CN-121994564-A - Transmission electron microscope sample preparation device and method based on supercritical fluid dispersion

Abstract

The invention discloses a device and a method for preparing a transmission electron microscope sample based on supercritical fluid dispersion, comprising the following steps of placing a dried molecular sieve to be tested in a high-pressure processing unit; the method comprises the steps of fixing a transmission electron microscope carrier net in a porous supporting structure, suspending the supporting structure in a high-pressure processing unit, sealing the high-pressure processing unit, introducing fluid, heating and boosting to a supercritical state, and fully contacting and flowing a molecular sieve and the fluid under the condition of stirring and/or forced circulation of the fluid, and directly dispersing and adsorbing on the carrier net. The invention utilizes the characteristic of supercritical fluid to realize in-situ direct dispersion adsorption of the sample on the carrier network and synchronous cleaning of the molecular sieve sample, and has the advantages of uniform dispersion, no organic solvent residue, high sample cleanliness, capability of effectively weakening the electron beam induced carbon deposition effect and the like.

Inventors

• LONG JIAJIE
• PAN ZE

Assignees

• 苏州大学

Dates

Publication Date

20260508

Application Date

20260210

Claims (10)

1. 1. The preparation method of the transmission electron microscope sample based on supercritical fluid dispersion is characterized by comprising the following steps of: s1, placing a dried molecular sieve to be tested in a high-pressure treatment unit; S2, fixing a transmission electron microscope carrier net in a porous supporting structure, and hanging the supporting structure in the high-pressure processing unit; S3, sealing the high-pressure treatment unit, introducing a fluid medium, heating and boosting to a supercritical state, fully contacting the molecular sieve with the supercritical state medium under the condition of stirring and/or forced circulation of the fluid, performing dispersion and cleaning effects, and directly dispersing and adsorbing on the carrier net.
2. 2. The method for preparing a transmission electron microscope sample based on supercritical fluid dispersion according to claim 1, wherein in S1, the drying is performed in a vacuum drying oven at 60-80 ℃ for 6-10 hours.
3. 3. The method for preparing a transmission electron microscope sample based on supercritical fluid dispersion according to claim 1, wherein in S2, the porous support structure is composed of n layers of metal meshes, wherein n is greater than or equal to 1, and the mesh number is 800-1000 mesh.
4. 4. The method for preparing a transmission electron microscope sample based on supercritical fluid dispersion according to claim 1, wherein in S3, the fluid medium is selected from carbon dioxide or a mixture of carbon dioxide and one or more inert gases, and the conditions of temperature rise and pressure rise are temperature 35-180 ℃ and pressure 10-40MPa.
5. 5. The method for preparing a transmission electron microscope sample based on supercritical fluid dispersion according to claim 1, wherein in S3, the stirring is mechanical stirring and/or ultrasonic stirring, and the forced circulation of the fluid is driven by an external circulation device and/or an internal centrifugal device.
6. 6. The method for preparing a transmission electron microscope sample based on supercritical fluid dispersion according to claim 1, wherein in S3, the fluid in the high-pressure processing unit is subjected to replacement processing every 5 to 90 minutes.
7. 7. A transmission electron microscope sample preparation device based on supercritical fluid dispersion is characterized by comprising a high-pressure processing unit, a heating unit for heating the high-pressure processing unit, a sealing cover body for sealing the high-pressure processing unit, a porous supporting structure suspended in the high-pressure processing unit, a stirring and/or fluid forced circulation device and a fluid inlet valve and an exhaust valve which are communicated with the high-pressure processing unit.
8. 8. The supercritical fluid dispersion based transmission electron microscope sample preparation apparatus according to claim 7, wherein the heating unit comprises a housing, a heating member, and a heat transfer medium filled in the housing, and the high pressure processing unit is disposed in the housing.
9. 9. The transmission electron microscope sample preparation device based on supercritical fluid dispersion according to claim 7, wherein the sealing cover is placed on top of the high pressure processing unit and is connected with the air inlet valve and the air outlet valve through air pipes, and the air inlet valve and the air outlet valve are communicated to the high pressure processing unit through the sealing cover.
10. 10. The supercritical fluid dispersion based transmission electron microscope sample preparation device according to claim 7, wherein the stirring and/or fluid forced circulation device is one or more selected from the group consisting of a mechanical stirrer, an ultrasonic stirrer, an external circulation device, and an internal centrifugation device.

