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Title: Electronic structure calculations of calcium silicate hydrates

Abstract

Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO{sub 3}) and xonotlite (Ca{sub 6}Si{sub 6}O{sub 17}(OH){sub 2}), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases.

Authors:
 [1];  [2]
  1. Univ. of California, Davis, CA (United States). Dept. of Physics|[Lawrence Livermore National Lab., CA (United States)
  2. Lawrence Livermore National Lab., CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab., CA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States); Atomic Energy of Canada Ltd., Montreal, PQ (Canada). CANDU Operations
OSTI Identifier:
212471
Report Number(s):
UCRL-JC-121437; CONF-951155-92
ON: DE96008711; TRN: 96:010561
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Technical Report
Resource Relation:
Conference: Fall meeting of the Materials Research Society (MRS), Boston, MA (United States), 27 Nov - 1 Dec 1995; Other Information: PBD: Nov 1995
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 05 NUCLEAR FUELS; CALCIUM SILICATES; ELECTRONIC STRUCTURE; PHASE STUDIES; RADIOACTIVE WASTE FACILITIES; BUILDING MATERIALS; CEMENTS; WASTE FORMS; CALCULATION METHODS; EXPERIMENTAL DATA; RADIOACTIVE WASTE DISPOSAL

Citation Formats

Sterne, P.A., and Meike, A. Electronic structure calculations of calcium silicate hydrates. United States: N. p., 1995. Web. doi:10.2172/212471.
Sterne, P.A., & Meike, A. Electronic structure calculations of calcium silicate hydrates. United States. doi:10.2172/212471.
Sterne, P.A., and Meike, A. Wed . "Electronic structure calculations of calcium silicate hydrates". United States. doi:10.2172/212471. https://www.osti.gov/servlets/purl/212471.
@article{osti_212471,
title = {Electronic structure calculations of calcium silicate hydrates},
author = {Sterne, P.A. and Meike, A.},
abstractNote = {Many phases in the calcium-silicate-hydrate system can develop in cement exposed over long periods of time to temperatures above 25 C. As a consequence, chemical reactions involving these phases can affect the relative humidity and water chemistry of a radioactive waste repository that contains significant amounts of cement. In order to predict and simulate these chemical reactions, the authors are developing an internally consistent database of crystalline Ca-Si-hydrate structures. The results of first principles electronic structure calculations on two such phases, wollastonite (CaSiO{sub 3}) and xonotlite (Ca{sub 6}Si{sub 6}O{sub 17}(OH){sub 2}), are reported here. The calculated ground state properties are in very good agreement with experiment, providing equilibrium lattice parameters within about 1--1.4% of the experimentally reported values. The roles of the different types of oxygen atoms, which are fundamental to understanding the energetics of crystalline Ca-Si-hydrates are briefly discussed in terms of their electronic state densities. The good agreement with experiment for the lattice parameters and the consistency of the electronic density of states features for the two structures demonstrate the applicability of these electronic structure methods in calculating the fundamental properties of these phases.},
doi = {10.2172/212471},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Nov 01 00:00:00 EST 1995},
month = {Wed Nov 01 00:00:00 EST 1995}
}

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