Hydrothermal hot-pressing induced phase transition in hexagonal boron nitride

2009 ◽  
Vol 11 (7) ◽  
pp. 1283-1287 ◽  
Author(s):  
Lingling Zhu ◽  
Miao Tan ◽  
Gang Lian ◽  
Xiao Zhang ◽  
Deliang Cui ◽  
...  
Keyword(s):  
Phase Transition ◽  
Boron Nitride ◽  
Hot Pressing ◽  
Hexagonal Boron Nitride

First-principles study on the heterostructure of twisted graphene/hexagonal boron nitride/graphene sandwich structure

2021 ◽  
Author(s):  
Yiheng Chen ◽  
Wen-Ti Guo ◽  
Zi-si Chen ◽  
Suyun Wang ◽  
Jian-Min Zhang
Keyword(s):  
Phase Transition ◽  
Boron Nitride ◽  
Charge Density ◽  
First Principles ◽  
Sandwich Structure ◽  
Hexagonal Boron Nitride ◽  
Mulliken Population ◽  
Metal Insulator ◽  
Insulator Phase Transition ◽  
Twisted Graphene

Abstract In recent years, the discovery of "magic angle" graphene has given new inspiration to the formation of heterojunctions. Similarly, the use of hexagonal boron nitride, known as white graphene, as a substrate for graphene devices has more aroused great interest in the graphene/hexagonal boron nitride (G/hBN) heterostructure system. Based on the first principles method of density functional theory, the band structure, density of states, Mulliken population, and differential charge density of a tightly packed model of twisted graphene/hexagonal boron nitride/graphene (G/hBN/G) sandwich structure have been studied. Through the establishment of heterostructure models TBG inserting hBN with different twisted angles, it was found that the band gap, Mulliken population, and charge density, exhibited specific evolution regulars with the rotation angle of the upper graphene, showing novel electronic properties and realizing metal-insulator phase transition. We find that the particular value of the twist angle at which the metal-insulator phase transition occurs and propose a rotational regulation mechanism with angular periodicity. Our results have guiding significance for the practical application of heterojunction electronic devices.

Reaction Synthesized Boron Nitride-Containing Composites (BNCC)

2007 ◽  
Vol 280-283 ◽  
pp. 1385-1390
Author(s):  
Guo Jun Zhang ◽  
Tatsuki Ohji ◽  
Shuzo Kanzaki
Keyword(s):  
Boron Nitride ◽  
Hot Pressing ◽  
High Performance ◽  
Hexagonal Boron Nitride ◽  
High Strength ◽  
Reactive Sintering ◽  
Boron Source ◽  
Inorganic Reactions ◽  
Reactive Hot Pressing

Based on the proposed inorganic reactions a series of high performance hexagonal boron nitride-containing composites (BNCC), include SiC-BN, Si3N4-SiC-BN, SiAlON-BN, AlN-BN, Al2O3-BN, AlON-BN and mullite-BN, have been prepared via reactive hot pressing or pressureless reactive sintering. Various boron-bearing components such as B, B4C, AlB2, SiB4, SiB6, B2O3 or H3BO3, 9Al2O3×2B2O3 (9A2B) and 2Al2O3×B2O3 (2AB) are used as the boron source. On the other hand, nitrogen gas or solid state nitirgen-bearing metal nitrides such as Si3N4 and AlN can be used as the nitrogen source. The in situ synthesized composites demonstrated homogeneous and isotropical microstructures with very fine (nano-sized) BN platelets or their agglomerates distributed in the matrixes. These composites showed high strength, low elasticity and improved strain tolerance. In this article the reaction design, thermodynamics, reaction mechanisms, reactive hot pressing or pressureless reactive sintering, microstructures and mechanical properties will be discussed.