Description

Transmission electron microscope sample preparation device and method based on supercritical fluid dispersion Technical Field The invention relates to the technical field of sample preparation, in particular to a device and a method for preparing a transmission electron microscope sample based on supercritical fluid dispersion. Background Scanning transmission electron microscopy (Scanning Transmission Electron Microscopy, STEM) technology, especially integrated differential phase contrast scanning transmission electron microscopy (INTEGRATED DIFFERENTIAL PHASE Contrast Scanning Transmission Electron Microscopy, iDPC-STEM) under double spherical aberration correction conditions, has become an important characterization means for studying molecular sieves, nanomaterials, porous materials and functional material microstructures. The technology can realize high-resolution imaging of light elements and pore canal structures under the condition of lower electron dose, and has more strict requirements on the dispersion state, the surface cleanliness and the structural integrity of the sample. In the double spherical aberration correction iDPC-STEM characterization process, the dispersion uniformity of the sample on the transmission electron microscope carrier network directly affects the selectivity and stability of an imaging area, and the cleanliness degree of the surface of the sample and the inside of a pore canal has decisive effects on the imaging signal-to-noise ratio, the phase contrast uniformity and the atomic-level structural analysis. Especially under the condition of long-time exposure or high magnification, the trace organic residue in the sample is extremely easy to generate carbonaceous deposition under the action of electron beams, and the actual characterization of light elements and pore canal structures is seriously interfered by iDPC-STEM imaging. At present, the preparation method of the transmission electron microscope sample still takes liquid phase dispersion as a main method, generally adopts solvents such as water, ethanol, acetone and the like to ultrasonically disperse the sample, then drops the sample onto a copper-carrying net, and obtains the sample to be detected through natural drying or heating drying. However, the method has the following defects that on one hand, particles are easy to migrate and agglomerate in the solvent volatilizing process, so that the sample is unevenly distributed on a carrier network, and the requirement on single particle dispersion under the condition of double spherical aberration correction is difficult to meet, on the other hand, the solvent residues or introduced organic impurities are easy to adsorb on the surface or inside a pore canal of the sample, cracking and carbon deposition occur under the irradiation of an electron beam, and the contrast and the spatial resolution capability of iDPC-STEM imaging are obviously reduced. In addition, the liquid phase dispersing and drying process may cause swelling, dissolution or surface reconstruction of part of the structural sensitive material, influence the intrinsic microstructure characteristics of the material, and further reduce the reliability of iDPC-STEM characterization results. In order to improve the cleanliness of the sample, the prior art attempts to adopt post-treatment modes such as plasma cleaning, ultraviolet ozone treatment or multiple solvent flushing, but the method often has the problems of complex process flow, poor repeatability, easiness in introducing new surface defects or electron beam sensitive sites, and the like, and is difficult to realize synchronous cleaning in the sample dispersing process. Therefore, there is a need for a method for preparing a transmission electron microscope sample without introducing a traditional liquid phase solvent, which can realize uniform dispersion of a molecular sieve sample in the sample preparation process, and perform in-situ deposition and synchronous cleaning on a transmission electron microscope carrier network, so as to effectively improve the dispersion uniformity of the sample and the cleanliness of the surface and pore channels, and remarkably weaken the carbon deposition effect generated by electron beam effect in the double spherical aberration correction iDPC-STEM imaging process, so as to meet the technical requirements of high resolution and multi-mode electron microscopic characterization on increasing sample quality. Disclosure of Invention Aiming at the defects in the prior art, the invention provides a device and a method for preparing a transmission electron microscope sample based on supercritical fluid dispersion, which are provided with a high-pressure processing unit, and are used for realizing in-situ dispersion and adsorption of a molecular sieve on a carrier network through contact of the molecular sieve and supercritical fluid under stirring and/or fluid forced circulation conditions. In order to solve the technic