Crystallization process of transparent conductive oxides Zn(k)In2O(k+3)

Area of Science:

• Materials Science
• Solid-State Chemistry
• Inorganic Chemistry

Background:

• Understanding the crystallization of homologous compounds is crucial for materials synthesis.
• The specific crystallization pathways of mixed metal oxides like Zn(k)In2O(k+3) are not fully elucidated.
• Previous studies have not detailed the sequential crystallization and structural evolution of these specific compounds.

Purpose of the Study:

• To investigate the crystallization process of homologous compounds Zn(k)In2O(k+3) derived from coprecipitants.
• To analyze the structural transformations of zinc oxide (ZnO) and indium oxide (In2O3) during the formation of Zn(k)In2O(k+3).
• To determine the influence of temperature on the crystallization behavior and interatomic distances.

Main Methods:

• X-ray Absorption Fine Structure (XAFS) spectroscopy was employed to probe local atomic environments.
• X-ray diffractometry (XRD) was used to identify crystalline phases and structures.
• Thermal analysis was conducted to observe phase transitions at different temperatures.

Main Results:

• Zinc oxide crystallized into wurtzite-type ZnO at 573K, while indium oxide remained amorphous.
• Bixbyite-type In2O3 appeared at specific temperatures (873K for k=5, 7; <773K for others).
• The In-O bond distance initially shortened in amorphous In2O3, then increased upon crystallization, and finally decreased to ~2.12A at 1173-1373K due to ZnO reaction.

Conclusions:

• The crystallization of Zn(k)In2O(k+3) involves distinct sequential steps for ZnO and In2O3.
• The observed changes in In-O bond distances reflect structural evolution and the final reaction between In2O3 and ZnO.
• This study provides insights into the formation mechanism of these homologous compounds, relevant for tailored material design.