The method for pulling large diameter single crystals with the abovesaid difficulties avoided is developed.Here the free melt surface does not depend on the growing crystal diameter and remains minimal during the whol...The method for pulling large diameter single crystals with the abovesaid difficulties avoided is developed.Here the free melt surface does not depend on the growing crystal diameter and remains minimal during the whole growing process.The essence of this method is that at the stage of radial crystal growth the melt level in the crucible of a variable cross-section(for instance,in a conical crucible)is raised.展开更多
Potassium Lithium Niobate (KLN) crystal belongs to tetragonal system and is ferroelectric crystal,which point group is 4mm and space group is P4bm .The melt point of KLN crystal is about 1050℃.KLN crystal possesses t...Potassium Lithium Niobate (KLN) crystal belongs to tetragonal system and is ferroelectric crystal,which point group is 4mm and space group is P4bm .The melt point of KLN crystal is about 1050℃.KLN crystal possesses tungsten bronze structure and its structure general expression is(A 1) 2(A 2) 4C 4(B 1) 2(B 4) 8O 3.KLN crystal is full fill up tungsten bronze structure crystal,in which the light of transmission band is 0.35-5.0μm.KLN crystal has excellent electro optical and nonlinear property and is superior double frequency crystal material for blue light.KLN crystal also is acoustic surface wave and photorefractive material.KLN crystal cracks easily during it grows.But when KLN crystal is doped in Mn 2O 3 to grow Mn∶KLN crystal,the crystal crack is reduced and the photorefractive property of the crystal is enhanced.KLN system is solid solution system and not congruent composition.The compounding ratio of Mn∶KLN crystal which we grew is 47.4mol% Nb 2O 5,17.3mol% Li 2CO 3,35mol% K 2CO 3 and 0.1mol% Mn 2O 3.The purity of Nb 2O 5,Li 2CO 3,K 2CO 3 and Mn 2O 3 is all 99.99%.Czochralski method was used to grow Mn∶KLN crystal.The technical parameters include the axial direction temperature gradient,the crystal growth rate and the rotation rate.Mn∶KLN crystal with 6mm×8mm×20mm size was grown in the condition that the axial direction temperature gradient is 30℃-40℃,the crystal growth rate is 0.5mm/h and the rotation rate is 10-15r/min.KLN crystal is one dimension ferroelectrics crystal.It has a paraelectrics ferroelectrics phase transition point curie point.So the crystal needs to be polarized in manual work.The direct current field was used to force the self polarization Ps in the same direction and the crystal turn to single domain.Before polarization,the c face needs to be confirmed exactly.The platinum pole was pasted to the two surfaces of c face and the direct current voltage about 220V was added the pole as the polarization outer electrical field.The polarization temperature is 460℃ and the polarization current density is 2mA/cm 2 .The thermal analyzer in TAS100 model was used to analyze the thermal expansion character of Mn∶KLN crystal and ascertain that the curie point of Mn∶KLN crystal is 435℃.It can be seen from the measurement result that the change of thermal expansion rate of Mn∶KLN crystal is smaller than that of pure KLN crystal. So doping Mn 2O 3 in KLN crystal to grow Mn∶KLN crystal can reduce the crack of the crystal.展开更多
ZnO(4mol%),In 2O 3(1mol%)and Fe 2O 3(0.05mol%)were doped in LiNbO 3 and Czochralski method was used to grow Zn∶In∶Fe∶LiNbO 3 crystal.The diameter of the crystal we grew is 30mm.The technology parameter we took is t...ZnO(4mol%),In 2O 3(1mol%)and Fe 2O 3(0.05mol%)were doped in LiNbO 3 and Czochralski method was used to grow Zn∶In∶Fe∶LiNbO 3 crystal.The diameter of the crystal we grew is 30mm.The technology parameter we took is that the axial temperature gradient is 40℃/cm,the growth rate is 1mm/h, the rotation rate is 15-25r/min,the temperature of polarization is 1220℃ and the current density of polarization is 5mA/cm 2.The wafer dimension is 10mm×10mm×3mm and was covered in Li 2CO 3 powder to reduce.The reduction temperature is 500℃ and reduction time is 30 hours. OH - stretch vibration transmission spectra were measured by Fourier infrared spectrophotometer. There are two absorption peaks in OH - spectra of Zn∶In∶Fe∶LiNbO 3,in which one is at 3534cm -1 (2.83μm) and the other is at 3505cm -1 (2.85μm).The peak at 2.85μm is far lower than that at 2.83μm. Because of the threshold effect of Zn 2+ and In 3+ ,the peak at 2.83μm is generated and the peak at 2.85μm is related with Fe 3+ .In LiNbO 3 only doped with Fe,Li + site is taken place by Fe 3+ .When doping Zn 2+ and In 3+ in high concentration,these two ions take place Nb that is at Li site and Fe 3+ substitutes for Nb 5+ at the same time.The interaction between Fe 3+ and OH - make the OH - peak shift to 2.85μm.展开更多
文摘The method for pulling large diameter single crystals with the abovesaid difficulties avoided is developed.Here the free melt surface does not depend on the growing crystal diameter and remains minimal during the whole growing process.The essence of this method is that at the stage of radial crystal growth the melt level in the crucible of a variable cross-section(for instance,in a conical crucible)is raised.
