CN-121517211-B - Preparation method of lithium niobate microcrystalline powder

CN121517211BCN 121517211 BCN121517211 BCN 121517211BCN-121517211-B

Abstract

The invention discloses a preparation method of lithium niobate microcrystalline powder, and belongs to the technical field of functional ceramic material powder preparation. The lithium niobate comprises the components of LiNbO 3 ; the preparation method of the lithium niobate microcrystalline powder comprises the following steps of firstly preparing potassium ion and sodium ion doped lithium niobate powder (K 0.5 Na 0.5 ) 1‑x Li x NbO 3 , x=0.5-0.9; the lithium niobate microcrystalline powder prepared by the method has the advantages of uniform particles, good dispersibility, high crystallinity of particles and pure phase of lithium niobate by combining XRD analysis results, simple and convenient steps, small mechanical pollution, small formula deviation, easy control of technological process, small deviation of chemical components and good stability, and can be produced in large scale and batch.

Inventors

Jia Chenning
LIU LIANGLIANG
HOU ZHAOPING

Assignees

太原理工大学

Dates

Publication Date: 20260512
Application Date: 20260115

Claims (3)

1. The preparation method of the lithium niobate microcrystalline powder is characterized by comprising the following steps: Preparing potassium ion and sodium ion doped lithium niobate powder (K 0.5 Na 0.5 ) 1-x Li x NbO 3 , x=0.5-0.9), wherein the specific process comprises the steps of weighing and mixing analytically pure potassium carbonate, sodium carbonate, lithium carbonate and niobium pentoxide powder according to the stoichiometric ratio of (0.5-0.5 x) to x:1, placing the mixture into a polytetrafluoroethylene ball milling tank, adding absolute ethyl alcohol to ball mill the mixture on a ball mill, placing the wet material after ball milling into an oven to dry, grinding the dried powder, placing the ground powder into a corundum crucible, heating the temperature to 850-1050 ℃ at the heating rate of 5 ℃ per minute, and preserving the temperature for 1-6 h, calcining the ground powder, and cooling the calcined powder to room temperature along with a furnace to obtain potassium ion and sodium ion doped lithium niobate powder; Weighing analytically pure potassium chloride, sodium chloride and potassium ion and sodium ion doped lithium niobate powder prepared in the first step, sequentially placing the potassium chloride, the sodium chloride powder and the potassium ion and sodium ion doped lithium niobate powder into a polyethylene ball milling tank, adding absolute ethyl alcohol, ball milling on a ball mill, placing the wet ball-milled material into a drying oven to obtain dry powder, grinding the dry powder into powder by an agate mortar to obtain a raw material mixture for preparing lithium niobate microcrystals, wherein the molar ratio of the potassium chloride to the sodium chloride is 1:1, and the mass ratio of the sum of the potassium chloride and the sodium chloride to the potassium ion and sodium ion doped lithium niobate powder is 1-5:1; The preparation method of the lithium niobate microcrystalline powder comprises the steps of placing the raw material mixture of the lithium niobate microcrystalline obtained in the step two into a corundum crucible for calcination, repeatedly washing and filtering in distilled water at 100 ℃ after calcination until Cl - is not detected in filtrate, drying the washed powder at 80 ℃ to obtain the lithium niobate microcrystalline powder, wherein the calcination process conditions are that the calcination is carried out at 750-1000 ℃ for 0.5-4 h.
2. The preparation method of the lithium niobate microcrystalline powder according to claim 1 is characterized by comprising the steps of firstly adding absolute ethyl alcohol, ball milling for 8-24 hours on a ball mill, wherein the weight ratio of the absolute ethyl alcohol to a raw material mixture is 1-2:1, and drying the wet material after ball milling for 5-10 hours at 60-90 ℃.
3. The preparation method of the lithium niobate microcrystalline powder according to claim 1 is characterized in that in the second step, the mass ratio of the added amount of absolute ethyl alcohol to the raw material mixture placed in a polyethylene ball milling tank is 1-2:1, the ball milling time is 8-24 hours, and wet materials after ball milling are dried for 5-10 hours at 60-90 ℃.

