Physical properties and phase transitions of β Cu2−xSe (0.20≤x≤0.25)

Ohtani, Toshio; Tachibana, Y.; Ogura, Jun; Miyake, Takafumi; Okada, Yuji; Yokota, Yasuhiro

doi:10.1016/s0925-8388(98)00674-4

Cited by 53 publications

(27 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1 in Supplement). In the temperature range 200-130 K the peaks from the Cu 3 Se 2 phase appear and no further changes occur at temperatures below 130 K. These changes in structure are in general agreement with the ␣ → ␤ and ␤ → ␤ phase transformations at ∼290 and ∼150 K reported previously [1,21]. Note that amount of Cu 3 Se 2 phase is substantially higher in the "slow" cooled sample than in the "quenched" one.…”

Section: Cu 175 Sesupporting

confidence: 90%

See 1 more Smart Citation

Neutron diffraction study of diffuse scattering in Cu2−δSe superionic compounds

Danilkin

Avdeev

Sakuma

et al. 2011

Journal of Alloys and Compounds

View full text Add to dashboard Cite

Section: Cu 175 Sesupporting

confidence: 90%

“…On cooling from 300 K modifications are seen between diffraction patterns at 300 K and 100 K reflecting the superstructural ␤ → ␤ transition at T ≈ 150 K [1,21]. At the same time spectra at 100 K and 4 K show very little difference apart from the change in peak positions with temperature.…”

Section: Cu 198 Sementioning

confidence: 97%

Neutron diffraction study of diffuse scattering in Cu2−δSe superionic compounds

Danilkin

Avdeev

Sakuma

et al. 2011

Journal of Alloys and Compounds

View full text Add to dashboard Cite

“…In line with earlier reports [12,[25][26][27][28], a reversible α to α superstructure transition is also evident in the sample studied here via an intensity rearrangement of the multiplet of superlattice peaks located in the Q region close to the (400) reflection in cubic notation (Fig. 2).…”

supporting

confidence: 92%

“…However, the structural determination of the ordered phase(s) still remains controversial [11]. Furthermore, despite some rare reports on samples with quite high Cu deficiency (e.g., Cu 2−x Se, 0.20 x 0.25) [12], a detailed study of the transport properties of stoichiometric Cu 2 Se at low temperatures is still desirable. In this paper, we report first-principles determination of the ground state along with several unexpected experimental findings regarding the lowtemperature transport properties of Cu 2 Se, which may indicate an intrinsic 2D quantum behavior.…”

mentioning

confidence: 99%

Low-temperature structural and transport anomalies inCu2Se

et al. 2014

View full text Add to dashboard Cite

Through systematic examination of symmetrically nonequivalent configurations, first-principles calculations have identified a new ground state of Cu 2 Se, which is constructed by repeating sextuple layers of Se-Cu-Cu-CuCu-Se. The layered nature is in accord with electron and x-ray diffraction studies at and below room temperature and also is consistent with transport properties. Magnetoresistance measurements at liquid helium temperatures exhibit cusp-shaped field dependence at low fields and evolve into quasilinear field dependence at intermediate and high fields. These results reveal the existence of weak antilocalization effect, which has been analyzed using a modified Hikami, Larkin, and Nagaoka model, including a quantum interference term and a classical quadratic contribution. Fitting parameters suggest a quantum coherence length L of 175 nm at 1.8 K. With increasing temperature, the classical parabolic behavior becomes more dominant, and L decreases as a power law of T −0.83 .Transition metal chalcogenides (TMCs) allow fruitful research in contemporary condensed matter physics, leading to intriguing discoveries and promising applications [1]. For example, the silver chalcogenides (e.g., Ag 2 Te) are renowned for their extraordinary large magnetoresistance (MR) [2] and have been recently identified as a new class of binary topological insulators (TI) with a highly anisotropic Dirac cone [3]. Additionally, transition metal dichalcogenides (TMDCs) MX 2 , where M is a transition metal element and X is a chalcogen atom (S, Se, or Te), are well known for their two-dimensional (2D) structures formed by X-M-X layers with strong inplane bonding and weak out-of-plane interactions. The unique intrinsic 2D nature of TMDCs has stimulated the search for novel states of matter, for instance, by offering a coexistence of superconductivity and the Mott commensurate charge density wave (CCDW) phase in 1T-TaS 2 [4]. Furthermore, the electronic band structures of TMDCs are believed to host exotic spin-orbit phenomena such as the systematic crossover from weak antilocalization (WAL) to weak localization (WL) [5,6].As an important member of the TMC family, the superionic Cu 2 Se has also received heightened attention in recent developments of thermoelectrics [7] and optoelectronics [8] due to the unique transport properties associated with its structural phase transition occurring at ∼400 K. The exact temperature of this well-known reversible second-order phase transition from the ordered room temperature (RT) monoclinic α phase to the disordered high temperature (HT) cubic β phase depends on the Cu deficiency in the metal sublattice [9] and is found to be tunable upon iodine doping on the selenium sites [10]. It is generally accepted that the disordered * Corresponding author: cuher@umich.edu HT β phase of Cu 2 Se [space group F m3m (O 5 h ,#225)] is constructed by statistically distributing Cu atoms over the 8c tetrahedral sites in a face-centered cubic (fcc) matrix formed by Se atoms. However, the structural determination ...

