Abstract
We examined the Raman scattering and IR absorption spectroscopy of 4H-SiC and its performance as an anvil material for high-pressure UV-visible absorption spectroscopic measurements. The first- and second-order Raman peaks of 4H-SiC and diamond do not coincide. 4H-SiC does not have obvious signals from 2330-5000 cm-1, suggesting that 4H-SiC anvils are beneficial for high-pressure studies of samples whose Raman signals locate in the region of diamond. Above 1800 cm-1, the transmitted signal of 4H-SiC in the IR absorption spectra, measured through 4.6 mm thickness is much higher than that of type IIa diamond. An in situ high-pressure UV-visible absorption spectroscopy study on CdI2 was carried out up to 28.0 GPa using 4H-SiC anvil cells (4H-SAC) with a 400 μm culet and the acquired band gap narrowed with increasing pressure. These results show that 4H-SiC has an excellent performance in high-pressure spectroscopic studies.
Highlights
Owing to the synergic development of various pressure devices and probing technology, highpressure research has been progressing rapidly during recent decades.[1]
For type IIa diamond, from 1600 cm-1 to 2670 cm-1 there is a strong absorption band that is troublesome in IR spectra when a diamond anvil cell (DAC) is used in high-pressure experiments
The first-and secondorder Raman peaks of 4H-SiC do not coincide with those of diamond. It shows a flat feature in the range of 2330-5000 cm-1, suggesting that 4H-SiC is beneficial for highpressure studies of samples with Raman signals in the range that overlaps with diamond
Summary
Owing to the synergic development of various pressure devices and probing technology, highpressure research has been progressing rapidly during recent decades.[1]. A 6H-SiC anvil cell achieved pressure over 55 GPa.[2,5,6] Xu et al conducted powder neutron diffraction of wustite (FeO) to 12 GPa by using large 6H-SiC as anvils.[7] SiC is suitable for electric conductivity measurements due to its wide-gap[8,9] and has no detectable magnetic signal to interfere with high-pressure magnetic measurements.[2] A 6H-SiC anvil cell was used to perform in situ synchrotron X-ray diffraction and double-sided laser heating experiments, achieving high temperatures of 3700 K.10. We performed Raman, IR absorption, and in situ high-pressure UV-visible absorption studies on 4H-SiC to compare 4H-SAC and DAC performance. Our results show that 4H-SiC is a preferable substitution for diamond in high-pressure spectroscopic study
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