Well-formed crystals of emerald, Be3AI2Si6O18:Cr, were easily grown from an Na2O-MoO3 flux by an isothermal technique. The crystal growth was conducted by heating a mixture of solute and flux at 1 100 ℃ for 24 h. The...Well-formed crystals of emerald, Be3AI2Si6O18:Cr, were easily grown from an Na2O-MoO3 flux by an isothermal technique. The crystal growth was conducted by heating a mixture of solute and flux at 1 100 ℃ for 24 h. The evaporation loss of flux depended on the amount of Na2O added to MoO3. Emerald crystals of lengths up to 2.1 mm and widths of 1. 4 mm were grown. The crystal sizes were dependent on the evaporation loss of the flux. The obtained crystals were transparent and exhibited the typical emerald-green color. The form of the emerald crystals was a twelve-sided prism bounded by well-developed faces. The aspect ratios were in the region of 1. 4 to 2. 3. The density was (2. 64±0.02) g/cm3. The IR absorption bands were in good agreement with the literature data.展开更多
Nd3+:GdAl3(BO3)4 (NGAB) crystal with the size of 30 mm was grown from the solvent system of K2O-Gd2O3-MoO3-B2O3 by combining accelerated seed rotation technology with medium seeded solution growth (MSSG) method, and i...Nd3+:GdAl3(BO3)4 (NGAB) crystal with the size of 30 mm was grown from the solvent system of K2O-Gd2O3-MoO3-B2O3 by combining accelerated seed rotation technology with medium seeded solution growth (MSSG) method, and its crystal structure has been determined by X-ray powder diffraction. It crystallizes in the trigonal system, space group R32 with a = 9.2734(2), c = 7.2438(1) ? V = 538 ?, Z = 3 and Dc = 4.379 g/cm3. The absorption and emission spectra of NGAB in the function of s and polarizations at room temperature have been measured. UV generation tuneable in 378～382 nm, green (531 nm) generation and blue generation tuneable in 436～443 nm as well as red (669 nm) generation by self-frequency changing were obtained with the output of 105, 119.5, 445 and 19 mJ/pulse, respectively, when the crystal was pumped by a dye laser.展开更多
Ca 4GdO(BO 3) 3 (GdCOB) single crystal is a new nonlinear optical crystal whi ch was discovere d in recent years.It has a large effective nonlinear optical coefficient,a high damage threshold,good chemical and physica...Ca 4GdO(BO 3) 3 (GdCOB) single crystal is a new nonlinear optical crystal whi ch was discovere d in recent years.It has a large effective nonlinear optical coefficient,a high damage threshold,good chemical and physical properties and insensitivity to moi sture.Its moderate birefringence is favorable for phase matching.These propertie s make it possible to obtain frequency doubling laser of 1.064μm.By doping,it may be a excellent self frequency doubling crystal.Transparent single crystals GdCOB as needle were grown by the flux method. Chemical compounds Gd 2O 3,CaCO 3,B 2O 3 and H 3BO 3 were used as starti ng materials.By many experiments,with different ratio,it is proper to mix the st arting materials according to the reaction Gd 2O 3+8CaCO 3+6H 3BO 3=2 Ca 4 G dO(BO 3) 3+8CO 2+9H 2O.PbO was used as the main flux ,adding moderate PbF 2 , and B 2O 3.B 2O 3 also can be used as initial compounds and it is also a goo d solvent,but at high temperature,it has heavy viscousness.The crystals grown fr om B 2O 3 commonly has inclusion,so we used H 3BO 3 instead of B 2O 3.At t he same time,we considered that at high temperature H 3BO 3 will be decomposed and evaporated,which would make the initial composition change.When proper B 2 O 3 was added,it not noly can be used as solvent,but also can stabilize solvent component.The melt was contained in a platinum crucible.After holding the melt 1200℃ for 24h,it was cooled at a rate of 0.5℃ per hour.Single crystals GdCOB were obtained.With microscope,we observed the crystals have defects such as inc lusion and bubbles,which are related to rapid cooling,imperfect melt transport a nd unstable temperature.展开更多
Pulling growth technique serves as a popular method to grow congruent melting single crystals with multiscale sizes ranging from micrometers to centimeters.In order to obtain high quality single crystals,the crystal c...Pulling growth technique serves as a popular method to grow congruent melting single crystals with multiscale sizes ranging from micrometers to centimeters.In order to obtain high quality single crystals,the crystal constituents would be arranged at the lattice sites by precisely controlling the crystal growth process.Growing interface is the position where the phase transition of crystal constituents occurs during pulling growth process.The precise control of energy at the growing interface becomes a key technique in pulling growth.In this work,we review some recent advances