On the Crystal Chemistry of RE2Si2O7: Revisited Structures, Group-Subgroup Relationship, and Insights of Ce3+-Activated Radioluminescence
On the Crystal Chemistry of RE2Si2O7: Revisited Structures, Group-Subgroup Relationship, and Insights of Ce3+-Activated Radioluminescence
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DOI：
10.1021/acs.chemmater.3c00245
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发表时间：
2023-03-07
影响因子：
8.6
通讯作者：
Lin，Litian
中科院分区：
文献类型：
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作者：
Chen，Pengyun;Zhou，Yuqiao;Lin，Litian
多晶型稀土二硅酸盐RE_2Si_2 O_7（RE = La-Lu，Y，Sc）作为热障涂层和隔热材料是一种很有吸引力的材料，然而，正交E（δ）型（RE = Eu-Ho，Y）和三斜F型（RE = Sm，Eu）的结构至今仍存在争议。本文利用X射线单晶衍射和粉末衍射研究了E（δ）-RE_2Si_2O_7（Pnma）、F-RE_2Si_2 O_7（P1 α）和G-La_2Si_2 O_7（P21/n）的晶体结构。Ce ~（3+）/Eu ~（3+）的二次谐波和/或局域结构敏感的VUV-UV-维斯发光证实了结构的确定。E（δ）-RE_2Si_2O_7（RE = Eu-Ho）取代了Pnma的一个亚群Pna_（21），以中心晶系Pn_（main）晶体形式存在。增大RE ~（3+）半径会导致重构型E（δ）ParticipF的结构转变和重构型群-群关系F ParticipG（RE = La-Nd）的结构转变。更重要的是，我们进行了17个结构类型超过63个化合物的RE 2Si 2 O 7及其相关的转换取决于RE 3+的半径的全面调查。在这些研究的基础上，人们可以（i）预测潜在的多晶型的RE 2Si 2 O 7，包括高压相和RE 2Si 2 O 7固溶体;（ii）相关的热膨胀系数（CTE）与晶体结构，和（iii）了解不寻常的放射性发光的（Gd，La）2Si 2 O 7：Ce 3+高温超导体。
Polymorphic rare-earth disilicates RE2Si2O7(RE = La–Lu, Y, and Sc) are attractive materials as thermal barrier coatings and scintillators; however, the orthorhombic E(δ)-type (RE = Eu–Ho and Y) and the triclinic F-type (RE = Sm and Eu) remain structurally controversial hitherto. In this work, we revisit the crystal structures of E(δ)-RE2Si2O7(Pnma), F-RE2Si2O7(P1̅), and the monoclinic G-La2Si2O7(P21/n) by X-ray single-crystal/powder diffraction. The second-harmonic generation (SHG) and/or the local-structure-sensitive VUV–UV–vis luminescence of Ce3+/Eu3+validate the structure determination. E(δ)-RE2Si2O7(RE = Eu–Ho) crystallizes in the centrosymmetricPnmainstead of the previous noncentrosymmetricPna21(a subgroup ofPnma). Increasing the RE3+radius results in structural transformations of the reconstructive-type E(δ) ↔ F and translationengleiche subgroup–group relationship F ↔ G (RE = La–Nd). More importantly, we perform a complete survey of 17 structure-types over 63 compounds of RE2Si2O7and their related transformations depending on the radius of RE3+. On the basis of these studies, one could (i) predict the potential polymorphs of RE2Si2O7, including the high-pressure phase and the RE2Si2O7solid solutions; (ii) correlate the coefficient of thermal expansion (CTE) with the crystal structure, and (iii) understand the unusual radioluminescence of (Gd,La)2Si2O7:Ce3+high-temperature scintillators.