Density functional theory study of the magnetic shielding mechanism for B-11 in pentaborate minerals: ulexite and probertite

ISL OpenIR > 青海盐湖研究所知识仓储

	Density functional theory study of the magnetic shielding mechanism for B-11 in pentaborate minerals: ulexite and probertite
	Zhou, Bing 1,2; Michaelis, Vladimir K.3; Yao, Yefeng 4,5; Sherriff, Barbara L.6; Kroeker, Scott 3; Pan, Yuanming 7
	2014
发表期刊	CRYSTENGCOMM
卷号	16 期号:45 页码:10418-10427
摘要	Nuclear magnetic resonance (NMR) parameters of B-11 in borates and borosilicates, unlike those of many other nuclei such as Si-29 and Al-27, vary only in limited ranges for a given polyhedral geometry, but mechanisms for such insensitivity to local structural environments remain poorly understood. In this contribution, ulexite and probertite, with the ([B5O6(OH)(6)](3-)) pentaborate polyanion as the fundamental building block, have been investigated in detail by ab initio theoretical calculations of the density of states (DOS) as implemented in WIEN2k, including optimization of the structures and determination of contributions to the magnetic shielding at each of the five distinct B sites. Calculated B-11 NMR parameters of these two pentaborates are compared with high-precision experimental data obtained at high (14 T) and ultrahigh (21 T) fields. Optimized structures using the linearized augmented plane-wave method with additional radial basis functions in the form of local orbitals (i.e., LAPW+lo) not only yield more accurate electric field gradients (EFG) at the distinct three-and fourfold-coordinated B sites (i.e., [BO3] or B-[3] and [BO4] or B-[4]) but also improve the calculated 11B magnetic shielding. In particular, the magnetic shielding variation trends among the B sites in ulexite and probertite are determined mainly by the valence states and especially by the local p orbitals of B and its nearest-neighbor O atoms. Calculations with the water molecules removed or K+ substituting for Na+ in the structures show that the next-nearest-neighbor cations and water molecules have negligible effects. Theoretical calculations also reveal that the systematic differences in shielding between B-[3] and B-[4] are caused by multiple factors such as the occupancies and imbalance in the sp hybrid orbitals between B and its nearest-neighbor O atoms.
语种	英语
引用统计
文献类型	期刊论文
条目标识符	http://ir.isl.ac.cn/handle/363002/5675
专题	青海盐湖研究所知识仓储中国科学院青海盐湖研究所
作者单位	1.Tongji Univ, Coll Mat Sci & Engn, Yangpu 21000, Peoples R China 2.Chinese Acad Sci, Qinghai Inst Salt Lakes, Beijing 810008, Peoples R China 3.Univ Manitoba, Dept Chem, Winnipeg, MB R3T 2N2, Canada 4.E China Normal Univ, Dept Phys, Shanghai 200062, Peoples R China 5.E China Normal Univ, Shanghai Key Lab Magnet Resonance, Shanghai 200062, Peoples R China 6.Univ Manitoba, Dept Geol Sci, Winnipeg, MB R3T 2N2, Canada 7.Univ Saskatchewan, Dept Geol Sci, Saskatoon, SK S7N 5E2, Canada
推荐引用方式 GB/T 7714	Zhou, Bing,Michaelis, Vladimir K.,Yao, Yefeng,et al. Density functional theory study of the magnetic shielding mechanism for B-11 in pentaborate minerals: ulexite and probertite[J]. CRYSTENGCOMM,2014,16(45):10418-10427.
APA	Zhou, Bing,Michaelis, Vladimir K.,Yao, Yefeng,Sherriff, Barbara L.,Kroeker, Scott,&Pan, Yuanming.(2014).Density functional theory study of the magnetic shielding mechanism for B-11 in pentaborate minerals: ulexite and probertite.CRYSTENGCOMM,16(45),10418-10427.
MLA	Zhou, Bing,et al."Density functional theory study of the magnetic shielding mechanism for B-11 in pentaborate minerals: ulexite and probertite".CRYSTENGCOMM 16.45(2014):10418-10427.