Wide-temperature-range inorganic negative thermal expansion material and synthesis method thereof

Abstract

The invention belongs to the field of inorganic nonmetals, discloses a wide-temperature-range inorganic negative thermal expansion material and a synthesis method thereof, and requests to protect application of a Mn2V2O7 material as a negative thermal expansion material. The Mn2V2O7 material can be prepared on the basis of a solid-phase reaction method. The negative thermal expansion performance of the Mn2V2O7 material is disclosed for the first time, the negative thermal expansion temperature range is large and is 69-497 DEG C, the negative thermal expansion coefficient reaches-4 * 10 <-6 > DEG C <-1 >, and the Mn2V2O7 material is a wide-temperature-range inorganic negative thermal expansion material. The Mn2V2O7 material does not contain Hf, Dy, Lu, W and other rare metal elements, has a large negative thermal expansion temperature interval, and can be compounded with organic matters, metals, ceramics and the like to adjust the thermal expansion coefficient of the Mn2V2O7 material.

Description

Technical Field

[0001] The present invention belongs to the field of inorganic non-metals, and more specifically, relates to an inorganic negative thermal expansion material with a wide temperature range and a synthesis method thereof. Background Art

[0002] Thermal expansion and contraction means that the volume of a material expands as the temperature rises, and contracts as the temperature drops. The dimensional changes caused by thermal expansion and contraction of materials can lead to thermal mismatch between different materials. Thermal mismatch can cause device failure, restricting the rapid development of integrated circuits, new energy vehicles, aerospace and other fields. The thermal contraction of negative thermal expansion materials can compensate for the thermal expansion of positive thermal expansion materials, obtaining thermal expansion-adapted materials and providing solutions.

[0003] At present, negative thermal expansion materials can be divided into two categories: (1) ZrW2O8, HfW2O8, Lu2W3O 12 、Dy2W3O 12 Frame-type negative thermal expansion materials represented by La(Fe, Si, Co) 13 , CaRuO4, etc. Although there are hundreds of negative thermal expansion materials reported, they have not yet been widely used in engineering technology, mainly due to their thermal expansion temperature range and negative thermal expansion coefficient. Under the premise that the negative thermal expansion temperature range is consistent with the device operating temperature range, they need to have excellent negative thermal expansion performance, and also have excellent high and low temperature stability. ZrW2O8, HfW2O8, Lu2W3O 12 、Dy2W3O 12 、La(Fe、Si、Co) 13 , CaRuO4, etc. contain rare metal elements such as Hf, Dy, Lu, W, La, and Ru, and have high costs; while Sc2Mo3O 12 The negative thermal expansion temperature range of is as narrow as -73℃~27℃, and the negative thermal expansion temperature range of Mg2P2O7 is 64℃~78℃. Therefore, negative thermal expansion materials with lower R&D cost, wider negative thermal expansion temperature range and coordinated optimization of various properties are of great scientific and application value. Summary of the invention

[0004] In view of the above defects or improvement needs of the prior art, the purpose of the present invention is to provide a wide temperature range inorganic negative thermal expansion material and a synthesis method thereof, which reveals for the first time the negative thermal expansion performance of Mn2V2O7 material, with a large negative thermal expansion temperature range of 69°C to 497°C and a negative thermal expansion coefficient of -4×10 -6 ℃ -1 , is an inorganic negative thermal expansion material with a wide temperature range.

[0005] To achieve the above objectives, according to one aspect of the present invention, a use of Mn2V2O7 material as a negative thermal expansion material is provided.

[0006] As a further preferred embodiment of the present invention, the negative thermal expansion temperature range of the negative thermal expansion material is 69°C to 497°C.

[0007] As a further preferred embodiment of the present invention, the negative thermal expansion coefficient of the negative thermal expansion material is -4×10 -6 ℃ -1 .

[0008] As a further preference of the present invention, the Mn2V2O7 material is prepared based on a solid phase reaction method.

[0009] As a further preferred embodiment of the present invention, the Mn2V2O7 material is prepared according to the following preparation method:

[0010] MnO powder and V2O5 powder are prepared according to the nominal chemical dosage ratio of Mn and V elements in the chemical formula Mn2V2O7, and then the powders are ground and mixed to obtain a mixture, which is then heated to perform a first solid phase reaction to obtain a Mn2V2O7 crude sample; the obtained solid phase reaction product is then crushed, ground, sieved, and solid phase reacted again to obtain a solid phase reaction product; this is repeated, and Mn2V2O7 material is obtained through at least 3 solid phase reactions.

[0011] As a further preferred embodiment of the present invention, the purity of MnO powder and V2O5 powder is not less than 99.9%.

[0012] As a further preferred embodiment of the present invention, each solid phase reaction is heated at a temperature of 300° C. to 700° C. for 6 to 24 hours.

