scholarly journals Metal-insulator transition in a semiconductor nanocrystal network

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw1462 ◽  
Author(s):  
Benjamin L. Greenberg ◽  
Zachary L. Robinson ◽  
Yilikal Ayino ◽  
Jacob T. Held ◽  
Timothy A. Peterson ◽  
...  
Keyword(s):  
Semiconductor Nanocrystals ◽  
Insulator Transition ◽  
Transparent Conductors ◽  
Contact Radius ◽  
Interparticle Contact ◽  
Metal Insulator Transition ◽  
Free Electron Density ◽  
Metal Insulator ◽  
Semiconductor Nanocrystal ◽  
Lower Temperature

Many envisioned applications of semiconductor nanocrystals (NCs), such as thermoelectric generators and transparent conductors, require metallic (nonactivated) charge transport across an NC network. Although encouraging signs of metallic or near-metallic transport have been reported, a thorough demonstration of nonzero conductivity, σ, in the 0 K limit has been elusive. Here, we examine the temperature dependence of σ of ZnO NC networks. Attaining both higher σ and lower temperature than in previous studies of ZnO NCs (T as low as 50 mK), we observe a clear transition from the variable-range hopping regime to the metallic regime. The critical point of the transition is distinctly marked by an unusual power law close to σ ∝ T1/5. We analyze the critical conductivity data within a quantum critical scaling framework and estimate the metal-insulator transition (MIT) criterion in terms of the free electron density, n, and interparticle contact radius, ρ.

scholarly journals Study of Microstructural, Electrical and Dielectric Properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 Ceramics

2019 ◽  
pp. 33-44 ◽  
Keyword(s):  
Transition Temperature ◽  
Frequency Dispersion ◽  
Insulator Transition ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Solid State Route ◽  
Distorted Structure ◽  
Lower Temperature

The present work studies the microstructural and electrical properties of La0.9Pb0.1MnO3 and La0.8Y0.1Pb0.1MnO3 ceramics synthesized by solid-state route method. Microstructure and elemental analysis of both samples were carried out by field emission scanning electron microscope (FESEM) and energy dispersive spectroscopy (EDS) method, respectively. Phase analysis by X-ray diffraction (XRD) indicated formation of single phase distorted structure. The XRD data were further analyzed by Rietveld refinement technique. Raman analysis reveals that Y atom substitutes La site into the LPMO with shifting of phonon modes. The temperature variation of resistivity of undoped and Y-doped La0.9Pb0.1MnO3 samples have been investigated. The electrical resistivity as a function of temperature showed that all samples undergo an metal-insulator (M-I) transition having a peak at transition temperature TMI. Y-doping increases the resistivity and the metal-insulator transition temperature (TMI) shifts to lower temperature. The temperature-dependent resistivity for temperatures less than metal-insulator transition is explained in terms the quadratic temperature dependence and for T > TMI, thermally activated conduction (TAC) is appropriate. Variation of frequency dispersion in permittivity and loss pattern due to La-site substitution in LPMO was observed in the dielectric response curve.

scholarly journals Metal–insulator transition in films of doped semiconductor nanocrystals

2015 ◽  
Vol 15 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Ting Chen ◽  
K. V. Reich ◽  
Nicolaas J. Kramer ◽  
Han Fu ◽  
Uwe R. Kortshagen ◽  
...  
Keyword(s):  
Semiconductor Nanocrystals ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator

scholarly journals Effect of The Calcination Process On The Magnetotransport Properties in Co-Precipitation Derived La0.67Ca0.33MnO3 Ceramics

2021 ◽  
Author(s):  
Yule Li ◽  
Ping Yu ◽  
Xiaojin Wang ◽  
Fuxin Ling ◽  
Qingming Chen ◽  
...  
Keyword(s):  
Colossal Magnetoresistance ◽  
Sol Gel ◽  
Insulator Transition ◽  
Precipitation Method ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Calcination Process ◽  
Temperature Ranges ◽  
Lower Temperature ◽  
Co Precipitation

Abstract La0.67Ca0.33MnO3 (LCMO) attracts considerable attention as a quintessential example for colossal magnetoresistance (CMR), metal-insulator transition and related temperature coefficient of resistance (TCR) studies. Here, co-precipitation method was utilized to prepare the LCMO ceramics, whose magnetotransport properties as a function of calcination temperature (Tcal) and calcination time (tcal) were investigated. The magnetotransport properties of these LCMO ceramics were significantly enhanced compared with LCMO derived by sol-gel methods. The TCR of LCMO increased firstly and then decreased as the Tcal increased, whereas the metal-insulator transition temperature (TMIT) shifted towards to the lower temperature. Magnetoresistance (MR) increased as Tcal rose and reached 82.4 % at Tcal = 800 ℃. The mechanism of such magnetotransport properties with different temperature ranges was discussed. The optimal TCR of 32.3%·K-1 in LCMO was prepared with Tcal = 500 ℃ and tcal = 8 h, showing that co-precipitation method would facilitate the potential application of LCMO in infrared detecting and magnetoresistive switching.

Fermi-surface reconstruction close to a pressure-induced metal-insulator transition

2004 ◽  
Vol 114 ◽  
pp. 277-281 ◽  
Author(s):  
J. Wosnitza ◽  
J. Hagel ◽  
O. Stockert ◽  
C. Pfleiderer ◽  
J. A. Schlueter ◽  
...  
Keyword(s):  
Fermi Surface ◽  
Surface Reconstruction ◽  
Insulator Transition ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Fermi Surface Reconstruction

Crystal growth and metal-insulator transition in two-dimensional layered rare-earth palladates

2018 ◽  
Vol 2 (8) ◽  
Author(s):  
Yoshiko Nanao ◽  
Yoshiharu Krockenberger ◽  
Ai Ikeda ◽  
Yoshitaka Taniyasu ◽  
Michio Naito ◽  
...  
Keyword(s):  
Rare Earth ◽  
Crystal Growth ◽  
Insulator Transition ◽  
Two Dimensional ◽  
Metal Insulator Transition ◽  
Metal Insulator
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