We synthesized pure polycrystalline cubic boron nitride

We synthesized pure polycrystalline cubic boron nitride (cBN) and wurtzite boron nitride (wBN) by the direct conversion method from hexagonal boron nitride. We measured their longitudinal-wave elastic constants CL between 20 and 300 K using picosecond ultrasound spectroscopy. Their room-temperature values are 945 ± 3 GPa and 930 ± 18 GPa for cBN and wBN, respectively. The shear modulus G of cBN was also determined by combining resonance ultrasound spectroscopy and micromechanics calculation as G


Elastic constants of cubic and wurtzite boron nitrides

What is Wurtzite boron nitride?Wurtzite boron nitride is a metastable superhard material that is a high-pressure polymorph of BN. Clarifying how the metastable high pressure material can be stabilized at atmospheric pressure is a challenging issue of fundamental scientific importance. Here, we fabricate millimeter-size w-BN bulk crystals via the hexagonal-to-wurtzite phase transformation at high pressure and temperatures. By combining transmission electron microscopy and ab initio molecular dyna


Related news

Role of Copper Oxides in Contact Killing of Bacteria

The potential of metallic copper as an intrinsically antibacterial material is gaining increasing attention in the face of the growing antibiotic resistance of bacteria. However, the mechanism of the so-called "contact killing" of bacteria by copper surfaces is poorly understood and requires further investigation. In particular, the influences of bacteria–metal interaction, media composition, and copper surface chemistry on contact killing are not fully understood. In this study, copper oxide fo


What is composite concrete foaming agent

composite concrete foaming agent is a non-polluting physical foaming agent produced by processing, deforming, and synthesizing various polymer components. It has good foaming ability, and its performance is neutral. Water has good affinity, and it is


Can gallium carbide be formed

What is gallium carbide?Based on DSC, IR, and Raman, it appears to be the formation of GaC. In contrast, the analysis by EXAFS and XANES demonstrated that the gallium, supported by carbon, is in a higher reduced state (almost metallic). The question that remains open, in addition to the one related to the formation of galium carbide, is whether a complex structure, including oxygen contamination, is involved in the layers surrounding Ga, as indicated by the EXAFS results. Can gallium carbide be

0086-0379-64280201 brad@ihpa.net skype whatsapp