<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE article  PUBLIC "-//NLM//DTD Journal Publishing DTD v3.0 20080202//EN" "http://dtd.nlm.nih.gov/publishing/3.0/journalpublishing3.dtd"><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" dtd-version="3.0" xml:lang="en" article-type="research article"><front><journal-meta><journal-id journal-id-type="publisher-id">CMP</journal-id><journal-title-group><journal-title>Advances in Condensed Matter Physics</journal-title></journal-title-group><issn pub-type="epub">2326-3512</issn><publisher><publisher-name>Scientific Research Publishing</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.12677/CMP.2023.122004</article-id><article-id pub-id-type="publisher-id">CMP-65510</article-id><article-categories><subj-group subj-group-type="heading"><subject>CMP20230200000_11196446.pdf</subject></subj-group><subj-group subj-group-type="Discipline-v2"><subject>数学与物理</subject></subj-group></article-categories><title-group><article-title>
 
 
  高响应NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>湿度传感器的制备及性能研究
  Study on the Preparation and Performance of NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> Humidity Sensor with High Response
 
</article-title></title-group><contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>米</surname><given-names>彦辉</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>李</surname><given-names>鹏</given-names></name><xref ref-type="aff" rid="aff2"><sup>2</sup></xref><xref ref-type="aff" rid="aff1"><sup>1</sup></xref></contrib></contrib-group><aff id="aff2"><addr-line>新疆大学物理科学与技术学院，新疆 乌鲁木齐</addr-line></aff><aff id="aff1"><addr-line>null</addr-line></aff><pub-date pub-type="epub"><day>16</day><month>05</month><year>2023</year></pub-date><volume>12</volume><issue>02</issue><fpage>24</fpage><lpage>35</lpage><permissions><copyright-statement>&#169; Copyright  2014 by authors and Scientific Research Publishing Inc. </copyright-statement><copyright-year>2014</copyright-year><license><license-p>This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/</license-p></license></permissions><abstract><p>
 
 
  本文采用水热法制备NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>纳米材料，系统地研究了其湿度传感性能。实验结果表明，NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>复合材料比表面积比纯NaTaO
  <sub>3</sub>更大，这使得复合材料表面吸附更多的水分子，增强了
  NaTaO
  <sub>3</sub>
  /
  SnO
  <sub>2</sub>湿度传感器的性能。
  NaTaO
  <sub>3</sub>
  /
  SnO
  <sub>2</sub>复合材料表面氧空位含量明显提升，使其吸附大量水分，促进水分子分解为导电离子，提高NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>湿度传感器的响应和恢复速度。该NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>湿度传感器电阻达到3个数量级，在11%~95%相对湿度范围内具有高响应度(303,959%)、良好的线性度、低的湿滞(1.99%)、长期稳定性和快的响应和恢复时间(分别为15 s和13 s)。通过对NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>湿度传感器的复阻抗谱分析，对其传感机理进行了解释。NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub>复合材料的成功制备也为具有高湿敏性能的NaTaO
  <sub>3</sub>基电阻传感器的设计开辟了新的方向。
   NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> nanomaterials were prepared by hydrothermal method, and their humidity sensing properties were studied systematically in this paper. The experimental results show that the specific surface area of NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> composite is larger than that of pure NaTaO
  <sub>3</sub>, which makes the surface of the composite absorb more water molecules and enhances the response of NaTaO
  <sub>3</sub>/SnO
  <sub>2 </sub>humidity sensor. The oxygen vacancies on the surface of NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> composite material are significantly increased, which makes it absorb a large amount of water, promote the decomposition of water molecules into conductive ions, and improve the response and recovery speed of NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> humidity sensor. The NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> humidity sensor has a resistance of 3 orders of magnitude, high responsiveness (303,959%), good linearity, low hysteresis (1.99%), long-term stability and fast response and recovery time (15 s and 13 s, respectively) in the range of 11%~95% relative humidity. By analyzing the complex impedance spectrum of NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> humidity sensor, the sensing mechanism was explained. The successful prepara-tion of NaTaO
  <sub>3</sub>/SnO
  <sub>2</sub> composites also provides a new direction for the design of high humidity-sensitive NaTaO
  <sub>3</sub>-based resistance sensors.
