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The perovskite oxides CaMnO3-δ, Ca0.5Sr0.5MnO3-δ, and SrMnO3-δ were synthesized in air using a solid-state method, and their structural, electrical, and electrocatalytic properties were studied in relation to their oxygen evolution reaction (OER) performance. Iodometric titration showed δ values of 0.05, 0.05, and 0.0, respectively, indicating that Mn is predominantly in the 4+ oxidation state across all materials, consistent with prior reports. Detailed characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), iodometric titration, and variable-temperature conductivity measurements. Four-point probe DC measurements revealed that CaMnO3-δ (δ = 0.05) has a semiconductive behavior over a temperature range from 25 °C to 300 °C, with its highest conductivity attributed to polaron activity. Cyclic voltammetry (CV) in 0.1 M KOH was employed to assess OER catalytic performance, which correlated with room-temperature conductivity. CaMnO3-δ exhibited superior catalytic activity, followed by Ca0.5Sr0.5MnO3-δ and SrMnO3-δ, demonstrating that increased conductivity enhances OER performance. The conductivity trend, CaMnO3-δ > Ca0.5Sr0.5MnO3-δ > SrMnO3-δ, aligns with OER activity, underscoring a direct link between electronic transport properties and catalytic efficiency within this series.
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Pellet-Based XRD: A Simplified Approach to Phase Purity Determination in Solid-State Materials
Phase purity determination is an essential step in the characterization of solid-state materials, typically conducted through powder X-ray diffraction (XRD). However, the reparation of powder samples is often time-consuming, can lead to material wastage, and risks altering the structural properties of the sample. In this study, we present an alternative method that involves the direct use of pelletized samples for XRD analysis, bypassing the need for powdering. Our investigation, conducted on 2 series of compounds or 6 samples of oxygen-deficient perovskite oxides, demonstrates that diffraction patterns from pellet samples are sufficiently distinct to confirm phase purity, offering a faster, more efficient alternative to traditional powder XRD methods. This method not only reduces the time and effort involved in sample preparation but also preserves the material's structural and physicochemical integrity. By minimizing the mechanical manipulation and thermal exposure of the samples, the direct pellet method allows for subsequent property measurements—such as electrical conductivity, magnetic behavior, thermoelectric behavior, catalytic activity, and electrode performance—without risking sample degradation. Our results show that this approach provides reliable phase purity assessment while conserving materials, making it an attractive option for researchers working with oxygen-deficient perovskite oxides and other complex materials.
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- PAR ID:
- 10649600
- Publisher / Repository:
- SCIREA
- Date Published:
- Journal Name:
- SCIREA Journal of Chemistry
- ISSN:
- 2995-6943
- Subject(s) / Keyword(s):
- XRD, solid-state reaction, perovskite oxides, oxygen deficiency
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.54647/chemistry150392
