Iordanova Reni, Gancheva Maria, Koseva Iovka, Tzvetkov Peter, Ivanov Petar
Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev, Str. Bld. 11, 1113 Sofia, Bulgaria.
Institute of Optical Materials and Technologies "Acad. Jordan Malinowski", Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria.
Materials (Basel). 2024 Jul 27;17(15):3724. doi: 10.3390/ma17153724.
CaWO nanoparticles were obtained by facile mechanochemical synthesis at room temperature, applying two different milling speeds. Additionally, a solid-state reaction was employed to assess the phase composition, structural, and optical characteristics of CaWO. The samples were analyzed by X-ray diffraction (XRD), transition electron microscopy (TEM), and Raman, infrared (IR), ultraviolet-visible (UV-Vis) reflectance, and photoluminescence (PL) spectroscopies. The phase formation of CaWO was achieved after 1 and 5 h of applied milling speeds of 850 and 500 rpm, respectively. CaWO was also obtained after heat treatment at 900 °C for 12 h. TEM and X-ray analyses were used to calculate the average crystallite and grain size. The Raman and infrared spectroscopies revealed the main vibrations of the WO groups and indicated that more distorted structural units were formed when the compound was synthesized by the solid-state method. The calculated value of the optical band gap of CaWO significantly increased from 2.67 eV to 4.53 eV at lower and higher milling speeds, respectively. The determined optical band gap of CaWO, prepared by a solid-state reaction, was 5.36 eV. Blue emission at 425 (422) nm was observed for all samples under an excitation wavelength of 230 nm. CaWO synthesized by the solid-state method had the highest emission intensity. It was established that the intensity of the PL peak depended on two factors: the morphology of the particles and the crystallite sizes. The calculated color coordinates of the CaWO samples were located in the blue region of the CIE diagram. This work demonstrates that materials with optical properties can be obtained simply and affordably using the mechanochemical method.
通过在室温下采用两种不同的研磨速度进行简便的机械化学合成，获得了钨酸钙纳米颗粒。此外，采用固态反应来评估钨酸钙的相组成、结构和光学特性。通过X射线衍射（XRD）、透射电子显微镜（TEM）以及拉曼光谱、红外（IR）光谱、紫外-可见（UV-Vis）反射光谱和光致发光（PL）光谱对样品进行了分析。分别在850和500 rpm的研磨速度下研磨1小时和5小时后，实现了钨酸钙的相形成。在900℃下热处理12小时后也获得了钨酸钙。使用TEM和X射线分析来计算平均微晶尺寸和晶粒尺寸。拉曼光谱和红外光谱揭示了WO基团的主要振动，并表明当通过固态方法合成该化合物时形成了更多扭曲的结构单元。在较低和较高研磨速度下，钨酸钙的光学带隙计算值分别从2.67 eV显著增加到4.53 eV。通过固态反应制备的钨酸钙的测定光学带隙为5.3 eV。在230 nm激发波长下，所有样品均在425（422）nm处观察到蓝色发射。通过固态方法合成的钨酸钙具有最高的发射强度。已确定PL峰的强度取决于两个因素：颗粒的形态和微晶尺寸。钨酸钙样品的计算色坐标位于CIE图的蓝色区域。这项工作表明，使用机械化学方法可以简单且经济地获得具有光学特性的材料。