 
</p></abstract><kwd-group><kwd>NaTaO<sub>3</sub>/SnO<sub>2</sub>，氧空位，高响应度, NaTaO<sub>3</sub>/SnO<sub>2</sub></kwd><kwd> Oxygen Vacancy</kwd><kwd> High Response</kwd></kwd-group></article-meta></front><body><sec id="s1"><title>摘要</title><p>本文采用水热法制备NaTaO<sub>3</sub>/SnO<sub>2</sub>纳米材料，系统地研究了其湿度传感性能。实验结果表明，NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料比表面积比纯NaTaO<sub>3</sub>更大，这使得复合材料表面吸附更多的水分子，增强了NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的性能。NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料表面氧空位含量明显提升，使其吸附大量水分，促进水分子分解为导电离子，提高NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的响应和恢复速度。该NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器电阻达到3个数量级，在11%~95%相对湿度范围内具有高响应度(303,959%)、良好的线性度、低的湿滞(1.99%)、长期稳定性和快的响应和恢复时间(分别为15 s和13 s)。通过对NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的复阻抗谱分析，对其传感机理进行了解释。NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的成功制备也为具有高湿敏性能的NaTaO<sub>3</sub>基电阻传感器的设计开辟了新的方向。</p></sec><sec id="s2"><title>关键词</title><p>NaTaO<sub>3</sub>/SnO<sub>2</sub>，氧空位，高响应度</p></sec><sec id="s3"><title>Study on the Preparation and Performance of NaTaO<sub>3</sub>/SnO<sub>2</sub> Humidity Sensor with High Response<sup> </sup></title><p>Yanhui Mi, Peng Li<sup>*</sup></p><p>School of Physics and Technology, Xinjiang University, Urumqi Xinjiang</p><p>Received: Apr. 6<sup>th</sup>, 2023; accepted: May 11<sup>th</sup>, 2023; published: May 19<sup>th</sup>, 2023</p></sec><sec id="s4"><title>ABSTRACT</title><p>NaTaO<sub>3</sub>/SnO<sub>2</sub> nanomaterials were prepared by hydrothermal method, and their humidity sensing properties were studied systematically in this paper. The experimental results show that the specific surface area of NaTaO<sub>3</sub>/SnO<sub>2</sub> composite is larger than that of pure NaTaO<sub>3</sub>, which makes the surface of the composite absorb more water molecules and enhances the response of NaTaO<sub>3</sub>/SnO<sub>2</sub>humidity sensor. The oxygen vacancies on the surface of NaTaO<sub>3</sub>/SnO<sub>2</sub> composite material are significantly increased, which makes it absorb a large amount of water, promote the decomposition of water molecules into conductive ions, and improve the response and recovery speed of NaTaO<sub>3</sub>/SnO<sub>2</sub> humidity sensor. The NaTaO<sub>3</sub>/SnO<sub>2</sub> humidity sensor has a resistance of 3 orders of magnitude, high responsiveness (303,959%), good linearity, low hysteresis (1.99%), long-term stability and fast response and recovery time (15 s and 13 s, respectively) in the range of 11%~95% relative humidity. By analyzing the complex impedance spectrum of NaTaO<sub>3</sub>/SnO<sub>2 </sub>humidity sensor, the sensing mechanism was explained. The successful preparation of NaTaO<sub>3</sub>/SnO<sub>2</sub> composites also provides a new direction for the design of high humidity-sensitive NaTaO<sub>3</sub>-based resistance sensors.