| Strontium titanate is a typical perovskite structure compound with excellent photoelectric properties.It can be used in optical lens,infrared window material and artificial gemstone,and it is the standard substrate for the epitaxial growth of high temperature superconducting thin film.The SrTiO3 single crystal is usually grown by the flame fusion method.This method is very strict on the morphology,particle size and fluidity of the raw powder.The raw material of SrTiO3 powder used in the traditional flame fusion method is prepared by liquid chemical precipitation method.Powder agglomeration appeared in this method.And the low preparation efficiency of the powder system can not meet the large commercial demand of the flame fusion method.In addition,the traditional fusion melting equipment depends on manual operation by manual experience,so the process parameters are unstable and the success rate of crystal growth is low.In this paper,solid phase method was used to prepare SrTiO3 powder material,whose particle size,morphology and fluidity meet the requirements of flame melting method.It has the advantages of simple process,high purity,high yield and high efficiency.At the same time,the single crystal furnace system was precisely controlled by computer,and a commercially available SrTiO3 single crystal was successfully prepared.And established a stable process parameters,the success rate of crystal growth increased to 90%.After wet ball milling,SrTiO3 powder was synthesized by high temperature solid phase.SrCO3 and TiO2 were used as raw materials and 1%PAA-NH4 was added as grinding aids in mixed powder.Then the mixed powder was milled for 24 hours.After ball milling,the block shape SrTiO3 powder can be obtained by holding at 1200? for 2 hours.The average particle size of the SrTiO3 powder is 0.26 ?m.The fluidity index of the SrTiO3 powder is 53.5,and the particle size distribution is narrow,which can meet the requirements of the single crystal furnace.The temperature and pressure distribution in the combustion chamber of single crystal furnace was simulated and calculated by fluent software in this experiment.According to the calculation results,it can be determined that the observation hole of the furnace body was set at 127 mm from the nozzle hole.The melting cap temperature can be controlled by H2 flow,but the O2 flow has little effect on the temperature,and the melting cap temperature will be reduced when the O2 flow exceed 9 L/min.The results can also be determined that the best sizes of the H2 and O2 nozzle holes were 2.88 mm and 5 mm,respectively.SrTiO3 single crystal was prepared by flame fusion method in this experiment.The single crystal of SrTiO3 grown at 10 mm/h speed was prepared under the conditions of H2 and O2,the flow rate were 24 L/min and 9 L/min,respectively.And it had a diameter of 25 mm and a length of 50 mm.The density of SrTiO3 crystal was 5.1161 g/cm3,and the hardness of Vivtorinox was 539 Hv.The infrared transmittance of the crystal was 60%. |
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