文摘Potassium Lithium Niobate (KLN) crystal belongs to tetragonal system and is ferroelectric crystal,which point group is 4mm and space group is P4bm .The melt point of KLN crystal is about 1050℃.KLN crystal possesses tungsten bronze structure and its structure general expression is(A 1) 2(A 2) 4C 4(B 1) 2(B 4) 8O 3.KLN crystal is full fill up tungsten bronze structure crystal,in which the light of transmission band is 0.35-5.0μm.KLN crystal has excellent electro optical and nonlinear property and is superior double frequency crystal material for blue light.KLN crystal also is acoustic surface wave and photorefractive material.KLN crystal cracks easily during it grows.But when KLN crystal is doped in Mn 2O 3 to grow Mn∶KLN crystal,the crystal crack is reduced and the photorefractive property of the crystal is enhanced.KLN system is solid solution system and not congruent composition.The compounding ratio of Mn∶KLN crystal which we grew is 47.4mol% Nb 2O 5,17.3mol% Li 2CO 3,35mol% K 2CO 3 and 0.1mol% Mn 2O 3.The purity of Nb 2O 5,Li 2CO 3,K 2CO 3 and Mn 2O 3 is all 99.99%.Czochralski method was used to grow Mn∶KLN crystal.The technical parameters include the axial direction temperature gradient,the crystal growth rate and the rotation rate.Mn∶KLN crystal with 6mm×8mm×20mm size was grown in the condition that the axial direction temperature gradient is 30℃-40℃,the crystal growth rate is 0.5mm/h and the rotation rate is 10-15r/min.KLN crystal is one dimension ferroelectrics crystal.It has a paraelectrics ferroelectrics phase transition point curie point.So the crystal needs to be polarized in manual work.The direct current field was used to force the self polarization Ps in the same direction and the crystal turn to single domain.Before polarization,the c face needs to be confirmed exactly.The platinum pole was pasted to the two surfaces of c face and the direct current voltage about 220V was added the pole as the polarization outer electrical field.The polarization temperature is 460℃ and the polarization current density is 2mA/cm 2 .The thermal analyzer in TAS100 model was used to analyze the thermal expansion character of Mn∶KLN crystal and ascertain that the curie point of Mn∶KLN crystal is 435℃.It can be seen from the measurement result that the change of thermal expansion rate of Mn∶KLN crystal is smaller than that of pure KLN crystal. So doping Mn 2O 3 in KLN crystal to grow Mn∶KLN crystal can reduce the crack of the crystal.
文摘ZnO(4mol%),In 2O 3(1mol%)and Fe 2O 3(0.05mol%)were doped in LiNbO 3 and Czochralski method was used to grow Zn∶In∶Fe∶LiNbO 3 crystal.The diameter of the crystal we grew is 30mm.The technology parameter we took is that the axial temperature gradient is 40℃/cm,the growth rate is 1mm/h, the rotation rate is 15-25r/min,the temperature of polarization is 1220℃ and the current density of polarization is 5mA/cm 2.The wafer dimension is 10mm×10mm×3mm and was covered in Li 2CO 3 powder to reduce.The reduction temperature is 500℃ and reduction time is 30 hours. OH - stretch vibration transmission spectra were measured by Fourier infrared spectrophotometer. There are two absorption peaks in OH - spectra of Zn∶In∶Fe∶LiNbO 3,in which one is at 3534cm -1 (2.83μm) and the other is at 3505cm -1 (2.85μm).The peak at 2.85μm is far lower than that at 2.83μm. Because of the threshold effect of Zn 2+ and In 3+ ,the peak at 2.83μm is generated and the peak at 2.85μm is related with Fe 3+ .In LiNbO 3 only doped with Fe,Li + site is taken place by Fe 3+ .When doping Zn 2+ and In 3+ in high concentration,these two ions take place Nb that is at Li site and Fe 3+ substitutes for Nb 5+ at the same time.The interaction between Fe 3+ and OH - make the OH - peak shift to 2.85μm.
