High Temperature Materials Unit, National Institute for Materials Science, Tsukuba, 305-0047, Japan(Received December 3, 2014 ; revised December 24, 2014 ; accepted December 24, 2014)AbstractWith increase in demand for higher operating temperatures of gas turbines, extensive research efforts havebeen carried out to enhance the performance of thermal barrier coatings (TBCs) in the field of coating pro-cessing as well as materials. In this study, thermal barrier coatings in lanthanum/gadolinium zirconate system,which is one of the most promising candidates for replacing yttira-stabilized zirconia (YSZ) in thermal barriercoating applications, are fabricated via suspension plasma spray. Dense, 300 ~ 400 µm thick coatings of fluorite-phase zirconate with modest amount of segmented microstructures are obtained by using suspension plasmaspray with suspensions of planetary-milled mixture between lanthanum and/or gadolinium oxide and nanozirconia. These coatings exhibit thermal conductivities of 1.6 ~ 1.7 W/mK at 1000