Calcium bismuth niobate(CaBi_(2)Nb_(2)O_(9))is regarded as one of the most potential high-temperature piezoelectric materials owing to its highest Curie point in bismuth layer-structured ferroelectrics.Nevertheless,lo...Calcium bismuth niobate(CaBi_(2)Nb_(2)O_(9))is regarded as one of the most potential high-temperature piezoelectric materials owing to its highest Curie point in bismuth layer-structured ferroelectrics.Nevertheless,low piezoelectric coefficient and low resistivity at high temperature considerably restrict its development as key electronic components.Herein,markedly improved piezoelectric properties and DC resistivity of CaBi_(2)Nb_(2)O_(9) ceramics through Naþand Sm^(3+)þco-doping are reported.The nominal compositions Ca_(1-2x)(Na,Sm)_(x)Bi_(2)Nb_(2)O_(9)(x=0,0.01,0.025,and 0.05)ceramics have been prepared via the conventional solid state method.An optimum composition of Ca_(0.95)(Na,Sm)_(0.025)Bi_(2)Nb_(2)O_(9) is obtained,which possesses a high Curie point of~949℃,a piezoelectric coefficient of~12.8 pC/N,and a DC electrical resistivity at 500℃ of~4×10^(7)Ω⋅cm.The improved d33 is probably ascribed to the reduction in domain size and the increase in domain wall density caused by the reduced grain size.More importantly,after annealing at 900℃ for 2 h,the piezoelectric coefficient still maintains about 90%of the initial d33 value,which displays a significant improvement compared to pure CaBi_(2)Nb_(2)O_(9) ceramic with only 44%of the initial d33 value.This work exhibits a feasible approach to simultaneously obtain high piezoelectric property and thermal stability in CaBi_(2)Nb_(2)O_(9) ceramics by Naþ/Sm^(3+)þco-doping.展开更多
In this work,the medium internal phase O/W Pickering emulsions stabilized with bamboo shoots nanocellulose(BSNC)was successfully fabricated.The nanocellulose extracted from bamboo shoots with an average width of 56.37...In this work,the medium internal phase O/W Pickering emulsions stabilized with bamboo shoots nanocellulose(BSNC)was successfully fabricated.The nanocellulose extracted from bamboo shoots with an average width of 56.37 nm and height of 7.44 nm showed great potential as an emulsifier in the Pickering emulsions.The effects of BSNC content,oil-water ratio and emulsification process on the structure,stability and rheology of the resultant Pickering emulsions was explored.The obtained emulsion with the BSNC content of 0.5 wt%at the oil to water volume ratio of 5:5 had a lower particle size of around 25μm.With the increasing BSNC content,the emulsions presented increased droplet size,and even demulsification occurred.Interestingly,the physicochemical properties of the emulsions could be significantly improved through twice shearing,which effectively reduced droplet size.The surface coverage was above 100%for the Pickering emulsions stabilized with the BSNC content of 0.5%-1.1%.With the increasing BSNC content,the apparent viscosity was increased first and then decreased,and all emulsions showed elastic behaviors.This work would provide theoretical guidance for preparing medium or high internal phase Pickering emulsions stabilized with nanocellulose.展开更多
基金supported by the National Key R&D Program of China(Grant No.2021YFB2012100)National Natural Science Foundation of China(Grant No.U19A2087)+1 种基金the Special Funding Support for the Construction of Innovative Provinces in Hunan Province of China(Grant No.2020GK2062)the Fundamental Research Funds for the Central Universities of Central South University,and the State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.Xuefan Zhou(Postdoc)is particularly grateful for the support from the China National Postdoctoral Program for Innovative Talents(Grant No.BX2021377).
文摘Calcium bismuth niobate(CaBi_(2)Nb_(2)O_(9))is regarded as one of the most potential high-temperature piezoelectric materials owing to its highest Curie point in bismuth layer-structured ferroelectrics.Nevertheless,low piezoelectric coefficient and low resistivity at high temperature considerably restrict its development as key electronic components.Herein,markedly improved piezoelectric properties and DC resistivity of CaBi_(2)Nb_(2)O_(9) ceramics through Naþand Sm^(3+)þco-doping are reported.The nominal compositions Ca_(1-2x)(Na,Sm)_(x)Bi_(2)Nb_(2)O_(9)(x=0,0.01,0.025,and 0.05)ceramics have been prepared via the conventional solid state method.An optimum composition of Ca_(0.95)(Na,Sm)_(0.025)Bi_(2)Nb_(2)O_(9) is obtained,which possesses a high Curie point of~949℃,a piezoelectric coefficient of~12.8 pC/N,and a DC electrical resistivity at 500℃ of~4×10^(7)Ω⋅cm.The improved d33 is probably ascribed to the reduction in domain size and the increase in domain wall density caused by the reduced grain size.More importantly,after annealing at 900℃ for 2 h,the piezoelectric coefficient still maintains about 90%of the initial d33 value,which displays a significant improvement compared to pure CaBi_(2)Nb_(2)O_(9) ceramic with only 44%of the initial d33 value.This work exhibits a feasible approach to simultaneously obtain high piezoelectric property and thermal stability in CaBi_(2)Nb_(2)O_(9) ceramics by Naþ/Sm^(3+)þco-doping.
基金This work was supported by the National Nature Science Foundation of China(32072177).
文摘In this work,the medium internal phase O/W Pickering emulsions stabilized with bamboo shoots nanocellulose(BSNC)was successfully fabricated.The nanocellulose extracted from bamboo shoots with an average width of 56.37 nm and height of 7.44 nm showed great potential as an emulsifier in the Pickering emulsions.The effects of BSNC content,oil-water ratio and emulsification process on the structure,stability and rheology of the resultant Pickering emulsions was explored.The obtained emulsion with the BSNC content of 0.5 wt%at the oil to water volume ratio of 5:5 had a lower particle size of around 25μm.With the increasing BSNC content,the emulsions presented increased droplet size,and even demulsification occurred.Interestingly,the physicochemical properties of the emulsions could be significantly improved through twice shearing,which effectively reduced droplet size.The surface coverage was above 100%for the Pickering emulsions stabilized with the BSNC content of 0.5%-1.1%.With the increasing BSNC content,the apparent viscosity was increased first and then decreased,and all emulsions showed elastic behaviors.This work would provide theoretical guidance for preparing medium or high internal phase Pickering emulsions stabilized with nanocellulose.
