A Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Preparation method of core-shell structured nanopowder

Abstract

The application discloses a kind of Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Preparation method of core-shell structure nano-powder, belong to solid electrolyte material field.The core-shell structure powder of the present application is with Ce 0.8 Gd 0.2 O 1.90 As inner core, with BaCe 0.9 Gd 0.1 O 3.95 As shell, comprising: (1) Ce (NO3) 3·6H2O, Gd (NO3) 3·6H2O, polyvinyl pyrrolidone is dissolved in distilled water, ammonia water is added to precipitate and filter to obtain A precipitate; (2) Ba (COOCH3) 2, sodium dodecyl benzene sulfonate is dissolved in water to prepare B solution; (3) A precipitate is mixed with B solution, ammonia water is added to adjust pH, and after precipitation and filtration, precipitate C is obtained; (4) after washing, drying and calcining precipitate C, Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Core-shell structure nano-powder is obtained.The Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Core-shell structure nano-powder prepared by the present application has good interface continuity and combination, high interface proportion, and is helpful to improve the conductivity of nano-powder.

Description

Technical Field

[0001] This invention belongs to the field of solid electrolyte materials, and relates to a Ce... 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Preparation method of core-shell structured nanopowders. Background Technology

[0002] CeO2 is an important ionic conductor solid electrolyte. Compared to the more traditional ZrO2 electrolyte, CeO2 exhibits higher ionic conductivity and has wide applications at medium and low temperatures, making it a promising electrolyte material for solid oxide fuel cells. One drawback of CeO2-based solid electrolytes is the tendency for some electronic conductivity to appear under reducing atmospheres. Current solutions typically involve introducing a second phase to protect the CeO2 grains and reduce electronic conductivity. BaCeO3 is a good proton conductor under hydrogen or humid air. Studies have shown that using BaCeO3 as a second phase can suppress electronic conductivity in CeO2 grains, and the CeO2 / BaCeO3 interface can also act as a proton conductor for hydrogen. + and O 2- While high-speed channels can improve conductivity, introducing a second phase to obtain multiphase ceramics to improve conductivity can easily lead to problems such as separation and discontinuity of the two-phase interface.

[0003] Meanwhile, although pure CeO2 has a higher ionic conductivity than traditional ZrO2 electrolytes, its conductivity is still relatively low. When low-valence ions are doped into the CeO2 lattice, a certain concentration of oxygen vacancies will be generated in the lattice due to the valence balance. Oxygen ions can be transferred within the grains through the vacancy transport mechanism, thereby improving the ionic conductivity (grain conductivity) of the CeO2-doped electrolyte. Pure BaCeO3 has poor chemical stability and is prone to forming BaCO3 in a CO2 atmosphere, resulting in poor mechanical strength of the electrolyte and reduced conductivity. However, by doping BaCeO3 with elements, the chemical stability of BaCeO3 can be greatly improved, thereby reducing the impact of BaCeO3's chemical stability on the electrolyte's mechanical strength and conductivity.

[0004] Core-shell structures refer to two materials bonded together by chemical bonds or other forces to form an ordered assembly structure. Core-shell structures can integrate the properties of the two materials and have wide applications in batteries, catalysis, and other fields. In-situ reactions refer to the direct use of intermediates in the preparation process for the next reaction, offering advantages such as simple operation, low production cost, and pure interface.

[0005] Therefore, this invention proposes a method for preparing Ce0.8Gd0.2O1.90@BaCe0.9Gd0.1O3.95 core-shell structured nanoparticles, by using BaCe at high temperature... 0.9 Gd 0.1 O 3.95 (BCG) and Ce 0.8 Gd 0.2 O 1.90 (GDC) in-situ reaction generates GDC@BCG core-shell structured nanopowder. The core-shell structure enables and maintains the continuity and stable distribution of the two-phase interface, thereby overcoming the problems caused by the introduction of a second phase. This results in ceramics obtained by sintering GDC@BCG core-shell structured nanopowder having superior electrical conductivity. Summary of the Invention

[0006] To overcome the problems in the prior art, this invention constructs a GDC@BCG core-shell structured nanopowder with GDC as the core and BCG as the shell, thereby improving the interfacial continuity and bonding between GDC and BCG, and increasing the interface ratio, thus significantly improving the electrical conductivity of the GDC@BCG core-shell structured nanopowder.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] The Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Core-shell structured powder with Ce 0.8 Gd 0.2 O 1.90 As the kernel, with BaCe 0.9 Gd 0.1 O 3.95 As the outer shell, the preparation method includes the following steps:

[0009] (1) Dissolve Ce(NO3)3·6H2O, Gd(NO3)3·6H2O and polyvinylpyrrolidone in 200ml of distilled water at a molar ratio of Ce(NO3)3·6H2O:Gd(NO3)3·6H2O:polyvinylpyrrolidone = 0.8:0.2:0.5. Then add ammonia to adjust the pH of the solution to 8-10, stir, and then sonicate. After sonication, filter to obtain precipitate A.

