PSEUDO-DENDRITIC GROWTH IN LEAD MOLYBDATE SINGLE-CRYSTAL BY CZOCHRALSKI TECHNIQUE

A pseudo-dendritic crystal growth of lead molybdate (PbMoO4) has been studied with the Czochralski technique. The observed dendritic growth is iso-directional, projecting from the circumference of the growth front, where the content of impurities, melt stoichiometry and temperature are expected to be varied. The dendrite arm length and inter-dendrite angle are closely correlated. It is found that the grown dendrite arms are bounded only by ten low-index crystallographic planes (001), (001BAR), (101), (101BAR), (101BAR), (101BAR)), (011BAR), (011BAR), (011BAR), and (011BAR). Based on this work, a facet transition pattern existing among the dendritic arms has been revealed. Further analysis for crystal grains in as-grown PbMoO4 single crystals indicates that a similar dendritic growth can also occur under conventional growth conditions. It is further suggested that the constitutional supercooling is a major factor causing the dendritic growth in PbMoO4 single crystals.