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Title: Studies on tetragonal Na{sub 2}CoP{sub 2}O{sub 7}, a novel ionic conductor

Abstract

Crystals of the tetragonal form of Na{sub 2}CoP{sub 2}O{sub 7} have been grown and characterized by single crystal X-ray diffraction. This compound crystallizes in the tetragonal system, space group P4{sub 2}/mnm with a = 7.7058(12), c = 10.301(2) {angstrom}, and Z = 4. The structure was solved by Patterson and Fourier methods, and refined to final agreement factors R(F{sup 2}) = 5.8%, Rw(F{sup 2}) = 12.4%, S(F{sup 2}) = 1.07. Their structure can be described as layered since it is formed by slabs of [CoP{sub 2}O{sub 7}]{sub {infinity}} with Na cations lying between the layers. The Co{sup 2+} cation adopts a tetrahedral coordination geometry unusual in inorganic solids. CoO{sub 4} tetrahedra share four oxygens with P{sub 2}O{sub 7} pyrophosphate groups and the Na{sup +} cations appear in a NaO{sub 8} quadrangular prismatic coordination geometry. Magnetic measurements reveal the presence of antiferromagnetic interactions in the Co{sup 2+} sublattice, at about 10 K. Magnetic correlations are also studied from the analysis of possible superexchange pathways in the structure. Impedance measurements (frequency range: 1--5 {times} 10{sup 6} Hz; temperature range: 90--540 C) show Na{sub 2}CoP{sub 2}O{sub 7} an ionic conductor being the conductivity at 300 C 2 {times} 10{sup {minus}5} Scm{sup {minus}1} andmore » the activation energy 0.61 eV. The possible motion of the Na{sup +} ions in the interlayer surface plane and through adjacent layers (c axis) is discussed.« less

Authors:
; ;  [1]; ;  [2]
  1. CSIC, Madrid (Spain). Inst. de Ciencia de Materiales
  2. Univ. Complutense, Madrid (Spain). Dept. de Quimica Inorganica
Publication Date:
OSTI Identifier:
679245
Resource Type:
Journal Article
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 145; Journal Issue: 2; Other Information: PBD: Jul 1999
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; MAGNETIC PROPERTIES; IONIC CONDUCTIVITY; SODIUM PHOSPHATES; COBALT PHOSPHATES; LAYERS; X-RAY DIFFRACTION; ANTIFERROMAGNETISM; EXPERIMENTAL DATA

Citation Formats

Sanz, F, Rojo, J M, Ruiz-Valero, C, Parada, C, and Saez-Puche, R. Studies on tetragonal Na{sub 2}CoP{sub 2}O{sub 7}, a novel ionic conductor. United States: N. p., 1999. Web. doi:10.1006/jssc.1999.8249.
Sanz, F, Rojo, J M, Ruiz-Valero, C, Parada, C, & Saez-Puche, R. Studies on tetragonal Na{sub 2}CoP{sub 2}O{sub 7}, a novel ionic conductor. United States. doi:10.1006/jssc.1999.8249.
Sanz, F, Rojo, J M, Ruiz-Valero, C, Parada, C, and Saez-Puche, R. Thu . "Studies on tetragonal Na{sub 2}CoP{sub 2}O{sub 7}, a novel ionic conductor". United States. doi:10.1006/jssc.1999.8249.
@article{osti_679245,
title = {Studies on tetragonal Na{sub 2}CoP{sub 2}O{sub 7}, a novel ionic conductor},
author = {Sanz, F and Rojo, J M and Ruiz-Valero, C and Parada, C and Saez-Puche, R},
abstractNote = {Crystals of the tetragonal form of Na{sub 2}CoP{sub 2}O{sub 7} have been grown and characterized by single crystal X-ray diffraction. This compound crystallizes in the tetragonal system, space group P4{sub 2}/mnm with a = 7.7058(12), c = 10.301(2) {angstrom}, and Z = 4. The structure was solved by Patterson and Fourier methods, and refined to final agreement factors R(F{sup 2}) = 5.8%, Rw(F{sup 2}) = 12.4%, S(F{sup 2}) = 1.07. Their structure can be described as layered since it is formed by slabs of [CoP{sub 2}O{sub 7}]{sub {infinity}} with Na cations lying between the layers. The Co{sup 2+} cation adopts a tetrahedral coordination geometry unusual in inorganic solids. CoO{sub 4} tetrahedra share four oxygens with P{sub 2}O{sub 7} pyrophosphate groups and the Na{sup +} cations appear in a NaO{sub 8} quadrangular prismatic coordination geometry. Magnetic measurements reveal the presence of antiferromagnetic interactions in the Co{sup 2+} sublattice, at about 10 K. Magnetic correlations are also studied from the analysis of possible superexchange pathways in the structure. Impedance measurements (frequency range: 1--5 {times} 10{sup 6} Hz; temperature range: 90--540 C) show Na{sub 2}CoP{sub 2}O{sub 7} an ionic conductor being the conductivity at 300 C 2 {times} 10{sup {minus}5} Scm{sup {minus}1} and the activation energy 0.61 eV. The possible motion of the Na{sup +} ions in the interlayer surface plane and through adjacent layers (c axis) is discussed.},
doi = {10.1006/jssc.1999.8249},
journal = {Journal of Solid State Chemistry},
number = 2,
volume = 145,
place = {United States},
year = {1999},
month = {7}
}