Growth zones and their boundaries in GaPO4

Gallium (ortho-)phosphate (GaPO4) is a piezoelectric material which is grow n from hydrothermal solutions. The growth zones, ie. parts of the crystal g rown by different faces, and their boundaries can influence the quality of the grown material. Thus, a theoretical and experimental study of form, siz e and properties of growth zones and their boundaries in GaPO4 was performe d. A program was developed with which the zones in the crystal as well as i n any plane cutting through it can be calculated and outlined, simulating t he facetted growth using growth rates determined from the crystal habit. Th is program was applied to spontaneous crystals as well as to crystals grown from seeds. Experimentally, growth zone boundaries which correspond to acc umulation of OH were determined by scanning infrared absorption measurement s.