Mechanical Properties of Cubic‐BN(111) Bulk Single Crystal Evaluated by Nanoindentation

Abstract

We performed nanoindentation measurements on the (111) plane of a cubic boron nitride (c‐BN) bulk single crystal and a c‐BN sintered compact at room temperature to evaluate the intrinsic mechanical properties of c‐BN. Our load–penetration depth curves for bulk single crystal feature a low noise level and small variation in the data. These features reflect the perfect phase purity and high crystal coherency of the c‐BN bulk crystal. The hardness and Young's modulus are determined to be 61 ± 1 and 1070 ± 30 GPa, respectively. These values are larger than those corresponding to the c‐BN sintered compact. The obtained Young's modulus followed a similar trend to previous experimental and calculation studies. Hence, we demonstrate the effectiveness of this evaluation method based on high‐quality bulk single crystals. We also compared the mechanical properties with our results for wurtzite boron nitride (w‐BN) bulk crystal.

Ultra-Hard (41 GPa) Isotopic Pure 10BP Semiconductor Microwires for Flexible Photodetection and Pressure Sensing

“…Furthermore, we studied and compared the hardness and growth temperature of some well-known semiconductors with high hardness, as shown in Figure c. Among them, the hardness of diamond and c-BN reaches 93.4 and 65.5 GPa , with an extremely high growth temperature reaching 2000 and 1800 °C under high pressure. − For β-SiC, , B 4 C, SiO 2 , Al 2 O 3 , , and AlN , (32.8, 30, 33, 31, and 18 GPa, respectively), although their hardness is much lower than that of other superhard materials, the growth temperature they need is also as high as 1800 °C. Therefore, in comparison, the temperature required by isotope-enriched 10 BP crystals is relatively lower (1200 °C), and simultaneously, a threshold of 40 GPa usually owned by superhard materials is also achieved.…”

Crystal Transformation of Cubic BN Nanoislands to Rhombohedral BN Sheets on AlN for Deep-UV Light-Emitting Diodes

“…Figure (a) presents the XRD 2θ scans of the thin BN layers grown, with a V/III ratio of 713, for 20 min and 1 h on the AlN template. In addition to the signals from AlN and sapphire (Al 2 O 3 ), the figure shows two peaks from BN, corresponding to rBN(003) at 26° and cBN(111) at 44.3°. ,− Since the c -axis interplanar spacings of rBN and hBN are very close to each other and indistinguishable in the XRD 2θ scan, HRTEM is used to differentiate the two sp 2 structures (to be shown later). It is clear that the peak intensity at 44.3° increases with growth time.…”

Materials science research of boron nitride obtained at high pressure and high temperature

“…3). 12) There is some confusion in recent literature about the hardness of ultrahard materials. There is a theoretical prediction that the hardness of wBN is larger than that of cBN and even diamond.…”

“…13) There are fine stacking faults in wBN oriented crystals, as discussed previously, and a report claims that fine stacking faults increase hardness. 14) Although care should be required for precise measurements, nanoindentation technique 12) seem useful as a method of assessing the hardness of ultrahard materials because the loaddisplacement curve can be obtained correctly in a hardness test and there is little effect of indenter deformation during hardness measurement. Although there is no evaluation comparing sintered materials with single crystals as predicted by theory, it seems that cBN is harder than wBN experimentally as shown in Fig.…”

“…Fig.3. Dependence of (a) hardness and Young's modulus on h max (maximum penetration depth of nanoindentation) of cBN and wBN obtained by nanoindentation method 12). …”