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Title: Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method

Abstract

Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.

Authors:
; ; ; ; ;  [1]
  1. Crystal Growth Centre, Anna University, Chennai (India)
Publication Date:
OSTI Identifier:
22113522
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1512; Journal Issue: 1; Conference: 57. DAE solid state physics symposium 2012, Mumbai (India), 3-7 Dec 2012; Other Information: (c) 2013 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOMIC FORCE MICROSCOPY; CRYSTAL DEFECTS; CRYSTAL GROWTH; ELECTRIC CONDUCTIVITY; HEAVY IONS; ION BEAMS; IRRADIATION; LITHIUM IONS; MEV RANGE; MONOCRYSTALS; MORPHOLOGY; NIOBATES; PHYSICAL RADIATION EFFECTS; POTASSIUM COMPOUNDS; ROUGHNESS; SCANNING ELECTRON MICROSCOPY; SODIUM COMPOUNDS

Citation Formats

Saravanan, R., Rajesh, D., Rajasekaran, S. V., Perumal, R., Chitra, M., and Jayavel, R. Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method. United States: N. p., 2013. Web. doi:10.1063/1.4791337.
Saravanan, R., Rajesh, D., Rajasekaran, S. V., Perumal, R., Chitra, M., & Jayavel, R. Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method. United States. doi:10.1063/1.4791337.
Saravanan, R., Rajesh, D., Rajasekaran, S. V., Perumal, R., Chitra, M., and Jayavel, R. Tue . "Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method". United States. doi:10.1063/1.4791337.
@article{osti_22113522,
title = {Structural, morphological and electrical studies of lithium ion irradiated sodium potassium niobate single crystal grown by flux method},
author = {Saravanan, R. and Rajesh, D. and Rajasekaran, S. V. and Perumal, R. and Chitra, M. and Jayavel, R.},
abstractNote = {Single crystals of sodium potassium niobate (K{sub 0.5}Na{sub 0.5})NbO{sub 3} (KNN) were grown by flux method and crystals were irradiated with 45 MeV Li ions to modify the electrical properties. Energy of the irradiated heavy ion was lower than the threshold energy to produce columnar defect and only clusters of defect was observed. The surface morphology of the irradiated single crystals was studied using scanning electron microscope (SEM) and atomic force microscope (AFM). The results show that the surface roughness value was found to increase with increasing fluence.},
doi = {10.1063/1.4791337},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1512,
place = {United States},
year = {Tue Feb 05 00:00:00 EST 2013},
month = {Tue Feb 05 00:00:00 EST 2013}
}
  • Epitaxial films of sodium potassium tantalate (Na{sub 0.5}K{sub 0.5}TaO{sub 3}, NKT) and sodium potassium niobate (Na{sub 0.5}K{sub 0.5}NbO{sub 3}, NKN) were grown on single-crystal lanthanum aluminate (LAO) (100) (indexed as a pseudo-cubic unit cell) substrates via an all-alkoxide solution (methoxyethoxide complexes in 2-methoxyethanol) deposition route for the first time. X-ray diffraction studies indicated that the onset of crystallization in powders formed from hydrolyzed gel samples was 550 C. {sup 13}C nuclear magnetic resonance studies of solutions of methoxyethoxide complexes indicated that mixed-metal species were formed, consistent with the low crystallization temperatures observed. Thermal gravimetric analysis with simultaneous mass spectrometry showedmore » the facile loss of the ligand (methoxyethoxide) at temperatures below 400 C. Crystalline films were obtained at temperatures as low as 650 C when annealed in air. {theta}-2{theta} x-ray diffraction patterns revealed that the films possessed c-axis alignment in that only (h00) reflections were observed. Pole-figures about the NKT or NKN (220) reflection indicated a single in-plane, cube-on-cube epitaxy. The quality of the films was estimated via {omega} (out-of-plane) and {psi} (in-plane) scans and full-widths at half-maximum (FWHMs) were found to be reasonably narrow ({approx}1{sup o}), considering the lattice mismatch between the films and the substrate.« less