</p><p>Keywords:NaTaO<sub>3</sub>/SnO<sub>2</sub>, Oxygen Vacancy, High Response</p><disp-formula id="hanspub.65510-formula10"><graphic xlink:href="//html.hanspub.org/file/3-2590153x5_hanspub.png?20230522094526716"  xlink:type="simple"/></disp-formula><p>Copyright &#169; 2023 by author(s) and Hans Publishers Inc.</p><p>This work is licensed under the Creative Commons Attribution International License (CC BY 4.0).</p><p>http://creativecommons.org/licenses/by/4.0/</p><p><img src="//html.hanspub.org/file/3-2590153x6_hanspub.png?20230522094526716" /> <img src="//html.hanspub.org/file/3-2590153x7_hanspub.png?20230522094526716" /></p></sec><sec id="s5"><title>1. 引言</title><p>湿度传感不仅应用于大气监测、国防科技和航空航天等行业中，而且在日常生活中还应用于工农业生产、食品加工和粮食蔬菜运输储存等方面。随着社会和科技的发展，人们对湿度传感器也有了更多的要求，进一步需求响应度更高、响应和恢复时间更短、可重复性和稳定性以及选择性更好的湿度传感器。因此，研究开发高性能的湿度传感器是非常必要的。NaTaO<sub>3</sub>不仅具有钙钛矿化合物制备响应快、长期稳定性好的独特优点，也具有与水相互作用的活性位点，且有一定湿敏性能，可以将其应用在湿度传感器中。然而，纯NaTaO<sub>3</sub>湿度传感器的性能受比表面积和氧空隙的影响，存在线性度差、测试范围有限、恢复时间长 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref1">1</xref>] 等缺点。</p><p>为了提高NaTaO<sub>3</sub>湿度传感器的性能，通常采用掺杂和复合的方法。SnO<sub>2</sub>由于其结构简单、容易制备、电化学稳定性好、成本低廉等优点，常被用于制作湿度传感器。NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的形成可以促进产生更大的比表面积，可以吸收更多的水分子，从而提高NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的响应。此外，NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料表面产生了丰富的氧空位缺陷，可以吸附大量水分子，并将水分子分解成导电离子，使复合材料的电导率有明显的提高，进而缩短了NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的响应时间。</p><p>本研究采用水热法制备了NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器。通过对NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的复阻抗谱分析，对其传感机理进行了解释。</p></sec><sec id="s6"><title>2. 实验</title><sec id="s6_1"><title>2.1. 材料制备</title><p>无水乙醇(C<sub>2</sub>H<sub>5</sub>OH)、氢氧化钠(NaOH)购自天津市鑫铂特化工有限公司。五氧化二钽(Ta<sub>2</sub>O<sub>5</sub>)、五水四氯化锡(SnCl<sub>4</sub>&#183;5H<sub>2</sub>O)购自阿拉丁试剂有限公司。化学试剂均为分析级(AR)，无需纯化；此外，实验全部过程均使用去离子水。</p><p>首先，分别将0.002 mol的SnCl<sub>4</sub>∙5H<sub>2</sub>O和Ta<sub>2</sub>O<sub>5</sub>加入含有40 ml无水乙醇溶液的中，磁力搅拌形成白色乳浊液A。在装有20 ml去离子水的烧杯中加入0.1 mol的NaOH，形成透明B溶液。将白色乳浊液A逐滴加入到透明B溶液形成C溶液。将C溶液转移到100特氟龙内衬的不锈钢高压釜中，160℃反应12 h。自然冷却到室温，多次洗涤和离心处理。沉淀物在80℃下干燥8 h，得到白色粉末。最白色粉末在350℃退火3 h，得到最终产物NaTaO<sub>3</sub>/SnO<sub>2</sub>。</p></sec><sec id="s6_2"><title>2.2. 表征</title><p>材料的结晶度和相结构分析所用的仪器是德国布鲁克D8 Advance X-射线衍射谱；形貌结构是由日本日立SU8010扫描电子显微镜测试获得。使用英国克拉托斯Axis Supra X-射线光电子能谱分析表面组成和元素状态。样品的结构使用美国赛默飞世尔Nicolet iS50傅里叶变换红外光谱仪进行了识别。</p></sec><sec id="s6_3"><title>2.3. 湿敏性能测试流程</title><p>首先，将1 ml去离子水和制备的样品分别少量倒入玛瑙研钵中研磨成糊状，涂在Ag-Pd叉指电极表面。然后，将Ag-Pd叉指电极置于80℃的烘箱中6 h，形成湿度传感元件。在24℃的温度下使用德国札纳公司Zennium X工作站进行湿度感应性能测试，测试交流电压设置为1 V。使用LiCl、MgCl<sub>2</sub>、K<sub>2</sub>CO<sub>3</sub>、NaBr、NaCl、KCl和KNO<sub>3</sub>饱和盐溶液分别获得11%、33%、43%、59%、75%、85%和95%的相对湿度(RH)环境。将湿度传感器置于不同的RH环境中进行测试，测试过程如图1所示。将NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器依次放置在11%~95% RH环境中，在每一个相对湿度环境一段时间后电阻达到一个稳定值，然后迅速切换到下一个湿度环境，转换时间小于1 s。</p><p>图1. NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器性能测试过程</p></sec></sec><sec id="s7"><title>3. 