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The Structure and Conductivity of K_8Nd_3Si_(12)O_(32)(OH): A Layered Silicate with Paths for Possible Fast-Ion Condution

Haile, S. M. and Wuensch, B. J. and Siegrist, T. (1999) The Structure and Conductivity of K_8Nd_3Si_(12)O_(32)(OH): A Layered Silicate with Paths for Possible Fast-Ion Condution. Journal of Solid State Chemistry, 148 (2). pp. 406-418. ISSN 0022-4596. https://resolver.caltech.edu/CaltechAUTHORS:20131125-162532510

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Abstract

Hydrothermally grown crystals of K_8Nd_3Si_(12)O_(32)(OH) have been examined by single crystal X-ray methods. The compound crystallizes in space group P bar l and has lattice constants a=6.9660(6) Å, b=11.4550(10) Å, c=11.6670(10) Å, α=87.677(8)°, β=87.491(9)°, γ=79.083(8)°. There are 29 nonhydrogen atoms in the asymmetric unit. With one formula unit per unit cell, the calculated density is 2.929 Mg m^(−3). Refinement was carried out with 5667 independent and significant [I≥2.5σ(I)] structure factors to a residual, R(F), of 0.047 (Rw(F)=0.057) using anisotropic temperature factors for all atoms. The structure, closely related to that of K_8Yb_3Si_(12)O_(32)(OH), is based on unusually flat Si_(12)O_(32) layers that are connected by Nd octahedra to form a three-dimensional framework. The silicate layer contains two types of six-membered rings, an eight-membered ring, and a meandering twelve-membered ring. It can be generated from a condensation of wollastonite-type chains and contains structural features found in the “ideal” silicate layers of α-K_3NdSi_6O_(15)·2H_2O and β-K_3NdSi_6O_(15). Potassium ions are located in the interstitial sites of the neodymia–silica framework, in channels that run between silicate layers; hydroxyl groups reside within channels that run through the layers. The conductivity in the [0 1 0] direction is given by σ=[1.4×10^3 K/Ωcm/T]×exp(−0.8 eV/k_bT). Charge transport appears to occur by the motion of OH^− ions.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1006/jssc.1999.8466DOIArticle
http://www.sciencedirect.com/science/article/pii/S0022459699984669PublisherArticle
ORCID:
AuthorORCID
Haile, S. M.0000-0002-5293-6252
Alternate Title:The Structure and Conductivity of K8Nd3Si12O32(OH), The Structure and Conductivity of K₈Nd₃Si₁₂O₃₂(OH):
Additional Information:Copyright c1999 by Academic Press. Received 24 March 1999; Revised 28 July 1999; Accepted 10 August 1999. Article ID jssc.1999.8466. The authors gratefully acknowledge the assistance of Mike Jercinov of the Massachusetts Institute of Technology and Dr. Robert Opila of Lucent Technologies with WDX and EDX composition measurements, respectively. Dr. Pat Gallagher, formerly of Lucent Technology, carried out the mass spectroscopy experiments. Dr. Harry Tuller of the Massachusetts Institute of Technology kindly provided access to his laboratory for ionic conductivity measurements. We also acknowledge the late Dr. Robert Laudise, in whose hydrothermal laboratory at Lucent Tehnologes crystals were grown, for his support and enthusiasm for this work.
Issue or Number:2
Record Number:CaltechAUTHORS:20131125-162532510
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20131125-162532510
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42722
Collection:CaltechAUTHORS
Deposited By: Jonathan Gross
Deposited On:02 Dec 2013 22:47
Last Modified:03 Oct 2019 06:01

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