Thermal conductivity and thermoelectric power of CuIr2S4 and CuIr2Se4 spinels

Balcerek, K.; Marucha, Cz.; Wawryk, R.; Tyc, Tomáš; Matsumoto, N.; Nagata, S.

doi:10.1080/014186399256899

Cited by 4 publications

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“…Many studies on different properties were performed, e.g. on ferro- and antiferromagnetism, superconductivity, − spin-glass transitions, and thermoelectric properties . In the past, thiospinels were also under investigation as cathodes for secondary lithium batteries during the 1980s and -90s …”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Physical Properties of a New CuTi₂S₄ Modification in Comparison to the Thiospinel

et al. 2004

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A new modification of CuTi(2)S(4) was prepared from the elements at 425 degrees C. It crystallizes in the rhombohedral space group Rm, with lattice parameters of a = 7.0242(4) A, c = 34.834(4) A, and V = 1488.4(2) A(3) (Z = 12). Two topologically different interlayer regions exist between the close-packed S layers that alternate along the c axis: one comprises both Cu (in tetrahedral voids) and Ti atoms (in octahedral voids), and the second exclusively Ti atoms (again in octahedral voids). In contrast to the known modification, the spinel, Cu-Ti interactions of 2.88 A occur that have bonding character according to the electronic structure calculations. Both CuTi(2)S(4) modifications are metallic Pauli paramagnets due to Ti d contributions. The Pauli susceptibility of the Rm form is larger than that of the thiospinel in quantitative agreement with the LMTO-ASA band structure calculations. The irreversible transformation to the spinel takes place at temperatures above 450 degrees C.

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Section: Introductionmentioning

confidence: 99%

Crystal Structure and Physical Properties of a New CuTi₂S₄ Modification in Comparison to the Thiospinel

et al. 2004

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“…I ntroduction The metal±insulator (M±I) transition in CuIr 2 S 4 has been extensively investigated in the past decade , Balcerek et al 1999, Burkov et al 2000a, b, Matsumoto and Nagata 2000, Endoh et al 2001. The sulphospinel CuIr 2 S 4 has the normal spinel-type structure where Cu ions occupy the A (tetrahedral) sites and Ir ions occupy the B (octahedral) sites, as shown in ®gure 1.…”

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confidence: 99%

Metal-insulator transition in the spinel-type Cu (Ir 1- x Ti x ) 2 S 4 system

Nagata¹,

Ito²,

Endoh³

et al. 2002

Philosophical Magazine B

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A bstractThe normal sulphospinel CuIr 2 S 4 exhibits a temperature-induced metal± insulator (M±I) transition around TM Iˆ230 K with a structural transformation. This T M I increases markedly with increasing pressure. It has been veri®ed that the 5d electrons of Ir ions at the B sites located at the Fermi surface play a signi®cant role for the strong correlated electron system. Conversely, CuTi2S4 remains metallic down to 4.2 K without any structural transformations. These two compounds have the same normal spinel structure, whereas the number of d electrons at the B sites are quite di erent. High-purity spinel-type Cu(Ir 1 ¡ x Ti x ) 2 S 4 specimens have been successfully synthesized. The value of the lattice constant a indicates a broad minimum around xˆ0:12, not obeying Vegard's law. We have systematically studied the structural transformation and electrical and magnetic properties of Cu(Ir1¡xTix † 2S4. A phase diagram between T M I and x will be provided for the Cu(Ir 1 ¡ x Ti x † 2 S 4 system. TM I varies drastically with x and disappears at around xˆ0:06. A novel relationship, namely a`mirror image e ect', between the value of residual resistivity and the magnitude of the electronic density of states, D … "F † , at the Fermi level, has been observed accurately. } 1. I ntroduction The metal±insulator (M±I) transition in CuIr 2 S 4 has been extensively investigated in the past decade (Furubayashi et al. ). The sulphospinel CuIr 2 S 4 has the normal spinel-type structure where Cu ions occupy the A (tetrahedral) sites and Ir ions occupy the B (octahedral) sites, as shown in ®gure 1. CuIr 2 S 4 exhibits the temperature-induce d M±I transition around T M Iˆ2 30 K with structural transformation , showing hysteresis on heating and cooling. The resistivity of CuIr 2 S 4 jumps discontinuousl y by nearly three orders of magnitude at T M I as indicated in ®gure 2. With decreasing temperature, the symmetry changes from cubic to tetragonal, accompanied by a change from high-temperatur e Pauli paramagnetism in the metallic state to weak diamagnetism due to the atomic core orbital in the insulating state. A detailed structure analysis of the insulating phase has been made (Oshima et al. 1999, Ishibashi et al. 2001, Oikawa et al. 2001, Sun et al. 2001, Radaelli et al. 2002. The temperature dependence of magnetic susceptibility

