Weak Crystal Field in Yttrium Gallium Garnet (YGG) Submicrocrystals Doped with Cr³⁺

Yttrium gallium garnet (YGG) submicrocrystals having 80 nm average diameters doped with Cr 3+ (0.1–40%) were synthesized by the citrate method. Pure cubic garnets were obtained in wide range (0.1–15%) of dopant concentration. Chromium ions replace Ga 3+ at the octahedral sites and experience an intermediate or weak crystal field, depending only on Cr 3+ concentration. The weak crystal field is observed when the dopant concentration exceeds 3%. The origin of such behavior is discussed.