Reversible thermochromic property of Cr, Mn, Fe, Co-doped Ca14Zn6Ga10O35
Reversible thermochromic property of Cr, Mn, Fe, Co-doped Ca14Zn6Ga10O35
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DOI：
10.1039/d0tc00921k
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发表时间：
2020-07
影响因子：
6.4
通讯作者：
Huanhuan Liu;Long Yuan;Xiaofeng Wu;Xiangyan Hou;Meng Tang;Changmin Hou;Huanwen Chen;S. Feng
中科院分区：
文献类型：
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作者：
Huanhuan Liu;Long Yuan;Xiaofeng Wu;Xiangyan Hou;Meng Tang;Changmin Hou;Huanwen Chen;S. Feng
热致变色材料是最重要的智能材料类型之一，在许多潜在应用中表现出可控的热指示性能。在本文中，我们报告了一个新的家庭的可逆中高温热致变色材料的基础上，四个过渡金属掺杂的Ca 14 Zn 6 Ga 10-xMxO 35（M = Cr，Mn，Fe，Co）材料的主体结构。利用粉末X射线衍射和高分辨透射电子显微镜研究了不同掺杂剂的相纯度和掺杂水平之间的关系。Ca 14 Zn 6 Ga 10 O35的晶体结构是由阴离子氧为中心的OZn 4衍生的四个ZnO 4四面体单元和孤立的（Ga，Zn）O 6八面体单元组成，这为过渡金属发色团离子在晶格中的位置选择性掺杂提供了多种可能性。四种掺杂剂均能明显诱导材料的热致变色，Cr、Mn、Fe和Co掺杂样品的颜色分别为红棕色、绿黄色、浅黄色和淡绿色。在四个系列的样品中，Mn掺杂的样品显示出最好的热致变色性能，这是由于Mn 4+和Mn 5+在四面体位置的共同贡献。所有材料的热致变色现象在25至460 °C的温度范围内都是可逆的，最高色差值为51（Ca 14 Zn 6 Ga 10 − xMnxO 35，x = 0.8）。材料的吸收光谱表明，Cr和Fe占据八面体位置，而Mn和Co占据四面体位置。材料的热致变色机理可以归结为热致晶格膨胀，热致晶格膨胀改变了发色团离子在不同晶场中的吸收带位置和强度。这类新型中高温热致变色材料在未来的各种热指示器领域有着广阔的应用前景。
Thermochromic materials are one of the most important types of intelligent materials that show controllable thermal indicator performance in many potential applications. In this paper, we report a host structure for a new family of reversible intermediate-to-high temperature thermochromic materials based on four transition metal doped Ca14Zn6Ga10−xMxO35 (M = Cr, Mn, Fe, Co) materials. The relationship between phase purity and doping level for different dopants was examined using powder X-ray diffraction and high-resolution transmission electron microscopy. The crystal structure of Ca14Zn6Ga10O35 is composed of anion-oxygen-centered OZn4-derived four ZnO4 tetrahedral units and isolated (Ga,Zn)O6 octahedral units, which provide versatile possibilities for site-selective doping of the transition metal chromophore ions in the crystal lattice. All of the four sets of dopants could clearly induce the thermochromic property of the materials, with the colors of reddish-brown, greenish-yellow, pale-yellow, and pale-green, for Cr, Mn, Fe, and Co doped samples, respectively. Among the four series of samples, Mn-doped samples show the best thermochromic performance, due to the co-contribution of Mn4+ and Mn5+ in the tetrahedral sites. The thermochromic phenomenon for all of the materials is reversible in the temperature range from 25 to 460 °C with the highest chromatic aberration value of 51 (Ca14Zn6Ga10−xMnxO35, x = 0.8). The absorbance spectra of the materials indicate that Cr and Fe occupy the octahedral sites, while Mn and Co occupy the tetrahedral sites in the structure. The thermochromic mechanism of the materials could be ascribed to thermally induced lattice expansion, which changes the positions and intensities of the absorption bands of chromophore ions in different crystal fields. The presented new family of intermediate-to-high temperature thermochromic materials may find promising applications in various thermal indicator fields in the future.