Appendix for the paper Hafnia: energetics of thin films and nanoparticles by Wei Zhou, Sergey V.
Ushakov, Tuo Wang, John G. Ekerdt, Alex A. Demkov, and Alexandra Navrotsky, submitted for
publication in Journal of Applied Physics to be deposited with Electronic Physics Auxiliary Publication
Service (EPAPS)
TABLE OF CONTENTS
FIG. 1. Experimental setup used for time-resolved high-temperature measurements on NSLS beamline
X7b.
FIG. 2. X-ray diffraction patterns of 76 nm HfO2 films at different temperatures on Inel CPS120
diffractometer
FIG. 3. Thermal analysis of amorphous HfO2 powder served as a precursor for synthesis of monoclinic
hafnia.
FIG. 4. Temperature program and 2D plot of XRD patterns on heating of amorphous HfO2 powder with
corundum standard.
FIG. 5. 3D plot of illustrating crystallization of amorphous HfO2 directly into monoclinic phase at 450
°C.
FIG. 6. Bright field TEM micrographs of monoclinic HfO2 samples used for solution calorimetry.
FIG. 7. Particle size distributions in monoclinic HfO2 samples used for solution calorimetry.
FIG. 8. Total water content from TG versus BET surface area for monoclinic HfO2 samples used for
solution calorimetry.
FIG. 9. Enthalpy of drop solution (corrected for physisorbed and chemisorbed water and for surface
energy contribution assuming 2.78 J/m2 reference value) plotted versus interface area. The negative of
the slope yields interfacial energy 1.6 ±0.1 J/m2.
FIG. 1. Experimental setup used on NSLS beamline X7b with Mar345 image plate. Red lines show Xray beam path and diffraction cones. Sapphire tube (Saphicon, 1mm OD, 0.7 mm ID) was filled with
amorphous HfO2 powder mixed with -Al2O3 and inserted into a spiral of Kanthal wire. K type
thermocouples (0.01" Omega HKMQSS-010U-6) were inserted inside the tube to contact the sample
and were used control the furnace and to record the sample temperature using Omega controller. The
single crystal reflections from sapphire tube were cut out from two dimensional diffraction patterns with
FIT2D software and the powder rings were integrated. Wavelength (0.92203 Å) and sample to detector
distance (192.085 mm) were calibrated with LaB6. Refinement of cell parameter of Si 640b NIST
standard material gave the value 5.4308(1) (wRp 6.6%), what is within uncertainty from standard value
5.430940(35).
o
500 C
o
450 C
o
re
400 C
atu
o
pe r
350 C
o
Tem
300 C
o
200 C
10
15
20
25
30
2 (degree)
35
40
45
FIG. 2. X-ray diffraction patterns of 76 nm HfO2 films at temperatures labeled. Measurements were
performed in air using high temperature attachment of Inel CPS120 diffractometer, Co Kα radiation (λ =
1.7902 Å), heating rate of 10 oC/min and collection time of 60 minutes per pattern. Crystallization into
monoclinic phase is apparent at 400 °C from two peaks at 40-45° (2 θ).
4.5
100
96
92
1.5
TG (%)
DSC (mw/mg)
3.0
88
0.0
84
200
400
600
800
1000
1200
o
Temperature ( C)
FIG. 3. Thermogravimetry (TG) and differential scanning calorimetry (DSC) traces on heating in
oxygen at 20 °C/min of amorphous HfO2 powder served as a precursor for synthesis of monoclinic
hafnia nanoparticles. Weight loss of ~15 wt% observed from 25-650 °C. Endothermic peak on DSC
trace below 400 °C corresponds to water loss, exothermic peak at 545 ± 7 °C corresponds to HfO2
crystallization in monoclinic phase with crystallization enthalpy -24 ± 7 kJ/mol (average from three
experiments).
3000
-
(111)
(111)
120
4000
Time, min
100
80
60
40
20
100
300 500
T, °C
FIG. 4. Time-resolved high temperature X-ray diffraction patterns on amorphous HfO2 powder with
corundum internal standard (NSLS beamline X7b wavelength 0.92203 Å) Collection time was 100
seconds per pattern with ~80 seconds image plate read-out time. Sample temperature is shown on the
left panel. Red overlaid trace is the fit of the last pattern with strongest lines for monoclinic HfO2
indexed. Amorphous HfO2 crystallizes directly into monoclinic phase after 40 minutes at 450 °C. BET
surface area of amorphous HfO2 measured before crystallization in a separate experiment was 85 m2/g.
4k
3k
2k
10
20
30
2-Theta Angle (Degrees)
FIG. 5. Crystallization of amorphous HfO2 into monoclinic phase at 450 °C (with corundum as internal
standard). 3D plot of the 10-30° 2-Theta region ( = 0.92203 Å) of XRD patterns collected with 180 s
interval. Intensity is plotted on the Y-axis in logarithmic scale. Direct crystallization into monoclinic
phase is apparent from appearance of strongest (-111) and (111) m-HfO2 peaks in 15-20 ° 2-Theta
region. See figures 2 and 3 on details on experimental setup and temperature program.
FIG. 6. Bright field TEM micrographs of monoclinic HfO2 samples used for solution calorimetry.
Annealing temperature (oC) indicated in the upper left corner. Measured with Phillips CM12
transmission electron microscope at 120 kV with LaB6 filament. Magnification of electron microscope
was calibrated with Ted Pella standard #603.
Counts
13±4 nm (77)
650 °C
18±5 nm (48)
700 °C
32±9 nm (70)
800 °C
36±11 nm (89)
900 °C
46±12 nm (91)
950 °C
44±13 nm (67) 1000°C
0
20
40
60
80
Particle size (nm)
FIG. 7. Particle size distributions in monoclinic HfO2 samples used for solution calorimetry. Measured
with Phillips CM12 transmission electron microscope operated at 120 kV with LaB6 filament.
Magnification was calibrated with TedPella standard #603. Average size with standard deviation (total
number of particles counted is given in parentheses) and annealing temperature are labeled in the top
right corner.
Water content (mol)
0.20
0.15
0.10
0.05
0.00
0
2000
4000
6000
8000
2
Surface area (m /mol)
FIG. 8. Total water content from TG versus BET surface area for monoclinic HfO2 samples used for
solution calorimetry.
Hds-2 - 0.00278*SA (kJ/mol)
20
19
18
17
16
15
14
0
600
1200
1800
2400
2
Interface area (m /mol)
FIG. 9. Enthalpy of drop solution (corrected for physisorbed and chemisorbed water and for surface
energy contribution assuming 2.78 J/m2 reference† value) plotted versus interface area calculated from
Eq. 1 (IA = 0.5[SA(XRD)-SA(BET)]). The negative of the slope yields interfacial energy 1.6 ±0.1 J/m2.
†A.
B. Mukhopadhyay, J. F. Sanz, and C. B. Musgrave, Chem. Mat. 18 (15), 3397 (2006)