[0010] (2) Dissolve Ba(COOCH3)2 and sodium dodecylbenzenesulfonate in 100 ml of distilled water at a molar ratio of Ba(COOCH3)2:sodium dodecylbenzenesulfonate = 0.4:0.6, and stir to obtain solution B;

[0011] (3) After mixing the A precipitate obtained in step (1) with the B solution obtained in step (2), add ammonia water to adjust the pH to 8-10, stir, and then perform ultrasonic dispersion. After ultrasonic dispersion, filter to obtain precipitate C.

[0012] (4) After washing, drying and calcining the precipitate C in step (3), Ce is obtained. 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Core-shell structured nanoparticles.

[0013] Preferably, in step (4), anhydrous ethanol is used to wash the precipitate C.

[0014] Preferably, in step (4), the drying temperature is 120°C and the drying time is 24 hours.

[0015] Preferably, in step (4), the calcination temperature is 900–950°C and the calcination time is 6 hours.

[0016] The beneficial effects of this invention are:

[0017] 1. This invention solves the problems of interface separation and discontinuity between the GDC phase and the BCG phase by preparing GDC@BCG core-shell structured nanopowder with GDC as the core and BCG as the shell, thereby improving the electrical conductivity of the nanopowder.

[0018] 2. This invention prepares GDC@BCG core-shell structure powder with GDC as the core and BCG as the shell, which can increase the interface ratio between the GDC phase and the BCG phase, thereby further improving the electrical conductivity of the nanopowder.

[0019] 3. This invention prepares the BCG shell through solid-state in-situ reaction, which can effectively reduce the introduction of other impurities into the grain boundaries during the reaction process, maintain high interface purity, thereby improving the grain boundary conductivity and ultimately increasing the total conductivity.

[0020] 4. This invention involves doping CeO2 with Gd. 3+ Using Gd 3+ With Ce 4+ The property of having similar ionic radii gives GDC the best conductivity.

[0021] 5. This invention involves doping BaCeO3 with Gd. 3+On the one hand, improving the chemical stability of BaCeO3 helps to improve the mechanical strength of GDC@BCG core-shell structured nanopowders. On the other hand, doping the same element in both GDC and BCG eliminates the need to purchase complex raw materials, which helps to reduce preparation costs.

[0022] 6. The GDC@BCG core-shell structured nanopowder prepared by the method of the present invention has good uniformity, the raw materials are readily available, and the preparation method is simple and easy to implement, which helps to reduce the preparation cost. Attached Figure Description

[0023] Figure 1 This is a TEM image of the GDC@BCG core-shell structured nanopowder prepared in Example 1 of this invention.

[0024] Figure 2 This is a TEM image of the GDC@BCG core-shell structured nanopowder prepared in Comparative Example 1 of this invention.

[0025] Figure 3 This is a TEM image of the GDC@BCG core-shell structured nanopowder prepared in Comparative Example 2 of this invention.

[0026] Figure 4 This is a SEM image of the GDC@BCG core-shell structured nanopowder prepared in Example 1 of this invention.

[0027] Figure 5 This is a SEM image of the GDC@BCG core-shell structured nanopowder prepared in Comparative Example 1 of this invention.

[0028] Figure 6 This is a SEM image of the GDC@BCG core-shell structured nanopowder prepared in Comparative Example 2 of this invention.

[0029] Figure 7 The image shows the XRD pattern of the GDC@BCG core-shell structured nanopowder prepared in Example 1 of this invention.

[0030] Figure 8 The image shows the XRD pattern of the GDC@BCG core-shell structured nanopowder prepared in Comparative Example 1 of this invention.

[0031] Figure 9 The image shows the XRD pattern of the GDC@BCG core-shell structured nanopowder prepared in Comparative Example 2 of this invention.

[0032] Figure 10 The AC impedance diagram is shown for the GDC@BCG ceramic prepared in Example 1.

[0033] Figure 11 This is a schematic diagram of the solid-phase in-situ synthesis process of the present invention. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to specific embodiments.

[0035] In the embodiments and comparative examples of this invention, unless otherwise specified, all chemical reagents used in the experiments were commercially available analytical grade.

[0036] Example 1

[0037] In this embodiment, GDC@BCG core-shell structured nanopowder was prepared using the following method:

[0038] (1) Weigh Ce(NO3)3·6H2O, Gd(NO3)3·6H2O, and polyvinylpyrrolidone according to the molar ratio of Ce(NO3)3·6H2O:Gd(NO3)3·6H2O:polyvinylpyrrolidone = 0.8:0.2:0.5. Dissolve Ce(NO3)3·6H2O, Gd(NO3)3·6H2O, and polyvinylpyrrolidone in 200ml of distilled water. Then add ammonia to adjust the pH of the solution to 8-10. Stir the solution with a magnetic stirrer for 2h. Then use an ultrasonic cleaner to ultrasonically disperse for 30min. After ultrasonic dispersion is uniform, filter to obtain precipitate A.

