Yttrium nitrate hexahydrate

Yttrium nitrate hexa-hydrate (Y(NO₃)₃∙6H₂O, 99.8%), ytterbium nitrate penta-hydrate (Yb(NO₃)₃∙5H₂O, 99.9%), erbium nitrate penta-hydrate (Er(NO₃)₃∙5H₂O, 99.9%), sodium fluoride (NaF, ≥99.0%), diethylene glycol (DEG, 99.0%), polyacrylic acid, N-(3-dimethylaminopropyl)-Nʹ-ethylcarbodimide hydrochloride (EDC), and N-hydroxy-succinimide (NHS, 98.0%) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Sodium citrate (C₆H₅Na₃O₇∙2H₂O, >99.0%) was provided by APS Biotech, Seoul. Nitric acid (HNO₃, 60.0%) was purchased from Samchun (Seoul, Korea), ethyl alcohol (C₂H₅OH) was provided by Emsure (Billerca, MA, USA), and cetyltrimethylammonium bromide (CTAB, >99.0%) was obtained from Daejung (Seoul). Sodium hydroxide (NaOH) was obtained from KANTO chemical (Tokyo), and dimethylsulfoxide (DMSO, 99.9%) was provided by Alfa Aesar (Ward Hill, MA, USA). All the purchased reagents were of analytical grade. Solutions were prepared using deionized (DI) water (Direct–Q^® Water Purification System, Millipore, Billerica, MA, USA).

Yttrium nitrate hexahydrate (Y(NO₃)₃·6H₂O, 99.98%, Sigma Aldrich), Ammonium niobate oxalate hydrate (NH₄NbO(C₂O₄)₂·xH₂O, 99.99%, Sigma Aldrich), Zirconium oxychloride (ZrOCl₂·xH₂O, 99.9%, Alfa Aesar), Ruthenium chloride hydrate (RuCl₃·xH₂O, Ru 40–49%, Sigma Aldrich), Rhodium chloride hydrate (RhCl₃·xH₂O, Rh 38∼40%, Sigma Aldrich), Urea (CH₄N₂O, ≥99%, Sigma Aldrich), Ethylene glycol (HOCH₂CH₂OH, 99%, Sigma Aldrich), and Polyvinyl pyrrolidone -PVP ((C₆H₉NO)_n, MW = 55 kDa, Sigma Aldrich). All reagents are used as received, without further purification.

The Nd:YAB powder was obtained with citric acid (C₅O₇H₈, Sigma-Aldrich) as a complexing agent, d-sorbitol (C₆O₆H₁₄, Sigma-Aldrich 98%) as polymerizing agent, boric acid (H₃BO₃, Ecibra 99.5%), aluminum nitrate nonahydrate (Al(NO₃)₃.9H₂O, Vetec 98%), yttrium nitrate hexahydrate (Y(NO₃)₃.6H₂O, Sigma-Aldrich 99.8%), and neodymium hexahydrate (Nd(NO₃)₃.6H₂O, Sigma-Aldrich 99.8%) as precursors for B, Al, Y, and Nd, respectively. The synthesis of the material was achieved by dissolving aluminum, yttrium, and neodymium nitrates in an aqueous solution of citric acid at room temperature. This solution was added to another solution of d-sorbitol and boric acid dissolved previously in water. The obtained solution was annealed at 150 ^oC in an oven to occur the polymerization process and form a dried resin. The molar ratio of citric acid to elements (metals + boron) was 3:1. The citric acid/d-sorbitol mass ratio was set to 3:2. The dried resin was calcinated at 400 ^oC during 24 h, and heat-treated at 700 ^oC/24 h and at 1100 ^oC/1 h.

Sodium fluoride (98%, NaF), ammonium fluoride (99.8%, NH₄F), yttrium fluoride (99.9%, YF₃), yttrium nitrate hexahydrate (99.8%, Y(NO₃)₃·6H₂O), lanthanum nitrate hexahydrate (99.999%, La(NO₃)₃·6H₂O), and europium nitrate pentahydrate (99.9%, Eu(NO₃)₃·5H₂O) were obtained from Sigma-Aldrich. Dysprosium fluoride (99.9%, DyF₃) and europium fluoride (99.99%, EuF₃) were purchased from Strem Chemicals. Lanthanum fluoride (99.99%, LaF₃) and lutetium oxide (99.99%, Lu₂O₃) were acquired from ChemPUR. Ammonium oxalate monohydrate (99.7%, (NH₄)₂C₂O₄·H₂O) was obtained from Baker chemicals. Ammonium phosphate monohydrate (99%, (NH₄)₂HPO₄·H₂O) was acquired from Merck. Boric acid (99.8%, H₃BO₃) was purchased from Merck. MilliQ water (H₂O) was used for washing and the preparation of aqueous solutions.

Yttrium nitrate hexahydrate (99%) and acetylacetone (AcAc, 99.5%) were purchased from Sigma-Aldrich Inc. (St. Louis, MO, USA); zirconium propoxide (ZIP, 70% sol. in 1-propanol), lithium methoxide (LiOMe, 2.2M sol. in methanol), and tetramethyl orthosilicate (TMOS 99%) were purchased from Acros Organics (Acros Organics™, Thermo Fisher Scientific, Waltham, MA, USA). All reagents were used as received. Methanol, ethanol, and isopropanol were kept on 3A molecular sieves for 48 h and further distilled under dry nitrogen.