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首页> 外文期刊>Chemistry: A European journal >Crystal structure, physical properties and HRTEM investigation of the new oxonitridosilicate EuSi2O2N2
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Crystal structure, physical properties and HRTEM investigation of the new oxonitridosilicate EuSi2O2N2

机译：新型氧杂三硅酸盐EuSi2O2N2的晶体结构，物理性质和HRTEM研究

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摘要

The new layered oxonitrido-silicate EuSi2O2N2 has been synthesized in a radio-frequency furnace at temperatures of about 1400 degrees C starting from europium(III) oxide (Eu2O3) and silicon diimide (Si(NH)(2)). The structure of the yellow material has been determined by single-crystal X-ray diffraction analysis (space group PI (no. 1), a = 709.5(1), b = 724.6(1), C = 725.6(1) pm, alpha = 88.69(2), beta = 84.77(2), gamma = 75.84(2)degrees, V = 360.19(9) X 10(6) pm(3), Z = 4, R1 = 0.0631, 4551 independent reflections, 175 parameters). Its anionic SiO2N22- layers consist of corner-sharing SiON3 tetrahedra with threefold connecting nitrogen and terminal oxygen atoms. High-resolution transmission electron micrographs indicate both ordered and disordered crystallites as well as twinning. Magnetic susceptibility measurements of EuSi2O2N2 exhibit Curie-Weiss behavior above 20 K with an effective magnetic moment of 7.80(5) mu(B) Eu-1, indicating divalent europium. Antiferromagnetic ordering is detected at 4.5(2) K. EuSi2O2N2 shows a field-induced transition with a critical field of 0.50(5) T. The four crystallographically different europium sites cannot be distinguished by Eu-151 Mossbauer spectroscopy. The room-temperature spectrum is fitted by one signal at an isomer shift of delta = -12.3(1) mm s(-1) subject to quadrupole splitting of Delta E-Q = -2.3(1) mm s(-1) and an asymmetry parameter of 0.46(3). Luminescence measurements show a narrow emission band with regard to the four crystallographic europium sites with an emission maximum at lambda = 575 nm.
机译：新的层状氧化三氮硅酸盐EuSi2O2N2已在射频炉中于约1400摄氏度的温度下从氧化from（Eu2O3）和二酰亚胺硅（Si（NH）（2））合成。黄色材料的结构已通过单晶X射线衍射分析确定（空间群PI（编号1），a = 709.5（1），b = 724.6（1），C = 725.6（1）pm， alpha = 88.69（2），beta = 84.77（2），γ= 75.84（2）度，V = 360.19（9）X 10（6）pm（3），Z = 4，R1 = 0.0631，4551个独立反射， 175个参数）。它的阴离子SiO2N22-层由角共享的四面体SiON3四面体组成，该四面体连接氮原子和末端氧原子。高分辨率透射电子显微照片显示有序和无序的微晶以及孪晶。 EuSi2O2N2的磁化率测量结果显示，在20 K以上时居里-魏斯行为，有效磁矩为7.80（5）mu（B）Eu-1，表明为二价euro。在4.5（2）K处检测到反铁磁有序。EuSi2O2N2显示出场致转变，其临界场为0.50（5）T。Eu-151 Mossbauer光谱学无法区分四个晶体学上不同的euro位。室温光谱通过一个异构体位移为δ= -12.3（1）mm s（-1）的信号进行拟合，该信号经过Delta EQ = -2.3（1）mm s（-1）的四极分裂并且不对称参数为0.46（3）。发光测量结果显示，相对于四个晶体学sites位置，发射带很窄，发射最大值为λ= 575 nm。

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