Negative Thermal Expansion Properties of Sm<sub>0.85</sub>Sr<sub>0.15</sub>MnO<sub>3-δ</sub>
oleh: Yucheng Li, Yang Zhang, Yongtian Li, Yifeng Wu
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2022-05-01 |
Deskripsi
A novel negative thermal expansion (NTE) material composed of Sm<sub>0.85</sub>Sr<sub>0.15</sub>MnO<sub>3-δ</sub> was synthesized using the solid-state method. By allowing Sr<sup>2+</sup> to partially replace Sm<sup>3+</sup> in SmMnO<sub>3</sub>, the ceramic material Sm<sub>0.85</sub>Sr<sub>0.15</sub>MnO<sub>3-δ</sub> exhibits NTE properties between 360K and 873K, and its average negative thermal expansion coefficient was −10.08 × 10<sup>−6</sup>/K. The structure of Sm<sub>0.85</sub>Sr<sub>0.15</sub>MnO<sub>3-δ</sub> is orthogonal, the space group is pbnm, the morphology is regular, and the grain size is uniform. The results of X-ray diffraction and XPS (X-ray photoelectron spectroscopy) suggest that the NTE phenomenon is related to the electron transfer of Mn ions. With the increase in temperature, Mn<sup>4+</sup> is rapidly transformed into Mn<sup>3+</sup>, accompanied by Mn<sup>4+</sup>O<sub>6</sub> octahedron distortion and oxygen defects. It was found that the sample volume continually decreased at the same time.