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Title: EPR of transition metal ions in NZP ceramics

Abstract

NZP-ceramics have been produced by different methods such as sol-gel, flux melting and sintering of dry salts or phosphates. Formation of NZP and related phases was confirmed by X-ray diffraction analysis. Electron paramagnetic resonance (EPR) was applied to evaluate a structure positions of paramagnetic ions and nature of radiation-induced centers. EPR responses from transition metal ions Fe{sup 3+} and Mn{sup 2+} with electron configuration 3d{sup 5} (ground state {sup 6}S{sub 5/2}) which occurred as impurities in raw materials were registered in powders of NZP-ceramics. Fine structure arising due to high spin iron complexes is well resolved. A part of Fe{sup 3+} ions substitutes for Zr{sup 4+} and another part of one substitutes for Na{sup +} ions in six-fold coordinated positions. A great value of hyperfine structure (hfs) constant (9.3 mT) shows a high ionic character of Mn-O bonds in the first coordination sphere. A coordination number is close to 6. Fine structure of Mn{sup 2+} ions are not well resolved. A comparison of the spectra of samples containing various alkali cations shows the substitution for cations in series of Li-Na-K-Rb-Cs does not result in fundamental variation in spectra except for CZP ceramics where the response with g=4.3 due to Fe{supmore » 3+} in strong ligand field rather than response with g=2.0 due to Fe{sup 3+} in weak field is observed. An investigation of some samples doped by 0.1...0.5 mole % of Fe{sup 3+} or Gd{sup 3+} has been carried out and principal spin-Hamiltonian parameters have been determined. The increase of Fe and Gd ions content as compared to impurity substituting for Zr and possibly Na in their own structural positions results in noticeable site distortion. Gamma irradiation of NZP ceramics results in formation of radiation-induced paramagnetic centers connected to phosphorus-oxygen. The nature and concentration of these centers depend on production method. The lowest defect concentration is in hot-pressed ceramics.« less

Authors:
;  [1];  [2]
  1. Univ. of Nizhnii Novgorod (Russian Federation)
  2. SIA Radon, Moscow (Russian Federation)
Publication Date:
OSTI Identifier:
178106
Report Number(s):
CONF-950917-
ISBN 0-7918-1219-7; TRN: 96:006619
Resource Type:
Book
Resource Relation:
Conference: 5. international conference on radioactive waste management and environmental remediation, Berlin (Germany), 3-9 Sep 1995; Other Information: PBD: 1995; Related Information: Is Part Of Fifth international conference on radioactive waste management and environmental remediation -- ICEM `95: Proceedings. Volume 1: Cross-cutting issues and management of high-level waste and spent fuel; Slate, S.; Feizollahi, F.; Creer, J. [eds.]; PB: 900 p.
Country of Publication:
United States
Language:
English
Subject:
05 NUCLEAR FUELS; 36 MATERIALS SCIENCE; RADIOACTIVE WASTE PROCESSING; MATRIX MATERIALS; ZIRCONIUM PHOSPHATES; ELECTRON SPIN RESONANCE; CERAMICS; SOLIDIFICATION; RADIOACTIVE WASTES; EXPERIMENTAL DATA; LITHIUM PHOSPHATES; SODIUM PHOSPHATES; RUBIDIUM PHOSPHATES; POTASSIUM PHOSPHATES; CESIUM PHOSPHATES; DOPED MATERIALS; MANGANESE PHOSPHATES; CALCIUM PHOSPHATES; BARIUM PHOSPHATES; STRONTIUM PHOSPHATES

Citation Formats

Yegor`kova, O, Kryukova-Orlova, A I, and Stefanovsky, S V. EPR of transition metal ions in NZP ceramics. United States: N. p., 1995. Web.
Yegor`kova, O, Kryukova-Orlova, A I, & Stefanovsky, S V. EPR of transition metal ions in NZP ceramics. United States.
Yegor`kova, O, Kryukova-Orlova, A I, and Stefanovsky, S V. Sun . "EPR of transition metal ions in NZP ceramics". United States.
@article{osti_178106,
title = {EPR of transition metal ions in NZP ceramics},
author = {Yegor`kova, O and Kryukova-Orlova, A I and Stefanovsky, S V},
abstractNote = {NZP-ceramics have been produced by different methods such as sol-gel, flux melting and sintering of dry salts or phosphates. Formation of NZP and related phases was confirmed by X-ray diffraction analysis. Electron paramagnetic resonance (EPR) was applied to evaluate a structure positions of paramagnetic ions and nature of radiation-induced centers. EPR responses from transition metal ions Fe{sup 3+} and Mn{sup 2+} with electron configuration 3d{sup 5} (ground state {sup 6}S{sub 5/2}) which occurred as impurities in raw materials were registered in powders of NZP-ceramics. Fine structure arising due to high spin iron complexes is well resolved. A part of Fe{sup 3+} ions substitutes for Zr{sup 4+} and another part of one substitutes for Na{sup +} ions in six-fold coordinated positions. A great value of hyperfine structure (hfs) constant (9.3 mT) shows a high ionic character of Mn-O bonds in the first coordination sphere. A coordination number is close to 6. Fine structure of Mn{sup 2+} ions are not well resolved. A comparison of the spectra of samples containing various alkali cations shows the substitution for cations in series of Li-Na-K-Rb-Cs does not result in fundamental variation in spectra except for CZP ceramics where the response with g=4.3 due to Fe{sup 3+} in strong ligand field rather than response with g=2.0 due to Fe{sup 3+} in weak field is observed. An investigation of some samples doped by 0.1...0.5 mole % of Fe{sup 3+} or Gd{sup 3+} has been carried out and principal spin-Hamiltonian parameters have been determined. The increase of Fe and Gd ions content as compared to impurity substituting for Zr and possibly Na in their own structural positions results in noticeable site distortion. Gamma irradiation of NZP ceramics results in formation of radiation-induced paramagnetic centers connected to phosphorus-oxygen. The nature and concentration of these centers depend on production method. The lowest defect concentration is in hot-pressed ceramics.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1995},
month = {12}
}

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