Access Type

Open Access Embargo

Date of Award

January 2020

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Chemistry

First Advisor

Federico A. Rabuffetti

Abstract

Thermosensitive phosphors are being continuously developed as luminescent thermal probes owing to their ability to function under inaccessible conditions with high spatial resolution. However, their practical implementation requires developing thermosensitive phosphors with adequate figures‐of‐merit (i.e., thermometric sensitivity, temperature resolution, and operational temperature range) for intended applications and temperature ranges. From this perspective, it is critical to place emphasis on the rational design and exploratory synthesis of novel thermosensitive phosphors with targeted thermometric performance characteristics. Expanding the current knowledge on thermosensitive phosphors by (1) screening potential host and activator combinations and (2) identifying chemical and structural features affecting the thermometric functionality are critical tasks in this regard. The work presented in this dissertation aims at reaching these tasks by employing Na4Mg(WO4)3 and La3MWO10 (M = Nb, Ta) as chemically and structurally tunable group V and VI d0 metal oxide hosts. Solid‐state synthesis, structural characterization, and variable‐temperature luminescence response of Mn4+:Na4Mg(WO4)3, Tb3+:Mn4+:Na4Mg(WO4)3, Eu3+:La3NbWO10, and Tb3+:Pr3+:La3TaWO10 phosphors are reported. Thermometric performance of these phosphors are evaluated under bandshift, dual‐activator ratiometric, single‐activator ratiometric, and dual‐activator ratiometric approaches, respectively. In particular, the effects of structural disorder of the host and multisite distribution of the activators on the thermometric functionality are discussed. Structural and chemical features affecting the thermometric response are identified with the aim of providing guidelines to design future thermosensitive phosphors. The significance of further exploring group V and VI metal oxides as hosts for thermosensitive phosphors in combination with appropriate activators is emphasized.

Available for download on Thursday, January 27, 2022

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