[0013] Through the above technical scheme conceived by the present invention, compared with the prior art, the present invention discloses for the first time a negative thermal expansion material with the chemical formula of Mn2V2O7, which does not contain rare metal elements such as Hf, Dy, Lu, and W, has a large negative thermal expansion temperature range of 69°C to 497°C, and a negative thermal expansion coefficient of -4×10 -6 ℃ -1 It is an inorganic negative thermal expansion material with a wide temperature range. It can be compounded with organic matter, metals, ceramics, etc. to adjust its thermal expansion coefficient.

[0014] Mn2V2O7 is a monoclinic system with a space group of C2 / m and unit cell parameters α=90°,β=103.57°,γ=90°. In the prior art, Mn2V2O7 is often used as a positive electrode material for lithium-ion batteries and sodium-ion batteries. The present invention first discovered the negative thermal expansion properties of Mn2V2O7 materials, expanded the negative thermal expansion materials, and provided an inorganic negative thermal expansion material with a wide temperature range.

[0015] In addition, the negative thermal expansion flame retardant material Mn2V2O7 in the present invention can be prepared by a solid phase reaction method, and the synthesis method is simple and the raw material cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The XRD spectrum and crystal structure diagram of Mn2V2O7 in Example 1 of the present invention are shown in FIG. Figure 1 (a) in the figure corresponds to the XRD measured pattern. Figure 1 (b) in the figure corresponds to the XRD refinement diagram. Figure 1 (c) in FIG. 1 corresponds to a schematic diagram of the crystal structure.

[0017] Figure 2 This is the SEM image of Mn2V2O7 in Example 1 of the present invention.

[0018] Figure 3 TEM image and selected area electron diffraction image of Mn2V2O7 in Example 1 of the present invention; wherein, Figure 3 (a) and Figure 3 (b) in the figure corresponds to TEM images at different magnifications (the scales in the figure represent 750nm and 5nm, respectively). Figure 3 (c) in the figure corresponds to the selected area electron diffraction pattern (the scale bar in the figure represents 1 / 5nm).

[0019] Figure 4 This is the TMA spectrum of Mn2V2O7 in Example 1 of the present invention.

[0020] Figure 5 This is the TG-DSC spectrum of Mn2V2O7 in Example 1 of the present invention. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] Example 1

[0023] This embodiment discloses a solid phase method for preparing a wide temperature range inorganic negative thermal expansion material Mn2V2O7, comprising the following steps:

[0024] (1) Weigh 1.42 g and 1.82 g of 99.9% pure MnO powder and V2O5 powder, respectively.

[0025] (2) Take an appropriate amount of alcohol, place the MnO powder and V2O5 powder in a mortar and grind them evenly. The mixture is recorded as A.

[0026] (3) Transfer the mixture A to an alumina crucible, and place the crucible in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 300°C, and a holding time of 4 h (the reaction atmosphere is air; the same below), to obtain a mixture B in which dry MnO powder and V2O5 powder are uniformly mixed.

[0027] (4) Grind the product B under dry conditions and then transfer it to an alumina crucible, and place the crucible in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12 h to obtain a crude product C.

[0028] (5) The product C was ground under dry conditions, passed through a 250# stainless steel sieve, and then transferred to an alumina crucible, and the crucible was placed in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12h to obtain product D.

[0029] (6) The product D was ground under dry conditions and then transferred to an alumina crucible, and the crucible was placed in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 24 h to obtain a uniform product E.

[0030] The product E was ground and passed through a 250# stainless steel sieve, and subjected to XRD, SEM, TEM characterization and TMA, TG-DSC testing.

[0031] The room temperature XRD results of product E are as follows: Figure 1 As shown in (a), it is a single phase, and its XRD refinement diagram is as follows Figure 1 As shown in (b), its crystal structure is Figure 1 As shown in (c), it is a monoclinic system with a space group of C2 / m and a unit cell parameter of α=90°, β=103.57°, γ=90°.

[0032] The SEM image of product E is as follows Figure 2 As shown, it can be seen that the morphology of Mn2V2O7 is an irregular ellipsoid.

[0033] The TEM and selected area electron diffraction test results of product E are as follows: Figure 3 As shown, the appearance is Figure 3 As shown in (a), it is an irregular ellipsoid. The TEM high-resolution test results are as follows Figure 3 As shown in (b), the interplanar spacing is 0.4383nm, corresponding to the Mn2V2O7(020) crystal plane;

[0034] The results of selected area electron diffraction test are as follows Figure 3 As shown in (c), it corresponds to the Mn2V2O7 (404) crystal plane, (240) crystal plane and crystal band axis

[212] .

