Evidence of a transition to reorientational disorder in the cubic alkali-metal dodecahydro-closo-dodecaborates

被引：27

作者：

Verdal, Nina ^{[1
]}

Wu, Hui ^{[1
,2
]}

Udovic, Terrence J. ^{[1
]}

Stavila, Vitalie ^{[3
]}

Zhou, Wei ^{[1
,2
]}

Rush, John J. ^{[1
,2
]}

机构：

[1] NIST, NIST Ctr Neutron Res, Gaithersburg, MD 20899 USA

[2] Univ Maryland, Dept Mat Sci & Engn, College Pk, MD 20742 USA

[3] Sandia Natl Labs, Livermore, CA 94551 USA

来源：

JOURNAL OF SOLID STATE CHEMISTRY | 2011年 / 184卷 / 11期

关键词：

B12F122-; Dodecahydro-closo-dodecaborate; Neutron powder diffraction; Phase transition; Reorientational disorder; NEUTRON-SCATTERING; CRYSTAL-STRUCTURE; KBH4; NMR; BOROHYDRIDES; DYNAMICS; NABH4; CS;

D O I：

10.1016/j.jssc.2011.09.010

中图分类号：

O61 [无机化学];

学科分类号：

070301 ; 081704 ;

摘要：

A neutron powder diffraction and differential scanning calorimetry (DSC) study indicates that Cs2B12H12 undergoes a second-order phase transition near 529 K that can be described as a reorientational disordering of the B12H122- icosahedral anions between two lowest-energy configurations within the cubic structure. Such a disordering requires the addition of another mirror plane to the low-temperature Fm (3) over bar structural symmetry to become Fm (3) over barm. Differential scanning calorimetry measurements suggest the possible persistence of some short-range anion order at and above the transition. Additional DSC measurements of the lighter alkali-metal cubic isomorphs, Rb2B12H12 and K2B12H12, also indicate second-order transitions for these compounds near 742 K and 811 K, respectively. These results are suggestive of similar order-disorder phase changes as for Cs2B12H12, although confirmation of their existence requires analogous diffraction measurements. Published by Elsevier Inc.

引用

页码：3110 / 3116

页数：7