Entropy–enthalpy interactions and optical properties of non-equiatomic multicomponent rare-earth oxides.

The multicomponent oxides (Ce_1/2Zr_1/2)_1−x(La_1/3Y_1/3Gd_1/3)_xO_2−σ with different elements ratio (x = 0.3, 0.45, 0.6, 0.75, 0.9; abbreviated as CZLYGx) were prepared by co-precipitation method. XRD patterns shows that the compostion with x = 0.9 exhibits mixing crystal structure of Fm-3 m and Ia-3 phases, while the others possess single-phase fluorite structures. Transmission electron microscopy shows that nanoparticles of CZLYG90 with a particle size of about 34 nm were synthesized. The competitive relationship between entropy and enthalpy are analyzed, low mixing enthalpy and high configurational entropy benefit the stabilization of single-phase multicomponent oxide. The direct band gap value of CZLYGx increases from 3.51 eV to 3.99 eV with x increasing, which exhibits promising candidate as an optical material. [ABSTRACT FROM AUTHOR]