Editing Boron nitride (section)

=== Atomically thin boron nitride ===
{{Main|Boron nitride nanosheet}}
Hexagonal boron nitride can be exfoliated to mono or few atomic layer sheets. Due to its analogous structure to that of graphene, atomically thin boron nitride is sometimes called ''white graphene''.<ref name="LiChen2016">{{cite journal|last1=Li|first1=Lu Hua|last2=Chen|first2=Ying|title=Atomically Thin Boron Nitride: Unique Properties and Applications|journal=Advanced Functional Materials|volume=26|issue=16|year=2016|pages=2594–2608|doi=10.1002/adfm.201504606|arxiv=1605.01136|bibcode=2016arXiv160501136L|s2cid=102038593}}</ref>

====Mechanical properties====
Atomically thin boron nitride is one of the strongest electrically insulating materials. Monolayer boron nitride has an average Young's modulus of 0.865TPa and fracture strength of 70.5GPa, and in contrast to graphene, whose strength decreases dramatically with increased thickness, few-layer boron nitride sheets have a strength similar to that of monolayer boron nitride.<ref>{{Cite journal|last1=Falin|first1=Aleksey|last2=Cai|first2=Qiran|last3=Santos|first3=Elton J.G.|last4=Scullion|first4=Declan|last5=Qian|first5=Dong|last6=Zhang|first6=Rui|last7=Yang|first7=Zhi|last8=Huang|first8=Shaoming|last9=Watanabe|first9=Kenji|date=2017-06-22|title=Mechanical properties of atomically thin boron nitride and the role of interlayer interactions|journal=Nature Communications|volume=8|pages=15815|doi=10.1038/ncomms15815|pmid=28639613|pmc=5489686|arxiv=2008.01657|bibcode=2017NatCo...815815F}}</ref>

====Thermal conductivity====
Atomically thin boron nitride has one of the highest thermal conductivity coefficients (751 W/mK at room temperature) among semiconductors and electrical insulators, and its thermal conductivity increases with reduced thickness due to less intra-layer coupling.<ref>{{Cite journal|last1=Cai|first1=Qiran|last2=Scullion|first2=Declan|last3=Gan|first3=Wei|last4=Falin|first4=Alexey|last5=Zhang|first5=Shunying|last6=Watanabe|first6=Kenji|last7=Taniguchi|first7=Takashi|last8=Chen|first8=Ying|last9=Santos|first9=Elton J. G.|date=2019|title=High thermal conductivity of high-quality monolayer boron nitride and its thermal expansion|journal=Science Advances|language=en|volume=5|issue=6|pages=eaav0129|doi=10.1126/sciadv.aav0129|issn=2375-2548|pmc=6555632|pmid=31187056|arxiv=1903.08862|bibcode=2019SciA....5..129C}}</ref>

====Thermal stability====
The air stability of graphene shows a clear thickness dependence: monolayer graphene is reactive to oxygen at 250&nbsp;°C, strongly doped at 300&nbsp;°C, and etched at 450&nbsp;°C; in contrast, bulk graphite is not oxidized until 800&nbsp;°C.<ref name="LiSantos2014"/> Atomically thin boron nitride has much better oxidation resistance than graphene. Monolayer boron nitride is not oxidized till 700&nbsp;°C and can sustain up to 850&nbsp;°C in air; bilayer and trilayer boron nitride nanosheets have slightly higher oxidation starting temperatures.<ref name="LiCervenka2014">{{cite journal|last1=Li|first1=Lu Hua|last2=Cervenka|first2=Jiri|last3=Watanabe|first3=Kenji|last4=Taniguchi|first4=Takashi|last5=Chen|first5=Ying|title=Strong Oxidation Resistance of Atomically Thin Boron Nitride Nanosheets|journal=ACS Nano|volume=8|issue=2|year=2014|pages=1457–1462|doi=10.1021/nn500059s|pmid=24400990|arxiv=1403.1002|bibcode=2014arXiv1403.1002L|s2cid=5372545}}</ref> The excellent thermal stability, high impermeability to gas and liquid, and electrical insulation make atomically thin boron nitride potential coating materials for preventing surface oxidation and corrosion of metals<ref name="LiXing2014">{{cite journal|last1=Li|first1=Lu Hua|last2=Xing|first2=Tan|last3=Chen|first3=Ying|last4=Jones|first4=Rob|title=Nanosheets: Boron Nitride Nanosheets for Metal Protection (Adv. Mater. Interfaces 8/2014)|journal=Advanced Materials Interfaces|volume=1|issue=8|year=2014|pages=n/a|doi=10.1002/admi.201470047|doi-access=free}}</ref><ref>{{Cite journal|last1=Liu|first1=Zheng|last2=Gong|first2=Yongji|last3=Zhou|first3=Wu|last4=Ma|first4=Lulu|last5=Yu|first5=Jingjiang|last6=Idrobo|first6=Juan Carlos|last7=Jung|first7=Jeil|last8=MacDonald|first8=Allan H.|last9=Vajtai|first9=Robert|date=2013-10-04|title=Ultrathin high-temperature oxidation-resistant coatings of hexagonal boron nitride|journal=Nature Communications|volume=4|issue=1|pages=2541|doi=10.1038/ncomms3541|pmid=24092019|bibcode=2013NatCo...4.2541L|doi-access=free}}</ref> and other two-dimensional (2D) materials, such as [[black phosphorus]].<ref>{{Cite journal|last1=Chen|first1=Xiaolong|last2=Wu|first2=Yingying|last3=Wu|first3=Zefei|last4=Han|first4=Yu|last5=Xu|first5=Shuigang|last6=Wang|first6=Lin|last7=Ye|first7=Weiguang|last8=Han|first8=Tianyi|last9=He|first9=Yuheng|date=2015-06-23|title=High-quality sandwiched black phosphorus heterostructure and its quantum oscillations|journal=Nature Communications|volume=6|issue=1|pages=7315|doi=10.1038/ncomms8315|pmid=26099721|pmc=4557360|arxiv=1412.1357|bibcode=2015NatCo...6.7315C}}</ref>

