Superionic conductors: Transitions, structures, dynamics

Boyce, J. B.; Huberman, Bernardo A.

doi:10.1016/0370-1573(79)90067-x

Cited by 417 publications

(279 citation statements)

References 182 publications

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“…Large volume changes (2.3% and 0.6%) at abrupt superionic phase transitions are strong evidence that stromeyerite undergoes a type-I superionic transition according to the classification of Boyce and Huberman [25]. The presence of an hcp sulfur sublattice in both β-and α-AgCuS implies that the β −→ α transformation is induced due to cation disordering effects (or clustering of mobile ions, which accelerates instability of the lowtemperature phase [26]), whereas a rearrangement of the rigid anion sublattice from hcp to fcc accompanies the α −→ δ transformation.…”

Section: Discussionmentioning

confidence: 99%

High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS

Trots

Senyshyn

Mikhailova

et al. 2007

J. Phys.: Condens. Matter

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Results of simultaneous thermal analysis, synchrotron and neutron powder diffraction in the range from room temperature up to the melting point at 936 K on non-superionic orthorhombic β-AgCuS as well as on superionic hexagonal α-and cubic δ-AgCuS are reported. On heating the sample is only stable in argon. The following phase transitions occur in AgCuS at elevated temperatures:The volume changes at the superionic β −→ α and α −→ δ phase transitions are about 2.3 and 0.6%. The volume thermal expansion coefficients are 26 × 10 −6 , 130 × 10 −6 and 85 × 10 −6 K −1 for the pure β-, α-and δ-phases, respectively. Models for the average structures of α-and δ-AgCuS are proposed and discussed. Ionic conductivity in δ-AgCuS may originate from cation jumps in 'skewed' 100 directions between nearest-neighbour tetrahedral sites via the peripheries of the octahedral cavities. A correlation between the temperature dependence of the cation redistribution in δ-AgCuS and the temperature dependence of the ionic conductivity is assumed. A two-dimensional nature of the ionic conductivity due to cation jumps in slabs perpendicular to the c-direction is supposed for α-AgCuS. There is no evidence for ionic diffusion through the ( 1 2 , 1 2 , 1 2 ) site in 111 directions in either superionic α-or δ-phases.

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Section: Discussionmentioning

confidence: 99%

High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS

Trots

Senyshyn

Mikhailova

et al. 2007

J. Phys.: Condens. Matter

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“…The total transformation enthalpy (i.e. integrated area of the peaks) remains large indicating that the cation-sublattice melting nature [33] of the transition still persists with Li doping. The distribution of the transformation enthalpy over a wide range of temperatures in both peaks likely indicates that both transitions happen gradually through a phase mixture region in the phase diagram, where the peak shape reflects the shape of the phase boundaries [32].…”

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confidence: 99%

Enhanced stability and thermoelectric figure-of-merit in copper selenide by lithium doping

Kang

Pöhls

Aydemir

et al. 2017

Materials Today Physics

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Superionic thermoelectric materials have been shown to have high figure-ofmerits, leading to expectations for efficient high-temperature thermoelectric generators. These compounds exhibit extremely high cation diffusivity, comparable to that of a liquid, which is believed to be associated with the low thermal conductivity that makes superionic materials good for thermoelectrics. However, the superionic behavior causes cation migration that leads to device deterioration, being the main obstacle for practical applications. It has been reported that lithium doping in superionic Cu 2-x Se leads to suppression of the Cu ion diffusivity, but whether the material will retain the promising thermoelectric properties had not yet been investigated. Here, we report a maximum zT > 1.4 from Li 0.09 Cu 1.9 Se, which is higher than what we find in the undoped samples. The high temperature effective weighted mobility of the doped sample is found higher than Cu 2-x Se, while the lattice thermal conductivity remains similar. We find signatures of suppressed bipolar conduction due to an enlarged band gap. Our findings set forth a possible route for tuning the stability of superionic thermoelectric materials.Thermoelectric generators produce electrical energy from a heat flux through the device. Having been proven for their reliability from stable implementations in space missions, the technology is now drawing interest for terrestrial applications. For example, using thermoelectric technology to convert waste industrial heat into electricity could deliver a significant alleviation to the energy crisis. However, wide-spread use of the technology is limited by the energy conversion efficiency, which is bottlenecked by what thermoelectric materials can offer. The maximum efficiency obtainable from a material is characterized by the figure-of-merit:where S is the Seebeck coefficient, σ is electrical conductivity, and κ is thermal conductivity. Thermoelectric materials research is thus heavily focused on the search for high zT materials. In the search for new material families for thermoelectrics, the revisit to superionic compounds as thermoelectric materials [1] has sparked great interest because of their inherently low thermal conductivity [2] which is advantageous in obtaining a high zT . In the superionic phase, cations exhibit liquid-like diffusivity [3,4] and this disordered nature typically results in a very low lattice thermal conductivity (<1 W m −1 K −1 ). Many of the superionic compounds, particularly those that are also good electric conductors, indeed show promising thermoelectric properties as exemplified by Cu 2 Se [1,5]

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“…Sodium doped β-alumina variants are good examples of type III superionic materials [24] . Thermodynamic studies of SIC have shown that during the phase transitions the entropy change per atom is approximately the same as the entropy change per atom upon melting [30] . For this reason, the transition to the superionic state is called "sublattice melting".…”

Section: Superionic Te Materialsmentioning

confidence: 99%

An Overview of Advanced Chalcogenide Thermo- electric Materials and Their Applications

Tesfaye¹

2018

JERA

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Thermoelectricity is a strong scientific and technological interest due to its wide application ranging from clean energy producing to photon sensing devices. Recent developments in theoretical studies on the thermoelectric (TE) effects as well as the newly discovered thermoelectric materials provide new opportunities for several applications. Though the scale of production is limited, thermoelectric technology provides an alternative to traditional methods of power generation, heating and cooling systems. TE technologies can be used in power generation, heating and cooling applications. They potentially offer significant energy savings through waste heat recovery and augmented cooling. This article critically discusses the current progress in chalcogenide TE materials and the advantages and limitations associated with the TE technologies. The need for new materials discoveries from the point of view of achieving higher figure-of-merit combined with thermal stabilities in intermediate-and hightemperature Peltier and Seebeck effects applications is also emphasized. Besides, this article aims to evaluate the main features of recently characterized multicomponent chalcogenide ionic compounds with high thermal stabilities as potential TE materials to harvest electric power from high-temperature heat flux via thermoelectricity.

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Superionic conductors: Transitions, structures, dynamics

Cited by 417 publications

References 182 publications

High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS

High-temperature thermal expansion and structural behaviour of stromeyerite, AgCuS

Enhanced stability and thermoelectric figure-of-merit in copper selenide by lithium doping

An Overview of Advanced Chalcogenide Thermo- electric Materials and Their Applications

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