LASER PROCESSING OF ORTHOPEDIC BIOMATERIALS - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 293

Sputtered 0 min
Sputtered 12 min
Sputtered 22 min
Base

TNZT
Ti2p

TiO 2 2p3/2

TiO 2 2p1/2

200000

TiO 2 2p3/2

180000

TiO 2 2p1/2

160000 TiO 2 2p3/2

140000

Ti 2p3/2

TiO 2 2p1/2

120000

TiO 2 2p3/2

100000

Ti 2p3/2

TiO 2 2p1/2

80000

60000

470 465 460 455 450

BE eV

Figure 9.13. XPS Spectra of Ti2p on the oxide and base TNZT. [Sonia Samuel, (M.S. Thesis,
Dept of Mater. Sci. and Eng., University of North Texas, 2007)]

The XPS runs were carried out on a Thermo VG Scientifi c ESCALAB MKII
spectrometer system using a standard Al-K X-ray source at 280W and electro-

static analysis in constant pass energy mode of 200 eV for survey scans and 20 eV
for regional scans. Argon sputtering was carried out for different time intervals to
assess the chemical compositions at different sputtered depths in a systematic
manner. The elements scanned for were C1s, O1s, Ti2p, Nb3d, Ta4f and Zr4f. XPS
scans were also performed on the surface of the base material without the oxide
layer for comparison. Carbon was present as a contaminant, and as expected, the
amount of carbon decreased with increasing sputter depth.
In Figure 9.13, XPS spectra corresponding to the energy window for the Ti2p
peak are shown, for sputter time periods of zero, twelve and twenty-two minutes
on the surface oxide of the TNZT alloy subjected to electrochemical testing. For
comparison, in the same fi gure, the spectra corresponding to the base TNZT alloy
without the oxide layer, sputtered for a time interval of 30 minutes is also shown.
As observed from the spectra, the TiO 2 2p3/2 (E b = 458.4 eV) [37] peak is observed
on the surface (zero minutes sputtering) as well as after sputtering for 22 minutes
into the oxide layer. The peak corresponding to metallic titanium is observed with
a binding energy of E b = 453.7 eV [37] after sputtering into the oxide layer for 22
minutes. The metallic titanium peak is also observed in case of the base material
(without oxide layer). These results indicate that 22 minutes of sputtering pre-
sumably removes the oxide layer and the base metallic alloy begins. Also the
presence of TiO 2 even after sputtering for 22 minutes suggests the presence of a

α