====Better surface adsorption====
Atomically thin boron nitride has been found to have better surface adsorption capabilities than bulk hexagonal boron nitride.<ref>{{Cite journal|last1=Cai|first1=Qiran|last2=Du|first2=Aijun|last3=Gao|first3=Guoping|last4=Mateti|first4=Srikanth|last5=Cowie|first5=Bruce C. C.|last6=Qian|first6=Dong|last7=Zhang|first7=Shuang|last8=Lu|first8=Yuerui|last9=Fu|first9=Lan|author9-link=Lan Fu (engineer)|date=2016-08-29|title=Molecule-Induced Conformational Change in Boron Nitride Nanosheets with Enhanced Surface Adsorption|journal=Advanced Functional Materials|volume=26|issue=45|pages=8202–8210|doi=10.1002/adfm.201603160|arxiv=1612.02883|bibcode=2016arXiv161202883C|s2cid=13800939}}</ref> According to theoretical and experimental studies, atomically thin boron nitride as an adsorbent experiences conformational changes upon surface adsorption of molecules, increasing adsorption energy and efficiency. The synergic effect of the atomic thickness, high flexibility, stronger surface adsorption capability, electrical insulation, impermeability, high thermal and chemical stability of BN nanosheets can increase the [[Raman spectroscopy|Raman sensitivity]] by up to two orders, and in the meantime attain long-term stability and reusability not readily achievable by other materials.<ref>{{Cite journal|last1=Cai|first1=Qiran|last2=Mateti|first2=Srikanth|last3=Yang|first3=Wenrong|last4=Jones|first4=Rob|last5=Watanabe|first5=Kenji|last6=Taniguchi|first6=Takashi|last7=Huang|first7=Shaoming|last8=Chen|first8=Ying|last9=Li|first9=Lu Hua|date=2016-05-20|title=Inside Back Cover: Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface-Enhanced Raman Spectroscopy (Angew. Chem. Int. Ed. 29/2016)|journal=Angewandte Chemie International Edition|volume=55|issue=29|pages=8457|doi=10.1002/anie.201604295|doi-access=free|hdl=10536/DRO/DU:30086239|hdl-access=free}}</ref><ref>{{Cite journal|last1=Cai|first1=Qiran|last2=Mateti|first2=Srikanth|last3=Watanabe|first3=Kenji|last4=Taniguchi|first4=Takashi|last5=Huang|first5=Shaoming|last6=Chen|first6=Ying|last7=Li|first7=Lu Hua|date=2016-06-14|title=Boron Nitride Nanosheet-Veiled Gold Nanoparticles for Surface-Enhanced Raman Scattering|journal=ACS Applied Materials & Interfaces|volume=8|issue=24|pages=15630–15636|doi=10.1021/acsami.6b04320|pmid=27254250|arxiv=1606.07183|bibcode=2016arXiv160607183C|s2cid=206424168}}</ref>

