Structural Chemical Studies of Gadolinium-and Erbium Compounds by Moessbauer Spectroscopy

观察到了14种元素的Moessbauer效应，其中大部分元素与Eu有关。对于其他元素，有技术上的困难：我们必须自己制作莫斯鲍尔源，并在很低的温度下对源和样品进行冷却。然而，我们已经成功地在核反应堆中用中子辐照制作了很好的窄线源^&lt；155&gt；Gd和^&lt；166&gt；Ed Moessbauer谱。我们测量了各种络合物、固溶体、金属间化合物和双氧化物在12K下的Moessbauer谱。结果表明，四极耦合常数(e^2Qq)是非常有用的参数，而有效磁场(H_(2q))和自旋-自旋弛豫时间(τ)在x=0.5时达到最大值，(1-x)≦_2-xGdO_(1.5)&gt；(1-x)≦_2-xGdO_(1.5)&gt；X≦为0.62.由于e^2QQ反映了Gd核周围电荷分布的不对称性，因此这种不对称性在x=0.5时的辉石结构中最大。观察到(1-x)ZrO_2-xGdO_&lt；1.5&gt；的^&lt；155&gt；Gd e^2QQ值与(1-y)ZrO_2-yEuO_&lt；1.5&gt；的^&lt；xGdO_&lt；1.5&gt；的δ值平行变化，这可以用M-O(M=Eu，Gd)键长的变化来解释。β-二酮-金属有机稀土(III)络合物的QQ值在0.54-0.65mms^&lt；-1&gt；范围很窄。此外，δ按GdO_&lt；6，7或8&gt；&gt；GdN_2O_&lt；6或7&gt；&gt；GdN_6O_2*的顺序减小，表明δ随着与Gd离子配位的氮原子数目的增加而减小。7个配位的β-二酮水合铒(III)配合物的自旋-自旋弛豫时间随着β-双酮的体积增大而增加。弛豫时间的增加被认为是由于Er^&lt；3+&gt；自旋之间的距离延长所致。

The Moessbauer effect of lanthanoid elements have been observed 14 elements, most of which is concerned with ^<151>Eu. For the other elements there are technical difficulties : we must make Moessbauer source by our self and cool both the source and sample at very low temperature. However we have succeeded in making a good narrow line source for ^<155>Gd and ^<166>Ed Moessbauer spectroscopy by neutron irradiation in nuclear reactor.We have measured those Moessbauer spectra at 12K of many kinds of complexes, solid solution, inter metallic comaounds and double oxides. The results have shown that the quadrupole coupling constant (e^2qQ) is verv useful aarameter for ^<155>Gd, and the effective magnetic field (H_<eff>) and the spin-spin relaxation time (τ) for ^<166>Ed.The e^2aQ values of (1-x)ZrO_2-xGdO_<1.5> increases with the increase of x in the ranse 0.18≦x≦0.50, reach maximum at x=0.5 (pyroclore structure) and then decrease in the range 0.50<x≦0.62. Since e^2qQ reflects the asymmetry of the charge distribution around the Gd nucleus, the asymmetry has been found to be the largest in the pyroclore structure of x=0.5. The parallel change of ^<155>Gd e^2qQ values of (1-x)ZrO_2-xGdO_<1.5> with that of ^<151>Eu isomer shift (δ) values of (1-y) ZrO_2-y EuO_<1.5> is observed which will be explained by the change of the M-O (M=Eu, Gd) bond length.The δ values of β-diketonatosadolinium (III) complexes fall in the very narrow range of 0.54-0.65mms^<-1>. Furthermore δ decrease in the order GdO_<6,7 or 8>>GdN_2O_<6 or7>>GdN_6O_2*, suggesting that δ decrease with the increase in the number of the nitrogen atoms coordinated to Gd ions.The spin-spin relaxation times of the seven coordinated β-diketonatoaqua erbium (III) complexes have been found to increase with the increase in the bulkiness of the β-diketons from their ^<>166Er Moessbauer saectra. The increase in the relaxation times is considered to originate from the lengthening of the distances between the Er^<3+> spins.