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Akaogiite (IMA symbol Aka [1]) is an exceedingly rare mineral, one of the natural forms of titanium dioxide (TiO 2). It is a high-pressure polymorph of TiO 2, along with anatase, brookite and another high-pressure phase called "TiO 2 II". [2] [3] [4] Rutile is the stable polymorph of TiO 2, most commonly found at standard temperatures and ...
Titanium dioxide, also known as titanium(IV) oxide or titania / t aɪ ˈ t eɪ n i ə /, is the inorganic compound derived from titanium with the chemical formula TiO 2. When used as a pigment, it is called titanium white, Pigment White 6 (PW6), or CI 77891. [4] It is a white solid that is insoluble in water, although mineral forms can appear ...
Brookite is the orthorhombic variant of titanium dioxide (TiO 2), which occurs in four known natural polymorphic forms (minerals with the same composition but different structure). The other three of these forms are akaogiite ( monoclinic ), anatase ( tetragonal ) and rutile ( tetragonal ).
Anatase is metastable at all temperatures and pressures, with rutile being the equilibrium polymorph. Nevertheless, anatase is often the first titanium dioxide phase to form in many processes due to its lower surface energy, with a transformation to rutile taking place at elevated temperatures. [7]
Rutile is an oxide mineral composed of titanium dioxide (TiO 2), the most common natural form of TiO 2. Rarer polymorphs of TiO 2 are known, including anatase, akaogiite, and brookite. Rutile has one of the highest refractive indices at visible wavelengths of any known crystal and also exhibits a particularly large birefringence and high ...
Following the success of platinum-based chemotherapy, titanium(IV) complexes were among the first non-platinum compounds to be tested for cancer treatment. The advantage of titanium compounds lies in their high efficacy and low toxicity in vivo. [24] In biological environments, hydrolysis leads to the safe and inert titanium dioxide.
Phase transitions (phase changes) that help describe polymorphism include polymorphic transitions as well as melting and vaporization transitions. According to IUPAC, a polymorphic transition is "A reversible transition of a solid crystalline phase at a certain temperature and pressure (the inversion point) to another phase of the same chemical composition with a different crystal structure."
The two phases have the same average composition but different density, molecular structure and hardness. [14] However whether the second phase is glassy or crystalline is also debated. [15] Continuous changes in density were observed upon cooling silicon dioxide or germanium dioxide. Although continuous density changes do not constitute a ...