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Neutron powder diffraction with (SM)-S-nat: Crystal structures and magnetism of a binary samarium deuteride and a ternary samarium magnesium deuteride

机译:(SM)-S-nat的中子粉末衍射:二元氘化and和三元氘化镁镁的晶体结构和磁性

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Binary SmH3 (trigonal, a = 656.7(3), c = 680.1(3) pm, P (3) over bar c1, Z = 6), ternary SmMg2H7 (tetragonal, a = 626.47(6), c = 937.2(2) pm, P4(1)2(1)2, Z = 4) and the corresponding deuterides SmD3 (a=653.9(1)m, c=676.7(2)pm) and SmMg2D7 (a=624.10(1), c=934.81(2)pm) have been prepared by hydrogenation (deuteration) of elemental samarium and the Laves phase SmMg2, respectively, and investigated by X-ray and neutron powder diffraction and SQUID and vibration magnetometry. The problem of the enormous neutron absorption of the natural isotopic mixture (Sm-nat) is circumvented by carefully choosing the neutron wavelength (approximate to 50 pm) and the use of double-walled cylindrical sample holders and a high-intensity neutron diffractometer (D4c at ILL). SmD3 crystallises with a tysonite-type structure and has three independently ordered deuterium atom sites with trigonal-planar, trigonal-pyramidal and tetrahedral metal environments and Sm-D bond lengths in the range 220(1)258(1) pm (average: 235 pm). SmMg2D7 is a new deuteride that crystallises with an LaMg2D7-type structure. It displays four fully occupied deuterium sites having triangular and tetrahedral metal environments and Sm-D bond lengths in the range 227.6(5)-246.8(8) put (average: 239 pm). These are the first samarium-deuterium bond lengths to be reported. Both deuterides are paramagnetic down to 2 K (SmD3: mu(eff) = 0.63(1) mu(B), theta(p)approximate to-4 K; SmMg2D7: mu(eff) =0.57(2)mu(B), theta(p)approximate to-4 K). Their crystal structures and chemical and physical properties suggest mainly ionic bonding according to the limiting ionic formulae Sm3+(H-)(3) and Sm3+(Mg2+)(2)(H-)(7).
机译:二进制SmH3(三角形,a = 656.7(3),c = 680.1(3)pm,在条形c1上的P(3),Z = 6),三元SmMg2H7(三角形,a = 626.47(6),c = 937.2(2) )pm,P4(1)2(1)2,Z = 4)和相应的氘代SmD3(a = 653.9(1)m,c = 676.7(2)pm)和SmMg2D7(a = 624.10(1),c分别通过元素sa和Laves相SmMg2的加氢(氘化)制得= 934.81(2)pm),并通过X射线和中子粉末衍射,SQUID和振动磁法研究。通过仔细选择中子波长(约50 pm)以及使用双壁圆柱样品架和高强度中子衍射仪(D4c),可以解决天然同位素混合物(Sm-nat)的巨大中子吸收问题。在ILL)。 SmD3结晶为钛铁矿型结构,具有三个独立排列的氘原子位点,具有三角平面,三角金字塔形和四面体金属环境,Sm-D键长范围为220(1)258(1)pm(平均:235)下午)。 SmMg2D7是一种新的氘化物,具有LaMg2D7型结构结晶。它显示了四个具有三角形和四面体金属环境且Sm-D键长在227.6(5)-246.8(8)范围内(平均:239 pm)的完全占据的氘位。这些是首次报道的the-氘键长度。两种氘核都是顺磁性的,直到2 K(SmD3:mu(eff)= 0.63(1)mu(B),theta(p)大约为-4 K; SmMg2D7:mu(eff)= 0.57(2)mu(B) ,θ(p)大约为4 K)。它们的晶体结构以及化学和物理性质表明,主要是根据极限离子式Sm3 +(H-)(3)和Sm3 +(Mg2 +)(2)(H-)(7)进行离子键合。

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