along with dielectric constant measurements. XRD, FESEM, TEM and FTIRRS confirm the nanocrystallization of LiTaO(3) (14-36 nm) in the LTSA glass matrix. A steep increase in dielectric constant (epsilon(r)) of glass-ceramics with heat-treatment time is observed due to high dielectric constant ferroelectric LiTaO(3) formation. The measured NIR photoluminescence spectra have exhibited emission transitions of (4)F(3/2) -> (4)I(J) (J = 9/2, 11/2 and 13/2) from Nd(3+) ions upon excitation at 809 nm. it is observed that the photoluminescent intensity and excited state ((4)F(3/2)) lifetime of Nd(3+) ions decrease with increase in heat-treatment time due to concentration quenching effect. The absorption spectra and fluorescence measurements reveal that the incorporation of Nd(3+) ions in the LiTaO(3) crystal lattice in the oxide glassy matrix is important for obtaining desirable fluorescence performance of the material. (C) 2009 Elsevier B.V. All rights reserved

Second harmonic generation in ferroelectric LiTaO3 and KNbO3 containing bulk nano glass-ceramics

The precursor glasses in (mol%) 25.53Li2O-21.53Ta2O5- 35.29SiO2-17.65Al2O3 (LTSA) and 25K2O-25Nb2O5-50SiO2 (KNS) glass systems were prepared by the melt-quench technique. Ferroelectric LiTaO3 (LT) and KNbO3 (KN) crystallites containing bulk nano glass-ceramics have been prepared by controlled crystallization of these precursor glasses respectively. Second harmonic generations (SHG) at 532 nm in both the glass-ceramics have been realized under fundamental beam of Nd3+:YAG laser source (1064 nm). The SHG power output has been found to increase up to 14 and 62.4 nJ with variation of rotation angle for LT and KN bulk nano glassceramics respectively due to orientation of ferroelectric domains under applied field

Effects of nano-LiTaO<SUB>3</SUB> crystallization on the dielectric and optical properties in Er<SUP>3+</SUP>-doped Li<SUB>2</SUB>O-Ta<SUB>2</SUB>O<SUB>5</SUB>-SiO<SUB>2</SUB>-Al<SUB>2</SUB>O<SUB>3</SUB> glasses

The precursor glass of LiTaO3 nanocrystals was prepared in a new Er3+-doped Li2O-Ta2O5-SiO2-Al2O3 system by the melt-quench technique. They were isothermally crystallized at 680°C for 3-100 h to obtain nanostructured glass-ceramics. The X-ray diffraction and transmission electron microscopy confirm the nanocrystallization of LiTaO3 (16-34 nm) yielding transparent glass-ceramics. A steep rise in the dielectric constant with the heat-treatment time is attributed to ferroelectric LiTaO3 crystallization. Photoluminescence spectra exhibit the 4l13/2&#8594; 4l15/2 emission transition of Er3+ ions at 1570 nm when excited at 984 nm. Its intensity and lifetime decrease with an increase in heat-treatment time due to concentration quenching effect

Structure, dielectric and optical properties of Nd<SUP>3+</SUP>-doped LiTaO<SUB>3</SUB> transparent ferroelectric glass-ceramic nanocomposites

Here, we present the structural, dielectric and optical properties of neodymium ion (Nd3+) doped novel transparent glass-ceramics containing LiTaO3 nanocrystals in the Li2O-Ta2O5-SiO2-Al2O3 (LTSA) glass system prepared by the melt-quenching technique. The precursor glasses were isothermally crystallized at 680 °C for 3-100 h, following the differential thermal analysis (DTA) data, to obtain nanostructured glass-ceramics. They were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), Fourier transform infrared reflection spectra (FTIRRS), optical absorption and luminescence spectroscopy along with dielectric constant measurements. XRD, FESEM, TEM and FTIRRS confirm the nanocrystallization of LiTaO3 (14-36 nm) in the LTSA glass matrix. A steep increase in dielectric constant (ε r) of glass-ceramics with heat-treatment time is observed due to high dielectric constant ferroelectric LiTaO3 formation. The measured NIR photoluminescence spectra have exhibited emission transitions of 4F3/2 → 4IJ (J = 9/2, 11/2 and 13/2) from Nd3+ ions upon excitation at 809 nm. It is observed that the photoluminescent intensity and excited state (4F3/2) lifetime of Nd3+ ions decrease with increase in heat-treatment time due to concentration quenching effect. The absorption spectra and fluorescence measurements reveal that the incorporation of Nd3+ ions in the LiTaO3 crystal lattice in the oxide glassy matrix is important for obtaining desirable fluorescence performance of the material