Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>]
The compound 0.9[KNbO<sub>3</sub>]-0.1[(BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] (KBNNO), a robust eco-friendly (lead-free) ferroelectric perovskite, has diverse applications in electronic and photonic devices. In this work, we report the die...
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MDPI AG
2021-12-01
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| author | Blanca Yamile Rosas Alvaro A. Instan Karuna Kara Mishra Srungarpu Nagabhusan Achary Ram S. Katiyar |
| author_facet | Blanca Yamile Rosas Alvaro A. Instan Karuna Kara Mishra Srungarpu Nagabhusan Achary Ram S. Katiyar |
| author_sort | Blanca Yamile Rosas |
| collection | DOAJ |
| description | The compound 0.9[KNbO<sub>3</sub>]-0.1[(BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] (KBNNO), a robust eco-friendly (lead-free) ferroelectric perovskite, has diverse applications in electronic and photonic devices. In this work, we report the dielectric, ferroelectric, and structural phase transitions behavior in the KBNNO compound using dielectric, X-ray diffraction, and Raman studies at ambient and as a function of temperature. Analyses of X-ray diffraction (XRD) data at room temperature (rtp) revealed the orthorhombic phase (sp. Gr. <i>Amm2</i>) of the compound with a minor secondary NiO cubic phase (sp. Gr. <i>Fm3m</i>). A direct optical band gap E<sub>g</sub> of 1.66 eV was estimated at rtp from the UV–Vis reflectance spectrum analysis. Observation of non-saturated electric polarization loops were attributed to leakage current effects pertaining to oxygen vacancies in the compound. Magnetization studies showed ferromagnetism at room temperature (300 K) in this material. XRD studies on KBNNO at elevated temperatures revealed orthorhombic-to-tetragonal and tetragonal-to-cubic phase transitions at 523 and 713 K, respectively. Temperature-dependent dielectric response, being leaky, did not reveal any phase transition. Electrical conductivity data as a function of temperature obeyed Jonscher power law and satisfied the correlated barrier-hopping model, indicating dominance of the hopping conduction mechanism. Temperature-dependent Raman spectroscopic studies over a wide range of temperature (82–673 K) inferred the rhombohedral-to-orthorhombic and orthorhombic-to-tetragonal phase transitions at ~260, and 533 K, respectively. Several Raman bands were found to disappear, while a few Raman modes such as at 225, 270, 289, and 831 cm<sup>−1</sup> exhibited discontinuity across the phase transitions at ~260 and 533 K. |
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| language | English |
| last_indexed | 2024-03-10T01:41:31Z |
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| spelling | doaj.art-93283c14a9aa48b2ae31466c3c11cc382023-11-23T13:24:09ZengMDPI AGCrystals2073-43522021-12-011213510.3390/cryst12010035Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>]Blanca Yamile Rosas0Alvaro A. Instan1Karuna Kara Mishra2Srungarpu Nagabhusan Achary3Ram S. Katiyar4Department of Physics, Institute for Functional Nanomaterials, University of Puerto Rico, P.O. Box 70377, San Juan, PR 00936, USADepartment of Physics, Institute for Functional Nanomaterials, University of Puerto Rico, P.O. Box 70377, San Juan, PR 00936, USADepartment of Physics, Institute for Functional Nanomaterials, University of Puerto Rico, P.O. Box 70377, San Juan, PR 00936, USAChemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, IndiaDepartment of Physics, Institute for Functional Nanomaterials, University of Puerto Rico, P.O. Box 70377, San Juan, PR 00936, USAThe compound 0.9[KNbO<sub>3</sub>]-0.1[(BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] (KBNNO), a robust eco-friendly (lead-free) ferroelectric perovskite, has diverse applications in electronic and photonic devices. In this work, we report the dielectric, ferroelectric, and structural phase transitions behavior in the KBNNO compound using dielectric, X-ray diffraction, and Raman studies at ambient and as a function of temperature. Analyses of X-ray diffraction (XRD) data at room temperature (rtp) revealed the orthorhombic phase (sp. Gr. <i>Amm2</i>) of the compound with a minor secondary NiO cubic phase (sp. Gr. <i>Fm3m</i>). A direct optical band gap E<sub>g</sub> of 1.66 eV was estimated at rtp from the UV–Vis reflectance spectrum analysis. Observation of non-saturated electric polarization loops were attributed to leakage current effects pertaining to oxygen vacancies in the compound. Magnetization studies showed ferromagnetism at room temperature (300 K) in this material. XRD studies on KBNNO at elevated temperatures revealed orthorhombic-to-tetragonal and tetragonal-to-cubic phase transitions at 523 and 713 K, respectively. Temperature-dependent dielectric response, being leaky, did not reveal any phase transition. Electrical conductivity data as a function of temperature obeyed Jonscher power law and satisfied the correlated barrier-hopping model, indicating dominance of the hopping conduction mechanism. Temperature-dependent Raman spectroscopic studies over a wide range of temperature (82–673 K) inferred the rhombohedral-to-orthorhombic and orthorhombic-to-tetragonal phase transitions at ~260, and 533 K, respectively. Several Raman bands were found to disappear, while a few Raman modes such as at 225, 270, 289, and 831 cm<sup>−1</sup> exhibited discontinuity across the phase transitions at ~260 and 533 K.https://www.mdpi.com/2073-4352/12/1/35multiferroicsphase transitionphononRaman spectroscopysolid solution |
| spellingShingle | Blanca Yamile Rosas Alvaro A. Instan Karuna Kara Mishra Srungarpu Nagabhusan Achary Ram S. Katiyar Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] Crystals multiferroics phase transition phonon Raman spectroscopy solid solution |
| title | Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] |
| title_full | Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] |
| title_fullStr | Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] |
| title_full_unstemmed | Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] |
| title_short | Studies of Optical, Dielectric, Ferroelectric, and Structural Phase Transitions in 0.9[KNbO<sub>3</sub>]-0.1 [BaNi<sub>1/2</sub>Nb<sub>1/2</sub>O<sub>3−δ</sub>] |
| title_sort | studies of optical dielectric ferroelectric and structural phase transitions in 0 9 knbo sub 3 sub 0 1 bani sub 1 2 sub nb sub 1 2 sub o sub 3 δ sub |
| topic | multiferroics phase transition phonon Raman spectroscopy solid solution |
| url | https://www.mdpi.com/2073-4352/12/1/35 |
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