Interactions of Hexagonal Boron Nitride with the Insulator-Metal Phase Transition of Vanadium Dioxide

2018 ◽  
Author(s):  
Samuel T. White ◽  
Alireza Fali ◽  
Thomas G. Folland ◽  
Joshua D. Caldwell ◽  
Yohannes Abate ◽  
...  
Keyword(s):  
Phase Transition ◽  
Boron Nitride ◽  
Vanadium Dioxide ◽  
Hexagonal Boron Nitride ◽  
Metal Phase ◽  
Metal Phase Transition

Corrugations of the basal planes in hexagonal boron nitride and their impact on the phase transition to cubic boron nitride

2015 ◽  
Vol 30 (S1) ◽  
pp. S90-S96 ◽  
Author(s):  
C. Schimpf ◽  
M. Schwarz ◽  
C. Lathe ◽  
E. Kroke ◽  
D. Rafaja
Keyword(s):  
Phase Transition ◽  
Boron Nitride ◽  
Basal Plane ◽  
High Pressures ◽  
Hexagonal Boron Nitride ◽  
Cubic Boron Nitride ◽  
Synthesis Product ◽  
Transmission Electron ◽  
Specific Shape ◽  
The Difference

Among the microstructure defects in hexagonal graphitic boron nitride, the basal plane corrugations are of high relevance for the sp2 to sp3 phase transition under high pressures (HP) and high temperatures (HT). A microstructure model is described, which is capable of quantifying the amplitude of the basal plane corrugations on the basis of the anisotropic X-ray diffraction line broadening. It is illustrated that this model correctly reproduces the specific shape of the diffraction lines from corrugated basal planes, i.e., the characteristic splitting of the 00l peaks. The results from XRD are verified by direct observation in the transmission electron microscope with high resolution. Subsequent HP/HT experiments were performed in order to highlight the difference in the phase transition kinetics between hexagonal boron nitride samples with different amount of basal plane corrugations. The effect of these microstructure defects on the conversion rate and on the obtained synthesis product is discussed.

Thermal Conductivity of Hot-Pressed BN Ceramics

2006 ◽  
Vol 510-511 ◽  
pp. 398-401 ◽  
Author(s):  
Sang Kee Lee ◽  
Kazuo Nakamura ◽  
Shoichi Kume ◽  
Koji Watari
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Hot Pressing ◽  
Hexagonal Boron Nitride ◽  
Nitrogen Atmosphere ◽  
Uniaxial Pressure ◽  
Sintering Additives ◽  
Nitride Ceramics

Hexagonal boron nitride ceramics with sintering additives were synthesized by uniaxial hot-pressing. Hot pressing was carried out at 1800oC for 2 h under the uniaxial pressure of 30 MPa under a nitrogen atmosphere. Thermal conductivity perpendicular and parallel to the direction of the hot-pressing axis was measured by the laser-flush method.

scholarly journals Hot pressing-induced alignment of hexagonal boron nitride in SEBS elastomer for superior thermally conductive composites

RSC Advances ◽  
2018 ◽  
Vol 8 (45) ◽  
pp. 25835-25845 ◽  
Author(s):  
Cuiping Yu ◽  
Wenbin Gong ◽  
Jun Zhang ◽  
Weibang Lv ◽  
Wei Tian ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Dimensional Stability ◽  
Hot Pressing ◽  
Hexagonal Boron Nitride ◽  
Composite Films ◽  
Conductive Composites ◽  
Thermally Conductive

Orientational hBN/SEBS composite films embued with superior thermal conductivity and improved dimensional stability were prepared by hot-pressing treatment.

Reaction of Hexagonal Boron Nitride Nano-crystals under Mild Hydrothermal Conditions

2008 ◽  
Vol 63 (6) ◽  
pp. 742-746 ◽  
Author(s):  
Lingling Zhu ◽  
Gang Lian ◽  
Miao Tan ◽  
Qilong Wang ◽  
Xian Zhao ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Hot Pressing ◽  
Hexagonal Boron Nitride ◽  
The Other ◽  
Ir Absorption ◽  
Pressing Pressure ◽  
Crystalline Perfection ◽  
Hydrothermal Conditions ◽  
Absorption Bands ◽  
Pressing Temperature

The reaction between hexagonal boron nitride (hBN) nano-crystals and water at low temperature and low pressure has been investigated. The results reveal that this reaction can be greatly promoted by increasing the hot-pressing temperature. However, when the temperature is above 280 °C, the reaction is too fast to be controlled by varying the hot-pressing pressure and time. On the other hand, stress and defects are induced in hBN nano-crystals by the hydrothermal hot-pressing process, resulting in a shift of the IR absorption bands and a deterioration of crystalline perfection. These results may be useful for synthesizing cBN by the hydrothermal method and converting hBN nanocrystals into cBN under moderate conditions.

Sign in / Sign up

Export Citation Format

Share Document