====Dielectric properties====
Atomically thin hexagonal boron nitride is an excellent dielectric substrate for graphene, molybdenum disulfide ({{chem2|MoS2}}), and many other 2D material-based electronic and photonic devices. As shown by electric force microscopy (EFM) studies, the electric field screening in atomically thin boron nitride shows a weak dependence on thickness, which is in line with the smooth decay of electric field inside few-layer boron nitride revealed by the first-principles calculations.<ref name="LiSantos2014">{{Cite journal|last1=Li|first1=Lu Hua|last2=Santos|first2=Elton J. G.|last3=Xing|first3=Tan|last4=Cappelluti|first4=Emmanuele|last5=Roldán|first5=Rafael|last6=Chen|first6=Ying|last7=Watanabe|first7=Kenji|last8=Taniguchi|first8=Takashi|year=2015|title=Dielectric Screening in Atomically Thin Boron Nitride Nanosheets|journal=Nano Letters|volume=15|issue=1|pages=218–223|doi=10.1021/nl503411a|pmid=25457561|arxiv=1503.00380|bibcode=2015NanoL..15..218L|s2cid=207677623}}</ref>

====Raman characteristics====
Raman spectroscopy has been a useful tool to study a variety of 2D materials, and the Raman signature of high-quality atomically thin boron nitride was first reported by Gorbachev et al. in 2011.<ref>{{Cite journal|last1=Gorbachev|first1=Roman V.|last2=Riaz|first2=Ibtsam|last3=Nair|first3=Rahul R.|last4=Jalil|first4=Rashid|last5=Britnell|first5=Liam|last6=Belle|first6=Branson D.|last7=Hill|first7=Ernie W.|last8=Novoselov|first8=Kostya S.|last9=Watanabe|first9=Kenji|date=2011-01-07|title=Hunting for Monolayer Boron Nitride: Optical and Raman Signatures|journal=Small|volume=7|issue=4|pages=465–468|doi=10.1002/smll.201001628|pmid=21360804|arxiv=1008.2868|s2cid=17344540}}</ref> and Li et al.<ref name="LiCervenka2014"/> However, the two reported Raman results of monolayer boron nitride did not agree with each other. Cai et al., therefore, conducted systematic experimental and theoretical studies to reveal the intrinsic Raman spectrum of atomically thin boron nitride.<ref>{{Cite journal|last1=Cai|first1=Qiran|last2=Scullion|first2=Declan|last3=Falin|first3=Aleksey|last4=Watanabe|first4=Kenji|last5=Taniguchi|first5=Takashi|last6=Chen|first6=Ying|last7=Santos|first7=Elton J. G.|last8=Li|first8=Lu Hua|date=2017|title=Raman signature and phonon dispersion of atomically thin boron nitride|journal=Nanoscale|volume=9|issue=9|pages=3059–3067|doi=10.1039/c6nr09312d|pmid=28191567|url=https://pure.qub.ac.uk/portal/en/publications/raman-signature-and-phonon-dispersion-of-atomically-thin-boron-nitride(5f58d958-22ab-450f-97fb-cd7c0f25f5b4).html|arxiv=2008.01656|s2cid=206046676}}</ref> It reveals that atomically thin boron nitride without interaction with a substrate has a G band frequency similar to that of bulk hexagonal boron nitride, but strain induced by the substrate can cause Raman shifts. Nevertheless, the Raman intensity of G band of atomically thin boron nitride can be used to estimate layer thickness and sample quality.[[Image:STMnm-2.JPG|thumb|left|150px|BN nanomesh observed with a [[scanning tunneling microscope]]. The center of each ring corresponds to the center of the pores]]
[[File:Oil absorption by BN aerogel.jpg|thumb|upright=1.5|Top: absorption of [[cyclohexane]] by BN aerogel. Cyclohexane is stained with [[Sudan II]] red dye and is floating on water. Bottom: reuse of the aerogel after burning in air.<ref name=nat>{{cite journal|doi=10.1038/srep10337|pmid=25976019|title=Ultralight boron nitride aerogels via template-assisted chemical vapor deposition|journal=Scientific Reports|volume=5|pages=10337|year=2015|last1=Song|first1=Yangxi|last2=Li|first2=Bin|last3=Yang|first3=Siwei|last4=Ding|first4=Guqiao|last5=Zhang|first5=Changrui|last6=Xie|first6=Xiaoming|pmc=4432566|bibcode=2015NatSR...510337S}}</ref>]]