Investigations of LiNb1−xTaxO3 Nanopowders Obtained with Mechanochemical Method

Abstract

Nanocrystalline compounds LiNb1−xTaxO3 of various compositions (x = 0, 0.25, 0.5, 0.75, 1) were synthesized by high-energy ball milling of the initial materials (Li2CO3, Nb2O5, Ta2O5) and subsequent high-temperature annealing of the resulting powders. Data on the phase composition of the nanopowders were obtained by X-ray diffraction methods, and the dependence of the structural parameters of LiNb1−xTaxO3 compounds on the value of x was established. As a result of the experiments, the optimal parameters of the milling and annealing runs were determined, which made it possible to obtain single-phase compounds. The Raman scattering spectra of LiNb1−xTaxO3 compounds (x = 0, 0.25, 0.5, 0.75, 1) have been investigated. Preliminary experiments have been carried out to study the temperature dependences of their electrical conductivity.

Mechanosynthesis, Structure and Photoluminescent Properties of the Pr3+ Doped LiNbO3, LiNbO3:Mg, LiTaO3 Nanopowders

“…The activation energy obtained for LN:Pr is equal to (1.00 ± 0.05) eV. In general, this value is in a good agreement with the values, obtained previously for polycrystalline lithium niobate and/or lithium tantalate as well as for LiNb 1−x Ta x O 3 nanopowders [14,15,[39][40][41][42], ranging from 0.88 eV to 1.09 eV. Such a wide range of activation energies may be related to their strong dependence on the grain size of the samples or as well as preparation method.…”

“…The milling was performed using the planetary ball mill (Pulverisette-7, Fritsch, Germany). The synthesis conditions were described elsewhere [13][14][15]. Thermal treatment of powders and pressed samples was carried out in air using a Nabertherm LHT 04/17 furnace (Lilienthal, Germany).…”

“…In our previous studies [13][14][15], the technological advantages were shown for obtaining lithium niobate and lithium tantalate nanopowders with a mechanosynthesis technique compared to the wet chemistry method-a smaller number of operations, no need to use hazardous chemicals or a protective gas environment, high pressures, etc. In the present study, the nanopowders with nominal compositions Li 0.98 Pr 0.02 NbO 3 (denoted as LN:Pr), Li 0.93 Mg 0.05 Pr 0.02 NbO 3 (LN:Mg,Pr), Li 0.98 Pr 0.02 TaO 3 (LT:Pr) were obtained with high-energy ball milling and subsequent annealing of the corresponding powders mixtures (Li 2 CO 3 , Nb 2 O 5 , Ta 2 O 5 , MgO, Pr 6 O 11 ) taken in mass ratios corresponding to stoichiometric compositions.…”

‘Horror Vacui’ in the Oxygen Sublattice of Lithium Niobate Made Affordable by Cationic Flexibility

“…Originally, the same was also assumed for LiNbO 3 (LN), and most authors did not (and many still do not) have any doubts about simply postulating vacant oxygen sites (V O ) capable of trapping one or two electrons (F + and F-centers, respectively) in discussions of their experiments and proposed applications (see, e.g., [1,2]). The controversy about the availability of oxygen vacancies manifests in the reviews of Sánchez-Dena et al [3,4], is touched upon by some topical reviews [5,6], and is also closely related to the topics of other papers [7][8][9][10][11] of the present Special Issue, and deserves a clarifying discussion.…”

New Trends in Lithium Niobate: From Bulk to Nanocrystals

“…Nanocrystalline LiNb 1−x Ta x O 3 samples with x between 0 and 1 were synthesized by high-energy ball milling and subsequent high-temperature annealing by Vasylechko et al [13]. The milling and annealing parameters were optimized to obtain single-phase LNT nanopowders checked by X-ray diffraction.…”