Manganese tungstate (MnWO4) nanoparticles were synthesized at room temperature by chemical precipitation method. The effect of high energy electron beam (EB) irradiation on the optical properties of MnWO4 nanoparticles was investigated. The absorption spectra, photoluminescence intensity, and Raman bands of the irradiated samples were modified, which has been attributed to defects and particle size variation. The present investigation found that the beam irradiation is a new and efficient method to enhance the optical absorption performance and photoactivity of MnWO4 nanoparticles. 1. Introduction Nanostructured tungstate materials have aroused much interest because of their luminescence behaviour, structural properties, and potential applications. MnWO4 has bulk electrical conductivity, relatively low melting point, novel magnetic property, and photocatalytic property [1, 2]. The optical and luminescence properties of MnWO4 have received great attention as they are widely used as scintillating detectors in high-energy particle physics, rare-event searches, and medical diagnosis [3]. The electrical conductivity of MnWO4 is also sensitive to changes in humidity, thereby making it useful as a humidity sensor with potential applications like meteorology, medicine, food production, agriculture, and industrial and domestic environment [4, 5]. There are a number of processes used to synthesize nanocrystalline MnWO4, such as microwave-assisted synthesis [1], surfactant-assisted complexation-precipitation method [2], melt solution process [6], solvothermal route [7], aqueous salt metathesis reaction [8], sol-gel technique [4, 9], ambient template synthesis [10], and solid state metathetic approach [11]. In the present work, manganese tungstate nanoparticles are synthesized by careful control of the reaction kinetics of aqueous precipitation. As-prepared MnWO4 nanoparticles are characterized by X-ray diffraction [XRD], transmission electron microscopy [TEM], UV-Visible absorption spectroscopy, photoluminescence [PL] spectroscopy and Raman spectroscopy. In addition, the optical properties of the pure and EB irradiated samples of MnWO4 nanoparticles were evaluated in context of the band gap. 2. Experimental Details Manganese chloride (MnCl2 4H2O) (99.8%, Sigma Aldrich) and sodium tungstate (Na2WO4 2H2O) (99.9%, Alfa Aesar) were used without further purification for the synthesis of MnWO4. Distilled water was used in all synthesis procedures. 2.1. Preparation of the Samples The synthesis procedures for the preparation of MnWO4 nanoparticles used in this work has
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