The microwave-absorbing behavior o f substituted M-type barium ferrite nano-particles was investigated.T he nano-particles were synthesized wi th coprecipitation-melted salt method.For the purpose of comparison,c orre...The microwave-absorbing behavior o f substituted M-type barium ferrite nano-particles was investigated.T he nano-particles were synthesized wi th coprecipitation-melted salt method.For the purpose of comparison,c orre-sponding micro-particles were also prepared through direct coprecipitation and sintering.XRD and TEM of th e nano-particles showed that the ferr ite was hexagonal in structure and wi dely distributed in size with partic le size being less than 100nm,the complex permittivity and permeability of a 1.50mm thick specimen and a 1.40mm thick specimen containing 60%by weight of substituted M-type barium ferrite n ano-particles and micro-particles were measured respectively in X band(8.2～12.4GHz )range,from which the reflection loss(R.L.)of microwaves was calculated and two comparative abso rption curves were given.The results showed that the synthetic nano-particles could well absorb microwaves in X ban d.The absorption was larger than 10dB in the range of 9.2～12.4GHz while the maximum absorption was 38.6dB at10.6GHz.展开更多
通过溶胶凝胶法制备钙钛矿结构的La_(1-x)Ba_xMnO_3(0≤x≤0.5),利用X射线衍射、四探针电阻测量仪、红外发射率测试仪、矢量网络分析仪分别研究Ba^(2+)掺杂对镧锰氧化物晶体结构、电阻率、红外发射率和微波吸收性能的影响。研究结果表明...通过溶胶凝胶法制备钙钛矿结构的La_(1-x)Ba_xMnO_3(0≤x≤0.5),利用X射线衍射、四探针电阻测量仪、红外发射率测试仪、矢量网络分析仪分别研究Ba^(2+)掺杂对镧锰氧化物晶体结构、电阻率、红外发射率和微波吸收性能的影响。研究结果表明:当Ba^(2+)掺杂浓度比较低时,掺杂的元素几乎不改变镧锰氧化物的晶体结构;当掺杂浓度增加时,晶格畸变开始增大;样品红外发射率随Ba^(2+)离子掺杂浓度的增大先降低后缓慢增加,与电阻率的变化保持一致;Ba^(2+)离子可以对样品在2~18 GHz微波吸收性能进行调控,当掺杂浓度x=0.3时,样品的吸收效果最佳;在频率为10.8 GHz时,最低反射率为-32 d B;掺杂合适元素的镧锰氧化物材料有可能应用在红外/雷达兼容隐身领域。展开更多
The preparation and microwave absorbing behavior of micrometric silica modified platelet iron particles (SMPLIP) were investigated. Through precipitation, hydrothermal reaction, silica modification and reduction with ...The preparation and microwave absorbing behavior of micrometric silica modified platelet iron particles (SMPLIP) were investigated. Through precipitation, hydrothermal reaction, silica modification and reduction with hydrogen, micrometric porous SMPLIP were yielded. The permittivity values of SMPLIP had been significantly decreased due to the presence of silica. Measurements and calculations showed that a 1.93mm thick sample containing SMPLIP as much as 60%by weight was capable of absorbing X band(8.2～12.4GHz) microwaves with reflection loss being greater than -10dB within the frequency range of 8.2～11.36GHz, while the maximum reflection loss was -14.8dB at 9.4GHz. The results had also shown that it was practicable to prepare thin, light weight microwave absorbent with SMPLIP.展开更多
以[Cu(tu)]Cl·1/2H2O纳米线作为自牺牲模板在室温下成功制备出形貌良好、纯度高的多孔硫化铜纳米管(PCSNTs)(硫脲=Tu)。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能谱仪(E...以[Cu(tu)]Cl·1/2H2O纳米线作为自牺牲模板在室温下成功制备出形貌良好、纯度高的多孔硫化铜纳米管(PCSNTs)(硫脲=Tu)。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能谱仪(EDS)和矢量网络分析仪(VNA)对样品的晶体成分和晶相结构、化学元素价态、微观形貌、元素种类和电磁参数进行分析测定。根据传输线理论,计算样品的反射损耗RL;同时,对PCSNTs/石蜡复合物的微波吸收机理和PCSNTs的形成原理进行分析讨论。结果表明,PCSNTs/石蜡复合物在厚度为2.2 mm时,表现出极强的微波吸收能力(在15.67 GHz时,RL=-45.02 d B),有效吸收(RL﹤-10 d B)频宽为4.75 GHz(13.25 GHz^18.00 GHz)。本制备方法简便快捷,产品纯度高、形貌均一,可用于工业化生产。自牺牲模板法是一种制备中空纳米结构的策略。展开更多
文摘The microwave-absorbing behavior o f substituted M-type barium ferrite nano-particles was investigated.T he nano-particles were synthesized wi th coprecipitation-melted salt method.For the purpose of comparison,c orre-sponding micro-particles were also prepared through direct coprecipitation and sintering.XRD and TEM of th e nano-particles showed that the ferr ite was hexagonal in structure and wi dely distributed in size with partic le size being less than 100nm,the complex permittivity and permeability of a 1.50mm thick specimen and a 1.40mm thick specimen containing 60%by weight of substituted M-type barium ferrite n ano-particles and micro-particles were measured respectively in X band(8.2～12.4GHz )range,from which the reflection loss(R.L.)of microwaves was calculated and two comparative abso rption curves were given.The results showed that the synthetic nano-particles could well absorb microwaves in X ban d.The absorption was larger than 10dB in the range of 9.2～12.4GHz while the maximum absorption was 38.6dB at10.6GHz.
