Doping effect of Nb on ionic polarization of SrTiO3
Doping effect of Nb on ionic polarization of SrTiO3
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DOI：
10.2109/jcersj2.19031
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发表时间：
2019-06-01
影响因子：
1.1
通讯作者：
Hoshina, Takuya
中科院分区：
文献类型：
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作者：
Nishiyama, Junji;Kanehara, Kazuki;Hoshina, Takuya
为了了解Nb掺杂对离子极化的影响，用远红外椭圆偏振光谱仪测量了掺Nb的钛酸锶单晶的THz介电谱。Slate横光(TO)模的频率随着Nb掺杂量的增加而增加，这意味着Nb掺杂降低了离子偏振度。从斯莱特频率到模式频率的变化估计，1%Nb掺杂的钛酸锶的离子极化率比未掺杂的钛酸锶降低了10.4%。这一结果表明，Nb掺杂的钛酸锶的本征介电常数比未掺杂的钛酸锶的本征介电常数低。第一性原理计算表明，Nb4d轨道有助于B位阳离子与O离子之间的共价性，而电子载流子掺杂抑制了共价性。掺杂电子使长程库仑力减小，短程弹性力增大，从而降低了离子的极化率。(C)2019年日本陶瓷学会。版权所有。
THz dielectric spectra of Nb-doped SrTiO3 single crystals were measured using the far-infrared spectroscopic ellipsometer to understand the doping effect of Nb on ionic polarization. The frequency of the Slater transverse optical (TO) mode increased with the doping amount of Nb, meaning the decrease in the ionic polarization by Nb doping. From the change in the Slater TO mode frequency, it was estimated that the ionic polarizability of 1% Nb-doped SrTiO3 was 10.4% lower than that of undoped SrTiO3. This result suggested that the intrinsic permittivity of Nb-doped SrTiO3 is lower than that of that of undoped SrTiO3. First principles calculations revealed that the Nb 4d-orbitals contributes to the covalency between B-site cations and O ions, however, the covalency is suppressed due to the electron carrier doping. The doped electrons causes the decrease in the long-range Coulomb force and the increase in short-range elastic force, and therefore the ionic polarizability is decreased by Nb doping. (C)2019 The Ceramic Society of Japan. All rights reserved.