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Title: Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}

Abstract

Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO{sub 2} have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.

Authors:
; ;  [1]; ;  [2]; ;  [3]
  1. Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru 560012 (India)
  2. Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India)
  3. Synchrotron SOLEIL, L'Orme des Merisiers Saint-Aubin, 91192 Gif-sur-Yvette (France)
Publication Date:
OSTI Identifier:
22590502
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 9; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CATIONS; DIELECTRIC MATERIALS; DIPOLES; DOPED MATERIALS; ENERGY STORAGE; EQUIPMENT; GRAIN BOUNDARIES; LOSSES; MICROELECTRONICS; PERMITTIVITY; RELAXATION; RUTILE; TITANIUM OXIDES

Citation Formats

Mandal, Suman, E-mail: suman.mandal@sscu.iisc.ernet.in, Pal, Somnath, Hazarika, Abhijit, Kundu, Asish K., Menon, Krishnakumar S. R., Rioult, Maxime, and Belkhou, Rachid. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}. United States: N. p., 2016. Web. doi:10.1063/1.4962219.
Mandal, Suman, E-mail: suman.mandal@sscu.iisc.ernet.in, Pal, Somnath, Hazarika, Abhijit, Kundu, Asish K., Menon, Krishnakumar S. R., Rioult, Maxime, & Belkhou, Rachid. Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}. United States. doi:10.1063/1.4962219.
Mandal, Suman, E-mail: suman.mandal@sscu.iisc.ernet.in, Pal, Somnath, Hazarika, Abhijit, Kundu, Asish K., Menon, Krishnakumar S. R., Rioult, Maxime, and Belkhou, Rachid. Mon . "Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}". United States. doi:10.1063/1.4962219.
@article{osti_22590502,
title = {Direct view at colossal permittivity in donor-acceptor (Nb, In) co-doped rutile TiO{sub 2}},
author = {Mandal, Suman, E-mail: suman.mandal@sscu.iisc.ernet.in and Pal, Somnath and Hazarika, Abhijit and Kundu, Asish K. and Menon, Krishnakumar S. R. and Rioult, Maxime and Belkhou, Rachid},
abstractNote = {Topical observations of colossal permittivity (CP) with low dielectric loss in donor-acceptor cations co-doped rutile TiO{sub 2} have opened up several possibilities in microelectronics and energy-storage devices. Yet, the precise origin of the CP behavior, knowledge of which is essential to empower the device integration suitably, is highly disputed in the literature. From spectromicroscopic approach besides dielectric measurements, we explore that microscopic electronic inhomogeneities along with the nano-scale phase boundaries and the low temperature polaronic relaxation are mostly responsible for such a dielectric behavior, rather than electron-pinned defect-dipoles/grain-boundary effects as usually proposed. Donor-acceptor co-doping results in a controlled carrier-hopping inevitably influencing the dielectric loss while invariably upholding the CP value.},
doi = {10.1063/1.4962219},
journal = {Applied Physics Letters},
number = 9,
volume = 109,
place = {United States},
year = {Mon Aug 29 00:00:00 EDT 2016},
month = {Mon Aug 29 00:00:00 EDT 2016}
}
  • Here in this article, we investigated the dielectric properties of (In + Nb) co-doped rutile TiO 2 single crystal and polycrystalline ceramics. Both of them showed colossal, up to 10 4, dielectric permittivity at room temperature. The single crystal sample showed one dielectric relaxation process with a large dielectric loss. The voltage-dependence of dielectric permittivity and the impedance spectrum suggest that the high dielectric permittivity of single crystal originated from the surface barrier layer capacitor (SBLC). The impedance spectroscopy at different temperature confirmed that the (In+Nb) co-doped rutile TiO 2 polycrystalline ceramic had semiconductor grains and insulating grain boundaries, andmore » that the activation energies were calculated to be 0.052 eV and 0.35 eV for grain and grain boundary, respectively. The dielectric behavior and impedance spectrum of the polycrystalline ceramic sample indicated that the internal barrier layer capacitor (IBLC) mode made a major contribution to the high ceramic dielectric permittivity, instead of the electron-pinned defect-dipoles.« less
  • An effective non-metal (N) and non-transition metal (Sb) passivated co-doping approach is proposed to improve the photoelectochemical performance of rutile TiO{sub 2} for water-splitting by using first-principles calculations. It is found that the band edges of N + Sb co-doped TiO{sub 2} match with the redox potentials of water, and a narrow band gap (2.0 eV) is achieved for enhanced visible light absorption. The compensated donor (Sb) and acceptor (N) pairs could prevent the recombination of photo-generated electron-hole pairs. In addition, the N + Sb defect pairs tend to bind with each other, which could enhance the stability and Nmore » concentration of the system.« less
  • Co-doped rutile TiO{sub 2} was synthesized by injecting Co ions into single crystal rutile TiO{sub 2} using high energy ion implantation. Microstructures of the implanted specimens were studied in detail using high-resolution transmission electron microscopy (HRTEM), energy dispersive x-ray spectroscopy, electron diffraction, and HRTEM image simulations. The spatial distribution and conglomeration behavior of the implanted Co ions, as well as the point defect distributions induced by ion implantation, show strong dependences on implantation conditions. Uniform distribution of Co ions in the rutile TiO{sub 2} lattice was obtained by implanting at 1075 K with a Co ion fluence of 1.25x10{sup 16}more » Co/cm{sup 2}. Implanting at 875 K leads to the formation of Co metal clusters. The precipitated Co metal clusters and surrounding TiO{sub 2} matrix exhibit the orientation relationships Co<110> parallel TiO{sub 2}[001] and Co{l_brace}111{r_brace} parallel TiO{sub 2}(110). A structural model representing the interface between Co metal clusters and TiO{sub 2} is developed based on HRTEM imaging and image simulations.« less
  • Of central interest in the research of dilute magnetic semiconductors is the coupling mechanism leading to a ferromagnetic ground state. Using x-ray resonant magnetic scattering, we have analyzed the element specific magnetic hysteresis curves of Co, Ti, and oxygen in Co-doped TiO{sub 2} synthesized by ion implantation. Magnetic dichroism was observed at the Co L{sub 2,3} edges, as well as at the O K edge, indicative of a spin polarization of oxygen atoms in the TiO{sub 2} host matrix. The hysteretic shapes and the coercive field values measured at the Co L{sub 3} and O K edges are identical (1.9more » kOe at 30 K)« less