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Title: Effect of particle size and strain on phase stability of (Li{sub 0.06} Na{sub 0.94}) NbO{sub 3}

Alkaline niobates are most suitable and excellent candidates for lead free piezoceramics, as they exhibit morphotropic phase boundary and have ultra-large piezoresponse similar to them. We provide direct experimental evidence of ferroelectric to paraelectric phase transition in (Li{sub 0.06} Na{sub 0.94})NbO{sub 3} with reduction of particle size using a combination of x-ray and neutron powder diffraction techniques at room temperature. Detailed Rietveld analyses of x-ray data show variation of particle sizes from micrometer to nanometer for sintered, calcined, and ball milled powders. The ferroelectric orthorhombic phase for micron sized powder (∼1.17 μm) is found to transform to paraelectric phase by reducing particle size to ∼10.8 nm. The crystal structure of paraelectric phase has been identified with tetragonal symmetry (P4{sub 2}/mmc) and is found to be a post perovskite phase. The low temperature neutron diffraction studies on the powders with different particle sizes reveal that orthorhombic to rhombohedral phase transition gets suppressed with reducing particle size.
Authors:
; ;  [1]
  1. Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai-40085 (India)
Publication Date:
OSTI Identifier:
22273456
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 17; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; FERROELECTRIC MATERIALS; LITHIUM COMPOUNDS; NEUTRON DIFFRACTION; NIOBATES; ORTHORHOMBIC LATTICES; PARTICLE SIZE; PHASE STABILITY; PHASE TRANSFORMATIONS; SODIUM COMPOUNDS; STRAINS; TETRAGONAL LATTICES; TRIGONAL LATTICES