Strontium zirconate crystal with controllable morphology and preparation thereof

Abstract

The invention discloses a shape-controllable strontium zirconate crystal and a preparation method thereof. The preparation method comprises the following steps: providing an aqueous solution containing strontium hydroxide and zirconium chloride in an oil bath reaction container, and reacting to obtain a mixture; and hermetically heating the mixture at constant temperature to obtain a crystal product. And adjusting the morphology of the obtained crystal product in an oil bath reaction container by adjusting the stoichiometric ratio of strontium and zirconium and optionally adding an additive. In a single water-phase solvent system, the morphology and size of the obtained strontium zirconate powder particles can be regulated and controlled by regulating and controlling the ratio of strontium to zirconium and optionally adding KOH and / or KCl, and the product is complete in crystal structure, uniform in morphology and high in purity.

Description

Technical Field

[0001] The present invention generally relates to a method for preparing strontium zirconate crystals. Background Art

[0002] There are many methods for synthesizing strontium zirconate. The strontium zirconate powder prepared by the traditional solid-phase reaction has problems such as non-uniformity, impurity contamination, rough powder structure, uneven particle size and distribution. In order to eliminate these problems, the synthesis of strontium zirconate powder adopts wet chemical methods such as sol-gel method, coprecipitation method, hydrothermal method and combustion method.

[0003] CN104403667B discloses a method of first reacting strontium nitrate with zirconium oxychloride octahydrate, then using cerium nitrate as an activator, hexapraseodymium undecoxide as an auxiliary activator, oxalic acid as a precipitant, and sodium dodecylbenzenesulfonate as a dispersant, and then washing, filtering, drying, calcining, grinding and sieving to obtain a shuttle-shaped strontium zirconate: (Ce, Pr) nanoluminescent powder. CN112876244B discloses a method of using a certain amount of zirconium oxychloride to dissolve with an organic ligand, adding a strontium source, and then adding a high molecular polymer, and then electrostatically spinning the obtained sol to obtain a strontium zirconate precursor fiber, and heating and keeping the product under atmospheric conditions to obtain a strontium zirconate fiber with a fiber diameter of 0.5-1.0 μm.

[0004] In the above-mentioned traditional methods for preparing strontium zirconate, the strontium zirconate obtained is usually in a layered, flaky and filamentous structure. In order to control the product morphology, complex operations or processes with high energy consumption are usually required, such as electrospinning, high-temperature calcination, etc. Although these methods have achieved the control of the morphology of strontium zirconate to a certain extent, they also increase the difficulty of preparation and product cleaning, and the concentration is low, the time is long and it is difficult to produce. In addition, the generation of strontium zirconate with a small specific surface area will also seriously reduce the catalytic activity of strontium zirconate in catalytic applications. Summary of the invention

[0005] The purpose of the present invention is to at least provide a method for preparing strontium zirconate crystals with controllable morphology.

[0006] According to a first aspect of the present invention, a method for preparing strontium zirconate crystals with controllable morphology is provided, comprising:

[0007] Providing an aqueous solution containing strontium hydroxide and zirconium chloride in an oil bath reaction container for reaction to obtain a mixture; and

[0008] The resulting mixture is heated in a sealed manner at a constant temperature to obtain a crystalline product.

[0009] The morphology of the obtained crystal product is adjusted by adjusting the strontium-zirconium stoichiometric ratio and optionally adding additives in an oil bath reaction vessel.

[0010] According to a preferred embodiment of the preparation method of the present invention, the oil bath reaction temperature may be about 80° C., and the reaction time may be about 30 min.

[0011] According to a preferred embodiment of the preparation method of the present invention, the constant temperature heating temperature may be about 200° C., and the heating time may be about 24 hours.

[0012] According to a preferred embodiment of the preparation method of the present invention, the method may further include separating, washing and drying the obtained crystalline product.

