论文部分内容阅读
用助熔剂缓冷法从Na_2WO_4—LiCl熔体中生长出NaLn(WO_4)_2(Ln=La,Pr,Nd)晶体。化学组成分析证明了所得晶体是NaLa(WO_4)_2、NaPr(WO_4)_2和NaNd(WO_4)_2。测定表明该类晶体属白钨矿型结构,四方晶系,空间群I4_1/a。计算了它们的晶胞参数,发现随着稀土元素(La、Pr、Nd)原子序数的增加,Ln~(3+)离子半径减小,Ln—O键长呈规律地递减,NaLn(WO_4)_2晶体的晶胞体积减小。测定了晶体的红外光谱和NaPr(WO_4)_2的激发光谱和荧光光谱。
NaLn (WO_4) _2 (Ln = La, Pr, Nd) crystals were grown from the Na_2WO_4-LiCl melt by slow fluxing. Chemical composition analysis confirmed that the crystals obtained were NaLa (WO_4) _2, NaPr (WO_4) _2 and NaNd (WO_4) _2. Determination shows that the type of crystal belongs to scheelite structure, tetragonal system, the space group I4_1 / a. Their unit cell parameters were calculated and found that the radius of Ln ~ (3+) ions decreased and the Ln-O bond length decreased regularly with increasing atomic numbers of rare earth elements (La, Pr, Nd) _2 crystal unit cell volume decreases. The infrared spectrum and the excitation and fluorescence spectra of NaPr (WO_4) _2 were measured.