Characterization of phases in the V2O5–Yb2O3 system obtained by high-energy ball milling and high-temperature treatment

Abstract

It has been demonstrated that apart from the known compounds YbVO 4 and Yb 8 V 2 O 17 , a substitutive solid solution is also formed in the binary oxide system V 2 O 5 -Yb 2 O 3 . This solid solution is characterized by limited solubility of vanadium(V) oxide in the crystal lattice of ytterbium oxide, and its general formula is Yb 2-5x h 2x V 3x O 3 , where 0.00 \ x \ 0.1667. The new solid solution was obtained from the mixtures of V 2 O 5 and Yb 2 O 3 oxides, containing vanadium(V) oxide in the amounts not exceeding 30 mol%, by high-energy ball milling in a planetary ball mill. The solid solution obtained was characterized using the methods XRD, DTA-TG, SEM, IR and UV-Vis-DR. It was found to crystallize in cubic system and to show a structure of Yb 2 O 3 . This solid solution was stable in air atmosphere at least up to * 800°C, and the temperature of its decomposition decreased with increasing x, so with increasing degree of Yb 3? replacement with V 5? in the crystal lattice of Yb 2 O 3 . The energy gap estimated for this solid solution varied from * 2.5 eV for x = 0.0322 to * 2.6 eV for x = 0.1176, which means that this new solid solution is a semiconductor.

Mechanochemical synthesis and thermal stability of phases in the Y2O3–Yb2O3 system

“…In view of growing depletion of natural resources and increasing cost of energy, rationalization of production processes has become an urgency [1][2][3][4]. A method for production of new materials proposed as an alternative to high-temperature treatment, sol-gel, hydrothermal, sonochemical or Pechini processes is mechanochemical synthesis [1][2][3][4][5][6][7][8][9][10][11]. Its main advantage is simplicity as the method is based on milling of all kinds of reagents in high-energy mills [1,2,4,8,9].…”

“…The mechanical energy generated upon milling is supplied to the substrates and accumulated in them in the form of all kinds of lattice stresses which can increase their reactivity. The process of high-energy milling can lead to very fine comminution of the product, often to nanosize particles [1,4,9]. Moreover, the mechanochemical method can lead to materials whose syntheses by other methods have failed [9].…”

“…The process of high-energy milling can lead to very fine comminution of the product, often to nanosize particles [1,4,9]. Moreover, the mechanochemical method can lead to materials whose syntheses by other methods have failed [9]. Such materials include solid solutions.…”

“…Such materials include solid solutions. According to the literature data, the solid solutions obtained by mechanochemical method often show a greater range of homogeneity than those obtained by the solid-state reactions [8,9].…”

Preface

“…In this context, O'Quinn and coworkers apply in our next paper a very powerful analytical method (High-resolution Neutron Total Scattering experiments with Pair Distribution Function (PDF) analysis), to compare short-versus long-range structural features of a multicomponent oxide, pyrochlore-type Er 2 Ti 2 O 7 , obtained by two different powder processing methods: conventional solid-state reaction at high temperature and mechanical milling [7]. Our next group of papers deals with mechanochemical effects in the synthesis, structure and properties of a wide variety of inorganic systems including metal alloys [8][9][10][11][12][13][14], oxides [15][16][17][18] and composites [19][20][21]; these studies include for example using cryomilling (milling attrition of powders with a cryogenic medium) to obtain nanocrystalline highentropy alloys [8], a shaker mill to produce nonequilibrium alloys in immiscible systems at room temperature [9], obtaining nanoparticulated LiFeM 2-O 6 (M = Ge, Ti) pyroxenes [18] and assessing the reactivity of highly exothermic metal oxide thermitetype composites subjected to mechanical activation [20], to mention some. Another group of papers studies the synthesis and properties of lanthanidedoped silicon nitride nanowires [22], Ti and Hf carbides [23], Ni boride [24], Zr boride ceramics [25] and Cu-and Sn-based sulfides [26,27].…”