以苯甲醛为原料,在催化剂作用下与乙醛通过羟醛缩合反应生成肉桂醛,探讨了催化剂催化反应的工艺条件,并采用了GC-MS、IR和1H NMR等手段对产物进行表征。实验结果表明:在使用Na2CO3/γ-Al2O3作为催化剂,11.60 g 40%乙醛,n(苯甲醛)∶n(乙...以苯甲醛为原料,在催化剂作用下与乙醛通过羟醛缩合反应生成肉桂醛,探讨了催化剂催化反应的工艺条件,并采用了GC-MS、IR和1H NMR等手段对产物进行表征。实验结果表明:在使用Na2CO3/γ-Al2O3作为催化剂,11.60 g 40%乙醛,n(苯甲醛)∶n(乙醛)为1.3∶1,反应温度30℃、反应时间1 h、催化剂用量1 g,肉桂醛得率可达40.9%。展开更多
Alpha particle radiation detectors with planar double Schottky contacts(DSC)are directly fabricated on 5-μm-thick epitaxial semi-insulating(SI)GaN:Fe film with resistivity higher than 1×10^(8)Ω·cm.Under 10...Alpha particle radiation detectors with planar double Schottky contacts(DSC)are directly fabricated on 5-μm-thick epitaxial semi-insulating(SI)GaN:Fe film with resistivity higher than 1×10^(8)Ω·cm.Under 10 V bias,the detector exhibits a low dark current of less than 5.0×10^(-11) A at room-temperature,which increases at higher temperatures.Linear behavior in the semi-log reverse current-voltage plot suggests that Poole-Frenkel emission is the dominant carrier leakage mechanism at high bias.Distinct double-peak characteristics are observed in the energy spectrum of alpha particles regardless of bias voltage.The energy resolution of the SI-GaN based detector is determined to be8.6%at the deposited energy of 1.209 MeV with a charge collection efficiency of81.7%.At a higher temperature of 90℃,the measured full width at half maximum(FWHM)rises to 235 keV with no shift of energy peak position,which proves that the GaN detector has potential to work stably in high temperature environment.This study provides a possible route to fabricate the low cost GaN-based alpha particle detector with reasonable performance.展开更多
基金Project supported by the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190302 and BK20201253).
文摘Alpha particle radiation detectors with planar double Schottky contacts(DSC)are directly fabricated on 5-μm-thick epitaxial semi-insulating(SI)GaN:Fe film with resistivity higher than 1×10^(8)Ω·cm.Under 10 V bias,the detector exhibits a low dark current of less than 5.0×10^(-11) A at room-temperature,which increases at higher temperatures.Linear behavior in the semi-log reverse current-voltage plot suggests that Poole-Frenkel emission is the dominant carrier leakage mechanism at high bias.Distinct double-peak characteristics are observed in the energy spectrum of alpha particles regardless of bias voltage.The energy resolution of the SI-GaN based detector is determined to be8.6%at the deposited energy of 1.209 MeV with a charge collection efficiency of81.7%.At a higher temperature of 90℃,the measured full width at half maximum(FWHM)rises to 235 keV with no shift of energy peak position,which proves that the GaN detector has potential to work stably in high temperature environment.This study provides a possible route to fabricate the low cost GaN-based alpha particle detector with reasonable performance.
