Single crystal synthesis and properties of lithium‐gallium‐, lithium‐aluminium‐oxide and mixed compounds (I) growing of LiGaO 2 ‐, LiAlO 2 ‐ and LiAl x Ga 1− x crystals from fluxes

LiGaO 2 forms a single eutectic with PbO/B 2 O 3 (molar ratio 9:4). A nearly linear slope of the liquidus curve is followed by a steep rise of the temperature coefficient of solubility. The solvent power at 1300°C is 0.35 g LiGaO 2 /g PbO, B 2 O 3 ; from 1000 to 1300°C there exist only poor differences in solubility of LiGaO 2 and LiAlO 2 in PbO/B 2 O 3 . LiGaO 2 crystals up to 1 p in weight grew spontaneously by slow cooling from fluxes or by evaporation of the solvent, those of about 1–1.5 p from seeds by cooling stirred fluxes. LiAlO 2 crystals are essentially smaller (6 mm). – By partial substitution of Ga 2 O 3 by Al 2 O 3 mixed crystals LiAl x Ga 1− x O 2 result. In the case of x ≦ 0.5 the coefficient of segregation remains ≦1. The al concentrations along the polar axis decrease by more than 25 p.c., perpendicular to [001] they keep constant till to the crystal surface. – Crystals show hypermorphism from mm 2 to mmm . With high initial exceedings only {110} and {011}, with lower ones also {120}, {130}, {210} and {310} as well as the reduced {100}, {010} combinations are observed. – LiGaO 2 crystals grow by nucleous, sceletal or faceted growth resp. during the cooling period. – Primarily at 1270°C formed nuclei up to 1150°C grow to critical dimensions (≈0.5 mm) and develop to the main branch along [001]. Primary branches deflect to [010]. The convex secondary branches intergrow along (110), often including flux. With decreasing temperature a new crystallisation front is formed at the periphery leading to a stable faceted growth at about 1000°C.