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Zirconium dioxide (ZrO 2 ), sometimes known as zirconia (not to be confused with zirconium silicate or zircon ), is a white crystalline oxide of zirconium . Its most naturally occurring form, with a monoclinic crystalline structure , is the mineral baddeleyite .
Discovered in 1892, the yellowish monoclinic mineral baddeleyite is a natural form of zirconium oxide. [2] The high melting point of zirconia (2750 °C or 4976 °F) hinders controlled growth of single crystals. However, stabilization of cubic zirconium oxide had been realized early on, with the synthetic product stabilized zirconia introduced ...
Metal toxicity or metal poisoning is the toxic effect of certain metals in certain forms and doses on life.Some metals are toxic when they form poisonous soluble compounds. . Certain metals have no biological role, i.e. are not essential minerals, or are toxic when in a certain for
Side effects may include sun sensitivity, skin redness, thickening, or itching. [6] Low concentrations may be used in cosmetics. [6] Kojic acid has been found to be an effective lightener in some studies and is also allowed to be used in cosmetics. [6] Side effects include redness and eczema. [6]
Castor oil and its derivatives are found in many cosmetics as it is "non-comedogenic" (does not exacerbate or contribute to acne). [3]Cerebrosides (cells from the nervous systems of cattle or swine) were once used in some high-end skin-care products to increase moisture retention and to create a smooth skin surface, [4] however the BSE controversy has put an end to this practice.
“These products shouldn’t even have these flame retardants to begin with,” she says. “They’re still associated with cancer, neurological effects and developmental harm.”
Zirconium compounds have no known biological role, though the element is widely distributed in nature and appears in small quantities in biological systems without adverse effects. There is no indication of zirconium as a carcinogen. The main hazards posed by zirconium are flammability in powder form and irritation of the eyes.
Yttria-stabilized zirconia (YSZ) is a ceramic in which the cubic crystal structure of zirconium dioxide is made stable at room temperature by an addition of yttrium oxide. These oxides are commonly called "zirconia" ( Zr O 2 ) and "yttria" ( Y 2 O 3 ), hence the name.