Ceramic compositions for thermal barrier coatings with improved mechanical properties

A thermally protected article, which comprises:

• A. a substrate;
• and
• B. a thermal barrier coating consisting essentially of:
• 1. at least about 93 mole % zirconia;
• and
• 2. a stabilizing amount up to about 5 mole % of a stabilizing metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof;
• and
• 3. a fracture toughness improving amount of from about 0.1 to about 2 mole % lanthana.

A method for preparing a thermal barrier coating for an underlying substrate, the method comprising the step of:

• a. depositing over the substrate a zirconia-containing ceramic composition to form a thermal barrier coating, the zirconia-containing ceramic composition consisting essentially of:
• 1. at least about 93 mole % zirconia;
• and
• 2. a stabilizing amount up to about 5 mole % of a stabilizer metal oxide selected from the group consisting of yttria, calcia, ceria, scandia, magnesia, india, gadolinia, neodymia, samaria, dysprosia, erbia, ytterbia, europia, praseodymia, and mixtures thereof;
• and
• 3. a fracture toughness improving amount of from about 0.1 to about 2 mole % lanthana.