The electronic and crystal structural properties of Bi-doped Sr3Ti2O7 are studied using the first principles density functional theory（DFT）based on pseudopotentials basis and plane-wave method.Our results show that ...The electronic and crystal structural properties of Bi-doped Sr3Ti2O7 are studied using the first principles density functional theory（DFT）based on pseudopotentials basis and plane-wave method.Our results show that the formation energy of Bi doping in Site-1 and Site-2 of Sr3Ti2O7 increases with increasing doping concentration.And at the same doping concentration,the formation energy of Bi doping in Site-2 is lower than that in Site-1.The undoped Sr3Ti2O7is found to be an insulator and its Fermi level stays at the top of the valence band.While the Fermi level of the Bi-doped Sr3Ti2O7moves into the bottom of conduction band,the system undergoes an insulator-to-metal phase transition.Furthermore,our calculation results demonstrated that the Fermi level of the Bi-doped Sr3Ti2O7goes deeper into the bottom of conduction band with increasing doping concentration.展开更多
钇铁石榴石(yttrium iron garnet,YIG)的自旋输运特性一直是自旋电子学的研究重点之一.Bi作为YIG最常见的掺杂元素,其薄膜Bi_(x)Y_(3-x)Fe_(5)O_(12)的磁光特性已经被广泛研究.但Bi^(3+)取代Y^(3+)对YIG自旋输运的影响规律还没有被系统...钇铁石榴石(yttrium iron garnet,YIG)的自旋输运特性一直是自旋电子学的研究重点之一.Bi作为YIG最常见的掺杂元素,其薄膜Bi_(x)Y_(3-x)Fe_(5)O_(12)的磁光特性已经被广泛研究.但Bi^(3+)取代Y^(3+)对YIG自旋输运的影响规律还没有被系统地研究过.本文利用溶液旋涂法制备了不同掺杂比的Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜,并研究Bi掺杂对YIG薄膜形貌结构和自旋输运性能的影响.结果表明Bi掺杂没有改变YIG的晶体结构,掺杂比上升令薄膜的吸收强度增大,带隙减小.XPS表明了Bi^(3+)和Bi^(2+)的存在.Bi掺杂在自旋输运上的调控体现在Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜的磁振子扩散长度相比纯YIG薄膜有所减小.同时研究发现Pt/Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜中依然可以检测到明显的自旋霍尔磁电阻,并在x=0.3时振幅最大.展开更多
Sr Ti O3属于ABO3型钙钛矿结构,具有良好的固溶能力,通过掺加杂质元素改善其性能。本研究利用固态法制备Sr_(1-1.5x)Bi_xTiO_3陶瓷(x=0.00、0.01、0.04、0.07、0.10),并探讨了Bi掺杂对其结构与介电常数的影响。研究结果表明:Bi掺杂量x≥...Sr Ti O3属于ABO3型钙钛矿结构,具有良好的固溶能力,通过掺加杂质元素改善其性能。本研究利用固态法制备Sr_(1-1.5x)Bi_xTiO_3陶瓷(x=0.00、0.01、0.04、0.07、0.10),并探讨了Bi掺杂对其结构与介电常数的影响。研究结果表明:Bi掺杂量x≥0.04时陶瓷的晶体结构是以立方晶与四方晶两相共存的形式存在,而Bi2+在Sr Ti O3结构中的固溶极限为x≤0.01,当x=0.04时陶瓷的最大介电常数约为1 200,相变温度则随x增加而逐渐向高温度方向偏移。展开更多
基金supported by the National Natural Science Foundation of China (NSFC) (Grant Nos.51575452,51475378 and 51474176)the Fundamental Research Funds for the Central Universities (No.3102015ZY025)+2 种基金the Research Fund of the State Key Laboratory of Solidification Processing,Northwestern Polytechnic University (Grant No.161-QP-2016)NSFC-Guangdong mutual funds (phase ii) supercomputing science and applied research under special fundingNational supercomputing center in Guangzhou
文摘The electronic and crystal structural properties of Bi-doped Sr3Ti2O7 are studied using the first principles density functional theory（DFT）based on pseudopotentials basis and plane-wave method.Our results show that the formation energy of Bi doping in Site-1 and Site-2 of Sr3Ti2O7 increases with increasing doping concentration.And at the same doping concentration,the formation energy of Bi doping in Site-2 is lower than that in Site-1.The undoped Sr3Ti2O7is found to be an insulator and its Fermi level stays at the top of the valence band.While the Fermi level of the Bi-doped Sr3Ti2O7moves into the bottom of conduction band,the system undergoes an insulator-to-metal phase transition.Furthermore,our calculation results demonstrated that the Fermi level of the Bi-doped Sr3Ti2O7goes deeper into the bottom of conduction band with increasing doping concentration.
文摘钇铁石榴石(yttrium iron garnet,YIG)的自旋输运特性一直是自旋电子学的研究重点之一.Bi作为YIG最常见的掺杂元素,其薄膜Bi_(x)Y_(3-x)Fe_(5)O_(12)的磁光特性已经被广泛研究.但Bi^(3+)取代Y^(3+)对YIG自旋输运的影响规律还没有被系统地研究过.本文利用溶液旋涂法制备了不同掺杂比的Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜,并研究Bi掺杂对YIG薄膜形貌结构和自旋输运性能的影响.结果表明Bi掺杂没有改变YIG的晶体结构,掺杂比上升令薄膜的吸收强度增大,带隙减小.XPS表明了Bi^(3+)和Bi^(2+)的存在.Bi掺杂在自旋输运上的调控体现在Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜的磁振子扩散长度相比纯YIG薄膜有所减小.同时研究发现Pt/Bi_(x)Y_(3-x)Fe_(5)O_(12)薄膜中依然可以检测到明显的自旋霍尔磁电阻,并在x=0.3时振幅最大.
文摘使用<511>取向Ga As籽晶,在直径2英寸的p BN坩埚中生长了2.5%Bi掺杂的Ga As晶体。能量分散谱仪(EDS)和透过光谱均有Bi相关谱峰的存在,说明Bi原子已掺杂到Ga As晶体中。X射线双摇摆曲线测得半高峰宽值为42″。与未掺杂Ga As晶体相比,所得晶体的禁带宽度出现红移,从1.43 e V移至近1.39 e V。扫面式电子显微镜(SEM)显示晶体中存在少量富Bi包裹物,晶体质量有待进一步改进。
文摘Sr Ti O3属于ABO3型钙钛矿结构,具有良好的固溶能力,通过掺加杂质元素改善其性能。本研究利用固态法制备Sr_(1-1.5x)Bi_xTiO_3陶瓷(x=0.00、0.01、0.04、0.07、0.10),并探讨了Bi掺杂对其结构与介电常数的影响。研究结果表明:Bi掺杂量x≥0.04时陶瓷的晶体结构是以立方晶与四方晶两相共存的形式存在,而Bi2+在Sr Ti O3结构中的固溶极限为x≤0.01,当x=0.04时陶瓷的最大介电常数约为1 200,相变温度则随x增加而逐渐向高温度方向偏移。
