TY - JOUR
T1 - Identification of a Pb-related Ti3+ center in flux-grown KTiOPO4
AU - Stevens, K. T.
AU - Halliburton, L. E.
AU - Roth, M.
AU - Angert, N.
AU - Tseitlin, M.
PY - 2000/12
Y1 - 2000/12
N2 - Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) have been used to identify a new Ti3+ center in KTiOPO4 crystals containing lead impurities. Many of the K+ vacancies in this set of KTP crystals are compensated nonlocally by Pb2+ ions substituting for K+ ions. During exposure to ionizing radiation (either 60 kV x rays or 355 nm photons from a tripled Nd:YAG laser), "free" electrons are trapped on Ti4+ ions near isolated Pb2+ ions, thus forming the perturbed Ti3+ ions observed with EPR and ENDOR. Four distinct Pb-related Ti3+ centers are formed by a 77 K irradiation, but only one remains after a 5 min anneal at 180 K. This latter defect, labeled the [Ti3+-Pb2+]A center, is thermally unstable above 250 K. Angular dependence data were used to determine the g matrix, one 207Pb hyperfine matrix, and two 31P hyperfine matrices for the [Ti3+-Pb2+]A center. More generally, we note that oxygen-vacancy-associated Ti3+ centers could not be formed in these Pb-containing KTP crystals. Replacing oxygen-vacancy-associated Ti3+ centers with the less stable [Ti3+-Pb2+] centers is expected to increase the gray-track resistance of KTP crystals used to generate the second harmonic of high power, near-infrared lasers.
AB - Electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) have been used to identify a new Ti3+ center in KTiOPO4 crystals containing lead impurities. Many of the K+ vacancies in this set of KTP crystals are compensated nonlocally by Pb2+ ions substituting for K+ ions. During exposure to ionizing radiation (either 60 kV x rays or 355 nm photons from a tripled Nd:YAG laser), "free" electrons are trapped on Ti4+ ions near isolated Pb2+ ions, thus forming the perturbed Ti3+ ions observed with EPR and ENDOR. Four distinct Pb-related Ti3+ centers are formed by a 77 K irradiation, but only one remains after a 5 min anneal at 180 K. This latter defect, labeled the [Ti3+-Pb2+]A center, is thermally unstable above 250 K. Angular dependence data were used to determine the g matrix, one 207Pb hyperfine matrix, and two 31P hyperfine matrices for the [Ti3+-Pb2+]A center. More generally, we note that oxygen-vacancy-associated Ti3+ centers could not be formed in these Pb-containing KTP crystals. Replacing oxygen-vacancy-associated Ti3+ centers with the less stable [Ti3+-Pb2+] centers is expected to increase the gray-track resistance of KTP crystals used to generate the second harmonic of high power, near-infrared lasers.
UR - http://www.scopus.com/inward/record.url?scp=0006542033&partnerID=8YFLogxK
U2 - 10.1063/1.1315624
DO - 10.1063/1.1315624
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AN - SCOPUS:0006542033
SN - 0021-8979
VL - 88
SP - 6239
EP - 6244
JO - Journal of Applied Physics
JF - Journal of Applied Physics
IS - 11
ER -