  • Single-crystal K{sub 8}Ga{sub 8.5}Sn{sub 37.5} was synthesized employing a self-flux method where Ga and Sn were used as fluxes. Single-crystal X-ray diffraction analyses revealed that this composition crystallizes in a cubic structure with the Pm3{sup ¯}n space group (number sign 223, a=11.9345(16) Å, V=1699.9(4) Å{sup 3}, Z=1, and R/wR=0.0187/0.0382). A large dynamic disorder and anisotropic atomic displacement parameters were observed for K atoms inside the larger polyhedra in the crystal structure of K{sub 8}Ga{sub 8.5}Sn{sub 37.5}. Electrical properties measurements indicate p-type conduction with onset of minority charge carrier conduction at temperatures above 270 K. - Graphical abstract: Single-crystal K{sub 8}Ga{submore » 8.5}Sn{sub 37.5} was synthesized via a double-flux method where Ga and Sn were used as fluxes. Large disorder for K inside the larger polyhedra in the crystal structure of K{sub 8}Ga{sub 8.5}Sn{sub 37.5} was observed. Measurements of the electronic properties indicate p-type conduction with the onset of minority charge carrier conduction at temperatures above 270 K. Highlights: • Single-crystal K{sub 8}Ga{sub 8.5}Sn{sub 37.5} synthesized for the first time, and fully structurally characterized. • Large disorder for K inside the larger polyhedra in the crystal structure of K{sub 8}Ga{sub 8.5}Sn{sub 37.5.} • Electronic properties indicate p-type conduction with relatively low thermal conductivity.« less
  • Thin films of SrBi{sub 4}Ti{sub 4}O{sub 15} (SBTi), a prototype of the Bi-layered-ferroelectric oxide family, were obtained by a soft chemical method and crystallized in a domestic microwave oven. For comparison, films were also crystallized in a conventional method at 700 deg. C for 2 h. Structural and morphological characterization of the SBTi thin films were investigated by X-ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Using platinum coated silicon substrates, the ferroelectric properties of the films were determined. Remanent polarization P{sub r} and a coercive field E{sub c} values of 5.1 {mu}C/cm{sup 2} and 135 kV/cm for themore » film thermally treated in the microwave oven and 5.4 {mu}C/cm{sup 2} and 85 kV/cm for the film thermally treated in conventional furnace were found. The films thermally treated in the conventional furnace exhibited excellent fatigue-free characteristics up to 10{sup 10} switching cycles indicating that SBTi thin films are a promising material for use in non-volatile memories.« less
  • Thin films of 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) develop low electrical resistivity (<10/sup -3/ ..cap omega.. cm) after irradiation with 2-MeV Ar/sup +/ ions. Electron microscopy and diffraction show that vacuum-deposited films of this material consist, prior to ion-irradiation, of discrete crystalline grains (approx.20--50 nm diameter) in which the molecules are disposed closely parallel to the substrate (average inclination approx.10/sup 0/--15/sup 0/). Upon irradiation with up to approx.10/sup 14/ Ar/sup +//cm/sup 2/, the grains become progressively more defect-ridden and eventually amorphous. At that stage, the resistivity begins to decrease by approx.12 orders of magnitude at doses between approx.10/sup 14/ and approx.5 xmore » 10/sup 16/ Ar/sup +//cm/sup 2/, while the intergranular boundaries become diffuse and the grains begin to merge. The temperature dependence of resistivity in this regime is as exp(const/T/sup 1//sup ///sup 2/), which is consistent with our morphological and structural results as it implies carrier hopping between conducting islands embedded in a nonconducting matrix. At the highest ion doses (>5 x 10/sup 16/ Ar/sup +//cm/sup 2/) the grains become connected into a rather uniform and featureless network akin to amorphous carbon, and the resistivity reaches its lowest value and becomes independent of temperature. The amorphous-carbon-like character of the highly irradiated material is evidenced not only by its diffraction pattern but also by its crystallization with a graphitic-type structure during annealing to 1200 /sup 0/C.« less