论文标题
概念证明的热电氧气传感器利用GDBACO2O5+δ的氧迁移率
Proof-of-concept thermoelectric oxygen sensor exploiting oxygen mobility of GdBaCo2O5+δ
论文作者
论文摘要
在本文中，我们使用polycrystalline $ GDBACO_2O__ {5+δ} $，其中0.45 <$δ$δ$ <0.55（GDCO），基于热电学原理演示了概念证明的氧气传感器。分层双钙钛矿氧化物中的晶格氧高度易受环境氧部分压。在环境条件下处理的ASSsynthesized GDCO样品显示纯正原骨（$ p_ {mmm} $ space group）和$δ$ - 值接近0.5，如X射线衍射retveld改进所证实。 X射线光电子光谱显示出明显的$ co^{3+} $氧化状态，除了$ co^{3+} $和$ co^{4+} $之外，在八面体站点中。如在电阻率和Seebeck系数测量中所见，在接近340 K处观察到绝缘体到金属过渡（MIT）。当气体氛围从100％的氧气变为100％氮，反之亦然，在室温下（300 K），塞贝克系数显示出大约10-13美元的$ $ v/k，时间常数约为20秒（300 K），在恒定的温度梯度下，较大的氧气响应在1 k的恒定温度下。氧气扩散到导致孔掺杂的晶格中显示载体浓度发生了巨大变化，从而导致塞贝克系数在绝缘状态下发生了巨大变化。另一方面，由于金属状态已经很大的载体浓度的增加，Seebeck的变化很小。但是，在MIT下方，响应在化学计量计$δ$ = 0.5 $ \ pm $ 0.05中相当可重复。该原理应具有设计在室温甚至低温温度下工作的氧气传感器的重要效用。
In this paper, we demonstrate a proof-of-concept oxygen sensor based on the thermoelectric principle using polycrystalline $GdBaCo_2O_{5+δ}$ where 0.45<$δ$<0.55 (GDCO). The lattice oxygen in layered double perovskite oxides is highly susceptible to the ambient oxygen partial pressure. The as-synthesized GDCO sample processed in ambient conditions shows pure orthorhombic ($P_{mmm}$ space group) phase and a $δ$-value close to 0.5 as confirmed from X-ray diffraction reitveld refinement. The X-ray photoelectron spectroscopy shows significant $Co^{3+}$ oxidation state in non-octahedral sites in addition to $Co^{3+}$ and $Co^{4+}$ in octahedral sites. The insulator-to-metal transition (MIT) is observed at nearly 340 K as seen in electrical resistivity and seebeck coefficient measurements. The seebeck coefficient shows a large change of about 10-13 $μ$V/K with time constant of ~20 sec, at room temperature (300 K) when the gas ambience changes from 100% oxygen to 100% nitrogen and vice versa, under a constant temperature gradient of 1 K. The response in seebeck is found to be particularly large below MIT. The diffusion of oxygen into the lattice leading to hole doping shows a large change in carrier concentration resulting in a large change in the seebeck coefficient in insulating state. On the other hand, due to insignificant increase in already large carrier concentration in metallic state the change in seebeck is minimal. Nevertheless, below MIT the response is fairly reproducible within stoichiometry $δ$ = 0.5 $\pm$ 0.05. This principle shall be of significant utility to design the oxygen sensors which work at room temperature or even cryogenic temperatures.
