**Acknowledgement**

This work was supported by MEXT\*-Supported Program for the Strategic Research Foundation at Private Universities, 2011-2015 (Kogakuin University–Energy Conversion Ecomaterials Center). \*Ministry of Education, Culture, Sports, Science and Technology

## **11. References**

316 Heat Treatment – Conventional and Novel Applications

electrodes for devices such as solar cells.

**10. Conclusion** 

processes.

**Author details** 

**Acknowledgement** 

Hiroki Nagai and Mitsunobu Sato

forming well-dispersed Ag nanoparticles in the titania matrix. This present Agnanoparticle/titania composite thin film is useful for fabrication of highly conductive

The importance of heat-treatment in the MPM was demonstrated through fabrication of thin films of anatase and rutile with unprecedentedly high photoreactivities. This is due to a photoreactive mechanism via O deficiency in the oxide thin films. Based on the excellent miscibilities of the molecular precursors in the SrTiO3 thin film fabrication, heat-treatment was shown to be an essential step. It eliminates organic ligands in the precursor metal complexes and provides important functions to the metal oxides in the chemical fabrication

The chemical fabrication of the first p-type Cu2O transparent thin film was also recently achieved using the MPM, although the heat-treatment of the spin-coated substrates resulted in the deposition of a large amount of powder on the substrates in previous sol–gel studies [96]. The electrical and optical properties of the Cu2O thin film fabricated using the MPM were consistent with those of similar thin films fabricated using physical procedures. It is very interesting that the charge on copper changes stepwise from +2 to +1 through 0 during heat-treatment of the precursor film involving a Cu–EDTA complex in an Ar gas flow. Based on these results, a transparent dry-type solar cell of area 20 × 20 mm2 with a combination of Vis-responsive anatase thin films was examined. This film is mentioned in the section **Vis-responsive anatase thin film fabricated using the MPM**. The structure of the solar cell was FTO electrode/n-Vis-responsive anatase/p-Cu2O/conductive polymer/Ag on a glass substrate, and the photovoltaic nature of the solar cell could be successfully measured under the light from a solar simulator. Thus, the present MPM is useful for fabricating Vis-responsive dry solar cells. The MPM coupled with heat-treatment of various precursor films allows transparent thin films of metal oxides such as Co3O4, ZnO, Ga2O3, and ZrO2 *etc.* to be examined and fabricated on glass and/or metallic substrates. The MPM has great potential as a fundamental technology for thin film fabrication by chemical

*Research Institute of Science and Technology, Kogakuin University, Nakano, Hachioji, Tokyo, Japan* 

This work was supported by MEXT\*-Supported Program for the Strategic Research Foundation at Private Universities, 2011-2015 (Kogakuin University–Energy Conversion Ecomaterials Center). \*Ministry of Education, Culture, Sports, Science and Technology

of Ag-nanoparticle/titania composite thin films with high conductivity.


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**Chapter 14** 

© 2012 Graça and Valente, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Graça and Valente, licensee InTech. This is a paper distributed under the terms of the Creative Commons

**Lithium Niobiosilicate Glasses Thermally Treated** 

The term glass comes from the latin word, vitrium, and refers to one of the oldest known material. It is defined in accordance with the ASTM C-169-92 norm, as an inorganic product obtained by quenching a melt until hardness conditions, without crystallization. This definition is however too restrictive because it only applies to glasses prepared by fusion method. A broader definition is that proposed by A. Paul: the glass shows the elastic behavior characteristic of the crystalline state and the behavior of the viscous liquid state. The most common properties of the glasses are the transparency to visible radiation, mechanical stability, inert at the biological level and dielectric material. However, due to the possibility of controlling the microstructure by changing the composition or by applying heat treatments, controlling the process of nucleation and crystallization, the properties of

The initial chemical composition is a factor, controllable, which allows to shape some of the properties of the glasses. In any glass, the units that define its structure can be divided into three categories, defined according to their structural function, network former; modifier and intermediate species. The formers are units that, without the addition of other elements, can form glass such as SiO2, B2O3, GeO2 and P2O5. The network modifiers, do not form glass by itself, but are often combined with a former. Examples of modifying elements are the alkaline elements (Li, Na, K, etc.) and alkaline-earth metals (Mg, Ca, etc.). The intermediate species are elements that can both play a role in forming or modifying the network (Al, Nb,

The formation of glass ceramics, for example by heat treatment of the as-prepared glass, shows at the technological level great advantages, for the single crystals and sintered ceramics, as the possibility of their properties (optical, electrical, mechanical, chemical, etc. ) be controlled via the volume fraction of the active phase dispersed in the matrix. For example, to maintain optical transparency, the process of nucleation and crystal growth

Manuel Pedro Fernandes Graça and Manuel Almeida Valente

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/50243

**1. Introduction** 

glasses can be modified.

etc.).

