Recently, it was reported that RF induction plasma of a purse-modulated ope
rating mode had been successfully generated, for the first time, at a suffi
ciently high electric power level for materials processing. The unique cond
itions in the plasma, such as a non-equilibrium situation at the instance o
f pulse-on and -off and the increase of chemically reactive radical species
, as well as the time-dependent change of plasma temperature, is expected t
o offer the unique physico-chemical conditions necessary for materials proc
essing. As the first step of the work directed to materials processing, the
thermal and chemical interactions between plasma and solid materials were
examined for both cases of pulse-modulated and continuous modes. Green comp
acts of titanium dioxide (TiO2), whose characteristics strongly depend on t
he formation of lattice defects and the incorporation of hydrogen, were tre
ated in Ar-H-2 plasma of continuous and pulse-modulated generation modes. T
he oxide disks were placed at the downstream of plasma flow. The sample pos
ition and the plasma generation pressure were changed as processing paramet
ers. The plasma-treated specimens were characterized by X-ray diffractometr
y and the hydrogen content was measured. The plasma treatment gave a therma
l effect, rather than a chemical one, on the surface of oxide specimens. Th
e oxides were thermally reduced by the plasma treatment and showed a change
of color at the surface, while XRD did not show a change of crystal struct
ure. Comparing specimens treated in the pulse-modulated plasma with those t
reated in the continuous plasma, the disk specimens had less of a thermal e
ffect on the plasma. (C) 2001 Elsevier Science B.V. All rights reserved.