Optical Properties of Bulk Single-Crystal Diamonds at 80-1200 K by Vibrational Spectroscopic Methods.

Zitao Shi,Kazuhito Nishimura,Nan Jiang,Yuezhong Wang,Bingxue Zhang,He Li,Qilong Yuan,Guojian Yang

doi:10.3390/ma14237435

Abstract

Bulk diamonds show great potential for optical applications such as for use in infrared (IR) windows and temperature sensors. The development of optical-grade bulk diamond synthesis techniques has facilitated its extreme applications. Here, two kinds of bulk single-crystal diamonds, a high-pressure and high-temperature (HPHT) diamond and a chemical vapor deposition (CVD) diamond, were evaluated by Raman spectroscopy and Fourier Transform Infra-Red (FTIR) spectroscopy at a range of temperatures from 80 to 1200 K. The results showed that there was no obvious difference between the HPHT diamond and the CVD diamond in terms of XRD and Raman spectroscopy at 300–1200 K. The measured nitrogen content was ~270 and ~0.89 ppm for the HPHT diamond and the CVD diamond, respectively. The moderate nitrogen impurities did not significantly affect the temperature dependence of Raman spectra for temperature-sensing applications. However, the nitrogen impurities greatly influence FTIR spectroscopy and optical transmittance. The CVD diamond showed higher transmittance, up to 71% with only a ~6% drop at temperatures as high as 873 K. This study shows that CVD bulk diamonds can be used for IR windows under harsh environments.

Highlights

Diamond is an allotrope of carbon which has attracted much attention because of its excellent physical and chemical properties [1]
Vibrational spectroscopy was used to investigate high-pressure and high-temperature (HPHT) diamonds and chemical vapor deposition (CVD) diamonds over a range of temperatures
The nitrogen content of the two diamonds evaluated by spectroscopic methods was ~270 ppm for the HPHT diamond and ~0.89 ppm for the CVD diamond, respectively

Summary

Introduction

Diamond is an allotrope of carbon which has attracted much attention because of its excellent physical and chemical properties [1]. Its main applications include optics [2], electron devices [3] and quantum sensors [4] under harsh conditions, such as irradiation, high temperatures, high power and high pressure. These extreme applications of diamonds benefit from their unique properties, which are closely related to their lattice structure and corresponding phonon spectrum [5]. There is a triply degenerate LTO optical phonon in the Brillouin zone center corresponding to the sharp first-order Raman line near 1332 cm−1 at room temperature.

Methods

Results

Conclusion