سنتز هیدروترمال و خواص نوری نانورنگدانه ­های CoAl2O4

 Hydrothermal synthesis and optical property of nano-sized CoAl2O4 pigment

سنتز هیدروترمال و خواص نوری نانورنگدانه ­های CoAl₂O₄

ABSTRACT

Nano-sized CoAl2O4 was synthesized by hydrothermal method. The powder was characterized by XRD, DTA–TG, TEM, BET, IR, XPS, and UV–Vis techniques. The particle size was ca. 70 nm, and the particle size distribution was narrow. The BET surface area was 29.22 m2 g
1. It was thermally stable. The maximum absorption was f600 nm. D 2002 Elsevier Science B.V. All rights reserved . CoAl2O4 is a double oxide with a normal spineltype structure. It is well known as Thenard’s blue for its impressive optical property and widely used in the ceramics, glass, paint industry, and color TV tubes as contrast-enhancing luminescent pigment.CoAl2O4 pigment is usually synthesized at high temperature at solid state from a mixture of the two oxide components . However, the reaction involves processing temperatures > 1000 jC for extended time periods, which influences the pigment tonalities. Recently, various solution chemical synthesis techniques  have been utilized to prepare the pigment. Among them, the sol–gel process has big advantages for coating; hydrothermal synthesis can prepare powders without calcination. Various oxides and complex oxides with narrow particle size distribution, single phase, and controlled particle morphology have been synthesized by hydrothermal technique. However, little attention has been paid to preparing spinel oxides. No literature precedence, to our knowledge, is available on the synthesis of CoAl2O4 by this method. In this letter, the hydrothermal method is introduced to synthesize CoAl2O4. The results illustrate the effectiveness of the technique in producing the nano-sized and narrow size distribution pigments.