CNRS, Université de Bordeaux, ICMCB, 87 avenue du Docteur Albert Schweitzer, 33608 Pessac Cedex, France.
J Phys Condens Matter. 2012 Apr 4;24(13):136001. doi: 10.1088/0953-8984/24/13/136001. Epub 2012 Mar 5.
Nd(5)CoSi(2) was obtained from the elements by arc-melting followed by annealing at 883 K. Its investigation by single-crystal x-ray and neutron powder diffraction shows that this ternary silicide crystallizes as Nd(5)Si(3) in a tetragonal structure deriving from the Cr(5)B(3)-type (I4/mcm space group; a = 7.7472(2) and c = 13.5981(5) Å as unit cell parameters). The structural refinements confirm the mixed occupancy on the 8h site between Si and Co atoms, as already observed for Gd(5)CoSi(2). Magnetization and specific heat measurements reveal a ferromagnetic behavior below T(C) = 55 K for Nd(5)CoSi(2). This magnetic ordering is further evidenced by neutron powder diffraction investigation revealing between 1.8 K and T(C) a canted ferromagnetic structure in the direction of the c-axis described by a propagation vector k = (0 0 0). At 1.8 K, the two Nd(3+) ions carry ordered magnetic moments equal respectively to 1.67(7) and 2.37(7) μ(B) for Nd1 and Nd2; these two moments exhibit a canting angle of θ = 4.3(6)°. This magnetic structure presents some similarities with that reported for Nd(5)Si(3).
采用电弧熔炼法从元素中获得 Nd(5)CoSi(2)，然后在 883 K 下退火。通过单晶 X 射线和中子粉末衍射研究表明，这种三元硅化物以 Nd(5)Si(3)的形式结晶，具有源自 Cr(5)B(3)-型（I4/mcm 空间群；a = 7.7472(2)和 c = 13.5981(5)Å 作为晶胞参数）的四方结构。结构精修证实了 8h 位置上 Si 和 Co 原子的混合占据，这在 Gd(5)CoSi(2)中已经观察到。磁化和比热测量表明 Nd(5)CoSi(2)在 T(C) = 55 K 以下表现出铁磁行为。中子粉末衍射研究进一步证明了这种磁有序，在 1.8 K 和 T(C)之间，在 c 轴方向上呈现出倾斜的铁磁结构，由传播矢量 k = (0 0 0)描述。在 1.8 K 时，两个 Nd(3+)离子分别携带有序磁矩，Nd1 为 1.67(7)μ(B)，Nd2 为 2.37(7)μ(B)；这两个矩表现出 θ = 4.3(6)°的倾斜角。这种磁结构与报道的 Nd(5)Si(3)的磁结构有一些相似之处。