[0035] The TMA results of product E are as follows Figure 4 As shown in the figure (the test temperature range is 40℃~500℃, and the temperature change step is 10℃ / min), its negative thermal expansion range is 69℃~497℃, and the negative thermal expansion coefficient is -4×10 -6 ℃ -1 .like Figure 4 As shown, the linear change of the material at 69°C is 5.8049×10 -3 , the linear change of the material at 497℃ is 4.0092×10 -3 , it can be calculated that in the range of 69℃~497℃, the thermal expansion coefficient of this material is -4×10 -6 ℃ -1 (correspond Figure 4 The slope of the line connecting the 69°C data point and the 497°C data point shows a negative thermal expansion effect.

[0036] The TG-DSC results of product E are as follows Figure 5 As shown (the tested temperature range is 40℃~500℃, and the temperature change step is 10℃ / min), in the range of 40℃~500℃, Mn2V2O7 has almost no thermal weight loss and no phase change, showing good thermal stability.

[0037] Example 2

[0038] (1) Weigh 1.42 g and 1.82 g of 99.9% pure MnO powder and V2O5 powder, respectively.

[0039] (2) Take an appropriate amount of alcohol, place the MnO powder and V2O5 powder in a mortar and grind them evenly. The mixture is recorded as A.

[0040] (3) Transfer the mixture A to an alumina crucible, and place the crucible in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 4 hours (the reaction atmosphere is air; the same below), to obtain a mixture B in which dry MnO powder and V2O5 powder are uniformly mixed.

[0041] (4) Grind the product B under dry conditions and then transfer it to an alumina crucible, and place the crucible in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12 h to obtain a crude product C.

[0042] (5) The product C was ground under dry conditions, passed through a 250# stainless steel sieve, and then transferred to an alumina crucible, and the crucible was placed in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12h to obtain product D.

[0043] (6) The product D was ground under dry conditions and then transferred to an alumina crucible, and the crucible was placed in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 24 h to obtain a uniform product E.

[0044] The product E was ground, passed through a 250# stainless steel sieve, and characterized by XRD. The test results were similar to those in Example 1.

[0045] Example 3

[0046] (1) Weigh 1.42 g and 1.82 g of 99.9% pure MnO powder and V2O5 powder, respectively.

[0047] (2) Take an appropriate amount of alcohol, place the MnO powder and V2O5 powder in a mortar and grind them evenly. The mixture is recorded as A.

[0048] (3) Transfer the mixture A to an alumina crucible, and place the crucible in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12 h (the reaction atmosphere is air; the same below), to obtain a mixture B in which dry MnO powder and V2O5 powder are uniformly mixed.

[0049] (4) Grind the product B under dry conditions and then transfer it to an alumina crucible, and place the crucible in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12 h to obtain a crude product C.

[0050] (5) The product C was ground under dry conditions, passed through a 250# stainless steel sieve, and then transferred to an alumina crucible, and the crucible was placed in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 12h to obtain product D.

[0051] (6) The product D was ground under dry conditions and then transferred to an alumina crucible, and the crucible was placed in a muffle furnace for reaction at a heating rate of 10°C / min, a reaction temperature of 700°C, and a holding time of 24 h to obtain a uniform product E.

[0052] The product E was ground, passed through a 250# stainless steel sieve, and characterized by XRD. The test results were similar to those in Example 1.

[0053] The above embodiments are merely examples. For example, in addition to being prepared by the solid phase reaction method, the Mn2V2O7 material may also be prepared by other methods known in the prior art.

[0054] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Application of Mn2V2O7 material as negative thermal expansion material.

2. The use according to claim 1, characterized in that: The negative thermal expansion temperature range of the negative thermal expansion material is 69°C to 497°C.

3. The use according to claim 2, characterized in that: The negative thermal expansion coefficient of negative thermal expansion material is -4×10 -6 ℃ -1 .

4. The use according to claim 1, characterized in that: Mn2V2O7 material is prepared based on solid phase reaction method.

5. The use according to claim 1, characterized in that: The Mn2V2O7 material is prepared according to the following preparation method: MnO powder and V2O5 powder are prepared according to the nominal chemical dosage ratio of Mn and V elements in the chemical formula Mn2V2O7, and then the powders are ground and mixed to obtain a mixture, which is then heated to perform a first solid phase reaction to obtain a Mn2V2O7 crude sample; the obtained solid phase reaction product is then crushed, ground, sieved, and solid phase reacted again to obtain a solid phase reaction product; this is repeated, and Mn2V2O7 material is obtained through at least 3 solid phase reactions.

6. The use according to claim 5, characterized in that The purity of MnO powder and V2O5 powder is not less than 99.9%.

7. The use according to claim 5, characterized in that Each solid phase reaction is heated at a temperature of 300°C to 700°C for 6 to 24 hours.

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