Titanium oxide, conductive titanium oxide, and processes for producing these

A process for producing titanium dioxide comprising the steps of:

• mixing titanium dioxide nucleus crystals, a titanium compound, an alkali metal compound and an oxyphosphorus compound prior to heating and firing, wherein:
• the titanium dioxide nucleus crystals have an aspect ratio of 5-40 and a weight-average major-axis length of 4.0-6.0 μm;
• the amount of titanium dioxide nucleus crystals used is in the range of 3-60 parts by weight of the total TiO2 content, and the amount of titanium compound used is in the range of 40-97 parts by weight of the total TiO2 content, and thus the total amount of titanium dioxide nucleus crystals and titanium compound is 100 parts by weight of the total TiO2 content;
• the amount of alkali metal compound used is 0.1-4 parts by weight based on 1 part by weight of the total TiO2 content in the mixture in terms of the alkali metal element;
• and
• the amount of the oxyphosphorus compound used is 0.01-0.6 parts by weight based on 1 part by weight of the total TiO2 content in the mixture in terms of phosphorus;
• and
• heating and firing the titanium dioxide nucleus crystals, the titanium compound, the alkali metal compound and the oxyphosphorus compound at 700-1000° C., thereby producing titanium dioxide in the shape of columnar particles, wherein:
• the ratio of weight-average major-axis length of the titanium dioxide nucleus crystals after growing to that of the titanium dioxide nucleus crystals used reaches 2-7,
• the particles have a weight-average major-axis length of 8.0-14.0 μm and the particles having a major-axis length of 10 μm or larger are included in a proportion of 35% by weight or more, and the particles have a specific surface area of 1.0-3.5 m2/g;
• the particles having a major-axis length of less than 5.0 μm are included in a proportion of 20% by weight or less;
• the particles having a major-axis length of 10-20 μm are included in a proportion of 25% by weight or more;
• the particles have a weight-average minor-axis length of 0.3-0.8 μm;
• and
• the aspect ratio (weight-average major-axis length/weight-average minor-axis length) is in the range of 5-40.