Investigation of ceramic boron nitride by terahertz time-domain spectroscopy

Dielectric Properties of Boron Nitride in THz Region Synthesized with Nonenergetic CVD

“…The variation of the refractive indices found by these authors is in the same range as was found in our study, however, the variations were attributed also to the changes in the porosity of the investigated samples. Distinct detection of the differences in refractive indexes related to the birefringence of pBN 23,24 reported in the literature could be responsible for these variations. Distinct detection of the differences in refractive indexes related to the birefringence of pBN 23,24 reported in the literature could be responsible for these variations.…”

“…In contrast, cBN reaches 70% of the hardness of diamond, making it the second hardest material. [18][19][20][21][22] Recently, Naftaly et al 23 has investigated the commercially available forms of hot-pressed hexagonal boron nitride using Terahertz time-domain spectroscopy. 7,8 Although synthesis methods for production of either hBN or cBN boron nitride are known, optimization of the synthesis routes is the subject of intensive scientific research.…”

“…It has very good thermal conductivity and optical transparency, high chemical stability against oxidation even at increased temperatures (up to 1800°C), and hence it is suitable as a hard layer coating material. 23,24 In this study, we have investigated the experimental conditions for the synthesis of pBN by nonenergetic chemical vapor deposition as a simple production route for some technical applications. [9][10][11][12][13][14] High pressure high temperature (HPHT) synthesis is used to synthesize bulk cBN from hBN in the presence of a suitable catalyst, while energetic chemical vapor deposition and ion-beamand/or plasma-assisted deposition are used to produce thin layers of cBN coatings.…”

Selected Emerging Opportunities for Ceramics in Energy, Environment, and Transportation

“…They have measured the loss coefficients ( α ) and refractive indices ( n ) of the ceramic samples by comparing THz transmission through two different thicknesses of these samples. Naftaly, Leist, and Dudley have extended these measurements to different grades of BN, demonstrating the need for control of the microstructures and properties of these ceramic materials for this application and showing that these materials can be used as windows.…”

Non-Destructive Evaluation of Aerospace Materials using Terahertz Time-Domain Imaging

“…While the use of terahertz (THz) imaging as an evaluation tool for novel materials and systems has found much success in recent years [1][2][3], there remain several possible application areas still in need of thorough investigation. Here, we investigate the use of terahertz imaging for the characterization and evaluation of materials and components used in advanced aerospace components.…”