陶瓷先驱体Polyvinylsilazane-b-Polystyrene的合成及纳米陶瓷颗粒的制备

以DTBA为链转移剂,VSZ和苯乙烯为单体,通过可逆加成断裂链转移(RAFT)聚合合成了嵌段共聚物陶瓷先驱体Polyvinylsilazane-b-Polystyrene(PVSZ-b-PS)。利用DLS、TEM、AFM等技术,考察了PVSZ-b-PS在选择性溶剂DMF中自组装成胶束的行为。结果表明,胶束为核-壳结构的球形,其中PVSZ为核、PS为壳,胶束直径70～110nm。PVSZ-b-PS胶束制成的聚合物膜能完整保留胶束的球形特征,800℃热解能制得直径为30～40 nm的纳米陶瓷颗粒。XRD结果表明陶瓷颗粒是SiC结晶相

Preparation and dielectric properties of different microstructured SiCNO ceramic

以双亲性嵌段共聚物F127(PEO106-PPO70-PEO106)为模板剂,聚乙烯基硅氮烷(PVSZ)为前驱体,采用软模板法和无压烧结工艺制备出不同微结构SiCNO陶瓷。利用扫描电镜、电子探针、X射线衍射仪、动态光散射、热重分析和阻抗分析仪等手段表征SiCNO陶瓷,并分析了不同形貌结构对陶瓷介电损耗特性的影响。结果表明,通过精确控制蒸发温度可制备出棒状、十字架状、球形和卵形结构SiCNO陶瓷;SiCNO陶瓷介电损耗与形貌结构密切相关,介电损耗值随着蒸发温度升高呈先增大后降低的趋势,当陶瓷微观结构为十字架结构时,介电损耗达到最高值为0.24;当陶瓷微观结构为卵形结构时,介电损耗最低值为0.03。The different microstructured SiCNO ceramics were prepared by using amphiphilic block copolymer F127(PEO106-PPO70-PEO106)as template agent and polyvinysilazane(PVSZ)as the precursors.The morphology and structure properties of the SiCNO ceramics were characterized by scanning electron microscopy,electron probe,X-ray diffraction,dynamic light scattering,thermogravimetric analysis and impedance analyzer.The results show that the SiCNO ceramics with rod like,cross shaped,spherical and oval structures were prepared by controlling the evaporation temperature.Furthermore,the influence of different microstructured SiCNO ceramic dielectric loss characteristics were studied,the dielectric loss of the lowest and highest values were 0.03and0.24,corresponding to the oval structure and the cross structure.国家自然科学基金资助项目(51675452,51302235);; 福建省高等学校新世纪优秀人才支持计划资助项目(2013);; 福建省科技创新平台建设计划资助项目(2014H2006

JUNO Sensitivity on Proton Decay p→νˉK+p\to \bar\nu K^+ Searches

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this paper, the potential on searching for proton decay in $p\to \bar\nu K^+$ mode with JUNO is investigated.The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits to suppress the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar\nu K^+$ is 36.9% with a background level of 0.2 events after 10 years of data taking. The estimated sensitivity based on 200 kton-years exposure is $9.6 \times 10^{33}$ years, competitive with the current best limits on the proton lifetime in this channel

JUNO sensitivity on proton decay p → ν K + searches*

The Jiangmen Underground Neutrino Observatory (JUNO) is a large liquid scintillator detector designed to explore many topics in fundamental physics. In this study, the potential of searching for proton decay in the $p\to \bar{\nu} K^+$ mode with JUNO is investigated. The kaon and its decay particles feature a clear three-fold coincidence signature that results in a high efficiency for identification. Moreover, the excellent energy resolution of JUNO permits suppression of the sizable background caused by other delayed signals. Based on these advantages, the detection efficiency for the proton decay via $p\to \bar{\nu} K^+$ is 36.9% ± 4.9% with a background level of $0.2\pm 0.05({\rm syst})\pm$$0.2({\rm stat})$ events after 10 years of data collection. The estimated sensitivity based on 200 kton-years of exposure is $9.6 \times 10^{33}$ years, which is competitive with the current best limits on the proton lifetime in this channel and complements the use of different detection technologies