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

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Nanoindentation measurements of a highly oriented wurtzite-Type boron nitride bulk crystal

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 dynamics simulations, we reveal a s

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Micro-grains of wurtzite boron nitride(wBN) crystal have been observed

Micro-grains of wurtzite boron nitride(wBN) crystal have been observed in 5.0-7.0 GPa pressure and 1800-2000 K temperature where cubic boron nitride has been synthesized in a catalyst. The wBN grain size is about 20-30 nm. The presence of these micro grains indicates that the pressure for wBN growth could be lower than that found in the previous work. The first, wurtzite boron nitride, is similar to diamond but comprises different atoms. The second, the mineral lonsdaleite, is made from carbon a

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Nonreversible Transition from the Hexagonal to Wurtzite Phase of Boron Nitride

Wurtzite Boron Nitride (wBN) is a wide band gap BN polymorph with unique mechanical properties such as hardness and stiffness. Initially synthesized in 1963 by transforming hexagonal BN (hBN) under high temperature and pressure conditions, wBN can now be stabilized at atmospheric pressure to obtain high-quality samples. Our first-principles study investigates the electronic, vibrational, and optical properties of wBN across a broad range of pressures. We account for the electron-hole interaction

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Wurtzite Boron Nitride Crystal Growth in the Region of Cubic Boron Nitride Crystal Synthesizing

What is Wurtzite Boron Nitride?Wurtzite Boron Nitride (wBN) is a wide band gap BN polymorph with unique mechanical properties such as hardness and stiffness. Initially synthesized in 1963 by transforming hexagonal BN (hBN) under high temperature and pressure conditions, wBN can now be stabilized at atmospheric pressure to obtain high-quality samples. Our first-principles study investigates the electronic, vibrational, and optical properties of wBN across a broad range of pressures. We account fo

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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

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Super Abrasive Wurtzite Boron Nitride

It's a relatively new super abrasive material used in conjunction with detonation. Wurtzite BN is the next step in the evolution of boron nitride, after the well-known cubic BN and another substance called graphite, which has a structure similar to hexagonal BN. Boron nitride is white graphite due to its similar hexagonal structure and lubricious properties. It is a rigid ceramic material and has a polycrystalline structure that provides superior cutting properties and sharpens itself by cutting

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What is Wurtzite boron nitride

Wurtzite boron nitride (w-BN) is a metastable high-pressure polymorph of BN, which can only be fabricated as micrometer-size powders by the shock compression of hexagonal BN. Here, we fabricate millimeter-size w-BN bulk crystals and reveal an unprecedented stabilization mechanism for w-BN. The simulation showed that wurtzite boron nitride would withstand 18 percent more stress than diamond and lonsdaleite 58 percent more. If the results are confirmed with physical experiments, both materials wou

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Wurtzite form W Boron nitride

What is Boron nitride?Boron nitride can be doped p-type with beryllium and n-type with boron, sulfur, silicon, or if co-doped with carbon and nitrogen. Both hexagonal and cubic BN are wide-gap semiconductors with band-gap energy corresponding to the UV region. If voltage is applied to h-BN or c-BN, it emits UV light in the range of 215–250 nm and, therefore, can potentially be used as light-emitting diodes (LEDs) or lasers. The partly ionic structure of BN layers in h-BN reduces covalency and el

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