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ＭｇＡｌ２Ｏ４晶体是一种高熔点（２１３０℃）、高硬度（莫氏８）的晶体材料。属面心立方结构，空间群为Ｆｄ３ｍ，晶格常数为０．８０８５ｎｍ。该晶格是一种优良的传声介质材料，在微波段的声衰减低，用它制作的微波延迟线插入损耗小。另外，与Ｓｉ的晶格匹配性能好，其膨胀系数也与Ｓｉ相近，因而外延Ｓｉ膜的形变歪扭小，制作的大规模超高速集成电路速度比用蓝宝石制作的速度要快。近来，国外又用ＭｇＡｌ２Ｏ４晶体作超导材料，效果很好。但是ＭｇＡｌ２Ｏ４晶体内部容易出现几种缺陷，对晶体实际应用影响很大。本工作针对ＭｇＡｌ２Ｏ４晶体中几种缺陷进行研究。在同一种尖晶石的熔体中生长出的晶体，有两个晶格常数，两种结构共存于同一晶体中的情况，而晶格常数的值取决于尖晶石组分的摩尔比，引起晶体在生长过程中晶体局部首先溶解及熔液温度无规律起伏，当两种尖晶石在晶格中排列有规律时，不会引起定向偏差，晶体在１０００℃退火时不出现多相，这种晶体不影响器件性能。当温度梯度不合适或工艺参数不匹配时或其他原因，晶体中两种尖晶石的晶格排列不均匀而无规律，在晶体中出现多相而引起定向偏差，这样的晶体严重影响器件性能，无法使用。为此，在生长ＭｇＡｌ２Ｏ４晶体时，必须选好合?
MgAl2O4 crystal is a high melting point (2130 ℃), high hardness (Morse 8) crystal material. It is a face-centered cubic structure with a space group of Fd3m and a lattice constant of 0.8085nm. The crystal lattice is an excellent sound-transmitting dielectric material with low acoustic attenuation in the microwave range and low insertion loss of the microwave delay line fabricated with it. In addition, the lattice matching performance with Si is good, and its expansion coefficient is also similar to that of Si. Therefore, the deformation of the epitaxial Si film is small and the manufacturing speed of the large-scale ultra-high speed integrated circuit is faster than that of the sapphire. Recently, foreign countries with MgAl2O4 crystal material for superconducting, the effect is very good. However, MgAl2O4 crystals prone to several defects, the actual application of a great impact on the crystal. This work focuses on several defects in MgAl2O4 crystal. Crystals grown in the same spinel melt have two lattice constants in which the two structures coexist in the same crystal and the value of the lattice constant depends on the molar ratio of the spinel component, Which causes the crystals to dissolve locally and the temperature of the melt irregularly rise and fall during the growth process. When the two spinel are regularly arranged in the lattice, the orientation deviation will not be caused and the crystal does not appear heterogeneous when annealed at 1000 ° C., This crystal does not affect device performance. When the temperature gradient is not suitable or the process parameters do not match or other reasons, the crystals of the two spinel lattice arrangement is uneven and irregular, appear in the crystal multiphase and cause directional deviation, such a crystal seriously affect the performance of the device ,Not available. To this end, the growth of MgAl2O4 crystal, you must choose a good match?