Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO
This paper demonstrates the possibility of creating oxygen deficiency in perovskites A<sup>+3</sup>B<sup>+3</sup>O<sub>3</sub> by introducing two types of cations with different charges into the B-sublattice. For this, it is proposed to introduce a two-charged cat...
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MDPI AG
2022-01-01
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| author | Ksenia Belova Anastasia Egorova Svetlana Pachina Irina Animitsa |
| author_facet | Ksenia Belova Anastasia Egorova Svetlana Pachina Irina Animitsa |
| author_sort | Ksenia Belova |
| collection | DOAJ |
| description | This paper demonstrates the possibility of creating oxygen deficiency in perovskites A<sup>+3</sup>B<sup>+3</sup>O<sub>3</sub> by introducing two types of cations with different charges into the B-sublattice. For this, it is proposed to introduce a two-charged cation, for example, Zn<sup>2+</sup>, as an alternative to alkaline earth metals. Previously, this possibility was demonstrated for aluminate LaAlO<sub>3</sub> and indate LaInO<sub>3</sub>. In this article, we have focused on the modification of the scandium-containing perovskite LaScO<sub>3</sub>. The novel oxygen-deficient perovskite La<sub>2</sub>ScZnO<sub>5.5</sub> and doped phases La<sub>1.9</sub>Ca<sub>0.1</sub>ScZnO<sub>5.45</sub>, La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub>, and La<sub>2</sub>Sc<sub>0.9</sub>Mg<sub>0.1</sub>ZnO<sub>5.45</sub> were obtained via a solid-state reaction process. Their phase composition and hydration were investigated by XRD and TGA + MS techniques. The conductivities of these materials were measured by the electrochemical impedance technique under atmospheres of various water vapor partial pressures. All phases crystallized in orthorhombic symmetry with the <i>Pnma</i> space group. The phases were capable of reversible water uptake; the proton concentration increased in the order of La<sub>2</sub>ScZnO<sub>5.5</sub> < La<sub>2</sub>Sc<sub>0.9</sub>Mg<sub>0.1</sub>ZnO<sub>5.45</sub> < La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub> ≈ La<sub>1.9</sub>Ca<sub>0.1</sub>ScZnO<sub>5.45</sub> and reached ~90% hydration limit for Ca<sup>2+</sup>-doped phases. The total conductivities increased with the increase in the free lattice volume in the sequence of σLa<sub>2</sub>ScZnO<sub>5.5</sub> < σLa<sub>2</sub>Sc<sub>0.9</sub>Mg<sub>0.1</sub>ZnO<sub>5.45</sub> < σLa<sub>1.9</sub>Ca<sub>0.1</sub>ScZnO<sub>5.45</sub> < σLa<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub>, the activation energy decreased in the same sequence. The sample La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub> showed the highest conductivity of about 10<sup>−3</sup> S∙cm<sup>−1</sup> at 650 °C (dry air pH<sub>2</sub>O = 3.5·10<sup>−5</sup> atm). Water incorporation was accompanied by an increase in conductivity in wet air (pH<sub>2</sub>O = 2·10<sup>−2</sup> atm) due to the appearance of proton conductivity. The sample La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub> showed a conductivity of about 10<sup>−5</sup> S∙cm<sup>−1</sup> at 350 °C (pH<sub>2</sub>O = 2·10<sup>−2</sup> atm). A comparison of conductivities of obtained phase La<sub>2</sub>ScZnO<sub>5.5</sub> with the conductivities of La<sub>2</sub>AlZnO<sub>5.5</sub> and La<sub>2</sub>InZnO<sub>5.5</sub> was made; the nature of the B-cation did not significantly affect the total conductivity. |
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| spelling | doaj.art-a28214a60fa54cc884b153e1f4a4fef82023-11-23T15:53:16ZengMDPI AGApplied Sciences2076-34172022-01-01123118110.3390/app12031181Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaOKsenia Belova0Anastasia Egorova1Svetlana Pachina2Irina Animitsa3The Institute of Natural Sciences and Mathematics, Ural Federal University, Mira st. 19, 620075 Yekaterinburg, RussiaThe Institute of Natural Sciences and Mathematics, Ural Federal University, Mira st. 19, 620075 Yekaterinburg, RussiaThe Institute of Natural Sciences and Mathematics, Ural Federal University, Mira