Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis
The electrical conductivity of nanocrystalline CuMnO<sub>2</sub> samples, obtained by microwave-assisted hydrothermal synthesis (MWH), is studied by impedance spectroscopy over a frequency range of 30 Hz to 2 MHz and a temperature range from 30 to 120 °C. Three samples are prepared to st...
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2025-05-01
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| author | Catalin N. Marin Maria Poienar Antoanetta Lungu Cristian Casut Paula Sfirloaga Iosif Malaescu |
| author_facet | Catalin N. Marin Maria Poienar Antoanetta Lungu Cristian Casut Paula Sfirloaga Iosif Malaescu |
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| description | The electrical conductivity of nanocrystalline CuMnO<sub>2</sub> samples, obtained by microwave-assisted hydrothermal synthesis (MWH), is studied by impedance spectroscopy over a frequency range of 30 Hz to 2 MHz and a temperature range from 30 to 120 °C. Three samples are prepared to start from a mixture of sulphate reactants, at two synthesis temperatures and different reaction times (of applying microwaves): sample S1 at 80 °C for 5 min; sample S2 at 120 °C for 5 min and sample S3 at 120 °C for one hour. The static conductivity values, σ<sub>DC</sub> of samples S2 and S3, are approximately equal but larger than those of sample S1. This result suggests that using MWH synthesis at 120 °C, with different reaction times (samples S2 and S3), is sufficient for microwaves to be applied for at least 5 min to obtain samples with similar electrical properties. The experimental data were analysed based on three theoretical models, demonstrating that the most appropriate theoretical model to explain the electrical conduction mechanism in the samples is Mott’s variable range hopping (VRH) model. Using this model, the activation energy of conduction, (E<sub>A,cond</sub>), the density of localized states near the Fermi level, <i>N(E<sub>F</sub>)</i>, the hopping distance, <i>R<sub>h</sub>(T)</i>, the hopping energy, <i>W<sub>h</sub>(T)</i> and the charge carrier mobility (μ) were determined for the first time, for microwave-assisted hydrothermally synthesized crednerite. Additionally, the band gap energy (<i>W<sub>m</sub></i>) and hopping frequency (ω<sub>h</sub>) were evaluated at various temperatures T. Understanding the electrical conduction mechanism in the polycrystalline CuMnO<sub>2</sub> materials is important for their use in photo-electrochemical and photocatalytic applications, photovoltaic devices, and, more recently, in environmental protection. |
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| institution | Kabale University |
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| publishDate | 2025-05-01 |
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| series | Crystals |
| spelling | doaj-art-68ed6847f2914c76b607dec7babf3d0e2025-08-20T03:27:01ZengMDPI AGCrystals2073-43522025-05-0115649710.3390/cryst15060497Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal SynthesisCatalin N. Marin0Maria Poienar1Antoanetta Lungu2Cristian Casut3Paula Sfirloaga4Iosif Malaescu5Faculty of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223 Timisoara, RomaniaInstitute for Advanced Environmental Research, West University of Timisoara (ICAM-WUT), Oituz Str., No. 4, 300086 Timisoara, RomaniaFaculty of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223 Timisoara, RomaniaNational Institute for Research and Development in Electrochemistry and Condensed Matter (INCEMC), Dr. A.P. Podeanu Str. No. 144, 300569 Timisoara, RomaniaNational Institute for Research and Development in Electrochemistry and Condensed Matter (INCEMC), Dr. A.P. Podeanu Str. No. 144, 300569 Timisoara, RomaniaFaculty of Physics, West University of Timisoara, Bd. V. Parvan No. 4, 300223 Timisoara, RomaniaThe electrical conductivity of nanocrystalline CuMnO<sub>2</sub> samples, obtained by microwave-assisted hydrothermal synthesis (MWH), is studied by impedance spectroscopy over a frequency range of 30 Hz to 2 MHz and a temperature range from 30 to 120 °C. Three samples are prepared to start from a mixture of sulphate reactants, at two synthesis temperatures and different reaction times (of applying microwaves): sample S1 at 80 °C for 5 min; sample S2 at 120 °C for 5 min and sample S3 at 120 °C for one hour. The static conductivity values, σ<sub>DC</sub> of samples S2 and S3, are approximately equal but larger than those of sample S1. This result suggests that using MWH synthesis at 120 °C, with different reaction times (samples S2 and S3), is sufficient for microwaves to be applied for at least 5 min to obtain samples with similar electrical properties. The experimental data were analysed based on three theoretical models, demonstrating that the most appropriate theoretical model to explain the electrical conduction mechanism in the samples is Mott’s variable range hopping (VRH) model. Using this model, the activation energy of conduction, (E<sub>A,cond</sub>), the density of localized states near the Fermi level, <i>N(E<sub>F</sub>)</i>, the hopping distance, <i>R<sub>h</sub>(T)</i>, the hopping energy, <i>W<sub>h</sub>(T)</i> and the charge carrier mobility (μ) were determined for the first time, for microwave-assisted hydrothermally synthesized crednerite. Additionally, the band gap energy (<i>W<sub>m</sub></i>) and hopping frequency (ω<sub>h</sub>) were evaluated at various temperatures T. Understanding the electrical conduction mechanism in the polycrystalline CuMnO<sub>2</sub> materials is important for their use in photo-electrochemical and photocatalytic applications, photovoltaic devices, and, more recently, in environmental protection.https://www.mdpi.com/2073-4352/15/6/497synthesiselectrical conductivityVRH modelhopping distancebandgap energy |
| spellingShingle | Catalin N. Marin Maria Poienar Antoanetta Lungu Cristian Casut Paula Sfirloaga Iosif Malaescu Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis Crystals synthesis electrical conductivity VRH model hopping distance bandgap energy |
| title | Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis |
| title_full | Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis |
| title_fullStr | Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis |
| title_full_unstemmed | Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis |
| title_short | Study of the Electrical Conduction Mechanism in Low-Frequency Field for CuMnO<sub>2</sub> Crednerite-Type Materials Obtained by Microwave-Assisted Hydrothermal Synthesis |
| title_sort | study of the electrical conduction mechanism in low frequency field for cumno sub 2 sub crednerite type materials obtained by microwave assisted hydrothermal synthesis |
| topic | synthesis electrical conductivity VRH model hopping distance bandgap energy |
| url | https://www.mdpi.com/2073-4352/15/6/497 |
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