[0013] According to the preparation method of the present invention, in an oil bath reaction vessel:

[0014] Only the molar ratio of strontium ions to zirconium ions is adjusted (without adding other components to the aqueous solution) to about 2:1 (for example, the zirconium ion concentration is about 0.0125 mol / L), thereby obtaining a strontium zirconate crystal product with a hydrangea morphology;

[0015] The molar ratio of strontium ions to zirconium ions is adjusted to about 1:1 (for example, the concentration of zirconium ions is about 0.025 mol / L), and the aqueous solution contains about 20 mol / L of KOH to obtain a strontium zirconate crystal product with a solid cubic morphology;

[0016] The molar ratio of strontium ions to zirconium ions is adjusted to about 1:1 (for example, the zirconium ion concentration is about 0.025 mol / L), and the aqueous solution contains about 20 mol / L of KOH and about 0.45 mol / L of KCl to obtain a strontium zirconate crystal product with a hollow cubic morphology.

[0017] In the above preparation method, although sodium hydroxide can be used instead of potassium hydroxide, irregular nanocubic strontium zirconate will be obtained.

[0018] According to another aspect of the present invention, a method for preparing strontium zirconate crystals is also provided, which is prepared according to the above method.

[0019] Compared with the prior art, the present invention has the following significant effects:

[0020] 1. In a single aqueous solvent system, the morphology and size of the obtained strontium zirconate powder particles can be controlled by adjusting the strontium-zirconium ratio and optionally adding KOH and / or KCl, and the product has a complete crystal structure, uniform morphology and high purity.

[0021] 2. The process of the present invention is simple, the conditions are mild, the reaction time is short, the requirements for the precision of experimental instruments are low, the controllability of the product morphology is high, and the repeatability is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1is a scanning electron microscope image of a hydrangea-shaped strontium zirconate crystal prepared according to the present invention;

[0023] Figure 2 is a scanning electron microscope image of a solid cubic strontium zirconate crystal prepared according to the present invention;

[0024] Figure 3 is a scanning electron microscope image of a hollow cubic strontium zirconate crystal prepared according to the present invention;

[0025] Figure 4 The following are XRD phase analysis diagrams of three types of strontium zirconate crystals prepared according to the present invention. DETAILED DESCRIPTION

[0026] The preparation method of the present invention is further described in detail below through specific examples and drawings, but they are not intended to limit the present invention.

[0027] Example 1: Preparation of hydrangea-shaped strontium zirconate crystals

[0028] (1) The oil bath reaction temperature was set at 80°C, 15 mL of a 0.05 mol / L aqueous solution of strontium hydroxide octahydrate and 15 mL of a 0.025 mol / L aqueous solution of zirconium chloride were fully mixed, and the mixture was stirred for 30 min.

[0029] (2) The obtained mixture is transferred to a (high temperature) reactor, and the reactor is placed in an oven for reaction at 200° C. for 24 hours. The product is centrifuged, washed alternately with ethanol and water, and dried to obtain strontium zirconate crystals with hydrangea morphology: Figure 1 As shown, the average particle size is 2-3 μm.

[0030] Example 2: Preparation of solid cubic strontium zirconate crystals

[0031] (1) The oil bath reaction temperature was set at 80° C., 30 mL of KOH aqueous solution was provided, strontium hydroxide and zirconium chloride were dissolved in the solution and mixed thoroughly, wherein the concentrations of zirconium ions and strontium ions were both 0.025 mol / L, and the concentration of KOH was 20 mol / L; the reaction was stirred for 30 min.

[0032] (2) The obtained mixture is transferred to a reaction kettle, and the reaction kettle is placed in an oven at 200° C. for 24 h. The product is centrifuged, and washed alternately with ethanol, water, and 0.1 mol / L HCl, and then dried to obtain solid cubic strontium zirconate crystals: Figure 2 As shown, the average particle size is 200-400nm.

[0033] Example 3: Preparation of hollow cubic strontium zirconate crystals

[0034] (1) The oil bath reaction temperature was set at 80°C, 30 mL of KOH aqueous solution was provided, strontium hydroxide, zirconium chloride and KCl were dissolved in the solution and mixed thoroughly, wherein the concentrations of zirconium ions and strontium ions were both 0.025 mol / L, the concentration of KCl was 0.45 mol / L, and the concentration of KOH was 20 mol / L; the reaction was stirred for 30 min.

