A new cyanometallate-based double perovskite-type compound has been synthesized with the formula of (HTz)₂[KCo(CN)₆] (HTz = thiazolium cation, 1). The basic building units of the framework are Co(CN)₆ and K ions. One K ion coordinates with six adjacent cyanide N atoms to form regular octahedral geometry. Meanwhile, the HTz rings exist in the cage. It undergoes two-step reversible structural phase transitions at 237 K and 210 K along with switchable dielectric transformation. Variable-temperature single-crystal structural analysis reveals that the relatively small displacements and/or thermal vibrations of the HTz rings cause the phase transitions. Meanwhile, the switchable dielectric constant of 1 means a dielectric transition between a low-dielectric state (switch off) and a high-dielectric state (switch on). This characteristic may enrich the family of stimuli-responsive materials and help find potential applications of switchable dielectric materials.

中文翻译：

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基于氰基金属酸盐的双钙钛矿型笼型化合物：[C3H4NS] 2 [KCo（CN）6]的可逆结构相变和可切换介电行为

合成了一种新的基于氰基金属酸盐的双钙钛矿型化合物，其化学式为（HTz）₂ [KCo（CN）₆ ]（HTz =噻唑鎓阳离子，1）。框架的基本构建单元是Co（CN）₆和K离子。一个K离子与六个相邻的氰化物N原子配位以形成规则的八面体几何形状。同时，HTz环存在于笼中。它在237 K和210 K处经历两步可逆的结构相变，以及可切换的介电转换。可变温度单晶结构分析表明，HTz环的相对较小的位移和/或热振动会引起相变。同时，可切换介电常数为1表示低介电态（关闭）和高介电态（打开）之间的介电过渡。该特性可以丰富刺激响应材料的种类，并有助于找到可切换介电材料的潜在应用。