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首页> 外文期刊>Nanoscale Research Letters >Synthesis and Properties of the La1???x???y Eu y Ca x VO4 (0?≤?x, y?≤?0.2) Compounds
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Synthesis and Properties of the La1???x???y Eu y Ca x VO4 (0?≤?x, y?≤?0.2) Compounds

机译：La 1 ??? x ??? y Eu 的合成和性质 y Ca x VO 4 （0？ ≤？ x ， y ？≤？0.2）化合物

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The La~(1??? x )Ca~( x )VO~(4) and La~(1??? x ??? y )Eu~( y )Ca~( x )VO~(4) (0?≤? x , y ?≤?0.2) microanosized powders were prepared by aqueous nitrate–citrate sol–gel synthesis. Phase composition of the sample depends on the x and y values. The La~(0.9)Ca~(0.1)VO~(4) is crystallized in monoclinic structure up to the x ?=?0.1. The La~(0.9)Eu~(0.05)Ca~(0.05)VO~(4) sample was also attributed to the monoclinic structure. Increasing concentration of europium and calcium ions in La~(1??? x ???y)Eu~( y )Ca~( x )VO~(4) solid solutions leads to the change of the crystal structure, and subsequently, stabilization of the tetragonal phase takes place. The obtained samples were characterized by XRD analysis, SEM microscopy, and IR spectroscopy. Luminescence properties of the synthesized powders were studied. Emission of the La~(1??? x )Ca~( x )VO~(4) samples is weak and consists of wide bands in the 450–800?nm spectral range. The observed bands at 570 and 630 were ascribed to electron transitions in the distorted VO~(4) _(3?) vanadate groups. Emission of the La~(1??? x ??? y )Eu~( y )Ca~( x )VO~(4) samples consists of narrow spectral lines in the 550–730?nm spectral range. The lines are caused by the _(5)D~(0)?→?_(7)F~(J) electron transitions in the Eu_(3+) ions. The Ca_(2+) ions incorporation increases the intensity of the Eu_(3+) ions luminescence. Structure of the spectra depends on Ca_(2+) concentration and excitation wave length. The carried out analysis has revealed that Eu_(3+) ions form at least two different types of emission centers in the La~(1??? x ??? y )Eu~( y )Ca~( x )VO~(4) samples. The assumption is made that type I centers are formed by the Eu_(3+) ions in their regular positions in the crystal lattice, while the type II centers have complex structure and consist of Eu_(3+) ions, Ca_(2+) cations, and oxygen vacancies.
机译：La〜（1 ??? x）Ca〜（x）VO〜（4）和La〜（1 ??? x ??? y）Eu〜（y）Ca〜（x）VO〜（4）（ 0？≤？x，y？≤？0.2）是通过硝酸硝酸盐-柠檬酸盐溶胶-凝胶合成法制备的微米级/纳米级粉末。样品的相组成取决于x和y值。 La〜（0.9）Ca〜（0.1）VO〜（4）以单斜晶结构结晶，直至x≥＝ 0.1。 La〜（0.9）Eu〜（0.05）Ca〜（0.05）VO〜（4）样品也归因于单斜晶结构。 La〜（1 ??? x ??? y）Eu〜（y）Ca〜（x）VO〜（4）固溶体中of和钙离子浓度的增加导致晶体结构的变化，随后，发生四方相的稳定化。通过XRD分析，SEM显微镜和IR光谱对获得的样品进行表征。研究了合成粉末的发光性能。 La〜（1 ??? x）Ca〜（x）VO〜（4）样品的发射很弱，由450-800？nm光谱范围内的宽带组成。在570和630处观察到的谱带归因于扭曲的VO〜（4）_（3？）钒酸盐基团中的电子跃迁。 La〜（1 ??? x ??????）Eu〜（y）Ca〜（x）VO〜（4）样品的发射由在550-730？nm光谱范围内的窄光谱线组成。这些线是由Eu_（3+）离子中的_（5）D〜（0）→→__（7）F〜（J）电子跃迁引起的。 Ca_（2+）离子的掺入增加了Eu_（3+）离子发光的强度。光谱的结构取决于Ca_（2+）浓度和激发波长。分析表明，Eu_（3+）离子在La〜（1 ??? x ?????? y）Eu〜（y）Ca〜（x）VO〜（）中形成至少两种不同类型的发射中心。 4）样品。假设I型中心是由Eu_（3+）离子在晶格中的常规位置形成的，而II型中心具有复杂的结构，并且由Eu_（3+）离子Ca_（2+）组成阳离子和氧空位。

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