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Issue 17, 2014
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Speciation of Cr(iii) in intermediate phases during the sol–gel processing of Cr-doped SrTiO3 powders

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Abstract

The local environment of Cr3+ during the sol–gel synthesis of 1% and 5% Cr3+-doped SrTiO3 (Cr3+:SrTiO3) bulk powders was systematically studied by structural characterization techniques and dopant-specific spectroscopies. After calcination at 800 °C, the precursors were annealed between 850 °C and 1050 °C for up to 6 h. We observe the formation of numerous phases in addition to the final product of SrTiO3. One of these is a metastable Ruddelsden–Popper phase (Sr2TiO4) that forms when the precursor is annealed at 1050 °C for less than 2 h. Electron paramagnetic resonance (EPR) spectroscopy reveals a new signal that correlates with appearance of the Sr2TiO4 phase and is consistent with Cr3+ substitution into the axially-compressed Ti4+ site in Sr2TiO4. The best agreement between experiment and the simulated EPR spectra of Cr3+:Sr2TiO4 is when |D| = 0.0207 cm−1, g = 1.9803 and g = 1.9793. The majority of the sample is converted to Cr3+:SrTiO3 with increasing annealing times at 1050 °C as detected by low-temperature emission and EPR spectroscopies, and powder X-ray diffraction.

Graphical abstract: Speciation of Cr(iii) in intermediate phases during the sol–gel processing of Cr-doped SrTiO3 powders

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Supplementary files

Article information


Submitted
01 Nov 2013
Accepted
06 Dec 2013
First published
06 Dec 2013

J. Mater. Chem. A, 2014,2, 6138-6145
Article type
Paper

Speciation of Cr(III) in intermediate phases during the sol–gel processing of Cr-doped SrTiO3 powders

K. A. Lehuta and K. R. Kittilstved, J. Mater. Chem. A, 2014, 2, 6138
DOI: 10.1039/C3TA14475E

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