skip to main content

SciTech ConnectSciTech Connect

Title: Effect of crystal structure on microwave dielectric properties of Li{sub 2}SrTa{sub 2(1−x)}Nb{sub 2x}O{sub 7} compounds

Highlights: • Synthesis of orthorhombic Li{sub 2}SrTa{sub 2(1−x)}Nb{sub 2x}O{sub 7} compounds • The mechanism for enhancement of quality factor by bond strength. • Deviation of τ{sub ƒ} with octahedral distortion of the compound. - Abstract: The Li{sub 2}SrTa{sub 2(1−x)}Nb{sub 2x}O{sub 7} (x = 0–1.0) with layered-perovskite type structure were synthesized by conventional solid state reaction method. The X-ray diffraction reveals that all these compounds possess orthorhombic crystal structure with Cmcm space group. B-site bond strength and B-site octahedral distortion of these compounds were calculated using bond lengths obtained from Rietveld refinement. The dielectric constant (ϵ{sub r}) decreased from 24.2 to 15.2 with increase in the Nb concentration, which was due to decrease in dielectric polarizability of compound. The non-monotonic variation in quality factor (Q × ƒ) was observed with Nb concentration. This variation of quality factor was correlated with the B-site bond strength. The B-site octahedral distortion was found to increase with Nb content, which was the major factor for increase in temperature coefficient of resonant frequency (τ{sub f}) of these compounds.
Authors:
;
Publication Date:
OSTI Identifier:
22475936
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 70; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CONCENTRATION RATIO; DIELECTRIC MATERIALS; LITHIUM COMPOUNDS; MICROWAVE RADIATION; NIOBATES; ORTHORHOMBIC LATTICES; PERMITTIVITY; PEROVSKITE; POLARIZABILITY; QUALITY FACTOR; SPACE GROUPS; STRONTIUM COMPOUNDS; SYNTHESIS; TANTALUM COMPOUNDS; TEMPERATURE COEFFICIENT; X-RAY DIFFRACTION