Comparison of the crystal structures and magnetic properties of the low- and high-temperature forms of AgCuPO4: Crystal structure determination, magnetic susceptibility measurements, and spin dimer analysis

Hamdi Yahia, Etienne Gaudin, Jacques Darriet, Dadi Dai, Myung Hwan Whangbo

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The crystal structure of the low-temperature form of AgCuPO4 (i.e., α-AgCuPO4) was determined by powder X-ray diffraction and was compared with that of the high-temperature form of AgCuPO4 (i.e., β-AgCuPO4). The magnetic properties of the two forms were examined by measuring their magnetic susceptibilities and evaluating the relative strengths of their spin-exchange interactions on the basis of spin-dimer analysis. Both forms of AgCuPO4 have layers of Cu 2P2O8 alternating with silver-atom double layers; β-AgCuPO4 has two Cu2P2O 8 layers per unit cell, while α-AgCuPO4 has one. The coordinate environment of each Cu2+ ion is close to being a distorted square pyramid in α-AgCuPO4, but it is close to being a distorted trigonal bipyramid in β-AgCuPO4. The magnetic susceptibilities of α- and β-AgCuPO4 are well simulated by an antiferromagnetic alternating-chain model, which leads to J/kB = -146.1 K and αJ/kB = -75.8 K for α-AgCuPO4, and J/kB = -82.6 K and aαj/kB = -31.7 K for β-AgCuPO4 (with the convention in which the spin-exchange parameter between two adjacent spin sites is written as 2J). The spin gaps, Δ/kB, obtained from these parameters are 93.7 K for α-AgCuPO4 and 62.3 K for β-AgCuPO4. The strongest spin exchange in both forms of AgCuPO4 comes from a super-superexchange path, and this interaction is stronger for α-AgCuPO4 than for β-AgCuPO4 by a factor of ∼2, in good agreement with the experiment. Our analysis supports the use of this model for β-AgCuPO4 and indicates that the spin lattice of α-AgCuPO4 would be better described by a two-dimensional net made up of weakly interacting alternating chains.

Original languageEnglish
Pages (from-to)5501-5509
Number of pages9
JournalInorganic Chemistry
Volume45
Issue number14
DOIs
Publication statusPublished - 10 Jul 2006
Externally publishedYes

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Magnetic susceptibility
Dimers
spin exchange
Magnetic properties
Crystal structure
dimers
magnetic properties
magnetic permeability
crystal structure
Temperature
Exchange interactions
Silver
X-Ray Diffraction
Powders
X ray powder diffraction
Ions
Atoms
pyramids
Experiments
silver

ASJC Scopus subject areas

  • Inorganic Chemistry

Cite this

Comparison of the crystal structures and magnetic properties of the low- and high-temperature forms of AgCuPO4 : Crystal structure determination, magnetic susceptibility measurements, and spin dimer analysis. / Yahia, Hamdi; Gaudin, Etienne; Darriet, Jacques; Dai, Dadi; Whangbo, Myung Hwan.

In: Inorganic Chemistry, Vol. 45, No. 14, 10.07.2006, p. 5501-5509.

Research output: Contribution to journalArticle

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abstract = "The crystal structure of the low-temperature form of AgCuPO4 (i.e., α-AgCuPO4) was determined by powder X-ray diffraction and was compared with that of the high-temperature form of AgCuPO4 (i.e., β-AgCuPO4). The magnetic properties of the two forms were examined by measuring their magnetic susceptibilities and evaluating the relative strengths of their spin-exchange interactions on the basis of spin-dimer analysis. Both forms of AgCuPO4 have layers of Cu 2P2O8 alternating with silver-atom double layers; β-AgCuPO4 has two Cu2P2O 8 layers per unit cell, while α-AgCuPO4 has one. The coordinate environment of each Cu2+ ion is close to being a distorted square pyramid in α-AgCuPO4, but it is close to being a distorted trigonal bipyramid in β-AgCuPO4. The magnetic susceptibilities of α- and β-AgCuPO4 are well simulated by an antiferromagnetic alternating-chain model, which leads to J/kB = -146.1 K and αJ/kB = -75.8 K for α-AgCuPO4, and J/kB = -82.6 K and aαj/kB = -31.7 K for β-AgCuPO4 (with the convention in which the spin-exchange parameter between two adjacent spin sites is written as 2J). The spin gaps, Δ/kB, obtained from these parameters are 93.7 K for α-AgCuPO4 and 62.3 K for β-AgCuPO4. The strongest spin exchange in both forms of AgCuPO4 comes from a super-superexchange path, and this interaction is stronger for α-AgCuPO4 than for β-AgCuPO4 by a factor of ∼2, in good agreement with the experiment. Our analysis supports the use of this model for β-AgCuPO4 and indicates that the spin lattice of α-AgCuPO4 would be better described by a two-dimensional net made up of weakly interacting alternating chains.",
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T1 - Comparison of the crystal structures and magnetic properties of the low- and high-temperature forms of AgCuPO4

T2 - Crystal structure determination, magnetic susceptibility measurements, and spin dimer analysis

AU - Yahia, Hamdi

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AU - Darriet, Jacques

AU - Dai, Dadi

AU - Whangbo, Myung Hwan

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N2 - The crystal structure of the low-temperature form of AgCuPO4 (i.e., α-AgCuPO4) was determined by powder X-ray diffraction and was compared with that of the high-temperature form of AgCuPO4 (i.e., β-AgCuPO4). The magnetic properties of the two forms were examined by measuring their magnetic susceptibilities and evaluating the relative strengths of their spin-exchange interactions on the basis of spin-dimer analysis. Both forms of AgCuPO4 have layers of Cu 2P2O8 alternating with silver-atom double layers; β-AgCuPO4 has two Cu2P2O 8 layers per unit cell, while α-AgCuPO4 has one. The coordinate environment of each Cu2+ ion is close to being a distorted square pyramid in α-AgCuPO4, but it is close to being a distorted trigonal bipyramid in β-AgCuPO4. The magnetic susceptibilities of α- and β-AgCuPO4 are well simulated by an antiferromagnetic alternating-chain model, which leads to J/kB = -146.1 K and αJ/kB = -75.8 K for α-AgCuPO4, and J/kB = -82.6 K and aαj/kB = -31.7 K for β-AgCuPO4 (with the convention in which the spin-exchange parameter between two adjacent spin sites is written as 2J). The spin gaps, Δ/kB, obtained from these parameters are 93.7 K for α-AgCuPO4 and 62.3 K for β-AgCuPO4. The strongest spin exchange in both forms of AgCuPO4 comes from a super-superexchange path, and this interaction is stronger for α-AgCuPO4 than for β-AgCuPO4 by a factor of ∼2, in good agreement with the experiment. Our analysis supports the use of this model for β-AgCuPO4 and indicates that the spin lattice of α-AgCuPO4 would be better described by a two-dimensional net made up of weakly interacting alternating chains.

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