Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions
The focus of this paper is centered on the thermal reduction of KMnO<sub>4</sub> at controlled temperatures of 400 and 800 °C. The materials under study were characterized by atomic absorption spectroscopy, thermogravimetric analysis, average oxidation state of manganese, nitrog...
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| Format: | Article |
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MDPI AG
2019-08-01
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| Series: | Nanomaterials |
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| Online Access: | https://www.mdpi.com/2079-4991/9/8/1156 |
| _version_ | 1818437488994156544 |
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| author | Nayda P. Arias María E. Becerra Oscar Giraldo |
| author_facet | Nayda P. Arias María E. Becerra Oscar Giraldo |
| author_sort | Nayda P. Arias |
| collection | DOAJ |
| description | The focus of this paper is centered on the thermal reduction of KMnO<sub>4</sub> at controlled temperatures of 400 and 800 °C. The materials under study were characterized by atomic absorption spectroscopy, thermogravimetric analysis, average oxidation state of manganese, nitrogen adsorption−desorption, and impedance spectroscopy. The structural formulas, found as a result of these analyses, were <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>K</mi> <mrow> <mn>0.29</mn> </mrow> <mo>+</mo> </msubsup> <mrow> <mo>(</mo> <mrow> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.84</mn> </mrow> <mrow> <mn>4</mn> <mo>+</mo> </mrow> </msubsup> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.16</mn> </mrow> <mrow> <mn>3</mn> <mo>+</mo> </mrow> </msubsup> </mrow> <mo>)</mo> </mrow> <msub> <mi>O</mi> <mrow> <mn>2.07</mn> </mrow> </msub> <mo>·</mo> <mn>0.61</mn> <msub> <mi>H</mi> <mn>2</mn> </msub> <mi>O</mi> </mrow> </semantics> </math> </inline-formula> and <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>K</mi> <mrow> <mn>0.48</mn> </mrow> <mo>+</mo> </msubsup> <mrow> <mo>(</mo> <mrow> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.64</mn> </mrow> <mrow> <mn>4</mn> <mo>+</mo> </mrow> </msubsup> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.36</mn> </mrow> <mrow> <mn>3</mn> <mo>+</mo> </mrow> </msubsup> </mrow> <mo>)</mo> </mrow> <msub> <mi>O</mi> <mrow> <mn>2.06</mn> </mrow> </msub> <mo>·</mo> <mn>0.50</mn> <msub> <mi>H</mi> <mn>2</mn> </msub> <mi>O</mi> </mrow> </semantics> </math> </inline-formula>. The N<sub>2</sub> adsorption−desorption isotherms show the microporous and mesoporous nature of the structure. Structural analysis showed that synthesis temperature affects the crystal size and symmetry, varying their electrical properties. Impedance spectroscopy (IS) was used to measure the electrical properties of these materials. The measurements attained, as a result of IS, show that these materials have both electronic and ionic conductivity. The conductivity values obtained at 10 Hz were 4.1250 × 10<sup>−6</sup> and 1.6870 × 10<sup>−4</sup> Ω<sup>−1</sup>cm<sup>−1</sup> for Mn4 at 298 and 423 K respectively. For Mn8, the conductivity values at this frequency were 3.7074 × 10<sup>−7</sup> (298) and 3.9866 × 10<sup>−5</sup> Ω<sup>−1</sup>cm<sup>−1</sup> (423 K). The electrical behavior was associated with electron hopping at high frequencies, and protonic conduction and ionic movement of the K<sup>+</sup> species, in the interlayer region at low frequencies. |
| first_indexed | 2024-12-14T17:25:29Z |
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| issn | 2079-4991 |
| language | English |
| last_indexed | 2024-12-14T17:25:29Z |
| publishDate | 2019-08-01 |
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| series | Nanomaterials |
