LaF3 superfine powder was synthesized from La（CH3COO）3 and NH4F by micro wave heating method,using ethanol or pure water as dispersants respectively. Th e results of XRD and SEM indicate that the superfine powder ha...LaF3 superfine powder was synthesized from La（CH3COO）3 and NH4F by micro wave heating method,using ethanol or pure water as dispersants respectively. Th e results of XRD and SEM indicate that the superfine powder has high purity,reg ular particle shape and narrow distribution of granularity. The granularity of t he best sample is in the range of 100200 nm.The influence of different dispersants on the crystal degree and microstructure was discussed. After the su perfine powder was formed into a slice at pressure of 2560 MPa,its ele ctrochemical impedance spectroscopy was tested by electrochemical impedance spec troscopy（EIS） measurement. The result shows that the grain refining of LaF3 po wder increases its ionic conductivity. Compared with traditional preparation met hods of LaF3 powder,the advantages of microwave heating method were summarize d.展开更多
Methanol is one of the characteristic gases that distinguish between healthy individuals and lung cancer(LC)lesions in exhaled human breath.Its concentration in exhaled breath is generally below one part per million(1...Methanol is one of the characteristic gases that distinguish between healthy individuals and lung cancer(LC)lesions in exhaled human breath.Its concentration in exhaled breath is generally below one part per million(1×10^(-6)).The second-phase composite is widely regarded as one of the methods to improve the gas-sensing perfor-mance of metal oxide semiconductor(MOS)materials.In this study,LaF_(3)-Co_(3)O_(4) was synthesized by a simple hydrothermal method to enhance its low-concentration methanol gas-sensing performance.5 at%LaF_(3)-Co_(3)O_(4) nanorods exhibited excellent methanol detection performance,including a wider linear detection concentration range(0.2×10^(-6)~5×10^(-6)),a response value exceeding 4.0 for 1×10^(-6)methanol at 275°C and 75%relative humidity(RH),long-term stability(maximum deviation within 15%over 2 weeks),and excellent selectivity.The mechanism of performance enhancement was studied using various techniques,and density functional theory.The special spinel structure of Co_(3)O_(4),the high ionic migration of F-in LaF_(3),the larger specific surface area of 5 at%LaF_(3)-Co_(3)O_(4) nanorods,and the generated crystal defects all explain the excellentmethanol gas-sensing property.This work provides a novel route to prepare MOS composite materials for low-concentration methanol gas detection.展开更多
文摘LaF3 superfine powder was synthesized from La（CH3COO）3 and NH4F by micro wave heating method,using ethanol or pure water as dispersants respectively. Th e results of XRD and SEM indicate that the superfine powder has high purity,reg ular particle shape and narrow distribution of granularity. The granularity of t he best sample is in the range of 100200 nm.The influence of different dispersants on the crystal degree and microstructure was discussed. After the su perfine powder was formed into a slice at pressure of 2560 MPa,its ele ctrochemical impedance spectroscopy was tested by electrochemical impedance spec troscopy（EIS） measurement. The result shows that the grain refining of LaF3 po wder increases its ionic conductivity. Compared with traditional preparation met hods of LaF3 powder,the advantages of microwave heating method were summarize d.
基金financially supported by the Outstanding Youth Foundation of Jiangsu Province of China(No.BK20211548)Yangzhou City-Yangzhou University Cooperation Foundation(No.YZ2021153)。
文摘Methanol is one of the characteristic gases that distinguish between healthy individuals and lung cancer(LC)lesions in exhaled human breath.Its concentration in exhaled breath is generally below one part per million(1×10^(-6)).The second-phase composite is widely regarded as one of the methods to improve the gas-sensing perfor-mance of metal oxide semiconductor(MOS)materials.In this study,LaF_(3)-Co_(3)O_(4) was synthesized by a simple hydrothermal method to enhance its low-concentration methanol gas-sensing performance.5 at%LaF_(3)-Co_(3)O_(4) nanorods exhibited excellent methanol detection performance,including a wider linear detection concentration range(0.2×10^(-6)~5×10^(-6)),a response value exceeding 4.0 for 1×10^(-6)methanol at 275°C and 75%relative humidity(RH),long-term stability(maximum deviation within 15%over 2 weeks),and excellent selectivity.The mechanism of performance enhancement was studied using various techniques,and density functional theory.The special spinel structure of Co_(3)O_(4),the high ionic migration of F-in LaF_(3),the larger specific surface area of 5 at%LaF_(3)-Co_(3)O_(4) nanorods,and the generated crystal defects all explain the excellentmethanol gas-sensing property.This work provides a novel route to prepare MOS composite materials for low-concentration methanol gas detection.
