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Chemical synthesis and characterization of nano-sized rare-earth ruthenium pyrochlore compounds Ln$_2$Ru$_2$O$_7$ (Ln $=$ rare earth)
R A PAWAR A K NIKUMBH D S BHANGE N J KARALE D V NIGHOT2 M B KHANVILKAR
Volume 40 Issue 7 December 2017 pp 1335-1345
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Keywords
Pyrochlore ruthenates ;nano-sized ;tartrate precursor ;d.c. electrical conductivity ;dielectric properties. -
Abstract
The rare-earth ruthenium pyrochlores Ln$_2$Ru$_2$O$_7$ (Ln $=$ La$^{3+}$, Pr$^{3+}$, Nd$^{3+}$, Sm$^{3+}$ and Gd$^{3+}$) have been synthesized by the tartrate co-precipitation method, which allowed control of their composition and morphology. The preparation processes were monitored by thermal studies (TG-DTA). The obtained ruthenates were characterized by X-ray diffraction (XRD), TEM, d.c. electrical conductivity, thermoelectric power and dielectric constant measurements. X-ray diffraction patterns for all pyrochlore samples indicate a single-phase crystalline material with a cubic structure except for LaRuO$_3$, which shows perovskite orthorhombic structure. The structural parameter for the solid obtained was successfully determined by Rietveld refinement based on the analysis of powder XRD pattern. The TEM photographs of these compounds exhibited the average particle size in the range of 36.4–73.8 nm. The data on the temperature variation of d.c. electrical conductivity showed that all rare-earth ruthanates are semiconductors and major carriers are electrons. The conduction mechanism of these compounds seems to be oxygen non-stoichiometry. The variation of dielectric constant at various frequencies showed initially interfacial polarization up to 275 kHz and beyond, which shows domain wall motion.
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Author Affiliations
R A PAWAR1 A K NIKUMBH2 D S BHANGE3 N J KARALE2 D V NIGHOT22 M B KHANVILKAR2
- Department of Chemistry, PDEA’s Baburaoji Gholap College, Sangvi, Pune 411 027, India
- Department of Chemistry, Savitribai Phule Pune University, Pune 411 007, India
- Department of Chemistry, Shivaji University, Kolhapur 416 004, India
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Dates
- Published
- 15 December 2017
- Manuscript received
- 6 November 2016
- Accepted
- 14 March 2017
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