Description

Preparation method of lithium niobate microcrystalline powder Technical Field The invention belongs to the technical field of functional ceramic material powder preparation, and particularly relates to a preparation method of lithium niobate microcrystalline powder. Background Lithium niobate (LiNbO 3) crystals are focused on the combination of ferroelectric, piezoelectric, electro-optical, acousto-optic, strong light refraction and photovoltaic effect, and have the reputation of silicon in photonics, which is one of the most widely applied materials in the modern optical and electrical fields. However, single crystals are expensive to produce, have long production cycles, are limited in size and shape, and are difficult to control in uniformity of components particularly in doping modification. Thus, there is an urgent need for a method for preparing lithium niobate ceramic materials that has strong designability and is easy to implement complex shapes and doping, and has low cost. According to the preparation process of the functional ceramic, the synthesis of lithium niobate powder with high crystallinity, uniform particle size and good dispersibility is a core technology in ceramic preparation. The main methods for preparing lithium niobate powder at present are wet chemical method, solid phase sintering method and molten salt method. Wet chemical methods have problems such as complicated operation and waste liquid treatment, although they can control the growth rate and morphology of crystals. The solid-phase sintering method is simple to operate and suitable for large-scale production, but has the practical problems of uneven chemical components and low crystallinity of the product, a large amount of impurity phases (such as Li 3NbO4、LiNb3O8 and the like) and the like. The molten salt method is considered as an effective method for preparing high-crystallinity powder, and researches show that the sintering activity of niobate microcrystals prepared by the molten salt method is obviously improved （L. Liu, et al. Oriented and ultrafine-grain potassium sodium niobate piezoelectric ceramics prepared by heterogeneous microcrystalline transformation. Ceram. Int. 49 (2023) 30897; L. Liu, et al. Dense KSr2Nb5O15 ceramics with uniform grain size prepared by molten salt synthesis, J. Alloys Compd. 616 (2014) 293）,, so that the densification process of related ceramics is further promoted. However, the lithium source raw material (Li 2CO3 or LiNbO 3) inevitably undergoes hetero-phase reaction and phase separation in molten salt, so that lithium niobate microcrystals are difficult to synthesize, and thus no report has been made about the preparation of lithium niobate microcrystals. Therefore, the development of a preparation technology of lithium niobate microcrystalline powder with high crystallinity and good chemical stability is a key point for developing lithium niobate ceramic materials. Disclosure of Invention In order to solve the problems of low crystallinity, poor chemical stability and the like of the existing lithium niobate powder, an ideal raw material is provided for preparing high-performance lithium niobate ceramic, and the invention provides a preparation method of lithium niobate microcrystalline powder with high crystallinity and chemical stability. The invention provides a preparation method of lithium niobate microcrystalline powder, which adopts a solid phase method to assist a molten salt method to prepare the lithium niobate microcrystalline powder. The lithium niobate powder doped with potassium ions and sodium ions is prepared by a solid phase method, the lithium ions in the raw materials are stabilized in ilmenite structure (distorted perovskite structure) phase particles due to the action of the potassium ions and the sodium ions and are not converted into other impurity phases, then the obtained lithium niobate powder is placed in sodium chloride and potassium chloride mixed molten salt, lithium niobate is separated out from ilmenite structure phase particles to form lithium niobate nuclear points, the lithium niobate nuclear points continuously absorb lithium niobate in ilmenite structure phases under the control of an Ostwald reaction mechanism (concentration gradient driving), the lithium niobate nuclear points gradually grow into lithium niobate microcrystals, and the ilmenite structure phase particles are cracked into perovskite structure potassium sodium niobate nano particles due to the separation of the lithium niobate, and then suspended in water in a desalting cleaning process to be removed, so that a final product, namely the lithium niobate microcrystal powder is obtained. The invention provides a preparation method of lithium niobate microcrystalline powder, which comprises the following steps of: Preparing potassium ion and sodium ion doped lithium niobate powder (K 0.5Na0.5)1-xLixNbO3, x=0.5-0.9), wherein the specific process is that analytically pure potassium carbona