[0039] (2) Weigh Ba(COOCH3)2 and sodium dodecylbenzenesulfonate according to the molar ratio of Ba(COOCH3)2: sodium dodecylbenzenesulfonate = 0.4:0.6, and dissolve Ba(COOCH3)2 and sodium dodecylbenzenesulfonate in 100ml of distilled water. Stir the solution with a magnetic stirrer for 30min to obtain solution B.

[0040] (3) After mixing precipitate A with solution B, add ammonia to adjust the pH to 8-10, stir the solution with a magnetic stirrer for 2 hours, put the solution into an ultrasonic cleaner for ultrasonic dispersion for 30 minutes, and then filter to obtain precipitate C.

[0041] (4) The precipitate C was washed with anhydrous ethanol, and then the washed precipitate C was placed in a drying oven and dried at 120°C for 24 hours. After that, it was calcined at 950°C for 6 hours to obtain GDC@BCG core-shell structured nanopowder.

[0042] The GDC@BCG core-shell structured nanopowder obtained in this embodiment was subjected to TEM, SEM, and XRD experiments. The TEM image of the GDC@BCG core-shell structured nanopowder in this embodiment is shown below. Figure 1 As shown, the SEM image is as follows: Figure 4 As shown, the XRD results are as follows Figure 7 As shown.

[0043] The GDC@BCG core-shell structured nanopowder obtained in this embodiment was sintered at 1600℃ for 10 h to obtain GDC@BCG ceramics. The GDC@BCG ceramics were then subjected to AC impedance testing at 600℃ under air atmosphere. The test results are as follows: Figure 10 As shown, the electrical conductivity of GDC@BCG ceramic can reach 0.91 × 10⁻⁶. -2 S / cm.

[0044] Example 2

[0045] This embodiment uses the same method as Example 1 to prepare GDC@BCG core-shell structured nanopowder, the difference being that the calcination temperature in this embodiment is 920℃.

[0046] The properties of the GDC@BCG core-shell structured nanopowder prepared in this embodiment are similar to those in Example 1.

[0047] Example 3

[0048] This embodiment uses the same method as Example 1 to prepare GDC@BCG core-shell structured nanopowder, the difference being that the calcination temperature in this embodiment is 900℃.

[0049] The properties of the GDC@BCG core-shell structured nanopowder prepared in this embodiment are similar to those in Example 1.

[0050] Comparative Example 1

[0051] This comparative example uses the same method as Example 1 to prepare GDC@BCG core-shell structured nanopowder, the difference being that the calcination temperature in this comparative example is 850℃.

[0052] The GDC@BCG core-shell structured nanopowder obtained in this comparative example was subjected to TEM, SEM, and XRD experiments. The TEM image of the GDC@BCG core-shell structured nanopowder in this comparative example is shown below. Figure 2 As shown, the SEM image is as follows: Figure 5 As shown, the XRD results are as follows Figure 8 As shown.

[0053] pass Figure 1 (Example 1) and Figure 2 (Comparative Example 1) The comparison shows that Figure 1 In Example 1, the lattice fringes and core-shell structure of the GDC@BCG core-shell nanopowder are more clearly defined, while Figure 2 In (Comparative Example 1), the solid-phase in-situ reaction was not fully carried out due to the sintering temperature being too low, resulting in low clarity of its lattice fringes and core-shell structure. The low clarity of the sample's lattice fringes and core-shell structure indicates that its crystallinity is poor.

[0054] pass Figure 4 (Example 1) and Figure 5(Comparative Example 1) The comparison shows that the average particle size of the powder increases with increasing calcination temperature. However, excessively large particle size can affect its electrical conductivity. Therefore, the calcination temperature needs to be controlled within a reasonable range to ensure that the GDC@BCG core-shell structured nanopowder has excellent crystallinity while avoiding excessively large particle size.

[0055] pass Figure 7 (Example 1) and Figure 8 (Comparative Example 1) It can be seen from the comparison that as the calcination temperature increases, the BCG phase is generated, and the in-situ reaction proceeds more thoroughly.

[0056] The GDC@BCG core-shell structured nanopowder obtained in this comparative example was sintered at 1600℃ for 10 h to obtain GDC@BCG ceramics. The AC impedance of the GDC@BCG ceramics was then tested at 600℃ in air. The conductivity of the GDC@BCG ceramics in this comparative example was lower than that of the GDC@BCG ceramics in Example 1. This is because the sintering temperature was too low, preventing the in-situ solid-phase reaction from proceeding sufficiently. This resulted in the inability to form a pure, high-conductivity two-phase interface, ultimately leading to a decrease in conductivity.

