Solution processing of conducting dense and porous films; doped ZnO and TiO2, and perovskites

• Soln. based processing of porous and dense films by all-alkoxide based precursor systems have been investigated and compared, with a focus on the connection between the precursors and heat-treatment, and the product oxide quality and structure.  Three systems were investigated typically with TGA, DSC, XPS, IR spectroscopy, X-ray diffraction, TEM-EDS and SEM-EDS, but also with other advanced characterization techniques: (i) manganate and cobaltate perovskites of the LCMO (La0.67Ca0.33MnO3), LSMO (La0.75Sr0.25MnO3), LNCMO (La0.33Nd0.33Ca0.33MnO3), LBSM (La0.75Ba0.125Sr0.125MnO3) and LSCO (La0.50Sr0.50CoO3) compns. were investigated.  Highly epitaxial films of LCMO and LSCO were prepd., and the CMR properties of the LCMO were comparable to those of PVD derived films.  Polycryst. films were prepd. for all perovskites.  (ii) Three routes to ZnO : Co/Al were investigated and compared; an acetate based route and two alkoxide based routes with different heat-treatments.  With the acetate based and the alkoxide based route using hydrolysis in air, a max. Co doping of 6% was obtained, while in absence of CO2 and O2, the doping range could be extended to 20%Co.  Both dense films and porous nano-structured films were prepd.  The magnetic properties of the Co-doped films did not show any room-temp. ferro-magnetism.  (iii) ZrO2 and NbO2.5 doped anatase TiO2 were prepd. by heat-treatment or hydrothermal routes.  Alio-valent doping of up to more than 35% of NbO2.5 could be achieved in the anatase.  It is believed that the pentavalent metal doping is compensated by metal vacancies, and as expected from this assumption, the materials have a low d.  ZrO2 doping in titania led to an increase in the dye-sensitized solar cell efficiency and highly active and stable photo-catalysts.

Subject headings

NATURVETENSKAP  -- Kemi -- Fysikalisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Physical Chemistry (hsv//eng)

Keyword

Physical chemistry

Fysikalisk kemi

Materials Chemistry

materialkemi

Publication and Content Type

ref (subject category)

art (subject category)