利用中子反射谱研究低温下一致锂铌酸锂单晶中的锂扩散。

Lithium diffusion in congruent LiNbO3 single crystals at low temperatures probed by neutron reflectometry.

机构信息

Clausthal University of Technology, Institute of Metallurgy, Microkinetics Group, Clausthal-Zellerfeld, Germany.

出版信息

Phys Chem Chem Phys. 2014 Feb 28;16(8):3670-4. doi: 10.1039/c3cp54939a.

PMID:24419100

Abstract

The self-diffusion of lithium in congruent LiNbO3 single crystals was investigated at low temperatures between 379 and 523 K by neutron reflectometry. From measurements on (6)LiNbO3 (amorphous film)/(nat)LiNbO3 (single crystal) samples, Li self-diffusivities were determined in single crystals down to extremely low values of 1 × 10(-25) m(2) s(-1) on small length scales of 1-10 nm. The measured diffusivities are in excellent agreement with (extrapolated) literature data obtained by experiments based on Secondary Ion Mass Spectrometry and Impedance Spectroscopy. The tracer diffusivities can be described by a single Arrhenius line over ten orders of magnitude with an activation enthalpy of 1.33 eV, which corresponds to the migration energy of a single Li vacancy. A deviation from the Arrhenius behaviour at low temperatures, e.g., due to defect cluster formation is not observed.

摘要

利用中子反射技术，在 379 至 523 K 的低温下，对同成分 LiNbO3 单晶中的锂离子自扩散进行了研究。通过对（6）LiNbO3（非晶薄膜）/（nat）LiNbO3（单晶）样品的测量，在 1-10nm 的小长度尺度上，确定了单晶中低至 1×10^(-25)m^2s^(-1)的极低的锂离子自扩散系数。所测量的扩散系数与基于二次离子质谱和阻抗谱的实验得到的（外推）文献数据非常吻合。示踪扩散系数在十个数量级上可以用单个阿仑尼乌斯线来描述，激活焓为 1.33eV，这对应于单个 Li 空位的迁移能。在低温下，没有观察到偏离阿仑尼乌斯行为的情况，例如，由于缺陷簇的形成。