Preparation and optical properties of group IV–VI2 chalcogenides having the CdI2 structure

Greenaway, David L.; Nitsche, R.

doi:10.1016/0022-3697(65)90043-0

Cited by 553 publications

(264 citation statements)

References 30 publications

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“…The data obtained by the X ray diffraction analysis for the parent hafnium diselenide and Ag x HfSe 2 samples are tabulated. Unit cell parameters of parent hafnium diselenide correspond to these found previously in [4,5], while the data for interca lated samples (similarly to the Cu x HfSe 2 system [15]) indicate an increase in parameters during intercalating the samples.…”

Section: Resultssupporting

confidence: 84%

“…A similar situation can be imple mented for intercalated dichalcogenides of transition metals TX 2 (T is the transition metal of Group IV or V, and X is the chalcogen). The main feature of their crystalline structure is the presence of a weak van der Waals bond between X-T-X three layer blocks, which allows us to intercalate atoms of other elements into the interlayer spacing [4][5][6][7]. Some dichalcogenides of transition metals, which are intercalated by lithium ions, are already used as electrodes for chemical cur rent sources [8].…”

Section: Introductionmentioning

confidence: 99%

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Transport properties and polarization phenomena in intercalated Ag x HfSe2 compounds

2013

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Abstract-The electrical properties of intercalated Ag x HfSe 2 compounds (x = 0.1, 0.2) have been investi gated for the first time. Investigations have been performed using various current electrodes, which make it possible to pass either the electron current or the ion current across the sample. Polarization effects, which indicate the self consistent migration of charge carriers in the samples, have been found for the samples at room temperature. Based on the characteristic features of polarization decay, coefficients of conjugated chemical diffusion have been evaluated.

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Section: Resultssupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Transport properties and polarization phenomena in intercalated Ag x HfSe2 compounds

2013

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“…The refinement of the X-ray pattern revealed a trigonal crystal system with a P-3m1 space group and a unit cell determined by α = β = 90 • and γ = 120 • and a = b = 3.6628(5) Å, c = 5.8270(10) Å for ZrS 2 and a = b = 3.7711(4) Å, c = 6.1282(9) Å for ZrSe 2 . The obtained results are in accordance with the ones reported in the literature [30,41].…”

Section: Discussionsupporting

confidence: 83%

Raman Spectra of ZrS2 and ZrSe2 from Bulk to Atomically Thin Layers

et al. 2016

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Abstract:In the race towards two-dimensional electronic and optoelectronic devices, semiconducting transition metal dichalcogenides (TMDCs) from group VIB have been intensively studied in recent years due to the indirect to direct band-gap transition from bulk to the monolayer. However, new materials still need to be explored. For example, semiconducting TMDCs from group IVB have been predicted to have larger mobilities than their counterparts from group VIB in the monolayer limit. In this work we report the mechanical exfoliation of ZrX 2 (X = S, Se) from bulk down to the monolayer and we study the dimensionality dependence of the Raman spectra in ambient conditions. We observe Raman signal from bulk to few layers and no shift in the peak positions is found when decreasing the dimensionality. While a Raman signal can be observed from bulk to a bilayer for ZrS 2 , we could only detect signal down to five layers for flakes of ZrSe 2 . These results show the possibility of obtaining atomically thin layers of ZrX 2 by mechanical exfoliation and represent one of the first steps towards the investigation of the properties of these materials, still unexplored in the two-dimensional limit.

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“…The band structure of 1T -TiSe 2 , as determined by angle-resolved photoemission spectroscopy, consists primarily of a Se 4p-valence band at the Γ point and a Ti 3d-conduction band at the L point of the Brillouin zone. But it is still debated whether it is a semiconductor or a semimetal with evidences claimed for both alternatives [6,[8][9][10].…”

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confidence: 99%

Scanning tunneling microscopy of the charge density wave in1T−TiSe2in the presence of single atom defects

et al. 2015

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We present a detailed low temperature scanning tunneling microscopy study of the commensurate charge density wave (CDW) in 1T -TiSe2 in the presence of single atom defects. We find no significant modification of the CDW lattice in single crystals with native defects concentrations where some bulk probes already measure substantial reductions in the CDW phase transition signature. Systematic analysis of STM micrographs combined with density functional theory modelling of atomic defect patterns indicate that the observed CDW modulation lies in the Se surface layer. The defect patterns clearly show there are no 2H-polytype inclusions in the CDW phase, as previously found at room temperature [Titov A.N. et al, Phys. Sol. State 53, 1073. They further provide an alternative explanation for the chiral Friedel oscillations recently reported in this compound [J. Ishioka et al., Phys. Rev. B 84, 245125, (2011)].PACS numbers: 68.37. Ef, 71.15.Mb, 74.70.Xa, 73.20.Hb The transition metal dichalcogenide (TMD) 1T -TiSe 2 has kept the scientific community wondering about a number of its striking physical properties for more than four decades [1][2][3][4][5][6][7]. 1T -TiSe 2 is a layered compound consisting of a hexagonal layer of Ti sandwiched between two hexagonal layers of Se to form Se-Ti-Se sandwiches that stack via weak Van-der-Waals (VdW) forces to form a single crystal. The band structure of 1T -TiSe 2 , as determined by angle-resolved photoemission spectroscopy, consists primarily of a Se 4p-valence band at the Γ point and a Ti 3d-conduction band at the L point of the Brillouin zone. But it is still debated whether it is a semiconductor or a semimetal with evidences claimed for both alternatives [6,[8][9][10].Below T CDW ≈ 202K, 1T -TiSe 2 undergoes a second order phase transition into a commensurate charge density wave (CDW). A comprehensive theory of this CDW formation is yet to be developed. Two main mechanisms are currently considered, driven either by a JahnTeller distortion [4,11] or an excitonic ground state [2,9,12,13]. The CDW phase has been found to melt upon copper intercalation [5] or when applying pressure [7]. In both instances, superconductivity develops in a dome shaped region around some optimal doping or optimal pressure, with a maximum critical temperature of 4.1K and 1.8K, respectively. More recently, chiral properties have been reported for the CDW in pristine and copper intercalated 1T -TiSe 2 based on polarized optical reflectometry and scanning tunneling microscopy (STM) [14][15][16].Here we focus on the CDW instability in 1T -TiSe 2 in the presence of native atomic scale defects. Past studies performed using macroscopic probes including resistivity, magnetic susceptibility and optical reflectivity have found atomic intercalation and substitution to be detrimental to the CDW [1,17]. This compound is usually non-stoichiometric with a strong correlation between increasing crystal growth temperature and Ti self-doping leading to the collapse of the CDW phase transition signature in temperature ...

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Preparation and optical properties of group IV–VI2 chalcogenides having the CdI2 structure

Cited by 553 publications

References 30 publications

Transport properties and polarization phenomena in intercalated Ag x HfSe2 compounds

Transport properties and polarization phenomena in intercalated Ag x HfSe2 compounds

Raman Spectra of ZrS2 and ZrSe2 from Bulk to Atomically Thin Layers

Scanning tunneling microscopy of the charge density wave in1T−TiSe2in the presence of single atom defects

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