Identification of Ti3+in potassium titanyl phosphate and its possible role in laser damage

摘要

Four related Ti3+centers in potassium titanyl phosphate (KTiOPO4or KTP) may be created with either application of dc electric fields or with hydrogen at 800thinsp;deg;C. Singlehyphen;crystal electron paramagnetic resonance allows determination of thegtensors of the four centers. Hyperfine coupling is observed with one47,49Ti and two (nearly) equivalent31P. The most abundant center is characterized bygx=1.7709(5),gy=1.8723(5),gz=1.9462(5), principal values of Verbar;ATiVerbar; of 80, 33, and 24 MHz, and axially symmetricAPrsquo;s with principal values of 16.3 and 21.8 MHz. Optical absorption centered at 13thinsp;000ndash;18thinsp;000 cmminus;1is quite broad, relatively strong, and approximately twice as intense for light whose electric vector is polarized parallel tocas it is foraorb. A charge transfer mechanism in addition todminus;dtransitions may account for the absorption. Ti3+is much more difficult to produce in hydrothermally grown KTP than in fluxhyphen;grown KTP, a difference ascribed to the presence of oxygen vacancies or interstitial potassium in the latter. Similarities in the energy and polarization of optical absorption suggest that coloration induced by laser damage is due also to Ti3+.