Related Experiment Video
Updated: Jan 31, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Sn4+/Sn2+ Aliovalent Substitution: A Strategy for Local Structure Engineering to Enhance Birefringence and Trigger
Bao Jiang1, Hong-Heng Chen2, Lei Wu1
1Key Laboratory of Oil & Gas Fine Chemicals, Ministry of Education & Xinjiang Uyghur Autonomous Region, School of Chemical Engineering and Technology, Xinjiang University, Urumqi 830017, China.
Abstract:
Aliovalent substitution involving cations with lone pair electrons is a powerful strategy for designing novel optical materials with enhanced properties. Herein, by substituting Sn4+ with stereochemically active Sn2+ in the α/β-LiSn2(PO4)3 parent structure, we successfully synthesized α/β-Li2SnP2O7 pyrophosphates, achieving a remarkable 5.5 time enhancement in birefringence. This oxidation-state-driven transformation converts the symmetric [SnO6] octahedra in α/β-LiSn2(PO4)3 into highly distorted [SnO4] tetrahedra in α/β-Li2SnP2O7. This conversion leads to the bond length distortion index boosting (from 9.42/9.95 × 10-3 to 47.17/49.21 × 10-3) and the bond angle varying (from 26.97/29.65 deg2 to 1054.2/1122.1 deg2), which triggers the [SnP6O24] clusters into [SnP2O9] three-membered rings, repectively. The increased distortion of Sn-O groups and the decreased symmetry of Sn-P-O blocks enhance the optical anisotropy of the compounds effectively. This aliovalent substitution strategy offers a valuable gudience for amplifying the intrinsically low birefringence of phosphates.
Related Concept Videos
Structures of Solids
Local Anesthetics: Chemistry and Structure-Activity Relationship
Structural Isomerism
Isomers are different chemical species that have the same chemical formula. Structural isomerism of coordination compounds can be divided into two subcategories, the linkage isomers and coordination-sphere isomers.
Linkage isomers occur when the coordination compound contains a ligand that can bind to the transition metal center through two different atoms. For example, the CN− ligand can bind through the carbon atom or through the nitrogen atom. Similarly, SCN− can...
Additional Subnuclear Structures
The nucleus contains many membrane-less subnuclear organelles or nuclear bodies, such as nucleoli, Cajal bodies, speckles,...
Structure of Lipids
Viral Structure

