About

The Instituto de Ciencia de Materiales de Madrid (ICMM) is an institute of the Consejo Superior de Investigaciones Cientificas (CSIC) (Spanish National Research Council) founded in December 1986, that belongs to the Area of Science and Technology of Materials, one of the eight Areas in which the CSIC divides its research activities.

 

Our mission is to create new fundamental and applied knowledge in materials of high technological impact, their processing and their transfer to the productive sectors at local, national and European scales (the true value of materials is in their use), the training of new professionals, and the dissemination of the scientific knowledge.

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Forthcoming Events

SEP09/12:00

Spin Dynamics in Inhomogeneously Magnetized Systems
Teruo Ono  read more

SEP16/12:00

Emergent Gauge fields and topological effects in Dirac matter
Yago Ferreiros Bas   read more

SEP19/12:00

Biomimetismo y Bioinspiracion: fuentes de conocimiento para innovar en Ciencia de Materiales

Clément Sanchez  read more

Modeling Ti/Ge Distribution in LiTi2–xGex(PO4)3 NASICON Series by 31P MAS NMR and First-Principles DFT Calculations

Diez-Gómez, V; Arbi, K; Sanz, J

Ti/Ge distribution in rhombohedral LiTi2-xGex(PO4)3 NASICON series has been analyzed by 31P magic-angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy and first-principles density functional theory (DFT) calculations. Nuclear magnetic resonance is an excellent probe to follow Ti/Ge disorder, as it is sensitive to the atomic scale environment without long-range periodicity requirements. In the samples considered here, PO4 units are surrounded by four Ti/Ge octahedra, and then, five different components ascribed to P(OTi)4, P(OTi)3(OGe), P(OTi)2(OGe)2, P(OTi)(OGe)3, and P(OGe)4 environments are expected in 31P MAS NMR spectra of R3¯c NASICON samples. However, 31P MAS NMR spectra of analyzed series display a higher number of signals, suggesting that, although the overall symmetry remains R3¯c, partial substitution causes a local decrement in symmetry. With the aid of first-principles DFT calculations, 10 detected 31P NMR signals have been assigned to different Ti-nGen arrangements in the R3 subgroup symmetry. In this assignment, the influence of octahedra of the same or different R2(PO4)3 structural units has been considered. The influence of bond distances, angles and atom charges on 31P NMR chemical shieldings has been discussed. Simulation of the LiTi-xGex(PO4)3 series suggests that detection of 10 P environments is mainly due to the existence of two oxygen types, O1 and O2, whose charges are differently affected by Ge and Ti occupation of octahedra. From the quantitative analysis of detected components, a random Ti/Ge distribution has been deduced in next nearest neighbor (NNN) sites that surround tetrahedral PO4 units. This random distribution was supported by XRD data displaying Vegard’s law.

J. Am. Chem. Soc. 138, 9479-9486 (2016)

Figure 1. Detail of NASICON structure with R octahedra denoted in gray, P tetrahedra in orange, O atoms in red, and Li atoms in purple.

Publications Highlights

ICMM-2016 - Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049 Madrid, Spain. Tel: +34 91 334 9000. Fax: +34 91 372 0623. info@icmm.csic.es