讨论</title><sec id="s7_1"><title>3.1. 材料表征与分析</title><p>图2所展示的是NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的X射线衍射谱图(XRD)，我们可以通过XRD来分析每个样品的结晶度和相结构。我们可以清楚地看到图中SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>样品的衍射峰，分别在26.58˚、33.87˚、51.77˚、65.96˚、83.71˚和89.77˚对应于(110)、(101)、(211)、(301)、(222)和(312)的晶格平面，这与正方金红石型SnO<sub>2</sub> (JCPDS, No. 71-0652)晶面一致 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref2">2</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref3">3</xref>] 。NaTaO<sub>3</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>样品的衍射峰，分别在22.9˚、32.46˚、46.64˚、58.11˚和68.25˚对应于(020)、(200)、(202)、(123)和(242)的正交晶型NaTaO<sub>3</sub> (JCPDS, No. 25-0863)吻合 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref4">4</xref>] 。由图2可知，NaTaO<sub>3</sub>/SnO<sub>2</sub>样品衍射峰中含有正交晶型NaTaO<sub>3</sub>和正方金红石型SnO<sub>2</sub>衍射峰。结果表明，NaTaO<sub>3</sub>/SnO<sub>2</sub>样品的相组成为SnO<sub>2</sub>和NaTaO<sub>3</sub>的混合物。图2的NaTaO<sub>3</sub>/SnO<sub>2</sub>样品中NaTaO<sub>3</sub>衍射峰的面积大于SnO<sub>2</sub>衍射峰面积，说明NaTaO<sub>3</sub>含量较多。图2中NaTaO<sub>3</sub>/SnO<sub>2</sub>样品衍射峰较窄且尖锐，说明结晶度好。同时，在XRD分析中未检测到其他杂峰，说明SnO<sub>2</sub>和NaTaO<sub>3</sub>具有化学相容性。</p><p>图2. NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的XRD谱图</p><p>图3. NaTaO<sub>3</sub> (a)与(d)、SnO<sub>2</sub> (b)与(e)和NaTaO<sub>3</sub>/SnO<sub>2</sub> (c)与(f)复合材料的SEM图</p><p>为了解样品的表面形貌。对NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的SEM图像进行分析，进一步表征其表面形貌。从图3(a)和图3(d)中可以看出，NaTaO<sub>3</sub>以300 nm的立方体颗粒形式出现，并且观察到轻微的团聚现象。如图3(b)和图3(e)所示，SnO<sub>2</sub>以不规则的直径为500 nm的扁平花状颗粒形式出现，并且观察到大量团聚现象。从图3(c)和图3(f)中我们可以看到，NaTaO<sub>3</sub>/SnO<sub>2</sub>样品有良好的结晶度，NaTaO<sub>3</sub>附着在SnO<sub>2</sub>表面，并且NaTaO<sub>3</sub>含量多于SnO<sub>2</sub>，这与图2中XRD分析的结果相一致。图3(c)和图3(f)中NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料有粗糙的表面也反映了复合材料比NaTaO<sub>3</sub>具有更大的比表面积；这些属性有助于产生大量的吸附位点，能吸附大量的水子，从而提高了传感器的响应。</p><p>为了解样品材料的化学状态和组成，对样品进行了XPS分析，研究了NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的化学状态和组成。在图4(a)的XPS全谱中可以看出，NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料中含有Ta、O、Na和Sn，进一步验证了复合材料制备是成功的。如图4(b)所示，可以明显看到SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>的Sn 3d峰。在SnO<sub>2</sub>中，Sn 3d<sub>5/2</sub>特征峰处的结合能为486.706 eV，在Sn 3d<sub>3/2</sub>特征峰处的结合能为495.173 eV，在NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料中，Sn 3d<sub>5/2</sub>特征峰处的结合能和Sn 3d<sub>3/2</sub>特征峰处的结合能分别为486.209 eV和494.671 eV。在SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>中，Sn 3d<sub>3/2</sub>与Sn 3d<sub>5/2</sub>特征峰处的结合能之差都为8.46 eV，此结果表明，样品中的Sn是以Sn<sup>4+</sup>的形式存在 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref5">5</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref6">6</xref>] 。在图4(b)中，我们可以清楚地看到在NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料中，Sn 3d峰的位置相对于SnO<sub>2</sub>的Sn 3d峰的位置移动了；并且峰值向结合能低的方向移动，这也表明NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料中Sn的结合能有所降低。