High temperature reactions of boron oxide and nickel with copper (I and II) or silver oxide

Abstract

The high temperature reactions between boron oxide and oxides of Cu(l), Cu(lI) and Ag(l) have been investigated in a nickel crucible at 1100°C in air. The ternary systems containing metallic nickel gave glassy products in two layers. Compositions of the fusion products have been determined by XRD, SEM, TEM, IR and chemical analyses and reaction pathways have also been elucidated.The reactions between CuO and B₂O₃ yield Cu₂Oand only Cu(l) borates, CuBO₂ or β -Cu₂B₄O₇ instead of CuO(II) borates, indicating predominant decomposition of CuO into CU₂O.The glasses obtained from Cu₂O and B₂O₃ give Cu(I) metaborate and the unexpected Cu(lI) metaborate CuO.B₂O₃ which can be decomposed to yield CU₂Oand CuBO₂. From the ternary Ag₂O-B₂O₃-Ni system, the only borates obtained are nickel borates . Nickel borates, unexpectedly rich in NiO content, 2NiO. B₂O₃ or 3NiO. B₂O₃, are observed in most glasses. Although the products do not show any significant electrical conductivity or magnetic properties, the hardness of material increases due to the presence of CuBO₂, β-Cu₂B₄O₇or CuB₂O₄ By controlling the reaction conditions the formation of such compounds can be ensured to obtain harder materials.