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“…8 Nevertheless, no attempt has been made to appreciate whether the transport properties in the metallic state of the compounds can be described within the framework of a conventional metallic conductivity mechanism, or they have some unusual features. The only transport property, which has been investigated for these compounds, is the resistivity ͑recently thermopower and thermal conductivity of CuIr 2 S 4 and CuIr 2 Se 4 were measured at 10 to 300 K, 9 but the results have not been published yet͒. The resistivity of CuIr 2 S 4 has been measured from about 20 K to room temperature, 1 whereas the resistivity of CuIr 2 Se 4 is known from room temperature down to 0.5 K. 3 No data have been available above room temperature.…”

Section: Introductionmentioning

confidence: 99%

Anomalous resistivity and thermopower of the spinel-type compoundsCuIr2S4and
Бурков
¹
,
Nakama
²
,
Hedo
³

et al. 2000
Phys. Rev. B
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Resistivity () and thermopower ͑S͒ of spinel-type compounds CuIr 2 S 4 and CuIr 2 Se 4 have been measured at temperatures from 2 to 900 K under magnetic field from 0 to 15 T. The thermopower is positive in the metallic phase of both compounds at high temperatures, as well as in the low-temperature insulating state of CuIr 2 S 4 . The positive thermopower of the insulating phase implies p-type charge carriers, in agreement with the recent photoemission results. The low-temperature resistivity of CuIr 2 S 4 is in good agreement with the Efros-Shklovskii variable-range hopping conductivity mechanism: ϭ 0 exp͓(T*/T) 1/2 ͔. The most striking result is that the resistivity of the metallic phases is well described by an exponential-type temperature dependence in a wide temperature range from 2 K to at least 900 K. This unusual result for metals type of the resistivity temperature dependence, as well as other features in the transport properties, imply a nonconventional conductivity mechanism. The magnetoresistivity ⌬ is positive and proportional to H 2 , while magnetothermopower ⌬SϭS(H,T)ϪS(0,T) is very small for both compounds at all temperatures.

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Thermal conductivity and thermoelectric power of CuIr2S4 and CuIr2Se4 spinels

Cited by 4 publications

References 0 publications

Crystal Structure and Physical Properties of a New CuTi₂S₄ Modification in Comparison to the Thiospinel

Crystal Structure and Physical Properties of a New CuTi₂S₄ Modification in Comparison to the Thiospinel

Metal-insulator transition in the spinel-type Cu (Ir 1- x Ti x ) 2 S 4 system

Anomalous resistivity and thermopower of the spinel-type compoundsCuIr2S4and
Бурков
¹
,
Nakama
²
,
Hedo
³

et al. 2000
Phys. Rev. B
Self Cite

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Thermal conductivity and thermoelectric power of CuIr2S4 and CuIr2Se4 spinels

Cited by 4 publications

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Crystal Structure and Physical Properties of a New CuTi2S4 Modification in Comparison to the Thiospinel

Crystal Structure and Physical Properties of a New CuTi2S4 Modification in Comparison to the Thiospinel

Metal-insulator transition in the spinel-type Cu (Ir 1- x Ti x ) 2 S 4 system

Anomalous resistivity and thermopower of the spinel-type compoundsCuIr2S4andБурков1, Nakama2, Hedo3 et al. 2000Phys. Rev. BSelf Cite

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Crystal Structure and Physical Properties of a New CuTi₂S₄ Modification in Comparison to the Thiospinel

Crystal Structure and Physical Properties of a New CuTi₂S₄ Modification in Comparison to the Thiospinel

Anomalous resistivity and thermopower of the spinel-type compoundsCuIr2S4and
Бурков
¹
,
Nakama
²
,
Hedo
³

et al. 2000
Phys. Rev. B
Self Cite