[0057] Comparative Example 2

[0058] This comparative example uses the same method as Example 1 to prepare GDC@BCG core-shell structured nanopowder, the difference being that in step (2) of this comparative example, the molar ratio of Ce(NO3)3·6H2O:Ba(COOCH3)2:Gd(NO3)3·6H2O:sodium dodecylbenzenesulfonate is 0.8:0.4:0.2:0.6.

[0059] The GDC@BCG core-shell structured nanopowder obtained in this comparative example was subjected to TEM, SEM, and XRD experiments. The TEM image of the GDC@BCG core-shell structured nanopowder in this comparative example is shown below. Figure 3 As shown, the SEM image is as follows: Figure 6 As shown, the XRD results are as follows Figure 9 As shown.

[0060] pass Figure 1 (Example 1) and Figure 3 (Comparative Example 2) It can be seen that the core-shell structure powder generated by the in-situ reaction method has clearer lattice fringes than that of the ordinary synthesis method, that is, it has better crystallinity.

[0061] pass Figure 4 (Example 1) and Figure 6(Comparative Example 2) The comparison shows that the core-shell structure powder generated by in-situ reaction has a finer particle size, while the core-shell structure powder generated by the method in Comparative Example 2 has a coarser particle size. This indicates that under the same calcination temperature and holding time, in-situ reaction can obtain powder with a relatively smaller particle size, which is beneficial to improving the electrical conductivity of GDC@BCG core-shell structure nanoparticles.

[0062] pass Figure 7 (Example 1) and Figure 9 (Comparative Example 2) It can be seen that, under the same calcination temperature and holding time, the sample prepared by the in-situ reaction method generates more BCG phase, that is, more high conductivity interfaces are formed between the two phases.

[0063] The GDC@BCG core-shell structured nanopowder obtained in this comparative example was sintered at 1600℃ for 10 h to obtain GDC@BCG ceramics. The AC impedance of the GDC@BCG ceramics was then tested at 600℃ in air. The conductivity of the GDC@BCG ceramics in this comparative example was lower than that of the GDC@BCG ceramics in Example 1. This is because the lack of in-situ solid-state synthesis led to the introduction of other impurities into the interface during the synthesis of the GDC@BCG core-shell structure, resulting in an impure interface between the two phases and ultimately causing a decrease in conductivity.

[0064] In summary, the GDC@BCG core-shell structured nanopowder prepared by the method of this invention effectively solves the problems of interface separation and discontinuity, improves the interface ratio, reduces the introduction of other impurities by preparing the BCG shell through solid-phase in-situ reaction, significantly improves the electrical conductivity of the GDC@BCG core-shell structured nanopowder, and expands the application range of the GDC@BCG core-shell structured nanopowder.

[0065] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 The method for preparing core-shell structured nanopowders is characterized by: The Ce 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 Core-shell structured powder with Ce 0.8 Gd 0.2 O 1.90 As the kernel, with BaCe 0.9 Gd 0.1 O 3.95 As the outer shell, the preparation method includes the following steps: (1) Dissolve Ce(NO3)3·6H2O, Gd(NO3)3·6H2O and polyvinylpyrrolidone in 200ml of distilled water at a molar ratio of Ce(NO3)3·6H2O:Gd(NO3)3·6H2O:polyvinylpyrrolidone = 0.8:0.2:0.

5. Then add ammonia to adjust the pH of the solution to 8~10, stir, and then ultrasonically disperse. After ultrasonic dispersion, filter to obtain A precipitate. (2) Dissolve Ba(COOCH3)2 and sodium dodecylbenzenesulfonate in 100 ml of distilled water at a molar ratio of Ba(COOCH3)2:sodium dodecylbenzenesulfonate = 0.4:0.6, and stir to obtain solution B; (3) After mixing the A precipitate obtained in step (1) with the B solution obtained in step (2), add ammonia water to adjust the pH to 8~10, stir, and then perform ultrasonic dispersion. After ultrasonic dispersion, filter to obtain precipitate C. (4) After washing, drying and calcining the precipitate C in step (3), Ce is obtained. 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 The core-shell structured nanopowder is calcined at a temperature of 900~950℃ for 6 hours.

2. A Ce according to claim 1 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 The method for preparing core-shell structured nanopowders is characterized by: In step (4), anhydrous ethanol is used to wash the precipitate C.

3. A Ce according to claim 1 0.8 Gd 0.2 O 1.90 @BaCe 0.9 Gd 0.1 O 3.95 The method for preparing core-shell structured nanopowders is characterized by: In step (4), the drying temperature is 120℃ and the drying time is 24h.

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