Gallary

 

• ZnO:NdにLiをドープすると結晶が軟らかくなることを第一原理計算で明らかにしました。
• 特にLi-O結合とZn-O結合の共有結合性の変化が重要であることがわかりました。
• 応力発光体の発光特性は機械的特性と密接に関係しており、この結果から発光特性を改善するための指針が得られました。
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• 第一著者は川名君（2023年度修士卒）です。

In this study, the elastic properties of the newly discovered mechanoluminescence (ML) material Li_xZn_1−xO:Nd³⁺ are investigated by first-principles calculations. The elastic properties such as Young's modulus, bulk modulus, and shear modulus are calculated from the elastic tensor. As a result of investigating the phase stability of Li_xZn_1−xO:Nd³⁺, it indicates that the wurtzite ZnO phase is stable in the Li additive range of 0 ≤ x ≤ 0.44, and an excess addition caused a structural transition to the h-BN structure. Besides, elastic properties, such as Young's modulus, bulk modulus, and shear modulus of Li_xZn_1−xO:Nd³⁺ are decreased with increasing Li concentration in the examined range of 0 ≤ x ≤ 0.44. Furthermore, it reveals from bonding analysis between cation and anion that the bonding strength of Li─O bonding for the covalent bonding is weaker than that of Zn─O bonding. The elastic softening derives from atomic interaction in the covalent bonding. Therefore, it concludes that elastic softening is promoted by the increase in Li─O bonding with weak covalent bonding as the Li concentration increases.