st. 19, 620075 Yekaterinburg, RussiaThe Institute of Natural Sciences and Mathematics, Ural Federal University, Mira st. 19, 620075 Yekaterinburg, RussiaThis paper demonstrates the possibility of creating oxygen deficiency in perovskites A<sup>+3</sup>B<sup>+3</sup>O<sub>3</sub> by introducing two types of cations with different charges into the B-sublattice. For this, it is proposed to introduce a two-charged cation, for example, Zn<sup>2+</sup>, as an alternative to alkaline earth metals. Previously, this possibility was demonstrated for aluminate LaAlO<sub>3</sub> and indate LaInO<sub>3</sub>. In this article, we have focused on the modification of the scandium-containing perovskite LaScO<sub>3</sub>. The novel oxygen-deficient perovskite La<sub>2</sub>ScZnO<sub>5.5</sub> and doped phases La<sub>1.9</sub>Ca<sub>0.1</sub>ScZnO<sub>5.45</sub>, La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub>, and La<sub>2</sub>Sc<sub>0.9</sub>Mg<sub>0.1</sub>ZnO<sub>5.45</sub> were obtained via a solid-state reaction process. Their phase composition and hydration were investigated by XRD and TGA + MS techniques. The conductivities of these materials were measured by the electrochemical impedance technique under atmospheres of various water vapor partial pressures. All phases crystallized in orthorhombic symmetry with the <i>Pnma</i> space group. The phases were capable of reversible water uptake; the proton concentration increased in the order of La<sub>2</sub>ScZnO<sub>5.5</sub> < La<sub>2</sub>Sc<sub>0.9</sub>Mg<sub>0.1</sub>ZnO<sub>5.45</sub> < La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub> ≈ La<sub>1.9</sub>Ca<sub>0.1</sub>ScZnO<sub>5.45</sub> and reached ~90% hydration limit for Ca<sup>2+</sup>-doped phases. The total conductivities increased with the increase in the free lattice volume in the sequence of σLa<sub>2</sub>ScZnO<sub>5.5</sub> < σLa<sub>2</sub>Sc<sub>0.9</sub>Mg<sub>0.1</sub>ZnO<sub>5.45</sub> < σLa<sub>1.9</sub>Ca<sub>0.1</sub>ScZnO<sub>5.45</sub> < σLa<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub>, the activation energy decreased in the same sequence. The sample La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub> showed the highest conductivity of about 10<sup>−3</sup> S∙cm<sup>−1</sup> at 650 °C (dry air pH<sub>2</sub>O = 3.5·10<sup>−5</sup> atm). Water incorporation was accompanied by an increase in conductivity in wet air (pH<sub>2</sub>O = 2·10<sup>−2</sup> atm) due to the appearance of proton conductivity. The sample La<sub>2</sub>Sc<sub>0.9</sub>Ca<sub>0.1</sub>ZnO<sub>5.45</sub> showed a conductivity of about 10<sup>−5</sup> S∙cm<sup>−1</sup> at 350 °C (pH<sub>2</sub>O = 2·10<sup>−2</sup> atm). A comparison of conductivities of obtained phase La<sub>2</sub>ScZnO<sub>5.5</sub> with the conductivities of La<sub>2</sub>AlZnO<sub>5.5</sub> and La<sub>2</sub>InZnO<sub>5.5</sub> was made; the nature of the B-cation did not significantly affect the total conductivity.https://www.mdpi.com/2076-3417/12/3/1181perovskiteacceptor dopingconductivitywater uptakeproton transport |
| spellingShingle | Ksenia Belova Anastasia Egorova Svetlana Pachina Irina Animitsa Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO Applied Sciences perovskite acceptor doping conductivity water uptake proton transport |
| title | Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO |
| title_full | Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO |
| title_fullStr | Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO |
| title_full_unstemmed | Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO |
| title_short | Crystal Structure, Electrical Conductivity and Hydration of the Novel Oxygen-Deficient Perovskite La<sub>2</sub>ScZnO<sub>5.5</sub>, Doped with MgO and CaO |
| title_sort | crystal structure electrical conductivity and hydration of the novel oxygen deficient perovskite la sub 2 sub sczno sub 5 5 sub doped with mgo and cao |
| topic | perovskite acceptor doping conductivity water uptake proton transport |
| url | https://www.mdpi.com/2076-3417/12/3/1181 |
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