</p><p>图4. (a) NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料XPS光谱全谱；(b) NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料和SnO<sub>2</sub>材料的Sn 3d 光谱</p><p>图5. (a) NaTaO<sub>3</sub>材料的Ta 4f光谱；(b) NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的Ta 4f光谱</p><p>图5(a)显示了NaTaO<sub>3</sub>的Ta 4f<sub>7/2</sub>和Ta 4f<sub>5/2</sub>两个特征峰下的结合能分别为25.839 eV和27.720 eV，其能带能差为1.88 eV，表明材料中存在正常的Ta<sup>5+</sup>状态 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref7">7</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref8">8</xref>] 。图5(b)中，NaTaO<sub>3</sub>/SnO<sub>2</sub>的Ta 4f<sub>7/2</sub>和Ta 4f<sub>5/2</sub>的两个特征峰下的结合能分别为25.29 eV和27.05 eV，其能带能差为1.76 eV，虽然能带差发生了细微的减小，但是材料中的Ta仍然是以Ta<sup>5+</sup>的形式存在 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref9">9</xref>] 。</p><p>NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的O 1s光谱如图6所示。O 1s峰，可分为O<sub>1</sub>、O<sub>2</sub>和O<sub>3</sub>峰，其中O<sub>1</sub>代表晶格氧，O<sub>2</sub>代表氧空位，O<sub>3</sub>代表化学吸附解离氧 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref10">10</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref11">11</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref12">12</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref13">13</xref>] 。在图6(a)中，可以清楚地看到NaTaO<sub>3</sub>的三个O 1s峰的结合能分别为529.74 eV、531.18 eV和533.74 eV。SnO<sub>2</sub>的三个O 1s峰的结合能分别为530.546 eV、530.755 eV和531.729 eV，如图6(b)中所示。在图6(c)中，NaTaO<sub>3</sub>/SnO<sub>2</sub>的三个O 1s峰的结合能分别为529.603 eV、530.256 eV和531.581 eV。在表1中，NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料中O<sub>2</sub>的含量分别为18.4%、37.8%和45.52%。NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的O<sub>2</sub>面积明显增大了许多，而且其O<sub>2</sub>的面积和占比远大于NaTaO<sub>3</sub>和SnO<sub>2</sub>中的。众所周知的是，氧空位(O<sub>2</sub>)不仅促进表面水分子的吸附，而且促进水分子的分解 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref14">14</xref>] 。因此，在NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料表面的大量的氧空位不仅能够吸附大量的水分子，还能促进表面水分子分解为导电离子，提高了响应速度，降低了响应恢复时间，从而增强了湿敏传感器的湿敏性能。</p><p>图6. NaTaO<sub>3 </sub>(a)、SnO<sub>2</sub> (b)和NaTaO<sub>3</sub>/SnO<sub>2</sub> (c)复合材料的O 1s光谱</p><table-wrap id="table1" ><label><xref ref-type="table" rid="table1">Table 1</xref></label><caption><title> The respective peak positions and percentages of O1, O2 and O3 in the O 1s spectr</title></caption><table><tbody><thead><tr><th align="center" valign="middle" >样品</th><th align="center" valign="middle" >O的种类</th><th align="center" valign="middle" >结合能(eV)</th><th align="center" valign="middle" >相对百分率(%)</th></tr></thead><tr><td align="center" valign="middle" >NaTaO<sub>3</sub></td><td align="center" valign="middle" >O<sub>2</sub></td><td align="center" valign="middle" >531.18</td><td align="center" valign="middle" >18.4</td></tr><tr><td align="center" valign="middle" >SnO<sub>2</sub></td><td align="center" valign="middle" >O<sub>2</sub></td><td align="center" valign="middle" >530.755</td><td align="center" valign="middle" >37.8</td></tr><tr><td align="center" valign="middle" >NaTaO<sub>3</sub>/SnO<sub>2</sub></td><td align="center" valign="middle" >O<sub>2</sub></td><td align="center" valign="middle" >530.256</td><td align="center" valign="middle" >45.52</td></tr></tbody></table></table-wrap><p>表1. 