Complex oxide ceramic, method for producing same, and article
A complex oxide ceramic according to an embodiment is a complex oxide ceramic including a rare earth element and at least one element selected from among molybdenum, tungsten, and vanadium. An example of the rare earth element is at least one species selected from among La, Ce, and Gd.
1. A complex oxide ceramic comprising a rare earth element and at least one element selected from among molybdenum, tungsten, and vanadium, wherein a surface of the complex oxide ceramic has a water contact angle of 88° to 119°, and wherein, at the surface of the complex oxide ceramic, a ratio of carbon to the sum of the rare earth element and the at least one element selected from among molybdenum, tungsten, and vanadium is 1.7 atm % to 2.1 atm %.
2. The complex oxide ceramic according to claim 1 , wherein the rare earth element is at least one species selected from among La, Ce, and Gd.
3. The complex oxide ceramic according to claim 1 , which is represented by (La 2-x Ce x )(Mo 2-y W y )O 9 (x=0 to 2, y=0 to 2).
4. The complex oxide ceramic according to claim 1 , which is represented by La 2 (Mo 2-y W y )O 9 (y=0 to 2).
5. The complex oxide ceramic according to claim 1 , which is represented by La 2 Mo 2 O 9 .
6. The complex oxide ceramic according to claim 1 , which is represented by La 2 W 2 O 9 .
7. The complex oxide ceramic according to claim 1 , wherein the percent bacterial or viral reduction as measured after passage of 6 hours through the film cover method is 99% or greater.
8. An article provided with a complex oxide ceramic as recited in claim 1 on at least a part of the surface thereof.
9. A method for producing a complex oxide ceramic which method comprises:
adding a hydroxycarboxylic acid and a glycol to an aqueous solution containing a rare earth element-containing compound and at least one element selected from among molybdenum, tungsten, and vanadium, and then heating to cause esterification reaction between the hydroxycarboxylic acid and the glycol, to thereby induce gelation;
drying a gel formed by the adding and heating;
calcining a powder obtained by drying the gel;
molding the calcined powder; and
firing a compact formed through the molding, wherein, in the firing, the compact is fired in an atmosphere having a water content of 1,000 ppm or lower and an organic substance concentration of 1,000 ppm or lower, and containing oxygen in an amount of 0.1% or greater.
10. The complex oxide ceramic production method according to claim 9 , wherein a rare earth nitrate salt is used as the rare earth element-containing compound, and
ammonium molybdate is used as a molybdenum-containing compound.
11. The complex oxide ceramic production method according to claim 9 , wherein lanthanum nitrate hexahydrate is used as the rare earth element-containing compound, and
ammonium molybdate tetrahydrate is used as a molybdenum-containing compound.
12. The complex oxide ceramic production method according to claim 9 , wherein the hydroxycarboxylic acid is citric acid, and
the glycol is ethylene glycol.