Вплив форми фосфату Na4Ni3(PO4)2P2O7 на іонну провідність

• Дата: 2025
• Автори: Strutynska, N. Yu., Titov, Y. A., Kuzmin, R. M., Petrenko, O. V., Slobodyanik, M. S.
• Формат: Стаття
• Мова: Українська
• Опубліковано: Chuiko Institute of Surface Chemistry National Academy of Sciences of Ukraine 2025
• Онлайн доступ: https://www.cpts.com.ua/index.php/cpts/article/view/774
• Назва журналу: Chemistry, Physics and Technology of Surface

Complex phosphates of alkali and polyvalent metals due to variety of their structural types, compositions and properties are promising materials for various functional purposes, including components of sodium-ion batteries. It is known that the chemical composition and forms (single crystals, ceramics, nanoparticles) of materials have a significant influence on their properties. The aim of the work was the synthesis of various forms (single crystals or glass ceramics) of mixed-anion phosphate Na4Ni3(PO4)2P2O7, that is a promising cathode material, and investigation of the effect of the phosphate form on its ion-conducting properties. In this work, for the first time the synthesis of Na4Ni3(PO4)2P2O7 in glass ceramic form was carried out by melting method at the molar ratio Na2O : NiO : P2O5 = 2 : 3 : 2. Mixed anionic phosphate was also obtained in single crystal form by the crystallization of a high-temperature self-flux of Na2O-NiO-P2O5 system at molar ratios Na2O/P2O5 = 1.2 and Ni/P = 0.2. According to X-ray powder diffraction data the synthesized Na4Ni3(PO4)2P2O7 belongs to the orthorhombic system (space group Pn21a), and the calculated cell parameters are close to the corresponding data from the literature. The FTIR spectroscopy results confirm the presence of two types of anions (РО4 and Р2О7) in the synthesized phosphates. The investigation of the ionic conductivity of the synthesized single crystals and glass ceramic forms by the impedance spectroscopy method revealed that the single crystal and glass ceramic forms of phosphate Na4Ni3(PO4)2P2O7 are characterized by close specific conductivity values at the temperature of 400 K, but the value of the activation energy for the glass ceramic sample is two times smaller. In the case of pressed glass ceramics, the characteristics of phosphate deteriorate significantly. In the future, the results obtained can be used in the preparation of materials for sodium-ion batteries based on Na4Ni3(PO4)2P2O7 glass ceramics with improved ion-conducting characteristics.