Dopant positions in strontium/chromium- and barium-doped KTP, determined with synchrotron X-radiation
Structure factors for strontium/chromium- (Sr/Cr) and barium- (Ba) doped potassium titanyl phosphate (KTiOPO(4), KTP) were measured with focused synchrotron X-radiation [0.75000 (9) A] using a fast avalanche photodiode counter. Space group Pna2(1), Z = 8, a = 12.786 (2), b = 6.3927 (8), c = 10.5585 (9) A, T = 293 (1) K, R = 0.028 (SrCrKTP); a = 12.851 (6), b = 6.418 (3), c = 10.620 (5) A, T = 120 (1) K, R = 0.031 (BaKTP). The refinement of the dopant positions showed that Ba(2+) is positioned in the larger of the two K cavities of KTP, while the smaller Sr(2+) ion is located in both. Split positions are found for the strontium dopant in both cavities and they are located in the positive c direction from the potassium cation. The chromium dopant has two different oxidation states, namely +III and +VI; in both states the dopant is located inside the TiO(6) octahedra. The two structures show slightly less distorted TiO(6) octahedra than pure KTP.
Norberg
ST
Inorganic Chemistry, Chalmers University of Technology, SE-412 96 Goteborg, Sweden. stn@inoc.chalmers.se.
Streltsov
VA
Svensson
G
Albertsson
J