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Two Types of Negative Thermal Expansion Observed in PbCr1–xTixO3
Chemistry of Materials ( IF 7.2 ) Pub Date : 2023-01-18 , DOI: 10.1021/acs.chemmater.2c02896
Yuki Sakai 1, 2 , Kana Matsuno 2 , Takumi Nishikubo 1, 2 , Masayuki Fukuda 2 , Shogo Wakazaki 2 , Masahito Ikeda 2 , Kazuki Takahashi 2 , Zhao Pan 2 , Lei Hu 2 , Masaki Azuma 1, 2
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Two negative thermal expansions (NTEs) with different mechanisms were observed in solid solutions of perovskite-type oxides PbCrO3 and PbTiO3. PbCr1–xTixO3 was found to adopt a cubic structure the same as that of PbCrO3 for x ≤ 0.6 and a PbTiO3-type tetragonal structure for x ≥ 0.7. The NTE observed at x ≤ 0.6 was accompanied by a cubic-to-cubic phase transition originating from the rearrangement of Pb2+/Pb4+ in a complex local structure called a charge glass. The volume shrinkage of −2.5% observed in PbCrO3 is sufficiently large despite the absence of intermetallic charge transfer, which is the origin of pressure-induced cubic-to-cubic phase transition and 9.8% volume collapse. The NTE in the tetragonal phase was caused by the ferroelectric-to-paraelectric phase transition, the same as in PbTiO3. We succeeded in significantly lowering the working temperature of PbTiO3 as an NTE material by Cr substitution while retaining a large volume shrinkage of 0.6%.

中文翻译:

在 PbCr1–xTixO3 中观察到的两种类型的负热膨胀

在钙钛矿型氧化物 PbCrO 3和 PbTiO 3的固溶体中观察到两种具有不同机制的负热膨胀 (NTE) 。发现PbCr 1– x Ti x O 3x ≤ 0.6时采用与 PbCrO 3相同的立方结构,在x ≥ 0.7时采用 PbTiO 3型四方结构。在x ≤ 0.6处观察到的 NTE伴随着立方到立方的相变,该相变源于 Pb 2+ /Pb 4+在称为电荷玻璃的复杂局部结构中的重排。在 PbCrO 中观察到 -2.5% 的体积收缩尽管没有金属间电荷转移,但3足够大,这是压力引起的立方体到立方体相变和 9.8% 体积坍缩的起源。四方相中的 NTE 是由铁电到顺电相变引起的,与 PbTiO 3中的相同。我们成功地通过 Cr 替代显着降低了作为 NTE 材料的 PbTiO 3的工作温度,同时保持了 0.6% 的大体积收缩率。
更新日期:2023-01-18
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