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High-Pressure Synthesis, Crystal Structures, and Properties of A-Site Columnar-Ordered Quadruple Perovskites NaRMn2Ti4O12 with R = Sm, Eu, Gd, Dy, Ho, Y.
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-06-09 , DOI: 10.1021/acs.inorgchem.0c00938 Ran Liu 1, 2 , Rebecca Scatena 3 , Dmitry D Khalyavin 4 , Roger D Johnson 5 , Yoshiyuki Inaguma 6 , Masahiko Tanaka 7 , Yoshitaka Matsushita 8 , Kazunari Yamaura 1, 2 , Alexei A Belik 1
Inorganic Chemistry ( IF 4.3 ) Pub Date : 2020-06-09 , DOI: 10.1021/acs.inorgchem.0c00938 Ran Liu 1, 2 , Rebecca Scatena 3 , Dmitry D Khalyavin 4 , Roger D Johnson 5 , Yoshiyuki Inaguma 6 , Masahiko Tanaka 7 , Yoshitaka Matsushita 8 , Kazunari Yamaura 1, 2 , Alexei A Belik 1
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The formation of NaRMn2Ti4O12 compounds (R = rare earth) under high pressure (about 6 GPa) and high temperature (about 1750 K) conditions was studied. Such compounds with R = Sm, Eu, Gd, Dy, Ho, Y adopt an A-site columnar-ordered quadruple-perovskite structure with the generic chemical formula A2A′A″B4O12. Their crystal structures were studied by powder synchrotron X-ray and neutron diffraction between 1.5 and 300 K. They maintain a paraelectric structure with centrosymmetric space group P42/nmc (No. 137) at all temperatures, in comparison with the related CaMnTi2O6 perovskite, in which a ferroelectric transition occurs at 630 K. The centrosymmetric structure was also confirmed by second-harmonic generation. It has a cation distribution of [Na+R3+]A[Mn2+]A′[Mn2+]A″[Ti4+4]BO12 (to match with the generic chemical formula) with statistical distributions of Na+ and R3+ at the large A site and a strongly split position of Mn2+ at the square-planar A′ site. We found a C-type long-range antiferromagnetic structure of Mn2+ ions at the A′ and A″ sites below TN = 12 K for R = Dy and found that the presence of Dy3+ disturbs the long-range ordering of Mn2+ below a second transition at lower temperatures. The first magnetic transition occurs below 8–13 K in all compounds, but the second magnetic transition occurs only for R = Dy, Sm, Eu. All compounds show large dielectric constants of a possible extrinsic origin similar to that of CaCu3Ti4O12. NaRMn2Ti4O12 with R = Er–Lu crystallized in the GdFeO3-type Pnma perovskite structure, and NaRMn2Ti4O12 with R = La, Nd contained two perovskite phases: an AA′3B4O12-type Im3̅ phase and a GdFeO3-type Pnma phase.
中文翻译：
R = Sm，Eu，Gd，Dy，Ho，Y的A-Site柱状有序四方钙钛矿NaRMn2Ti4O12的高压合成，晶体结构和性质。
研究了在高压（约6 GPa）和高温（约1750 K）条件下NaRMn 2 Ti 4 O 12化合物（R =稀土）的形成。这样的具有R ＝ Sm，Eu，Gd，Dy，Ho，Y的化合物采用具有通用化学式A 2 A'A” B 4 O 12的A位柱状有序四重钙钛矿结构。通过粉末同步辐射X射线和1.5至300 K的中子衍射研究了它们的晶体结构。与相关的CaMnTi 2相比，它们在所有温度下都保持了具有中心对称空间群P 4 2 / nmc（No. 137）的顺电结构。Ø 6钙钛矿，其中铁电跃迁在630 K发生。中心对称结构也通过二次谐波产生得到证实。其阳离子分布为[Na + R 3+ ] A [Mn 2+ ] A' [Mn 2+ ] A” [Ti 4+ 4 ] B O 12（与通用化学式匹配），其统计分布为Na +和R 3+在较大的A位点处，而Mn 2+的强烈分裂位置在方形A'位处。我们发现了Mn 2+的C型远程反铁磁结构R = Dy时，在T N = 12 K以下的A'和A''位点上的离子发生变化，发现Dy 3+的存在干扰了较低温度下第二转变以下Mn 2+的长程有序。在所有化合物中，第一个磁转变发生在8-13 K以下，但是仅在R = Dy，Sm，Eu时才发生第二个磁转变。所有化合物均表现出与CaCu 3 Ti 4 O 12类似的大的介电常数，该介电常数可能来自于外部。具有R = Er–Lu的NaRMn 2 Ti 4 O 12以GdFeO 3型Pnma钙钛矿结构结晶，而NaRMn 2的Ti 4 ø 12与R =镧，钕包含在两个钙钛矿阶段：AA' 3乙4 ø 12型林3相和GdFeO 3型晶Pnma相。
更新日期：2020-07-06
中文翻译：
R = Sm，Eu，Gd，Dy，Ho，Y的A-Site柱状有序四方钙钛矿NaRMn2Ti4O12的高压合成，晶体结构和性质。
研究了在高压（约6 GPa）和高温（约1750 K）条件下NaRMn 2 Ti 4 O 12化合物（R =稀土）的形成。这样的具有R ＝ Sm，Eu，Gd，Dy，Ho，Y的化合物采用具有通用化学式A 2 A'A” B 4 O 12的A位柱状有序四重钙钛矿结构。通过粉末同步辐射X射线和1.5至300 K的中子衍射研究了它们的晶体结构。与相关的CaMnTi 2相比，它们在所有温度下都保持了具有中心对称空间群P 4 2 / nmc（No. 137）的顺电结构。Ø 6钙钛矿，其中铁电跃迁在630 K发生。中心对称结构也通过二次谐波产生得到证实。其阳离子分布为[Na + R 3+ ] A [Mn 2+ ] A' [Mn 2+ ] A” [Ti 4+ 4 ] B O 12（与通用化学式匹配），其统计分布为Na +和R 3+在较大的A位点处，而Mn 2+的强烈分裂位置在方形A'位处。我们发现了Mn 2+的C型远程反铁磁结构R = Dy时，在T N = 12 K以下的A'和A''位点上的离子发生变化，发现Dy 3+的存在干扰了较低温度下第二转变以下Mn 2+的长程有序。在所有化合物中，第一个磁转变发生在8-13 K以下，但是仅在R = Dy，Sm，Eu时才发生第二个磁转变。所有化合物均表现出与CaCu 3 Ti 4 O 12类似的大的介电常数，该介电常数可能来自于外部。具有R = Er–Lu的NaRMn 2 Ti 4 O 12以GdFeO 3型Pnma钙钛矿结构结晶，而NaRMn 2的Ti 4 ø 12与R =镧，钕包含在两个钙钛矿阶段：AA' 3乙4 ø 12型林3相和GdFeO 3型晶Pnma相。
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