Transparent glass and glass‐ceramic in the binary system NaPO₃‐Ta₂O₅

Abstract

Transparent and homogeneous tantalum phosphate glasses were prepared in the binary system (100‐x)NaPO3‐xTa2O5 with x varying from 10 to 50 mol%. Thermal, structural, and optical properties, as well as crystallization mechanisms, were investigated by thermal analysis, X‐ray diffraction, Fourier‐transform infrared spectroscopy (FTIR) and Raman spectroscopies, optical absorption, transmission electron microscopy in terms of Ta2O5 content. FTIR and Raman results support the tantalum insertion in the phosphate chains with [TaO6] polyhedra cross‐linking the phosphate units. At higher Ta2O5 content, [TaO6] clusters are formed and connected to the phosphate network by P‐O‐Ta bonds. This structural evolution is in good agreement with the thermal features measured by differential scanning calorimetry (DSC) with a strong increase of the Tg temperatures up to 920°C, high thermal stability against crystallization for low Ta2O5 content and increasing of crystallization tendency for the most Ta‐concentrated samples. Besides, due to the progressive insertion of [TaO6] units, the precipitation of Na2Ta8O21 perovskite‐like phase was identified in the sample with 50 mol% of Ta2O5. The optimal heat treatment conditions were identified using DSC measurements and a transparent glass‐ceramic from 50NaPO3 to 50Ta2O5 composition was prepared. The obtaines glass‐ceramic has great potential for optical applications, such as host for rare‐earth ions, nonlinear optical materials, and ferroelectric domain.

Ta2O5 nanocrystals strengthened linear, nonlinear, and Faraday properties of heavy metal oxide diamagnetic material

“…The excited state is 5 d 0 state of Ta 5+ whereas the ground state is 2 p 6 , which is associated with the oxide ions. The octahedral coordinated and other octahedral coordinated TM ions, for example, MoO 6 , WO 6 , and TiO 6 , are known as rather efficiently luminescent centers through metal‐to‐ligand transition 13 . Furthermore, the complex is a kind of self‐luminescent center, in which blue emission can be ascribed to the transition between Nb4 d and O2 p orbitals 42 .…”

“…The octahedral coordinated 6 and other octahedral coordinated TM ions, for example, MoO 6 , WO 6 , and TiO 6 , are known as rather efficiently luminescent centers through metalto-ligand transition. 13 Furthermore, the NbO 3 − 4 complex is a kind of self-luminescent center, in which blue emission can be ascribed to the transition between Nb4d and O2p orbitals. 42 Therefore, considering the similarities in coordination and electron configuration between TaO 7 − 6 and NbO 3 − 4 , an electron in O2p orbital is excited to Ta 5d 0 by absorbing UV photon and then thermally relaxed to the lowest vibrational state of Ta 5d 0 energy level.…”

“…In addition, Ta 5+ ions with an empty d shell ( d 0 ions) having completely occupied outermost electronic shell are regarded as disadvantageous to electronic transitions in luminescence, even though intense emissions at 419 nm from 5 d 0 Ta 5+ ions have been observed in soda‐lime glass 9 . Due to the above mentioned reasons, studies on Ta 2 O 5 are limited to several Ta 2 O 5 ‐doped silicate, 10 phosphate, 11‐13 germinate, 14 and tellurite 15 glasses for coating, photovoltaic, crystallization, and dielectric applications. Recently Gokhan Kilic group published the synthesis and radiation shielding property of Ta 2 O 5 powder‐doped Bi 2 O 3 –TeO 2 –ZnO glasses 16 and ZnO–Ta 2 O 5 –TeO 2 17 .…”

Ta2O5 Nanocrystals Strengthened Mechanical, Magnetic, and Radiation Shielding Properties of Heavy Metal Oxide Glass

“…However, except for several Ta 2 O 5 thin films, Ta 2 O 5 has been less investigated due to its lower solubility in classical glass formers, as well as its high melting temperature (1825 °C). The studies of Ta 2 O 5 are limited to several Ta 2 O 5 -doped silicate [ 7 ], phosphate [ 8 , 9 , 10 ], germinate [ 11 ], and tellurite [ 12 ] glasses for coating, photovoltaic, crystallization, and dielectric studies. Rare Ta 2 O 5 -doped heavy metal oxide glasses are reported, except recently published Bi 2 O 3 –TeO 2 –ZnO glasses [ 12 ] and ZnO–Ta 2 O 5 –TeO 2 [ 8 ] by the Gokhan Kilic group.…”