| spelling | doaj.art-2af475659c684510ab71f08b12e4e51f2022-12-21T22:53:14ZengMDPI AGNanomaterials2079-49912019-08-0198115610.3390/nano9081156nano9081156Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State ReactionsNayda P. Arias0María E. Becerra1Oscar Giraldo2Grupo de Investigación en Procesos Químicos, Catalíticos y Biotecnológicos, Universidad Nacional de Colombia-Sede Manizales, Kilometro 9 vía al aeropuerto, La Nubia, Manizales 170003, ColombiaGrupo de Investigación en Procesos Químicos, Catalíticos y Biotecnológicos, Universidad Nacional de Colombia-Sede Manizales, Kilometro 9 vía al aeropuerto, La Nubia, Manizales 170003, ColombiaGrupo de Investigación en Procesos Químicos, Catalíticos y Biotecnológicos, Universidad Nacional de Colombia-Sede Manizales, Kilometro 9 vía al aeropuerto, La Nubia, Manizales 170003, ColombiaThe focus of this paper is centered on the thermal reduction of KMnO<sub>4</sub> at controlled temperatures of 400 and 800 °C. The materials under study were characterized by atomic absorption spectroscopy, thermogravimetric analysis, average oxidation state of manganese, nitrogen adsorption−desorption, and impedance spectroscopy. The structural formulas, found as a result of these analyses, were <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>K</mi> <mrow> <mn>0.29</mn> </mrow> <mo>+</mo> </msubsup> <mrow> <mo>(</mo> <mrow> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.84</mn> </mrow> <mrow> <mn>4</mn> <mo>+</mo> </mrow> </msubsup> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.16</mn> </mrow> <mrow> <mn>3</mn> <mo>+</mo> </mrow> </msubsup> </mrow> <mo>)</mo> </mrow> <msub> <mi>O</mi> <mrow> <mn>2.07</mn> </mrow> </msub> <mo>·</mo> <mn>0.61</mn> <msub> <mi>H</mi> <mn>2</mn> </msub> <mi>O</mi> </mrow> </semantics> </math> </inline-formula> and <inline-formula> <math display="inline"> <semantics> <mrow> <msubsup> <mi>K</mi> <mrow> <mn>0.48</mn> </mrow> <mo>+</mo> </msubsup> <mrow> <mo>(</mo> <mrow> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.64</mn> </mrow> <mrow> <mn>4</mn> <mo>+</mo> </mrow> </msubsup> <mi>M</mi> <msubsup> <mi>n</mi> <mrow> <mn>0.36</mn> </mrow> <mrow> <mn>3</mn> <mo>+</mo> </mrow> </msubsup> </mrow> <mo>)</mo> </mrow> <msub> <mi>O</mi> <mrow> <mn>2.06</mn> </mrow> </msub> <mo>·</mo> <mn>0.50</mn> <msub> <mi>H</mi> <mn>2</mn> </msub> <mi>O</mi> </mrow> </semantics> </math> </inline-formula>. The N<sub>2</sub> adsorption−desorption isotherms show the microporous and mesoporous nature of the structure. Structural analysis showed that synthesis temperature affects the crystal size and symmetry, varying their electrical properties. Impedance spectroscopy (IS) was used to measure the electrical properties of these materials. The measurements attained, as a result of IS, show that these materials have both electronic and ionic conductivity. The conductivity values obtained at 10 Hz were 4.1250 × 10<sup>−6</sup> and 1.6870 × 10<sup>−4</sup> Ω<sup>−1</sup>cm<sup>−1</sup> for Mn4 at 298 and 423 K respectively. For Mn8, the conductivity values at this frequency were 3.7074 × 10<sup>−7</sup> (298) and 3.9866 × 10<sup>−5</sup> Ω<sup>−1</sup>cm<sup>−1</sup> (423 K). The electrical behavior was associated with electron hopping at high frequencies, and protonic conduction and ionic movement of the K<sup>+</sup> species, in the interlayer region at low frequencies.https://www.mdpi.com/2079-4991/9/8/1156Birnessitenanoporous metal oxidesimpedance spectroscopy |
| spellingShingle | Nayda P. Arias María E. Becerra Oscar Giraldo Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions Nanomaterials Birnessite nanoporous metal oxides impedance spectroscopy |
| title | Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions |
| title_full | Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions |
| title_fullStr | Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions |
| title_full_unstemmed | Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions |
| title_short | Structural and Electrical Studies for Birnessite-Type Materials Synthesized by Solid-State Reactions |
| title_sort | structural and electrical studies for birnessite type materials synthesized by solid state reactions |
| topic | Birnessite nanoporous metal oxides impedance spectroscopy |
| url | https://www.mdpi.com/2079-4991/9/8/1156 |
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