Nonstoichiometric Li-Pseudobrookite(ss) in the Li2O-Fe2O3-TiO2System
Nonstoichiometric Li-Pseudobrookite(ss) in the Li2O-Fe2O3-TiO2System
复制标题
Li2O-Fe2O3-TiO2 体系中的非化学计量 Li-准板钛矿 (ss)
DOI：
10.1006/jssc.1998.7959
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
T. Ness
中科院分区：
文献类型：
--
作者：
I. Grey;C. Li;T. Ness
用淬灭法研究了Li 2 O-Fe 2 O3-TiO 2体系在900和1000°C下的相平衡。两个新的三元固溶体，铁板钛矿和ramsdellite结构类型的基础上，确定和结构特征使用Rietveld细化粉末X射线数据。随着Li+Ti取代Fe量的增加，铁板钛矿（ss）从M3 O 5化学计量向富金属成分的方向发展，从Fe 2 TiO 5到Li0.81Fe0.27Ti2.09O5（M3.17O5）。对Li0.81Fe0.27Ti2.09O5进行了中子衍射精修，空间群为Ccmm，a =9.6576（2），B =3.7532（1），c =9.8820（2）.钛在八重M2位点有序，而锂与少量铁和钛一起在四重M1位点有序。过量的锂（0.17 Li/分子式单元）位于结构中的间隙位置，具有四方锥配位。提出了一个Li-Li= 2.3A的Li 3团簇局域有序模型。
Abstract Phase equilibria in the Li 2 O-Fe 2 O 3 -TiO 2 system were studied at 900 and 1000°C using the quenching method. Two new ternary solid solutions, based on the pseudobrookite and ramsdellite structure types, were identified and structurally characterised using Rietveld refinements of powder X-ray data. The pseudobrookite(ss) showed deviations from M 3 O 5 stoichiometry towards metal-rich compositions which increased with increasing substitution of Li+Ti for Fe, from Fe 2 TiO 5 to Li 0.81 Fe 0.27 Ti 2.09 O 5 (≡M 3.17 O 5 ). A neutron diffraction refinement was made on Li 0.81 Fe 0.27 Ti 2.09 O 5 , space group C cmm , with a =9.6576(2), b =3.7532(1), c =9.8820(2) A. Titanium is ordered in the eight-fold M2 site while lithium, together with minor iron and titanium, is ordered in the four-fold M1 site. The excess lithium (0.17 Li per formula unit) was located in interstitial sites in the structure, having square-pyramidal coordination. A local-ordering model is presented which involves Li 3 clusters with Li-Li=2.3 A.