在O 1s光谱中，O<sub>1</sub>、O<sub>2</sub>和O<sub>3</sub>各自的峰位和百分比</p><p>在图7中，利用FTIR分析了NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的化学键。在NaTaO<sub>3</sub>中，在649.35 cm<sup>−</sup><sup>1</sup>和3357.03 cm<sup>−</sup><sup>1</sup>处有二个峰，分别对应于Ta-O的拉伸振动模式和O-H的拉伸振动模式 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref15">15</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref16">16</xref>] 。图中SnO<sub>2</sub>有三个峰，在625.87 cm<sup>−1</sup>处为Sn-O拉伸振动模式，在1634.82 cm<sup>−1</sup>处为水分子的弯曲振动模式，在3390.11 cm<sup>−1</sup>处也为O-H的拉伸振动模式 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref17">17</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref18">18</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref19">19</xref>] 。然而，由于NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料在350摄氏度条件下退火的原因，导致部分O-H消失。因此，NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料也只有两个明显的峰，在618.64 cm<sup>−1</sup>处的是Ta-O和Sn-O的拉伸振动模式，在3383.74 cm<sup>−1</sup>处的仍然是NaTaO<sub>3</sub>/SnO<sub>2</sub>的拉伸振动模式。O-H为亲水基团，有助于吸收水分子，从而增强了湿敏传感器的性能。在本文中，湿度传感器的湿敏性能主要还是通过氧空位(O<sub>2</sub>)来体现的。</p><p>图7. NaTaO<sub>3</sub>、SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的FTIR光谱</p></sec><sec id="s7_2"><title>3.2. NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的湿敏性能</title><p>图8(a)为在工作频率为100 Hz的条件下，NaTaO<sub>3</sub>、SnO<sub>2</sub>、NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在不同相对湿度下的阻抗变化曲线。在图中，可以看出NaTaO<sub>3</sub>和SnO<sub>2</sub>湿度传感器的阻抗变化是2个多数量级，而NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的阻抗变化提高到了3个数量级。此外，还可以发现NaTaO<sub>3</sub>湿度传感器在11%相对湿度到33%相对湿度之间阻抗几乎没变，这说明NaTaO<sub>3</sub>湿度传感器在低湿度不响应，其线性度很差，而SnO<sub>2</sub>和NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器线性度好。</p><p>NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器不仅阻抗变化大，而且线性度好。因此，NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器优于NaTaO<sub>3</sub>和SnO<sub>2</sub>湿度传感器。响应度计算公式 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref20">20</xref>] 如(1)所示：</p><p>R = R L − R H R H &#215; 100 % (1)</p><p>其中，R<sub>L</sub>是湿度传感器在11%相对湿度环境下的阻抗值，R<sub>H</sub>是95%相对湿度环境下的阻抗值。</p><p>利用响应度公式(1)计算出NaTaO<sub>3</sub>、SnO<sub>2</sub>、NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的响应分别为160,201%、17,378%和303,959%。NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的响应度最大，主要是因为复合材料具有丰富的氧空位(O<sub>2</sub>)，非常有利于吸附水分子并分解水分子，增加了响应度，缩短了响应恢复时间。</p><p>图8(b)研究了不同频率下NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器阻抗随相对湿度的变化而变化。随着相对湿度的增大，传感器阻抗在40 kHz~100 kHz范围内呈下降趋势。NaTaO<sub>3</sub>/SnO<sub>2</sub>传感器在40 Hz和100 Hz时响应度高，然而在40 Hz下，低相对湿度环境中响应不明显并且线性度较差。从1 kHz到100 kHz，NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在较低相对湿度时几乎没有明显的响应，导致整体线性度较差。