of pulling technique towards rare earth single crystal growth.In Czochralski pulling growth,the optimized growth parameters were designed for rare earth ions doped Y_3Al_5O_(12)and Ce:(Lu_(1-x)Y_x)_2Si O_5on the basis of anisotropic chemical bonding and isotropic mass transfer calculations at the growing interface.The fast growth of high quality rare earth single crystals is realized by controlling crystallization thermodynamics and kinetics in different size zones.On the other hand,the micro pulling down technique can be used for high throughput screening novel rare earth optical crystals.The growth interface control is realized by improving the crucible bottom and temperature field,which favors the growth of rare earth crystal fibers.The rare earth laser crystal fiber can serve as another kind of laser gain medium between conventional bulk single crystal and glass fiber.The future work on pulling technique might focus on the mass production of rare earth single crystals with extreme size and with the size near that of devices.展开更多
Large crystal growth of Cr-doped h-YMnO3has been investigated by using a high pressure optical floatingzone method. The size of the grown crystals is typically 60–70 mm in length and 4–5 mm in diameter. The structur...Large crystal growth of Cr-doped h-YMnO3has been investigated by using a high pressure optical floatingzone method. The size of the grown crystals is typically 60–70 mm in length and 4–5 mm in diameter. The structure of the grown crystals is analyzed by powder X-ray diffraction and scanning electron microscopy.The defects in the as-grown crystals, including low-angle grain boundary and inclusions are studied. An off-stoichiometric phenomenon is found with a slight Cr deficiency in different parts. The relationship between defects and growth conditions during crystal growth is also discussed. The magnetic properties show spin-glass phase features with weak ferromagnetic behavior below 30 K.展开更多
In this paper,we present a model for grown-in point defects inside indium antimonide crystals grown by the Czochralski(CZ)technique.Our model is similar to the ones used for silicon crystal,which includes the Fickian ...In this paper,we present a model for grown-in point defects inside indium antimonide crystals grown by the Czochralski(CZ)technique.Our model is similar to the ones used for silicon crystal,which includes the Fickian diffusion and a recombina-tion mechanism.This type of models is used for the first time to analyze grown-in point defects in indium antimonide crystals.The temperature solution and the advance of the melt-crystal interface,which determines the time-dependent domain of the model,are based on a recently derived perturbation model.We propose a finite difference method which takes into account the moving interface.We study the effect of thermal flux on the point defect patterns during and at the end of the growth process.Our results show that the concentration of excessive point defects is positively correlated to the heat flux in the system.展开更多
文摘Well-formed crystals of emerald, Be3AI2Si6O18:Cr, were easily grown from an Na2O-MoO3 flux by an isothermal technique. The crystal growth was conducted by heating a mixture of solute and flux at 1 100 ℃ for 24 h. The evaporation loss of flux depended on the amount of Na2O added to MoO3. Emerald crystals of lengths up to 2.1 mm and widths of 1. 4 mm were grown. The crystal sizes were dependent on the evaporation loss of the flux. The obtained crystals were transparent and exhibited the typical emerald-green color. The form of the emerald crystals was a twelve-sided prism bounded by well-developed faces. The aspect ratios were in the region of 1. 4 to 2. 3. The density was (2. 64±0.02) g/cm3. The IR absorption bands were in good agreement with the literature data.
基金Supported by the Natural Science Foundation of Fujian province (2000F007)
文摘Nd3+:GdAl3(BO3)4 (NGAB) crystal with the size of 30 mm was grown from the solvent system of K2O-Gd2O3-MoO3-B2O3 by combining accelerated seed rotation technology with medium seeded solution growth (MSSG) method, and its crystal structure has been determined by X-ray powder diffraction. It crystallizes in the trigonal system, space group R32 with a = 9.2734(2), c = 7.2438(1) ? V = 538 ?, Z = 3 and Dc = 4.379 g/cm3. The absorption and emission spectra of NGAB in the function of s and polarizations at room temperature have been measured. UV generation tuneable in 378～382 nm, green (531 nm) generation and blue generation tuneable in 436～443 nm as well as red (669 nm) generation by self-frequency changing were obtained with the output of 105, 119.5, 445 and 19 mJ/pulse, respectively, when the crystal was pumped by a dye laser.
