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Beta-silicon carbide whiskers are being grown by a vapour-liquid-solid (VLS) process which produces a very high purity, high strength single crystal fibre about 6/~m in diameter and 5-100 mm long. Details of the growth process are given along with a general explanantion of the effects of the major growth parameters on whisker growth morphology.

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The system erbia-hafnia was investigated using thermal expansion measurements and room-temperature X-ray diffraction of quenched and annealed samples. The range of existence of the solid solutions based on HfOz and ErZO3 was determined by the precision lattice parameter method. Three compounds with hexagonal structure are reported: the first is an ordered fluorite-related phase with the ideal formula Er4Hf3OI2 and decomposes with increasing temperature at = 1500°C into a solid solution of the fluorite type; the second is formed at 4 5 mol% ErZ03, corresponding closely to the formula ErSHfz011.5, and undergoes a transformation at = 1650°C into cubic solid solutions to fluorite and C type. The third compound is formed within the concentration range between 60 and 90 mol% Er203. This compound, Er6HfOll, decomposes at =1700"C into a cubic solid solution of the C type. A proposed phase diagram for the system erbia-hafnia is presented.