| Abstract
| - A thorough study of the RbTiOPO4(RTP) crystallization in its self-flux and WO3-containingfluxes (10, 20, and 30 mol % WO3) has been performed. The composition regions and isothermsof crystallization were obtained, and most of the crystallized neighboring phases wereidentified. Afterward, the possibilities of doping and codoping RTP crystals with Er3+ andNb5+ were studied. Adding Nb2O5 substituting TiO2 in the solution increases the distributioncoefficient of Er3+ but changes the crystal morphology toward thin plates significantly. Thismeans it is difficult to grow crystals of sufficient quality and size for research andapplications. To optimize the crystal growth process, the conditions for growing doped andcodoped RTP single crystals with Er3+ and Nb3+ by the top seeded solution growth technique(TSSG) were studied. For crystal growth from self-flux, stirring the solution with an immersedplatinum turbine significantly increased the efficiency of the crystal growth process. Theseconditions allow achieving 0.65 × 1020 atom·cm-3 as an Er3+ dopant concentration in thecrystal. The Judd−Ofelt parameters for Er3+ in RTP:Nb determined from the 300 K opticalabsorption spectra are Ω2 = 5.99 × 10-20, Ω4 = 0.54 × 10-20, and Ω6 = 0.37 × 10-20 cm2.Finally, the second harmonic generation (SHG) efficiency of RTP:Nb single crystals increasedas the concentration of Nb increased up to a 4 atom % of Ti4+ substitution, after which theSHG efficiency decreased.
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