文摘Ca 4GdO(BO 3) 3 (GdCOB) single crystal is a new nonlinear optical crystal whi ch was discovere d in recent years.It has a large effective nonlinear optical coefficient,a high damage threshold,good chemical and physical properties and insensitivity to moi sture.Its moderate birefringence is favorable for phase matching.These propertie s make it possible to obtain frequency doubling laser of 1.064μm.By doping,it may be a excellent self frequency doubling crystal.Transparent single crystals GdCOB as needle were grown by the flux method. Chemical compounds Gd 2O 3,CaCO 3,B 2O 3 and H 3BO 3 were used as starti ng materials.By many experiments,with different ratio,it is proper to mix the st arting materials according to the reaction Gd 2O 3+8CaCO 3+6H 3BO 3=2 Ca 4 G dO(BO 3) 3+8CO 2+9H 2O.PbO was used as the main flux ,adding moderate PbF 2 , and B 2O 3.B 2O 3 also can be used as initial compounds and it is also a goo d solvent,but at high temperature,it has heavy viscousness.The crystals grown fr om B 2O 3 commonly has inclusion,so we used H 3BO 3 instead of B 2O 3.At t he same time,we considered that at high temperature H 3BO 3 will be decomposed and evaporated,which would make the initial composition change.When proper B 2 O 3 was added,it not noly can be used as solvent,but also can stabilize solvent component.The melt was contained in a platinum crucible.After holding the melt 1200℃ for 24h,it was cooled at a rate of 0.5℃ per hour.Single crystals GdCOB were obtained.With microscope,we observed the crystals have defects such as inc lusion and bubbles,which are related to rapid cooling,imperfect melt transport a nd unstable temperature.
基金supported by Jilin Province Science and Technology Development Project(Grant No.21521092JH)
文摘Pulling growth technique serves as a popular method to grow congruent melting single crystals with multiscale sizes ranging from micrometers to centimeters.In order to obtain high quality single crystals,the crystal constituents would be arranged at the lattice sites by precisely controlling the crystal growth process.Growing interface is the position where the phase transition of crystal constituents occurs during pulling growth process.The precise control of energy at the growing interface becomes a key technique in pulling growth.In this work,we review some recent advances of pulling technique towards rare earth single crystal growth.In Czochralski pulling growth,the optimized growth parameters were designed for rare earth ions doped Y_3Al_5O_(12)and Ce:(Lu_(1-x)Y_x)_2Si O_5on the basis of anisotropic chemical bonding and isotropic mass transfer calculations at the growing interface.The fast growth of high quality rare earth single crystals is realized by controlling crystallization thermodynamics and kinetics in different size zones.On the other hand,the micro pulling down technique can be used for high throughput screening novel rare earth optical crystals.The growth interface control is realized by improving the crucible bottom and temperature field,which favors the growth of rare earth crystal fibers.The rare earth laser crystal fiber can serve as another kind of laser gain medium between conventional bulk single crystal and glass fiber.The future work on pulling technique might focus on the mass production of rare earth single crystals with extreme size and with the size near that of devices.
基金financial support of the National Natural Science Foundation of China (Nos. 51471135 and 51301133)the National Key Research and Development Program (No. 2016YFB1100101)Shaanxi International Cooperation Program
文摘Large crystal growth of Cr-doped h-YMnO3has been investigated by using a high pressure optical floatingzone method. The size of the grown crystals is typically 60–70 mm in length and 4–5 mm in diameter. The structure of the grown crystals is analyzed by powder X-ray diffraction and scanning electron microscopy.The defects in the as-grown crystals, including low-angle grain boundary and inclusions are studied. An off-stoichiometric phenomenon is found with a slight Cr deficiency in different parts. The relationship between defects and growth conditions during crystal growth is also discussed. The magnetic properties show spin-glass phase features with weak ferromagnetic behavior below 30 K.
文摘In this paper,we present a model for grown-in point defects inside indium antimonide crystals grown by the Czochralski(CZ)technique.Our model is similar to the ones used for silicon crystal,which includes the Fickian diffusion and a recombina-tion mechanism.This type of models is used for the first time to analyze grown-in point defects in indium antimonide crystals.The temperature solution and the advance of the melt-crystal interface,which determines the time-dependent domain of the model,are based on a recently derived perturbation model.We propose a finite difference method which takes into account the moving interface.We study the effect of thermal flux on the point defect patterns during and at the end of the growth process.Our results show that the concentration of excessive point defects is positively correlated to the heat flux in the system.
