Project No.： （font: 12 points and bold）

Title: Laser-induced Formation of TiO2 with Controllable Phase on theSurface of Titanium（Divide a page into 2 columns）[１］Organization:
Riga Technical University
Title: Professor, Dr. habil. Phys.
Name: Arturs Medvids
Address : 3/7 Paula Valdena Str., LV-1048, Riga, Latvia
Phone: +37167089445
Fax : +37167089074
E-mail: medvids@latnet.lv［２］Research Progress（10.5 points）
Titanium (Ti) and its alloys have excellent properties such as highcorrosion resistance and an excellent balance of strength and ductility.
They have therefore been used in aerospace, military, electrical andchemical industries. Recently, their use has been extended tobiomedical applications such as implants because of their low
allergenicityandhighbonecompatibility[1,2].Alayeroftitania (TiO2)
on Ti and its alloys improves their corrosion resistance andbiocompatibility[3, 5] and affords them photocatalytic activity [6] TiO2
has various polymorphic phases rutile, anatase and brookite. On themacroscopic scale, rutile is more thermodynamically stable thananatase and brookite. Moreover, it has been reported that an anataselayeronTiimplantsimproves theirbonecompatibility[3,4,7]. Further,anatase and composites of anatase + rutile and anatase + brookite areknown to exhibit high levels of photocatalytic activity [8, 9]. Thermaloxidation in a gas atmosphere is a simple and low-cost method tosynthesize a TiO2 layer on Ti. The merits of thermal oxidation are [1]the synthesized TiO2 layer adheres well to Ti substrates, and [2] thismethod can be used even for Ti substrates with complex geometries.
Many reports on the formation of the rutile phase by the thermaloxidation of Ti are present [10]. The aim of this investigation is to show
the possibility to form TiO2 layer on Ti substrate with controllable
phase.

References[1] P.-I.Brånemark:J.Prosthet.Dent.50 (1983)399410.
[2] P.-I.Brånemark,B.O.Hansson,R.Adell,U.Breine,J.Lindström,O.
Hallénand A.Öhman:Scand.J.Plast.Reconst.Surg.11 (Suppl.16)(1977)1132.
[3] B.Liang,S.Fujibayashi,M.Neo,J. Tamura,H.-M.Kim,M.Uchida,T.
Kokuboand T.Nakamura:Biomaterials24 (2003)49594966.
[4] C.-M.LinandS.-K.Yen:Mater.Sci.Eng.C26 (2006)5464.
[5]X.-F.Yang, Y.Chen,F.Yang,F.-M.Heand S.-F.Zhao:Dent.Mater.25(2009)473480.
[6]A.Fujishima,T.N.Raoand D.A.Tryk:J.Photochem.Photobio.C
Photochem.Rev.1 (2000)121.
[7]X.Cui,H.-M.Kim,M.Kawashita,L.Wang, T.Xiong,T.Kokuboand
T.Nakamura:Dent.Mater.25 (2009)8086.
[8] T.Kawahara,T.Ozawa,M.Iwasaki,H.Tadaand S.Ito:J.Colloid
InterfaceSci.267 (2003)377381.
[9] T.Ozawa,M.Iwasaki,H.Tada,T.Akita,K.TanakaandS.Ito:J.Colloid InterfaceSci.281 (2005)510513.
[10]H.Dongand X. Y.Li:Mater.Sci.Eng.A280 (2000)303310.

［３］Results（10.5 points）(３－１) Research results
Laser-induced oxidation method of Ti substrate was used forformation of TiO2layer. The phase composition and morphology ofthe obtained layers by XRD, FESEM, AFM and Raman
spectroscopy were characterized. It was found that irradiation of Ti
substrate by the pulsed Nd: YAG laser (wavelength =1060 nm,
pulse duration τ=6 ns, frequency f=10 Hz, laser intensity I=52.8
MW/cm2 and doses: D1=1.5x1020 phot, D2=1.9x1020 phot,
D3=2.6x1020 phot) allows to control TiO2 phase. At the laser intensity
52.8 MW/cm2and dose D1=1.5x1020 phot TiO2 layer in anatase
phase, basically, is formed, which possesses the highest photocatalytic,antibacterial and adhesion properties. Photocatalytic decomposition
reaction constant of methylene orange solution at D1 is maximal

3.2×10-4 min-1 under UV-A irradiation and decreases with dose. The
thickness of TiO2 layer increases from 50 nm to 100 nm with the laser
dose. This effect of increase of penetration depth of laser radiation withdose is explained by presence of positive feedback during theirradiation process. The increase of thickness of TiO2 layer is explainedby formation of the TiO2 layer, as a result of photochemical reaction ofTi substrate with O atmosphere atoms. Increase of the thickness leads
to decrease of TiO2/Ti structure adhesion (critical delamination force)from 800 nN for D1 to 400 nN for D3 due to formation ofnonhomogeneous TiO2 layer formed at doses D2 and D3.Thecolonization intensity of P. Aeruginosa and S. Epidermidis of TiO2/Ti
decreasees more than 10 times comperison with Ti substrate. These
results are explane by formation of TiO2 layer in anatase phase at dose
D1 and the layer partially transformation to rutile one at D1 and D2.
This conclusion is support by Raman spectra and X-ray diffraction
patterns.
(３－２) Ripple effects and further developments
Exchange of scientific expertise between the participants
was very helpful for coordination of experimental work
towards the goal of this project. Also, it has contributed tostrengthening of domestic and international collaborationat Research Institute of Electronics. Joint work anddiscussions between the participants of this project havebroadened the scope of existing domestic and international
research collaborations at RIE and RTU.

［４］Achievements (List of Publications)（10.5 points）（１）Anatase Phase of TiO2 on Ti Substrate Formation
by Laser Radiation: Mechanical, Photocatalytic andAntibacterial Properties
A. Medvids, P. Onufrijevs, E. Letko, L. Grase, R. Eglitis,
H. Mimura, A. Zunda, I. Skadins. (Prepered for publication).
（２）

（Page 2: Divide a page into 2 columns）（Page 3 is for travelling report, 1 column）

Page 3：１ column
Travelling Report（Mention each travel by CRP budget.）Name：Prof.Arturs Medvids
Affiliation：Riga Technical University
Period of time：01.11.2018-23.11.2018.
Destination：Shizuoka University, Japan
Purpose：To carry out a joint research, plan
the future collaboration, participate at the workshop
and report previously obtained results.
Name of receiver：Prof. Hidenori Mimura