RU2550206C1 - Method of producing lithium and zinc borate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: double lithium and zinc borate LiZnBO₃ is obtained via heat treatment, wherein the starting components used are a mixture of LiBO₂ (37.80 wt %), ZnO (61.79 wt %), H₃BO₃ (0.41 wt %) obtained in advance while raising temperature in steps from 350°C to 700°C to 260 hours. Lithium borate LiBO₂ is obtained in advance from a mixture of Li₂CO₃ and H₃BO₃, taken in molar ratio of 1:1, which is annealed in air at 650°C for 50 hours.

EFFECT: shorter duration of synthesis by using readily available and cheap reactants.

1 dwg, 2 tbl, 1 ex

Description

The invention relates to the field of materials science, in particular, to a method for producing polycrystalline borates, which can be used as catalysts and solid electrolytes (TEL).

Known methods for producing double lithium and zinc borate composition LiZnBO ₃ crystallizing in monoclinic syngony with sp.gr. C2 / s.

(1. Belkebir A., Tarte P., Rulmont A., Gilbert, B. Synthesis, structural and vibrational analysis of LiMBO ₃ orthoborates (M = Mg, Co, Zn) // New Journal of Chemistry. 1996. 20 (3 ), P.311-316.

2. Tsuyumoto I., Kihara A. Synthesis, characterization and charge-discharge properties of layer-structure lithium zink borate, LiZnBO ₃ // Materials Science and Applications. 2013. Vol. 4. P.246-249).

The disadvantage of these methods for producing LiZnBO ₃ is the high synthesis temperature (1000 ° C).

Closest to the claimed invention is a method for producing borate LiZnBO ₃ by heating a stoichiometric mixture of LiBO ₂ · 8H ₂ O and ZnO at 600 ° C for one month with several intermediate grindings.

(3. Chen X., Yang S., Chang X., Zang H., Xiao W. Syntheses and characterization of two alkali-metal zinc borates, α-LiZnBO ₃ and Li _0.48 Na _0.52 ZnBO ₃ // Solid State Sciences. 2009. Vol.11. P.2086-2092).

However, the known method has the following disadvantages. Firstly, a significant duration of synthesis (one calendar month). Secondly, the need to use an industrial reagent (LiBO ₂ · 8H ₂ O).

The purpose of the invention is to reduce the duration of the synthesis by using affordable and inexpensive reagents.

This goal is achieved in that as the starting reagents in the preparation of LiZnBO ₃ , a mixture of LiBO ₂ (37.80 wt.%), ZnO (61.79 wt.%), H ₃ BO ₃ (0.41 wt.%) Is used. which is subjected to multi-stage heat treatment in air when the temperature rises from 350 ° C to 700 ° C for 260 hours. Lithium borate LiBO _{2 is} preliminarily obtained from a mixture of lithium carbonate Li ₂ CO ₃ and boric acid H ₃ BO ₃ , taken in a 1: 1 molar ratio. The resulting mixture was subjected to heat treatment at 650 ° C for 50 hours.

The invention is illustrated by the following example.

Example. A mixture of Li ₂ CO ₃ weighing 4.0645 g (33.3 mol%) and H ₃ BO ₃ weighing 6.7980 g (66.7 mol%) were thoroughly ground in an agate mortar. The resulting mixture was annealed in a platinum crucible in air at a temperature of 350 ° C, then 500 ° C and 650 ° C for 10, 20 and 20 hours, respectively. A mixture of LiBO ₂ weighing 1.4940 g (37.80 wt.%), ZnO weighing 2.4420 g (61.79 wt.%) And H ₃ BO ₃ - 0.0160 g (0.41 wt.%) thoroughly ground in an agate mortar. The resulting mixture was annealed in a platinum crucible in air at 350 ° C, then 650 ° C and 700 ° C for 10, 50, and 200 hours, respectively (a comparison of the synthesis modes is presented in Table 1).

The starting materials were: lithium carbonate Li ₂ CO _{3 of the} grade “chemically pure”, boric acid H ₃ BO _{3 of the} grade “chemically pure”, zinc oxide ZnO of the grade “chemically pure”. Preliminarily, lithium carbonate Li ₂ CO _{3 was} calcined at 400 ° C, and zinc oxide ZnO at 500 ° C for 5 hours to constant weight.

The completeness of the reaction was monitored by x-ray diffraction [automatic powder diffractometer D8 Advance Bruker AXS (Cu K _α radiation, graphite monochromator)]. The X-ray diffraction pattern of the obtained LiZnBO ₃ compound is shown in the figure. The unit cell parameters of the LiZnBO ₃ compound (space group C2 / s) were refined using the least squares method (LSM) using data obtained from a single crystal [3]. The crystallographic characteristics of the obtained compound are presented in table.2.

Brief Description of the Drawings

FIG.

X-ray patterns of LiZnBO ₃ (a) - our data; (b) - data [3].

Table 1 Solid State Synthesis Conditions Structure Source charge T, ° C Annealing time Way α-LiZnBO ₃ LiBO ₂ · 8H ₂ O, ZnO 600 ° C 1 month famous LiBO ₂ Li ₂ CO ₃ , ZnO, H ₃ BO ₃ 350 ° C-650 ° C 50 h LiZnBO ₃ LiBO ₂ , ZnO, H ₃ BO ₃ 350 ° C-700 ° C 260 h claimed

table 2 Crystallographic characteristics of the obtained compound LiZnBO ₃ Compound Syngonia a, Å b, Å s, Å β, deg. Lit. α-LiZnB03 LiZnB03 monocle. monocle. 8.746 (2) 8.742 (6) 5.091 (1) 5.087 (3) 6.129 (1) 6.119 (3) 118.75 (3) 118.97 (4) 3 declared

Using the proposed method for producing double lithium and zinc borate provides the following advantages in comparison with existing methods.

As a result of using a mixture of the starting components of lithium borate LiBO ₂ - 37.80 wt.%, Zinc oxide ZnO - 61.79 wt.% And boric acid H ₃ BO ₃ - 0.41 wt.%, Double lithium borate and zinc LiZnBO ₃ , which is synthesized with a shorter duration of annealing.

Using the claimed invention allows to obtain a double borate LiZnBO ₃ , which can be used as a catalyst or solid electrolyte.

Claims (1)

A method of obtaining a double borate of lithium and zinc LiZnBO ₃ by heat treatment, characterized in that as the starting components use a mixture of pre-obtained LiBO ₂ (37.80 wt.%), ZnO (61.79 wt.%), N ₃ IN ₃ (0.41 wt.%) With a stepwise rise in temperature from 350 ° C to 700 ° C for 260 hours.

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