Abstract: An apparatus having a crucible (1) for holding a raw material, a heating means (11) for heating the raw material in the crucible (1) and a crystal transporting means (17) for transporting a seed crystal (13) upwards from the inside of the crucible (1), which further comprises a heat conducting member (3) which extends upwards at least from the vicinity of the upper end of the crucible (1), surrounds a single crystal (15) formed, and is made of a material having heat conductivity, and an interface portion radiation heat blocking member (7) for blocking, at least during cooling after the formation of a single crystal, the radiation heat toward an upper portion above the interface between a taper portion (15a) of the formed single crystal (15) connecting with the seed crystal (13) and a straight bulge portion (15b) having a cylindrical shape connecting with the taper portion (15a) of the formed single crystal (15).

Abstract: When produced as a single crystal ingot, a rare earth silicate single crystal 1 can be formed by cutting out from the single crystal ingot. The single crystal 1 has a crystal face F100 whose Miller indices can be determined by X-ray diffraction. The crystal face F100 is composed of a plurality of smooth partial region surfaces (for example, the partial region surface f100A and partial region surface f100B), the plurality of partial region surfaces each have an area detectable by X-ray diffraction, and the angles ? formed between the normal vectors of the plurality of partial region surfaces satisfy the following inequality: 0.1°???2.0°.

Abstract: An apparatus having a crucible (1) for holding a raw material, a heating means (11) for heating the raw material in the crucible (1) and a crystal transporting means (17) for transporting a seed crystal (13) upwards from the inside of the crucible (1), which further comprises a heat conducting member (3) which extends upwards at least from the vicinity of the upper end of the crucible (1), surrounds a single crystal (15) formed, and is made of a material having heat conductivity, and an interface portion radiation heat blocking member (7) for blocking, at least during cooling after the formation of a single crystal, the radiation heat toward an upper portion above the interface between a taper portion (15a) of the formed single crystal (15) connecting with the seed crystal (13) and a straight bulge portion (15b) having a cylindrical shape connecting with the taper portion (15a) of the formed single crystal (15).

Abstract: When produced as a single crystal ingot, a rare earth silicate single crystal 1 can be formed by cutting out from the single crystal ingot. The single crystal 1 has a crystal face F100 whose Miller indices can be determined by X-ray diffraction. The crystal face F100 is composed of a plurality of smooth partial region surfaces (for example, the partial region surface f100A and partial region surface f100B), the plurality of partial region surfaces each have an area detectable by X-ray diffraction, and the angles ? formed between the normal vectors of the plurality of partial region surfaces satisfy the following inequality: 0.1°???2.0° (1).