Date of Award

2016

Document Type

Open Access Dissertation

Department

Chemistry and Biochemistry

Sub-Department

College of Arts and Sciences

First Advisor

Hans-Conrad zur Loye

Second Advisor

Daniel Reger

Abstract

Exploratory crystal growth is a versatile technique and one that can advance materials discovery. Through exploratory crystal growth, it is possible to synthesize many new materials that can have applications in many fields, including solid-state lighting. There exist many adaptations for exploratory crystal growth, including the use of alkali halide flux growth and hydroflux growth, both reported herein. By changing variants in these techniques like reactant ratios, temperature, reaction profile, and, most importantly here, the flux compositions, it is possible to change the products formed or fine tune reactions for product purity.

For solid-state lighting applications, compounds that adopt colorless frameworks, like tungstates, germanates, and silicates are of interest. Herein, we report on the synthesis, structure determination and physical property measurements of Na5Ln(OH)6WO4 (Ln = Er, Tm, Yb), Na5Ln4F[GeO4]4 (Ln = Pr, Nd), NaxLn10-x(SiO4)6O2- yFy, CaxLn10-x(SiO4)6O2-yFy (Ln = Nd, Sm, Eu, Gd), Gd9.34(SiO4)6O2, K1.32Pr8.68(SiO4)6O1.36F0.64, Na5Ln4F[SiO4]4 (Ln = Pr, Nd, Sm-Tm), K5Pr4F[SiO4]4, K3LnSi2O7 (Ln = Sm, Y), Na3LnSi2O7 (Ln = Ho, Yb), NaLnSiO4 (Ln = La, Yb), K5Ln2Si4O13F (Ln = Y, Sc), and Cs3LnSi4O10F2 (Ln = Gd, Tb, Dy). These new compositions have been studied for magnetic properties, second harmonic generation, and optical properties, including fluorescence quantum yield, when practical.

Antiferromagnetic ordering has been observed in Na5Tb4F[SiO4]4 and Na5Dy4F[SiO4]4. The Na5RE4F[SiO4]4 (RE = Pr, Sm-Tm) series exhibits second harmonic generation and fluorescence has been observed in NaEu9(SiO4)6O2, Na1.5Eu8.5(SiO4)6OF, Eu9.34(SiO4)6O2, Gd9.34(SiO4)6O2, Na5Eu4F[SiO4]4, Na5Gd4F[SiO4]4, Na5Tb4F[SiO4]4, and K3YSi2O7. Fluorescence quantum yield was measured on Na5Eu4F[SiO4]4, Na5Gd4F[SiO4]4, and Na5Tb4F[SiO4]4. The optical properties are exciting as they indicate that a silicate material, composed of the earth abundant element silicon, may be able to be used as a framework for new potential phosphor coatings for light emitting diodes (LEDs). Using silicate materials as new host structures could decrease the cost of LEDs.

Included in

Chemistry Commons

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