Surface morphological study of flux grown lead doped rare-earth manganite single crystals

Rare-earth manganites with divalent doping have attracted attention because of their interesting physical phenomena. Manganites, doped with divalent lead, are grown from solvent PbO-PbF2. Single crystals of R1−xPbxMnO3 and mixed rare-earth (RyR′1−y)1−xPbxMnO3, where R′, R=La, Nd and Pr are grown with different values of x using eutectic composition of PbO: PbF2 as solvent. Growth temperature can then be significantly reduced. Optimized charge-to-flux ratio 1:6 yields large crystals with dimension up to 4×3×2 mm3. A variety of surface features such as hillocks, micro and macro step patterns, dendrites as well as clear featureless surfaces are observed on as-grown crystals. Clear surfaces reveal that growth occurred predominantly by two-dimensional layer growth mechanism. The hillocks might have originated at the site of screw dislocation, which suggests the growth mechanism at low supersaturation. Hopper growth observed on a few crystals is suggestive of unstable growth. Optimum growth parameters are employed to achieve better yield and good quality crystals.