show abstract

“…The ordering of Cu ions in β-Cu 2-δ Se results in a complicated superstructure, which is very sensitive to the composition and preparation conditions. Recently a first-order transition of order-disorder type was observed in Cu 1.75 Se at 170 -180 K. Below 170 K the fcc modification transforms to a new phase with a (2 × 2 × 2) superlattice [9].…”

Section: Introductionmentioning

confidence: 99%

Phase transitions and transport phenomena in Li_0.25Cu_1.75Se superionic compound

Балапанов

Биккулова²,

Mukhamed’yanov

et al. 2004

Physica Status Solidi (b)

View full text Add to dashboard Cite

Phase transformation points in Li 0.25 Cu 1.75 Se mixed electronic-ionic conductor have been determined by calorimetric, conductometric and thermoelectric measurements. The phase transformation (PT) from triclinic to monoclinic occurs at 403 -413 K. At 503 -515 K the monoclinic phase is followed by a rhombohedral modification. Both of these PTs are accompanied by drops on the calorimetric curve. At about 653 K observed anomalies in the temperature dependencies of the ionic conductivity, of the chemical diffusion coefficient and the jump of the ionic Seebeck coefficient have been induced by the PT to hexagonal phase. Neutron diffraction studies reveal the cubic structure of Li 0.25 Cu 1.75 Se compound (with space group Fm3m) at 773 K. The corresponding PT causes anomalies in the electrical and diffusion properties at 703-713 K. Cu ions are statistically distributed over tetrahedral and trigonal voids in an Fm3m cage; lithium ions randomly occupy 32(f) positions.

show abstract

Physical properties and phase transitions of β Cu2−xSe (0.20≤x≤0.25)

Cited by 53 publications

References 24 publications

Neutron diffraction study of diffuse scattering in Cu2−δSe superionic compounds

Neutron diffraction study of diffuse scattering in Cu2−δSe superionic compounds

Low-temperature structural and transport anomalies inCu2Se

Phase transitions and transport phenomena in Li_0.25Cu_1.75Se superionic compound

Contact Info

Product

Resources

About

Physical properties and phase transitions of β Cu2−xSe (0.20≤x≤0.25)

Cited by 53 publications

References 24 publications

Neutron diffraction study of diffuse scattering in Cu2−δSe superionic compounds

Neutron diffraction study of diffuse scattering in Cu2−δSe superionic compounds

Low-temperature structural and transport anomalies inCu2Se

Phase transitions and transport phenomena in Li0.25Cu1.75Se superionic compound

Contact Info

Product

Resources

About

Phase transitions and transport phenomena in Li_0.25Cu_1.75Se superionic compound