文摘通过溶胶凝胶法制备钙钛矿结构的La_(1-x)Ba_xMnO_3(0≤x≤0.5),利用X射线衍射、四探针电阻测量仪、红外发射率测试仪、矢量网络分析仪分别研究Ba^(2+)掺杂对镧锰氧化物晶体结构、电阻率、红外发射率和微波吸收性能的影响。研究结果表明:当Ba^(2+)掺杂浓度比较低时,掺杂的元素几乎不改变镧锰氧化物的晶体结构;当掺杂浓度增加时,晶格畸变开始增大;样品红外发射率随Ba^(2+)离子掺杂浓度的增大先降低后缓慢增加,与电阻率的变化保持一致;Ba^(2+)离子可以对样品在2~18 GHz微波吸收性能进行调控,当掺杂浓度x=0.3时,样品的吸收效果最佳;在频率为10.8 GHz时,最低反射率为-32 d B;掺杂合适元素的镧锰氧化物材料有可能应用在红外/雷达兼容隐身领域。
文摘The preparation and microwave absorbing behavior of micrometric silica modified platelet iron particles (SMPLIP) were investigated. Through precipitation, hydrothermal reaction, silica modification and reduction with hydrogen, micrometric porous SMPLIP were yielded. The permittivity values of SMPLIP had been significantly decreased due to the presence of silica. Measurements and calculations showed that a 1.93mm thick sample containing SMPLIP as much as 60%by weight was capable of absorbing X band(8.2～12.4GHz) microwaves with reflection loss being greater than -10dB within the frequency range of 8.2～11.36GHz, while the maximum reflection loss was -14.8dB at 9.4GHz. The results had also shown that it was practicable to prepare thin, light weight microwave absorbent with SMPLIP.
基金National Science Foundation of China(11364005,11174132)Foundation of the National Key Project for Basic Research(2010CB923402,2011CB922102)+1 种基金International Cooperation Project of Guizhou Province(2012-7002)National Science Foundation of Guizhou Province(2014-2059)
文摘以[Cu(tu)]Cl·1/2H2O纳米线作为自牺牲模板在室温下成功制备出形貌良好、纯度高的多孔硫化铜纳米管(PCSNTs)(硫脲=Tu)。利用X射线衍射仪(XRD)、X射线光电子能谱仪(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线能谱仪(EDS)和矢量网络分析仪(VNA)对样品的晶体成分和晶相结构、化学元素价态、微观形貌、元素种类和电磁参数进行分析测定。根据传输线理论,计算样品的反射损耗RL;同时,对PCSNTs/石蜡复合物的微波吸收机理和PCSNTs的形成原理进行分析讨论。结果表明,PCSNTs/石蜡复合物在厚度为2.2 mm时,表现出极强的微波吸收能力(在15.67 GHz时,RL=-45.02 d B),有效吸收(RL﹤-10 d B)频宽为4.75 GHz(13.25 GHz^18.00 GHz)。本制备方法简便快捷,产品纯度高、形貌均一,可用于工业化生产。自牺牲模板法是一种制备中空纳米结构的策略。
