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Yttrium is commonly found in rare-earth minerals and some uranium ores, but it is never found freely in the Earth's crust. With a concentration of about 31 ppm, it ranks as the 28th most abundant element, making it significantly more common than silver. Due to its chemical similarity to lanthanides, yttrium is extracted from the same ores and through similar refinement processes. It has an electronic configuration of [Kr]4d1 5s2, with 39 electrons. Yttrium typically forms a 13 oxidation state, resulting from the loss of electrons from its 5s and 4d subshells.
Yttrium isotopes, particularly 91Y and 90Y, are important products of uranium nuclear fission in nuclear reactions. The most stable isotope is 89Y, which is naturally occurring and more abundant due to the s-process, allowing for decay of other isotopes formed by different processes.
To obtain pure yttrium from mixed oxide ores, a common method involves dissolving the oxide in sulfuric acid, followed by fractionation through ion-exchange chromatography. Yttrium oxalate is precipitated by adding oxalic acid, which is then converted to oxide by heating in the presence of oxygen. Reacting the resulting yttrium oxide with hydrogen fluoride produces yttrium fluoride. By using quaternary ammonium salts as extractants, high-purity yttrium salts can be obtained.
Yttrium is found in approximately a hundred different minerals, including halides, oxides, carbonates, phosphates, and silicates. Some examples include chukhrovite-(Y), fergusonite-(Y), bastnasite-(Y), and xenotime-(Y). These minerals showcase the diverse crystal structures that can incorporate yttrium, highlighting its versatility in nature.
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