Single crystal heat treatment method

A single crystal heat treatment method, comprising a step of heating a single crystal of a cerium-doped silicate compound represented by general formula (3) below in an oxygen-containing atmosphere,

• wherein the oxygen-containing atmosphere is an atmosphere having an oxygen concentration of 100 vol %, or an atmosphere containing nitrogen or an inert gas and having an oxygen concentration of 1 vol % or higher but less than 100 vol %,
• wherein the single crystal is heated at a temperature ranging from 300° C. to 1150° C. in the heating step
• Gd2−(p+q)LnpCeqSiO5 (3)
• (wherein Ln represents at least one elemental species selected from a group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y and Sc, which are rare earth elements having an ionic radius smaller than Tb, p represents a numerical value greater than 0 but less than or equal to 2, and q represents a numerical value greater than 0 but less than or equal to 0.2).

A single crystal heat treatment method, comprising a step of heating a single crystal of a cerium-doped silicate compound represented by general formula (4) below in an oxygen-containing atmosphere,

• wherein the oxygen-containing atmosphere is an atmosphere having an oxygen concentration of 100 vol %, or an atmosphere containing nitrogen or an inert gas and having an oxygen concentration of 1 vol % or higher but less than 100 vol %,
• wherein the single crystal is heated at a temperature ranging from 300° C. to 1150° C. in the heating step
• Gd2−(r+s)LurCesSiO5 (4)
• (wherein r represents a numerical value greater than 0 but less than or equal to 2, and s represents a numerical value greater than 0 but less than or equal to 0.2).

A single crystal heat treatment method, comprising a step of heating a single crystal of a cerium-doped silicate compound represented by any of general formulae (1), (2), (3) and (4) below in an oxygen-containing atmosphere,

• wherein the oxygen-containing atmosphere is an atmosphere having an oxygen concentration of 100 vol %, or an atmosphere containing nitrogen or an inert gas and having an oxygen concentration of 1 vol % or higher but less than 100 vol %,
• wherein the single crystal of the cerium-doped silicate compound contains 0.00005 to 0.1 wt %, with respect to the total weight of the single crystal, of at least one elemental species selected from a group consisting of Mg, Ca, Sr, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo and W, and
• wherein the single crystal is heated at a temperature of 700° C. to 1300° C. in the heating Step
• Y2−(x+y)LnxCeySiO5 (1)
• (wherein Ln represents at least one elemental species selected from a group consisting of elements belonging to the rare earth elements, x represents a numerical value from 0 to 2, and y represents a numerical value greater than 0 but less than or equal to 0.2)
• Gd2−(z+w)LnzCewSiO5 (2)
• (wherein Ln represents at least one elemental species selected from a group consisting of elements belonging to the rare earth elements, z represents a numerical value greater than 0 but less than or equal to 2, and w represents a numerical value greater than 0 but less than or equal to 0.2)
• Gd2−(p+q)LnpCeqSiO5 (3)
• (wherein Ln represents at least one elemental species selected from a group consisting of Dy, Ho, Er, Tm, Yb, Lu, Y and Sc, which are rare earth elements having an ionic radius smaller than Tb, p represents a numerical value greater than 0 but less than or equal to 2, and q represents a numerical value greater than 0 but less than or equal to 0.2)
• Gd2−(r+s)LurCesSiO5 (4)
• (wherein r represents a numerical value greater than 0 but less than or equal to 2, and s represents a numerical value greater than 0 but less than or equal to 0.2).