Rare earth oxyfluoride sintered body and method for producing same
View Patent ↗A sintered rare earth oxyfluoride compact is composed of Ln a O b F c (wherein Ln is a rare earth element; and a, b, and c each independently represent a positive number, provided that they are not equal to each other) or Ca-stabilized LnOF as a primary phase and LnOF unstabilized with Ca as a secondary phase. The intensity ratio of the XRD peak of the (018) or (110) plane of the unstabilized LnOF to the highest XRD peak of Ln a O b F c is preferably 0.5% to 30%.
1. A sintered rare earth oxyfluoride compact comprising:
a primary phase, and
a secondary phase,
wherein the primary phase includes Ln a O b F c , where Ln is a rare earth element, and a, b, and c each independently represent a positive number that are not equal to each other, and
wherein the secondary phase includes unstabilized LnOF.
2. The sintered rare earth oxyfluoride compact according to claim 1 , wherein the intensity ratio of the XRD peak of the (018) or (110) plane of the unstabilized LnOF to the highest XRD peak of the Ln a O b F c is 0.5% to 30%.
3. The sintered rare earth oxyfluoride compact according to claim 2 , wherein the unstabilized LnOF is present in the boundaries between the grains of the Ln a O b F c .
4. The sintered rare earth oxyfluoride compact according to claim 1 , having a three-point flexural strength of 50 to 300 MPa.
5. The sintered rare earth oxyfluoride compact according to claim 1 , having a surface roughness Ra, as specified in JIS B0601, of 1 μm or smaller.
6. The sintered rare earth oxyfluoride compact according to claim 1 , having an inflection-point of dimensional change with temperature occurring at a temperature ranging from 200° to 800° C.
7. The sintered rare earth oxyfluoride compact according to claim 1 , wherein the primary phase has an average grain size of 1 to 200 μm, the secondary phase has an average grain size of 0.1 to 5 μm, and the average grain size of the primary phase is larger than that of the secondary phase.
8. The sintered rare earth oxyfluoride compact according to claim 1 , wherein the Ln a O b F c is Y 5 O 4 F 7 .
9. The sintered rare earth oxyfluoride compact according to claim 1 , wherein the Ln a O b F c is La 10 O 7 F 16 .
10. The sintered rare earth oxyfluoride compact according to claim 1 , wherein the Ln a O b F c is NdO 0.67 F 1.66 .
11. The sintered rare earth oxyfluoride compact according to claim 1 , wherein the Ln a O b F c is Eu 6 O 5 F 8 .
12. A method for producing a sintered rare earth oxyfluoride compact including:
a primary phase, and
a secondary phase,
wherein the primary phase includes Ln a O b F c , where Ln is a rare earth element, and a, b, and c each independently represent a positive number that are not equal to each other, and
wherein the secondary phase includes unstabilized LnOF, the method comprising:
mixing Ln 2 O 3 and LnF 3 at a mixing ratio such that the amount of Ln 2 O 3 is in excess of the stoichiometric ratio for forming the Ln a O b F c to prepare a mixed powder;
forming the mixed powder into a green body; and
firing the green body.