Difference Between Rutile and Anatase Titanium Dioxide

The key difference between rutile and anatase titanium dioxide is that rutile titanium dioxide has a deep red color appearance whereas the appearance of anatase titanium dioxide is colorless or white.

Titanium dioxide or TiO₂ is a very important mineral that has many favorable properties such as the production of titanium metal, to obtain TiO2 nanoparticles, etc. The different properties of the two major types of titanium dioxide, rutile and anatase) are discussed below.

CONTENTS

1. Overview and Key Difference
2. What is Rutile Titanium Dioxide
3. What is Anatase Titanium Dioxide
4. Side by Side Comparison – Rutile vs Anatase Titanium Dioxide in Tabular Form
5. Summary

What is Rutile Titanium Dioxide?

Rutile titanium dioxide or commonly rutile is a mineral that primarily has TiO₂ with a deep red appearance. It is the most abundant naturally occurring form of titanium dioxide due to its high stability. Rutile has polymorphs such as anatase, brookite, etc. Rutile mainly occurs in igneous rocks and metamorphic rocks that are in high temperatures and high-pressure conditions.

When considering the crystal structure of rutile, it has a tetragonal unit cell consist of titanium cations and oxygen anions. There, the titanium cations (Ti⁺⁴) in these cells have a coordination number of 6. The oxygen anion (O^2-) has the coordination number 3. The most important properties of rutile are as follows:

• High refractive index at visible wavelengths
• Large birefringence
• High dispersion

The three main uses of rutile are to produce refractory ceramics, to produce titanium dioxide pigments and for the production of titanium metal. In addition, finely powdered rutile is important in producing paints, plastics, and paper. That is because the finely powdered rutile has a brilliant white color. Moreover, nao-TiO₂ particles are used in cosmetic industry because these particles are transparent to visible light and can absorb UV light at the same time.

What is Anatase Titanium Dioxide?

Anatase titanium dioxide is a form of TiO₂  that has an appearance with yellow to blue color. This mineral occurs as a black solid in nature. This dark color is due to the presence of impurities. Otherwise, it is colorless or white.

Anatase occurs with a tetragonal crystal system but it does not resemble the arrangement of atoms of rutile (they have different arrangements). Anatase is optically negative (while rutile is optically positive). It has a metallic appearance when compared to the appearance of rutile. Sometimes, manufacturers produce this mineral as a synthetic compound because it has many applications in producing semiconductors. Ex: sol-gel method involves the production of anatase type TiO₂. There, hydrolysis of titanium tetrachloride (TiCl₄) involves.

What is the Difference Between Rutile and Anatase Titanium Dioxide?

Rutile vs Anatase Titanium Dioxide
Rutile titanium dioxide or commonly rutile is a mineral that primarily has TiO2 with a deep red appearance.	Anatase titanium dioxide is a form of TiO2 that has an appearance with yellow to blue color.
Color
It has a deep red color and finely powdered rutile has a brilliant white color.	It has a dark color when impurities present, but the pure form is colorless or white.
Optical Activity
Rutile is optically positive.	Anatase is optically negative.
Occurrence
Rutile is the most abundant form of titanium dioxide in nature.	Anatase is less abundant in nature when compared to rutile.
UV Absorption
The UV absorption by rutile is high.	The UV absorption by anatase is low.
Hardness
The hardness of rutile is high.	Anatase is less hard.
Specific Gravity
The specific gravity of rutile is high.	The specific gravity of anatase is low.

Summary – Rutile vs Anatase Titanium Dioxide

Rutile and anatase are two mineralogical terms that give the two major forms of naturally occurring titanium dioxide. The difference between rutile and anatase titanium dioxide is that rutile titanium dioxide has a deep red color appearance whereas the appearance of anatase titanium dioxide is colorless or white.

Reference:

1. “Rutile.” Wikipedia, Wikimedia Foundation, 7 May 2018. Available here
2. “Anatase.” Wikipedia, Wikimedia Foundation, 2 May 2018. Available here  
3. User, Super. “Titanium Dioxide Powder (Rutile Grade) (TiO2).” Cerium Oxide Powder (CeO2). Available here

Image Courtesy:

1.’Rutile-tuc1055c’By Rob Lavinsky (C BY-SA 3.0) via Commons Wikimedia  
2.’Anatase-107152’By Christian Rewitzer, (CC BY-SA 3.0) via Commons Wikimedia