Date of Award

5-2007

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Chemistry

Advisor

Hwu, Shiou-Jyh

Abstract

Due to the excellent diverse properties and performance, solid-state material with low-dimensional crystal structure has always been interested by solid-state scientists. Besides the interesting properties, the low-dimensional-structured materials are used as the platform for further research and application of semiconductor and optical devices, as well as theoretic studies. My dissertation research mainly focuses on two aspects: discovery of solids with low-dimensional crystal structure; fabrication and investigation of new materials using the discovered materials as the platform.
The idea of mixed-anion-framework has been used in synthesis of novel low-dimensional-structured solid-state materials. The stereo-active Sb3+/Bi3+ chalcogenides building units and their halogen-containing derivatives have been applied for the new structure search and design. Four chalcohalides families with novel structures: CdMQ2X; CdSb2Se3Br2; InM2Q4X (M = Sb, Bi; Q = S, Se; X = Cl, Br and I); In2Bi3Se7I and one new discovered oxyhalide LiSb2O3Cl have been designed, synthesized and characterized. Two DMS systems -- Mn-doped CdBiS2Cl and CdBiSe2I with confined crystal structures have been fabricated and characterized; the ferromagnetism has been firstly observed in the discussed chemical system. Also, the correlation between magnetism and structure has been investigated and rationalized.
In this thesis, the exploratory synthetic work (conceptual structure design and crystal growth), the characterization of properties (X-ray crystal structure analysis, optical, and magnetic studies) and the theoretic calculation (band structure and bond valance analysis) will be discussed in details.

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