Structure types samarium

Arsenate. — The arsenates of the rare earths crystallize [263] in two structural types, the huttonite and the zircon. The structural change from huttonite (La—Nd) to zircon (Sm—Lu) occurs at samarium. The lattice parameters of EuAsCU are a = 7.167 and c — 6.374 A. The rare earth arsenates can be prepared by reacting the nitrates with (NEU HAsCU, and heating the product to 700° C. 

Double chromates of lanthanum, promethium and neodymium of the type RbLn-(Cr04)2 have been found to be anhydrous. The samarium compound crystallized with 0.5 molecules of water whilst those from europium to lutetium had the composition RbLn(Cr04)2,H20. Y-Ray and i.r. studies showed the existence of three structural types as the rare earth element series was transversed. 

The crystal structure of the compound SmPd2Ge (6) was found to be of the YPd2Si type (a = 0.7501, i = 0.6996, c = 0.5673 X-ray powder diffraction) by Jorda et al. (1983). For the experimental procedure, see LaPd2Ge under La—Pd-Ge. The starting materials were palladium 99.99 mass% germanium, specpure quality samarium 99.9 mass%. Barakatova (1994) confirmed the structure type and determined the lattice parameters a = 0.7504, b= 0.6995, c = 0.5680 from X-ray powder analysis. 

Berkelium(iii) orthophosphate has been prepared and characterized by x-ray powder diffraction and solid-state absorption and Raman spectroscopy [112, 113]. Analysis of the x-ray data has shown this compound to be isostructural with samarium and europium orthophosphates and to exhibit similar lattice parameters [112]. The structure type was confirmed by the direct correlation of the Raman spectrum of BkP04 with those of the isostructural lanthanide orthophosphates [113]. 

The anhydrous rare earth iodates of structure type HI and those dehydrated from monohydrates are hygroscopic. The solubility of R(I03)3 (R = La, Ce, Sm, Eu) in water varies between 0.3 and 2.6mmol/dm, being lowest for samarium and highest for cerium (Chloupek et al., 1932 Monk, 1951b Laurie and Monk, 1963 Shklovskaya et al., 1977). The properties of the water solutions have been studied by Firsching and Paul (1966). 

Sm-Cu-Sb. A ternary compound of samarium with copper and antimony of the stoichiometric ratio 3 3 4 was identified and studied by means of X-ray analysis by Skolozdra et al. (1993). The compound Sm3Cu3Sb4 was found to have the Y3Au3Sb4 type structure with a lattice parameter of a = 0.9620 (X-ray powder diffraction). For experimental details, see the Y-Cu-Sb system. 

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