This paper describes an original and facile polyol-mediated solvothermal synthesis of elliptical iron glycolate nanosheets (IGNSs) combined with precursor thermal conversion into γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 porous nanosheets (PNSs), α-Fe2O3 nanochains (NCs), and elliptical Fe3O4 nanorings (NRs). The IGNSs were produced via the oxidation-reduction and co-precipitation reactions in the presence of iron(III) salts, ethylene glycol, polyethylene glycol, and ethylenediamine. Control over Fe(3+) concentration, temperature, and time can considerably modulate the size and phase of the products. The IGNSs can be transformed to γ-Fe2O3 and α-Fe2O3/γ-Fe2O3 PNSs, α-Fe2O3 NCs, and elliptical Fe3O4 NRs by heat treatment under various annealing temperatures and ambiences. The PNSs and NCs exhibited high soft magnetic properties and coercivity, respectively. Visible-light photocatalytic activity toward RhB in the presence of H2O2 by PNSs and NCs was phase-, SBET, size-, porosity-, and local structure-dependent, following the order: α-Fe2O3 NCs > α-Fe2O3/γ-Fe2O3 PNSs > γ-Fe2O3 PNSs > IGNSs. In particular, α-Fe2O3/γ-Fe2O3 PNSs possessed significantly enhanced photocatalytic activity with good recyclability and could be conveniently separated by an applied magnetic field because of high magnetization. We believe that the as-prepared α-Fe2O3/γ-Fe2O3 PNSs have potential practical use in waste water treatment and microwave absorption.

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Lanthanide-ion-based thermometers have been widely researched and utilized as contactless temperature sensing materials. Cooperating with the unique optical and excellent physical properties of transparent ceramics, Er 3+ /Yb 3+ co-doped Y 2 Zr 2 O 7 transparent ceramics were successfully fabricated as temperature sensing window materials. Homogeneous distribution of elements inside samples together with high transmittance (nearly 73%) makes it possible as an observing window. Upon excitation at 980 nm, room-temperature luminescent performance was systemically researched for explaining the energy transfer mechanism between Yb 3+ and Er 3+ ions. The FIR method was introduced for thermally coupled energy levels to realize temperature sensing ability. Detecting sensitivity at different temperatures was also calculated (1.24% K −1 at 303 K), suggesting that Yb 3+ , Er 3+ :Y 2 Zr 2 O 7 are adequate for high sensitivity temperature detecting application. It is also investigated that the concentration of Yb 3+ ions not only affects the emission color at room-temperature but also has influence on the sensitivity of temperature and 10 mol % Yb 3+ , 2 mol % Er 3+ :Y 2 Zr 2 O 7 was found to be the most sensitive one. A demonstration experiment was also carried out to validate its application as a smart temperature sensing window. These results suggested that Yb 3+ , Er 3+ :Y 2 Zr 2 O 7 transparent ceramics can have potential for temperature monitoring applications, especially as novel window materials under extreme circumstances.

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