• Journal of the Korean Crystal Growth and Crystal Technology
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• v.1 no.2
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• pp.71-78
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• 1991

The congruent composition of $LiNbO_3$ was determined by measuring Curie temperature($T_c$) of crystals and residual melt grown from the range 48.45 to 48.60mole%$Li_2O$ melts. The $T_c$ of $LiNbO_3$ varied with compositon largely. The variation of $T_c$ with composition was found to follow $T_c=l0.4184c^2-962. 996C + 23342$, where C is mole % LizO. DSC-1500 was used to measure $T_c$. Distribution coefficients for $LiNbO_3$$ LiNbO_3$ contains 48.52mole$Li_2O$ and has a measured Tc of $1145{\pm}^{\circ}C$

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.179-181
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• 1997

When grown the oxide single crystal including Li-ion, optimum oxygen condition is needed. Color and crack are caused in single crystal according too the change in the condition of the oxygen. LiTaO₃ crystals grown from off-composition of congruent melt composition under oxygen deficieny condition didn't generate any crack. LiNbO₃. LiTaO₃ crystals grown from congruent melt composition under optimum oxygen condition caused pale yellow color or colorless with no crack. Color gradually became colorless and generated cracks according to Oxygen excess.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.3 no.2
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• pp.99-106
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• 1993

A relationship $(T_c = -17.869C^2+1840.2C-46623)$ between Curie Temperature$(T_c)$ and (C), $Li_2O$ mole percent(%) was established from the measurement results of Curie temperature $(T_c)$) analysed by DTA(Differential Thermal Analysis) in the range from 48.50 to 49.00 $Li_2O$ mole %. Congruent melt composition of $LiTaO_3$ single crystal was to be 48.65 $Li_2O$ mole % and its Curie temperature was also determined to be $610{\pm}1^{\circ}C$ from the results of Curie temperature difference, ${\Delta}T (T_{c(Top)}-T{_c(Tail)})$ of Czochralski grown $LiTaO_3$ crystals and the distribution coefficient(k). The k was calculated from $LiO_2$ mole ratio of initial melt to final melt and initial crystal to final crystal in the range from 48.60 to 48.70 $Li_2O$ mole %.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.9 no.3
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• pp.267-272
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• 1999

Micro-defects in the undoped and MgO-doped $LiNbO_3$ single crystals, which were grown from a congruent melting composition (48.6 mol% $Li_2$O) by the CZ (Czochralski) method, were analyzed using microscopic techniques such as optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Effects of the dopant and g value (the fraction solidfied) on the domain structure and micro-defect were investigated to build a corelationship with a growth condition of crystal. It was observed that the micro-defect concentrated near the domain wall is caused by high stress. Especially, the micro-defect was observed to be biased toward a certain side of the domain wall.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1998.06a
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• pp.111-114
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• 1998

Lithium Niobate {{{{ { LiNbO}_{ 3} }}}} single crystals grown by Czichralski method at the congruent composition, have ferroelectric microdomains. These microdomins were investigated by chemical etching with hydrofluoric acid (HF) AND NITRIC ACID ({{{{ { HNO}_{3 } }}}}), and by us ing optical microscopy, scanning electron microscopy and atomic force microscopy

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.220-221
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• 1999

Single crystals of Yttrium Calcium Oxyborate (YCOB) doped with different concentrations of Er3+ and Yb3+ ions were growth by Czochralski method. High qualities of crystals in morphology and transparency were obtained . Analysis on crystal structure and lattice parameters were performed by X-ray diffraction method. It was found that congruent melting composition is YCA4.2O1.2(BO3)3. Absorption and fluorescence properties of grown crystals were also reported.

• Journal of the Korean Ceramic Society
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• v.31 no.1
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• pp.39-46
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• 1994

LiTaO3 single crystals were growth without cracking using Pt-Rh crucible and Ir crucible. The starting composition to get the melt of congruent melting composition, which has been dependent upon the experimental procedure, was taken after fixing the total growing process by the result of preliminary experiments. The Rh contamination from the Pt-Rh crucible was to be neglected if the crystal had been grown under inert atmosphere, which resulted in the crystal color being slightly yellow. This color was decolored after 24 hour's annealing at 1200℃ under air atmosphere. The optimum conditions for the crystal growing and the diameter control were so dependent upon the crucible material in spite of using the crucible of the same size. The liquid-solid interface of LiTaO3 crystal of 1" diameter has been flat if the rotation speed was 45rpm.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.12 no.1
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• pp.50-55
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• 2002

$Nd_2O_3$0.2~0.5 wt.% doped $LiNbO_3$single crystals were grown by the Czochralski method. The ZnO doping by 2~8 mole% can improve the resistance of optical damage. In this study, Nd : LiNbO$_3$ single crystals with the periodical domain structure were obtained by CZ method.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.6-17
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• 1997

Lithium niobate single crystals with various [Li]/[Nb] ratios were grown by the Czochralski method from melts having compositions varing between 48.6 ~ 58.0 mol % $Li_2O$. A vapor transport equilibration technique has been used to improve the homogeneity and adjust the [Li]/[Nb] ratio in small $LiNbO_3$ single crystals grown by the Czochralski method. When equilibrated with a Li-rich powder (65 mol%$Li_2O$), containing a mixture of $LiNbO_3$ and $Li_3NbO_4$, crystals of nearly stoichiometric composition can be obtained. This was established by studying the composition dependence of the following properties; lineshape, intensity and linewidth for the electron paramagnetic resonance (EPR) of $Fe^{3+}$ energy of the fundamental absorption edge and $OH^-$ absorption spectra.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.2 no.1
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• pp.20-29
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• 1992

In $BaTiO_3-NaNbO_3$ system, complete series of solid solution occurs and $30BaTiO_3{cdot}70NaNbO_3$ composition is congruently melted. Single crystals of $30BaTiO_3{cdot}70NaNbO_3$, composition were grown by Czochralski method in this investigation. Single crystals with dimensions of 15 - 20mm diameter and 20 - 30mm length, were grown at the pulling rate of 2.0mm/h and the rotation rate of 5.0 -l0rpm. Core structures were found in the grown crystals and inclusions, cellular boundaries existed at the core region. The origin of core occuring was unstability of the crystal- melt interface due to the poor conductivity of latent heat through the crystal during the crystal growing process. Obtained crystals were optically homogeneous except the core region and showed high optical transmittance in the visible range.