Growth studies of YVO4 crystals (II). Changes in YVO‐stoichiometry
Growth studies of YVO4 crystals (II). Changes in YVO‐stoichiometry
复制标题
YVO4 晶体的生长研究 (II)。
DOI：
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发表时间：
1994
期刊：
影响因子：
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通讯作者：
F. Ainger
中科院分区：
文献类型：
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作者：
S. Erdei;G. G. Johnson;F. Ainger
原钒酸钇（YVO 4）熔体的不一致的钒氧化物蒸发产生氧和钇-钒（YV）化学计量的变化。轻微改性的YVO 4或YVO 4 + Y8 V2 O 17相由连续变化的熔体系统形成，这取决于它们的起始组成。用激光加热基座法生长的原钒酸钇晶体光纤中Y_8V_2O_（17）的存在可以通过使用合适的过量V_2O_5的起始组分而简单地消除。与此相反，缺氧YVO 4-x黑相是一个固有的缺氧相，在YVO 4 YVO 3子系统的Y2 O3 V2 O 5 V2 O3复杂的三元相图接近全等YVO 4组成（49.3摩尔% V2 O 5 -50.7摩尔% Y2 O3）的有限的固溶体。从详细的XRD数据确定，更大的氧缺乏YVO 4-x试样具有较小的晶格参数。用电子探针分析了陶瓷喂料棒和由喂料棒生长的纤维晶体的特征。由于三维三元相图的双重限制固溶体系统，沿纤维沿着观察到YV和氧化学计量的变化。因此，Y8 V2 O 17相的存在和YV化学计量比随氧缺乏的变化都导致从氧化钇过量熔体生长YVO 4晶体的困难。
Incongruent vanadium oxide vaporization of yttrium orthovanadate (YVO4) melt generates changes in both oxygen and yttrium-vanadium (YV) stoichiometry. Slightly modified YVO4 or YVO4 + Y8V2O17 phases are formed from continuously changing melt systems depending on their starting compositions. The occurrence of Y8V2O17 in yttrium orthovanadate crystal fibers grown by laser heated pedestal growth (LHPC) technique can be simply eliminated by utilization of suitable V2O5-excess starting compositions. In contrast, the oxygen-deficient YVO4–x black phase is an inherently oxygen deficient phase with limited solid solution in the YVO4YVO3 subsystem of Y2O3V2O5V2O3 complex ternary phase diagram close to the congruent YVO4 composition (49.3 mol% V2O5–50.7 mol% Y2O3). The greater oxygen deficiency YVO4–x specimens have smaller lattice parameters as determined from detailed XRD data. Ceramic feed rod and fiber crystal grown from the feed rod with slight yttrium oxide excess starting composition were characterized by electron microprobe analysis. Changes in both YV and oxygen stoichiometry were observed along the fiber, due to double limited solid solution system of three dimensional ternary phase diagram. Consequently, both the presence of Y8V2O17 phase and change of YV stoichiometry over oxygen deficiency cause difficulties for YVO4 crystal growth from yttrium oxide excess melt.