这种现象主要是由于水分子在高频下不易极化造成的 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref20">20</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref21">21</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref22">22</xref>] 。因此，可以看出NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的最佳工作频率是100 Hz。</p><p>图8(c)是不同相对湿度水平下NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器对水分子的吸附和解吸过程。在RH相同条件下，吸附和解吸的阻抗最大差可定义为滞后。</p><p>湿滞误差公式如(2)所示：</p><p>γ H = Δ H max 2 F F S (2)</p><p>其中，ΔH<sub>max</sub>为阻抗在吸附和解吸过程的最大差值，F<sub>FS</sub>为满量程量输出 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref23">23</xref>] 。</p><p>最大滞后发生在43% RH下，用湿滞误差公式(2)计算得出NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器滞后误差为1.99%。NaTaO<sub>3</sub>/SnO<sub>2</sub>传感器吸附解析过程曲线很相似，说明可逆性好。图8(d)为NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在最佳频率100 Hz条件下的线性拟合响应函数。其函数公式如(3)所示：</p><p>Y = 1.059 &#215; 10 8 e − X / 20.29 − 2.37 &#215; 10 6 (3)</p><p>其中，X为RH，Y为阻抗。</p><p>其回归系数为(R<sup>2</sup> = 0.9817)，这说明NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的线性度还是很不错的。</p><p>图8. (a) NaTaO<sub>3</sub>、SnO<sub>2</sub>、NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在最佳频率100 Hz不同相对湿度环境下的阻抗变化；(b) NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在不同频率下的阻抗随相对湿度的变化；(c) NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的湿滞回线；(d) NaTaO<sub>3</sub>/SnO<sub>2</sub>的线性拟合响应函数</p><p>图9(a)为NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在11%相对湿度和95%相对湿度下连续3个周期的响应和恢复曲线测试。响应或恢复时间定义为水分子的吸附或解吸过程中阻抗变化值达到稳态变化的90%所需的时间 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref24">24</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref25">25</xref>] 。可计算出NaTaO<sub>3</sub>/SnO<sub>2</sub>传感器的响应和恢复时间分别为15 s和13 s。NaTaO<sub>3</sub>/SnO<sub>2</sub>展现出快的响应和恢复速度，这主要是由于NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料表面存在大量的氧空位(O<sub>2</sub>)，使水分子快速分解为H<sub>3</sub>O<sup>+</sup>，H<sub>3</sub>O<sup>+</sup>为导电离子，从而提高了湿度传感器的响应速度 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref14">14</xref>] 。如图9(b)所示，测量了30天内的NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在不同相对湿度水平下阻抗变化的情况，来验证其稳定性。图中在相同的相对湿度水平下，我们可以看到该湿度传感器的阻抗基本没有变化。因此，NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器具有良好的稳定性，可以长时间用于测量环境的湿度。</p><p>图9. (a) 响应/恢复特性曲线；(b) NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在不同相对湿度水平下的长期稳定性</p></sec></sec><sec id="s8"><title>4. 机理解释</title><p>图10. 11%~59% RH下NaTaO<sub>3</sub>/SnO<sub>2</sub>传感器的复阻抗谱(CIS)及对应的等效电路(EC)</p><p>众所周知，钙钛矿氧化物和金属氧化物的湿敏传感机理都是与其表面吸附的水分子相关 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref26">26</xref>] 。为了进一步分析NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的传感机理，我们结合其复数阻抗谱(CIS)和等效电路(EC)来进行分析。</p><p>如图10(a)所示，在11%相对湿度下的复数阻抗谱图为曲率极小的弧线，几乎呈现出一条直线，此时化学吸附到NaTaO<sub>3</sub>/SnO<sub>2</sub>材料表面和空隙中的极少量水分子形成了化学吸附水层。化学吸附水层很难转移，此时的阻抗值很高可以说代表NaTaO<sub>3</sub>/SnO<sub>2</sub>固有阻抗，对应的等效电路近似元件CPE ‎[<xref ref-type="bibr" rid="hanspub.65510-ref27">27</xref>] ‎[<xref ref-type="bibr" rid="hanspub.65510-ref28">28</xref>] 。