Investigation of the microstructure in the Yttrium-Tantalate-Zirconia system Thursday, August 27, 2015

Yttrium-Tantalate-Zirconia system

Thermal conductivities of the system Very low thermal conductivities (< 2 Wm-1K-1)

Quasi-binary phase diagram 3 phases in the 30 to 60 mol % ZrO2 region?

Transition takes place at 1475 °C for pure YTaO4 Phases of YTaO4 Transition takes place at 1475 °C for pure YTaO4

Imaging techniques used Transmission Electron Microscopy Scanning Electron Microscopy

Transmission Electron Microscopy at the Center for Nanoscale Systems (CNS) JEOL 2100 TEM

Inside a TEM

Requirements for TEM Sample has to be very thin (<100 nm) Hence specific technique to prepare samples Hand polishing and ion milling Focused Ion beam

Sample Preparation Chosen method was hand polishing and ion milling Started from discs and cut cross section Polish down to about 100 m

Fischione Model 200 Dimpling Grinder

Gatan Model 691 Precision Ion Polishing System Ion milling Trickiest part in sample preparation Sputtering of molybdenum on the sample Gatan Model 691 Precision Ion Polishing System

Finding a recipe that works Fischione Model 1010 Ion mill

New equipement CNS bought Fischione Model 1050 TEM mill

Contacting an expert Contact Rocco Cerchiara, TEM sample preparation expert from Fischione, to ask for a possible recipe for ion milling Suggested using high angles and low energy to remove molybdenum being sputtered

Double tilt Beryllium sample holder Ready for Imaging!!! Double tilt Beryllium sample holder

TEM Image of 50 mol % ZrO2

HRTEM Image of 50 mol % ZrO2

Selected area electron diffraction of 50 mol % ZrO2

SEM Image of 50 mol % ZrO2

SEM Image of 50 mol % ZrO2 cross section Probably bands seen on previous SEM image?

Concluding remarks Finally find a good recipe for sample preparation but not enough time to complete observations!!! Bands structure in 50 mol % ZrO2 possibly due to the fact that this composition is very close to the eutectoid composition

Any Questions?