Hydrogenation and Dopant Concentration-Dependent Structural, Optical, and Magnetic Properties of Synthesized Manganese/Aluminum–Codoped Anatase Nanoparticles

Abstract

Abstract In the present work, titanium oxide (TiO2) codoped with 2 at % and 5 at % manganese/aluminum nanoparticle samples were synthesized by a coprecipitation method. The effects of manganese/aluminum dopant concentrations and hydrogenation temperatures on the structural, optical, and magnetic properties of the synthesized nanoparticles were studied. The investigation was aimed at considering manganese dopant ions as the foundation of stable magnetic properties and using Al3+ ions to supply itinerant electrons to study and synthesize a dilute magnetic semiconductor based on TiO2. The synthesized doped nanopowders were studied by several methods: X-ray diffraction, optical absorption spectroscopy, and magnetic measurements. It was established that the Anatase structure was the main structure of the synthesized codoped powders. The dopant and the hydrogenation did not introduce qualitative change in the phase structure of the powder. It was found that the hydrogenation increased the crystallite size, and the high-temperature hydrogenation (500°C) deteriorated the crystalline structures. The optical study was aimed at investigating the formation of F+-centers. The shift in the optical absorption edge was explained in terms of the Urbach and Moss-Burstein effects. The magnetic energy parameter was calculated to compare the strength of the resulting room-temperature ferromagnetic ordering in the samples. The greatest saturation magnetization parameter was 0.005 μB/manganese for the sample with the lower studied doping level (2 %) and hydrogenated (H) at low temperature (400°C); TiO2: 2 % manganese: aluminum–H (hydrogenated). The magnetic saturation magnetization was lowered for a higher doping level and higher hydrogenation temperature (500°C).