二甲亚砜硝酸稀土晶体的生长及其组成与性质的研究

本文合成出除Pm以外的全部稀土硝酸盐的二甲亚砜晶体,并生长出大尺寸的La和Nd的晶体(分别为60×28×25和80×28×28mm)。从La至Gd的组成为RE(NO₃)₃·4DMSO,从Tb至Lu(包括Y)的组成为为RE(NO₃)₃·3DMSO,由于镧系收缩引起的空间位阻,使结合的DMSO的数目从4减为3。测定了一些稀土的光谱和发光性质。比较Nd³⁺在水溶液中和在DMSO中的吸收光谱,观察到在DMSO中Nd³⁺的谱带向长波位移,表明了在DMSO中,RE—O键具有一定程度的共价性。当晶体在850℃的空气中进行热分解时,三价稀土的热分解产物的组成为RE₂0₂SO₄。测定了全部稀土硝酸盐的二甲亚砜晶体的磁化率,它们随原子序的增大呈现具有双峰的周期性变化。

STUDY ON THE CRYSTAL GROWTH,COMPOSITION AND SOME PROPERTIES OF DIMETHYLSULPHOXIDE COMPLEXES OF RARE EARTH NITRATES

All dimethylsulphoxide complexes of rare earth nitrates (except Pm) weresynthesized. Large dimensional crystals of La or Nd (60×28×25mm or 80×28×28mm respectively)were grown. The composition of complexes with fromLa to Gd is RE(NO₃)₃·4DMSO and those with from Tb to Lu (including Y)is RE(NO₃)₃·3DMSO. Because of steric hindrance causing by lanthanide con-traction, the number of the bound DMSO is decreased from 4 to 3 and thecoordination number is decreased from 10 to 9. Comparing the absorption spectra of Nd³⁺ ion in aqueous solution with those in DMSO solution,red shift of the spectral bands of Nd³⁺ ion in DM-SO solution has been observed, this implies that in the DMSO solution thereexists a certain degree of covalency in the RE-O bond. When the crystals are thermal decomposed in air at 850℃, the composi-tion of the thermal decomposed products of the trivalent rare earth ions beco-mes RE₂O₂SO₄(RE=Nd³⁺, Eu³⁺,Y³⁺). The magnetic susceptibilities X_g of all dimethylsulphoxide complexes ofrare earth nitrates have been determined. As the atomic number (Z) of rareearths increases they change periodically and there appear two maxima in theplot of X_gvs. Z. The absorption, excitation and fluorescence spectra of Pr (NO₃)₃·4DMSO and Tb(NO₃)₃3DMSO were determined.