随着相对湿度的增加到33%时，少量水分子物理吸附到材料表面，水分子与活性位点相互作用以及与氧空位相互作用下解离出少量的氢氧根离子(OH<sup>−</sup>)和氢离子(H<sup>+</sup>)，(H<sup>+</sup>)在氧空位周围电场作用下在相邻水分子间定向移动形成微弱的电流 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref29">29</xref>] ，此电流可称为漏导电流。</p><p>随着湿度增加吸附的水分子也逐渐增加，从而漏导电流也逐渐增大，因此复数阻抗谱图如10(b)所示：从一条曲率极小的近似直线的曲线逐渐变成为曲率逐渐增大的弧线。此时，对应的等效电路由电容器(C)和电阻(R)并联组成。当相对湿度增加到43%相对湿度时，复数阻抗谱图已完全变成为半圆弧，如图10(c)所示。在图10(d)中，当相对湿度增加到59%时，复数阻抗谱图呈现出在半圆弧的尾部区域有一条长的低频尾线 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref30">30</xref>] ，此低频尾线代表Warburg阻抗(Z<sub>w</sub>)。此时，对应的等效电路为电容器(C)和电阻(R)先并联然后再与阻抗(Z<sub>w</sub>)串联 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref31">31</xref>] 。</p><p>在59%相对湿度条件下，大量的水分子被吸附到NaTaO<sub>3</sub>/SnO<sub>2</sub>材料表面，形成连续的液态水层。在液态水层上水分子逐渐分解为OH<sup>−</sup>和H<sub>3</sub>O<sup>+</sup>，此时发生Grotthuss循环机制(H<sub>2</sub>O + H<sub>3</sub>O<sup>+</sup> → H<sub>3</sub>O<sup>+</sup> + H<sub>2</sub>O) ‎[<xref ref-type="bibr" rid="hanspub.65510-ref32">32</xref>] ，实现水合氢离子的传递而导电。Grotthuss机制一般都在低频发生，因此在复数阻抗谱图的低频端会有一条拖尾线出现。</p><p>图11. 高湿度75%~95% RH下NaTaO<sub>3</sub>/SnO<sub>2</sub>传感器的复阻抗谱(CIS)及对应的等效电路(EC)</p><p>随着湿度不断增加，从75%相对湿度到95%相对湿度，NaTaO<sub>3</sub>/SnO<sub>2</sub>材料表面吸附的水分子越来越多，水合氢离子的导电能力也越来越强，复数阻抗谱图11(a)~(c)中高频区的半圆弧已经消失，低频区的拖尾直线越来越长，最后基本就只剩一条拖尾直线。此时，复合材料表面吸附了大量的水分，Grotthuss链式反应明显增强，水合氢的数量增多且传播速度加快，从而使材料的电阻迅速下降。与之对应的等效电路是电容(C)与Z<sub>w</sub>的串联，此时Z<sub>w</sub>占绝对优势 ‎[<xref ref-type="bibr" rid="hanspub.65510-ref33">33</xref>] 。</p></sec><sec id="s9"><title>5. 结论</title><p>本文采用水热法成功地制备了高性能的NaTaO<sub>3</sub>/SnO<sub>2</sub>湿敏传感传感器，系统地研究了其湿度传感性能。制备的材料通过XRD、SEM、XPS、FTIR表征，结果表明，NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料比表面积比纯NaTaO<sub>3</sub>更大，这使得复合材料表面吸附更多的水分子，增强了NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的性能。NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料表面氧空位含量明显提升，使其吸附大量水分，促进水分子分解为导电离子，提高NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的响应和恢复速度。NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器在11%~95%相对湿度范围内具有高响应度(303,959%)、良好的线性度、低的湿滞(1.99%)、长期稳定性和快的响应和恢复时间(分别为15 s和13 s)。通过对NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的复阻抗谱分析，对其传感机理进行了解释。NaTaO<sub>3</sub>/SnO<sub>2</sub>复合材料的成功制备也为具有高湿敏性能的NaTaO<sub>3</sub>基电阻传感器的开发提供了新的思路，具有一定的应用前景。</p></sec><sec id="s10"><title>致谢</title><p>感谢新疆固态物理与器件重点实验室的支持。</p></sec><sec id="s11"><title>文章引用</title><p>米彦辉,李 鹏. 高响应NaTaO<sub>3</sub>/SnO<sub>2</sub>湿度传感器的制备及性能研究Study on the Preparation and Performance of NaTaO<sub>3</sub>/SnO<sub>2</sub> Humidity Sensor with High Response[J]. 凝聚态物理学进展, 2023, 12(02): 24-35. https://doi.org/10.12677/CMP.2023.122004</p></sec><sec id="s12"><title>参考文献</title></sec></body><back><ref-list><title>References</title><ref id="hanspub.65510-ref1"><label>1</label><mixed-citation publication-type="other" xlink:type="simple">Zhang, Y., Chen, Y., Zhang, Y., Cheng, X., Feng, C., Chen, L., Zhou, J. and Ruan, S. 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