Co^(2+)离子掺杂含量对Li_(1.3+x)Al_(0.3-x)Co_(x)Ti_(1.7)(PO_(4))_(3)陶瓷导电和吸波性能的影响

Effects of Co^(2+) ion doping content on conductivities and microwave absorption properties of Li_(1.3+x)Al_(0.3-x)Co_(x)Ti_(1.7)(PO_(4))_(3) ceramics

采用高温固相法制备Li_(1.3+x)Al_(0.3-x)Co_(x)Ti_(1.7)(PO_(4))_(3)(x=0、0.04、0.08、0.12)陶瓷,研究Co2+离子含量对其微观形貌、物相成分、导电性能、介电性能和吸波性能的影响规律。结果表明:Li_(1.3+x)Al_(0.3-x)Co_(x)Ti_(1.7)(PO_(4))_(3)陶瓷晶粒为立方状,相对密度均在90%以上,物相呈菱方LiTi2(PO4)3相,无杂质产生。Li_(1.34)Al_(0.26)Co_(0.04)Ti_(1.7)(PO_(4))_(3)陶瓷具有最高的离子电导率1.14×10^(-3)S·cm^(-1),低价掺杂能够降低Li~+离子与骨架离子间的束缚力,适量掺杂能够获得合适的Li~+离子通道尺寸,从而使得Li~+离子具有最小活化能0.29 eV,易产生热离子松弛极化,也就同时具有了最高的复介电常数,ε’为12.9~13.7,ε’’为3.1~3.8;基于极化损耗和电导损耗的共同作用,Li_(1.34)Al_(0.26)Co_(0.04)Ti_(1.7)(PO_(4))_(3)陶瓷具有较优的吸波性能,吸收带宽可覆盖整个X 波段,最小反射率在9.67 GHz达到-17.3 dB,有望成为一种高温轻质吸波材料。

Li_(1.3+x)Al_(0.3-x)Co_(x)Ti_(1.7)(PO_(4))_(3)(x=0,0.04,0.08,0.12) ceramics were prepared by high temperature solid-state method.The effects of Co2+ ion doping content on the morphology,phase,ion conductivity,dielectric property and microwave absorption property were studied.Results show that Li_(1.3+x)Al_(0.3-x)Co_(x)Ti_(1.7)(PO_(4))_(3) ceramics had cubic grains with relative densities of 90%,and they are single rhombohedral LiTi2(PO4)3 phase without any impurity.Li_(1.34)Al_(0.26)Co_(0.04)Ti_(1.7)(PO_(4))_(3) ceramic has the highest ionic conductivity of 1.14×10^(-3) S·cm^(-1).A lower valent cation occupying the Ti(Al) site can reduce the coulombic repulsion between Li^(+)ions and skeleton ions,and appropriate doping content can obtain suitable size of Li^(+) ions channel.Then,Li^(+) ion has a minimum activation energy of 0.29 eV,which is easy to generate thermal ion relaxation polarization.Therefore,Li_(1.34)Al_(0.26)Co_(0.04)Ti_(1.7)(PO_(4))_(3)ceramic also has the highest complex permittivity,ε’ is 12.9-13.7 and ε" is 3.1-3.8.In addition,due to the combined effect of polarization loss and conductance loss,it has the optimum microwave absorption property of an absorption bandwidth covering the whole X-band and a minimum reflection loss of-17.3 dB at 9.67 GHz,which is a potential candidate of high-temperature lightweight microwave absorption material.