High-Pressure Diffusion Control: Na Extraction from NaAlB14
High-Pressure Diffusion Control: Na Extraction from NaAlB14
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DOI：
10.1021/acs.chemmater.3c00318
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发表时间：
2023-03
影响因子：
8.6
通讯作者：
M. Fujioka;Mihiro Hoshino;Suguru Iwasaki;H. Morito;Masaya Kumagai;Y. Katsura;Khurelbaatar Zagarzusem;M. Ono;J. Nishii
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文献类型：
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作者：
M. Fujioka;Mihiro Hoshino;Suguru Iwasaki;H. Morito;Masaya Kumagai;Y. Katsura;Khurelbaatar Zagarzusem;M. Ono;J. Nishii
本文提出了一种新的合成方法——高压扩散控制（HPDC）法。该方法将立方顶锤高压合成与各向异性扩散控制技术相结合；通过同时调节温度、压力和电压，可在高达4gpa、1000°C以上的高压和高温环境下进行电气处理。这种非平衡状态对于产生亚稳材料是有效的。将该新技术应用于含硼共价骨架的多晶naal14。尽管在该材料中电子传导占主导地位，即使在高温下也没有观察到Na离子传导，但HPDC方法利用Na和B之间的键强度差异成功地提取了Na离子，在保持其基本晶体结构的同时创造了亚稳材料alb14。在Na浓度降低过程中，根据体积变化施加高压压缩样品，使多晶样品在晶界处保持良好的接触，促进Na离子的扩散。Na的萃取起到了电子载流子调制的作用，显著降低了材料的电阻率。所开发的HPDC方法有望适用于各种组成元素之间的结合强度不同的化合物，并有可能在具有致密烧结态的多晶亚稳材料的无机合成和调节其物理性质方面开辟新的途径。
A novel synthesis technique, called the high-pressure diffusion control (HPDC) method, was developed in this study. The method combined the high-pressure synthesis using a cubic anvil apparatus and an anisotropic diffusion control technique; the electrical processing in high-pressure and high-temperature environments of up to 4 GPa and over 1000 °C is enabled by simultaneously adjusting the temperature, pressure, and voltage. This nonequilibrium state is effective in creating metastable materials. The developed novel technique was applied to polycrystalline NaAlB14with a boron covalent framework. Although electronic conduction is dominant in this material and no Na-ion conduction is observed even at high temperatures, the HPDC method successfully extracted Na ions by utilizing the difference in bond strength between Na and B, creating the metastable material AlB14while maintaining its basic crystal structure. During the decrease in the Na concentration, applying a high pressure compressed the sample according to the volume change and maintained good contact at the intergrain boundary in the polycrystalline sample, promoting Na-ion diffusion. The Na extraction functioned as electron carrier modulation and significantly reduced the electrical resistivity. The developed HPDC method is expected to be applicable to various compounds with a difference in the bond strength between constituent elements and has the potential to open up new avenues in the inorganic synthesis of polycrystalline metastable materials with dense sintered states and modulate their physical properties.