Quaternary Selenides EuLnCuSe₃: Synthesis, Structures, Properties and In Silico Studies

Area of Science:

• Solid State Chemistry
• Materials Science
• Inorganic Chemistry

Background:

• Exploration of novel heterometallic compounds for advanced material applications.
• Understanding structure-property relationships in quaternary selenides.

Purpose of the Study:

• To synthesize and characterize new heterometallic quaternary selenides of the Eu⁺²Ln⁺³Cu⁺¹Se₃ composition.
• To investigate their crystal structures, optical, and magnetic properties.
• To correlate structural variations with observed physical properties.

Main Methods:

• Synthesis of novel quaternary selenides.
• Crystal structure refinement using derivative difference minimization (DDM) from powder X-ray diffraction data.
• Vibrational spectroscopy, magnetic studies, diffuse reflectance spectroscopy, and ab initio calculations.

Main Results:

• Compounds crystallized in orthorhombic space groups Pnma and Cmcm, with structural type dependent on the ionic radius of Ln³⁺.
• EuLnCuSe₃ compounds (Ln = Tb, Dy, Ho, Tm) exhibit ferrimagnetic properties (4.7–6.3 K), with EuHoCuSe₃ showing negative magnetization.
• Optical band gaps range from 1.87–2.09 eV, with deviations explained by electronic structure and charge-transfer states.

Conclusions:

• Successful synthesis of Eu⁺²Ln⁺³Cu⁺¹Se₃ selenides with distinct structural types.
• Demonstrated correlation between ionic radius, crystal symmetry, and magnetic behavior.
• Established optical properties and provided insights into electronic structure contributing to band gap variations.