The Zr（0.5）Hf（0.5）VPO7 is successfully synthesized by the solid-state method with near-zero thermal expansion. Powder x-ray diffraction（XRD）, Raman spectroscopy, thermal dilatometry, and scanning electron micros...The Zr（0.5）Hf（0.5）VPO7 is successfully synthesized by the solid-state method with near-zero thermal expansion. Powder x-ray diffraction（XRD）, Raman spectroscopy, thermal dilatometry, and scanning electron microscopy（SEM） are used to investigate the structure, the phase transition, and the coefficient of thermal expansion（CTE） of Zr（0.5）Hf（0.5）VPO7. The investigation results show that the samples are of the single cubic type with a space group of Pa3ˉ at room temperature（RT）.It can be inferred that the superstructure is transformed from the 3 × 3 × 3 superstructure to the 1 × 1 × 1 ideal crystal in a temperature range between 310 K and 323 K. The CTE is measured by a dilatometer to be 0.59 × 10^（-6） K^（-1）（310 K–673 K）. The values of intrinsic（XRD） and extrinsic（dilatometric） thermal expansion are both near zero. The results show that Zr（0.5）Hf（0.5）VPO7 has near-zero thermal expansion behavior over a wide temperature range.展开更多
We report a new type of near-zero thermal expansion materialβ-CuZnV_(2)O_(7)in a large temperature range from 173 K to 673 K.It belongs to a monoclinic structure(C2/c space group)in the whole temperature range.No str...We report a new type of near-zero thermal expansion materialβ-CuZnV_(2)O_(7)in a large temperature range from 173 K to 673 K.It belongs to a monoclinic structure(C2/c space group)in the whole temperature range.No structural phase transition is observed at atmospheric pressure based on the x-ray diffraction and Raman experiment.The high-pressure Raman experiment demonstrates that two structural phase transitions exist at 0.94 GPa and 6.53 GPa,respectively.The mechanism of negative thermal expansion inβ-CuZnV_(2)O_(7)is interpreted by the variations of the angles between atoms intuitively and the phonon anharmonicity intrinsically resorting to the negative Grüneisen parameter.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11574276,U173112,and 41401384)the Project of Shandong Provincial Higher Educational Science and Technology Program,China(Grant No.J17KB127)+1 种基金the Science and Technology Development Plans of Binzhou City,China(Grant Nos.2014ZC0307 and 2015ZC0210)Binzhou University Research Fund Project,China(Grant Nos.BZXYG1513 and BZXYG1706)
文摘The Zr（0.5）Hf（0.5）VPO7 is successfully synthesized by the solid-state method with near-zero thermal expansion. Powder x-ray diffraction（XRD）, Raman spectroscopy, thermal dilatometry, and scanning electron microscopy（SEM） are used to investigate the structure, the phase transition, and the coefficient of thermal expansion（CTE） of Zr（0.5）Hf（0.5）VPO7. The investigation results show that the samples are of the single cubic type with a space group of Pa3ˉ at room temperature（RT）.It can be inferred that the superstructure is transformed from the 3 × 3 × 3 superstructure to the 1 × 1 × 1 ideal crystal in a temperature range between 310 K and 323 K. The CTE is measured by a dilatometer to be 0.59 × 10^（-6） K^（-1）（310 K–673 K）. The values of intrinsic（XRD） and extrinsic（dilatometric） thermal expansion are both near zero. The results show that Zr（0.5）Hf（0.5）VPO7 has near-zero thermal expansion behavior over a wide temperature range.
基金supported by the National Natural Science Foundation of China(Grant Nos.11874328,12004339,11574276,and 21905252)the China Postdoctoral Science Foundation(Grant Nos.2018M640679,2019T120629,and 2019M652558)the Zhongyuan Academician Foundation(Grant No.ZYQR201810163)。
文摘We report a new type of near-zero thermal expansion materialβ-CuZnV_(2)O_(7)in a large temperature range from 173 K to 673 K.It belongs to a monoclinic structure(C2/c space group)in the whole temperature range.No structural phase transition is observed at atmospheric pressure based on the x-ray diffraction and Raman experiment.The high-pressure Raman experiment demonstrates that two structural phase transitions exist at 0.94 GPa and 6.53 GPa,respectively.The mechanism of negative thermal expansion inβ-CuZnV_(2)O_(7)is interpreted by the variations of the angles between atoms intuitively and the phonon anharmonicity intrinsically resorting to the negative Grüneisen parameter.