[0035] (2) The obtained mixture is transferred to a high-temperature reactor, and the reactor is placed in an oven at 200° C. for 24 h. The product is centrifuged, and washed alternately with ethanol, water, and 0.1 mol / L HCl, and then dried to obtain hollow cubic strontium zirconate crystals: Figure 3 As shown, the average particle size is 50-100nm.

[0036] Performance Testing

[0037] Figure 1-3 The following are scanning electron microscope images of the strontium zirconate crystals prepared in Examples 1-3 respectively; it can be seen that the obtained crystals have a complete structure and a uniform morphology. Figure 4It is the XRD phase analysis diagram of the strontium zirconate crystals prepared in Examples 1-3; it can be seen that the diffraction peaks of the obtained strontium zirconate crystals are completely consistent with the standard diffraction peaks of strontium zirconate (PDF#44-0161), and their 2θ angles are 21.6°, 24.2°, 30.7°, 30.8°, 32.6°, 34.4°, 34.5°, 36.2°, 36.3°, 37.8°, 37.9°, 39.5°, 41.1°, 44.0°, 45.5°, 48.2°, 48.3°, 49.5°, 49.6°, 50.8°, respectively. °, 51.0°, 54.6°, 55.9°, 57.0°, 57.2°, 58.3°, 60.6°, 60.7°, 63.9°, 64.1°, 64.2°, 65.0°, 67.3°, 67.4°, 68.3°, 68.4°, 68.5°, 69.5°, 72.6°, 72.7°, 72.8°, 73.7°, 73.8°, 77.9°, 78.0°, 80.9°, 81.2°, 82.0°, 84.1°, 84.2°, 84.3°, 84.9°, 85.1°, 85.9°, 86.2°, 88.9°, 89.1° and 89.3°, corresponding to (101), (111), (200), (121), (210), (201), (102), (211), (112), (220), (022), (131), (221), (202), (230), (231), (132), (301), (222), (311), (113), (321), (042), (232), (302), (203), (213), (331), (151), (400), (242), (004), (410), (332), (233), (420), (341), (060), (313), (402), (323), (161), (430), (252), (351), (153), (440), (044), (432), (234), (352), (253), (015), (501), (343), (511), (171), (521), (442) and (244) crystal planes.

[0038] As can be seen from the above, the present invention can achieve controllable preparation of strontium zirconate crystals with three different morphologies, namely, hydrangea shape, solid cube shape and hollow cube shape, by regulating the strontium-zirconium ratio of the precursor, the concentration of KOH in the aqueous solution and the concentration of chloride ions.

Claims

1. A method for preparing strontium zirconate crystals with controllable morphology, comprising: Providing an aqueous solution containing strontium hydroxide and zirconium chloride in an oil bath reaction container for reaction to obtain a mixture; and The resulting mixture is heated in a sealed manner at a constant temperature to obtain a crystalline product. The morphology of the obtained crystal product is adjusted by adjusting the stoichiometric ratio of strontium to zirconium and optionally adding additives in an oil bath reaction vessel.

2. The preparation method according to claim 1, wherein the oil bath reaction temperature is about 80°C and the reaction time is about 30 min.

3. The preparation method according to claim 1, wherein the constant temperature heating temperature is about 200°C and the heating time is about 24 hours.

4. The preparation method according to claim 1, further comprising separating, washing and drying the obtained crystalline product.

5. The preparation method according to any one of claims 1 to 4, in an oil bath reaction vessel, The molar ratio of strontium ions to zirconium ions is only adjusted to about 2:1 to obtain a strontium zirconate crystal product with a hydrangea morphology; The molar ratio of strontium ions to zirconium ions is adjusted to about 1:1, and the aqueous solution contains about 20 mol / L of KOH to obtain a strontium zirconate crystal product with a solid cubic morphology; The molar ratio of strontium ions to zirconium ions is adjusted to about 1:1, and the aqueous solution contains about 20 mol / L of KOH and about 0.45 mol / L of KCl to obtain a strontium zirconate crystal product with a hollow cubic morphology.

6. A strontium zirconate crystal prepared by the method according to any one of claims 1 to 5.

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