Ammonia zinc carbonate crystal, preparation method and application thereof

Abstract

The invention provides a preparation method of an ammonia zinc carbonate crystal, and belongs to the technical field of abnormal mechanical materials, a solvent, zinc acetate and urea are subjected to a solvothermal reaction, cooling and separation are performed after the reaction is finished, and the ammonia zinc carbonate crystal is obtained.The invention provides an efficient, controllable and low-cost ammonia zinc carbonate single crystal synthesis route. A solvothermal method of a specific mixed solvent is adopted, urea controllable hydrolysis is utilized, growth of crystals of a specific spiral chain structure is achieved under the mild condition, stable, reversible and linear negative linear compression (NLC) behaviors are shown in the wide pressure range of 0-5 GPa, the key technical bottlenecks that an existing NLC material is narrow in pressure range and responds to nonlinearity are solved, and the preparation method is suitable for industrial production. An ideal solid molecular spring material is provided for high-pressure precision sensing and driving; the method is simple in process and good in repeatability, and a reliable and high-quality material source is provided for subsequent research and application.

Description

Technical Field

[0001] This application relates to the field of anomalous mechanical materials technology, and in particular to a zinc ammonium carbonate crystal, its preparation method, and its application. Background Technology

[0002] Negative linear compressibility refers to the phenomenon where, under uniform pressure, a crystal expands anomalously in a specific direction while its volume decreases. This anomalous mechanical behavior is extremely rare in nature, and its mechanisms mainly include ferroelastic phase transitions, helical structures, polyhedral torsion, layer slip mechanisms, pressure-induced charge transfer, and special molecular geometries, such as wine rack structures and scissor configurations. Negative linear compressibility materials have significant application value and can be used in fields such as brakes, artificial muscles, bulletproof vests, smart wearables, high-sensitivity pressure sensors, submarine optical cables, earthquake-resistant materials, biomimetic engineering, extreme environment detection, and high-voltage energy storage. They can also significantly enhance piezoelectric properties; for example, piezoelectric MOF materials exhibit ultra-high voltage piezoelectric properties due to negative linear compressibility. This is an important means of obtaining novel physical properties (such as superconductivity and piezoluminescence) and breaking through the performance limits of conventional materials (such as Poisson's ratio and piezoelectric coefficient) through pressure-controlled structures. It holds promise for applications in highly stable optoelectronic signal transmission under large pressure fluctuations, providing new solutions for optoelectronic information functional materials in extreme environments.

[0003] In existing technologies, negative linear compressibility materials generally suffer from drawbacks such as a narrow response pressure range (typically limited to 0-2 GPa) and nonlinear compressibility (making it impossible to precisely control the strain response). Especially in high-pressure applications, existing materials struggle to simultaneously meet the requirements of a wide range and high precision. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing zinc ammonium carbonate crystals, the preparation method and its application, so as to meet the requirements of wide range and high precision in high-pressure applications.

[0005] To solve the above-mentioned technical problems, this application adopts the following technical solution: One of the objectives of this application is to provide a method for preparing zinc ammonium carbonate crystals, comprising the following steps: A solvent, zinc acetate, and urea were subjected to a solvothermal reaction. After the reaction was completed, the mixture was cooled and separated to obtain zinc ammonium carbonate crystals.

[0006] In some embodiments, the solvent is a mixed solvent comprising water and N,N-dimethylformamide.

[0007] In some embodiments, the mass ratio of urea, zinc acetate and solvent is 1:7:50-80.

[0008] In some embodiments, the temperature of the solvothermal reaction is 150-155°C.

[0009] In some embodiments, the separation step includes collecting transparent, long needle-like crystals from the reaction products.

[0010] In some embodiments, the method further includes a step of vacuum drying the separated crystals.

[0011] The second objective of this application is to provide zinc ammonium carbonate crystals, which are prepared by any of the preparation methods described in this application.

[0012] The third objective of this application is to provide a zinc ammonium carbonate crystal, wherein the crystal is orthorhombic and its space group is [space group number missing]. Pna 21 has a helical network structure composed of ZnOCO-ZnOCO chains; and, within a pressure range of 0-5 GPa, the crystal exhibits stable and reversible negative linear compression behavior in the b-axis direction, and its b-axis lattice parameter increases linearly with increasing pressure.

[0013] In some embodiments, the optical band gap of the crystal is greater than or equal to 5.8 eV.

[0014] A third objective of this application is to provide a pressure sensing element comprising the zinc ammonium carbonate crystal described herein.

[0015] In some embodiments, the zinc ammonium carbonate crystals are configured such that their b-axis direction is parallel to the direction of the pressure to be measured, in order to provide a linear strain response in the pressure range of 0-5 GPa.

[0016] The fourth objective of this application is to provide a Fabry-Perot cavity fiber optic pressure sensor, comprising: An optical resonant cavity, and a pressure-sensitive element disposed within the optical resonant cavity; The pressure-sensitive element includes the zinc ammonium carbonate crystal, and the b-axis of the crystal is parallel to the direction of change of the cavity length of the optical resonant cavity. When external pressure is applied to the sensor, the zinc ammonium carbonate crystal elongates linearly along the b-axis, causing a corresponding change in the cavity length of the optical resonant cavity, which in turn leads to a shift in the interference spectrum.

[0017] Furthermore, the aforementioned Fabry-Perot cavity fiber optic pressure sensor is responsive to micropascal-level pressure changes and is suitable for real-time minimally invasive monitoring of arterial blood pressure.

[0018] The fifth objective of this application is to provide an adaptive damper, comprising: An energy dissipation core layer is provided, comprising the zinc ammonium carbonate crystals described above; wherein the zinc ammonium carbonate crystals are oriented with their b-axis direction perpendicular to the expected main impact force direction; when subjected to impact, the crystals expand significantly perpendicular to the impact direction to disperse and absorb impact energy.

[0019] Furthermore, the shock absorber is applied to aerospace structures, automotive safety systems, or high-performance sports equipment.

[0020] The sixth objective of this application is to provide a zero Poisson's ratio compression-resistant buffer composite material, comprising: An elastic polymer matrix; and zinc ammonium carbonate crystals dispersed in the elastic polymer matrix; wherein, when the composite material is subjected to pressure, the negative linear expansion behavior of the zinc ammonium carbonate crystals along the b-axis offsets or partially offsets the positive Poisson contraction of the elastic polymer matrix, thereby causing the composite material to exhibit a macroscopically close to zero or negative Poisson's ratio.

[0021] Furthermore, the zero Poisson's ratio compression-resistant composite material is used as a structural stabilizing component in deep-sea exploration equipment or deep-space probes under pressure fluctuation environments.

[0022] The seventh objective of this application is to provide a deep ultraviolet optical window element comprising the aforementioned zinc carbonate crystal.

[0023] Furthermore, the aforementioned deep ultraviolet optical window element is used in deep ultraviolet optical detection equipment operating in extreme high-pressure or vacuum environments.

[0024] The present application adopts the above technical solution, and its beneficial effects are as follows: The method for preparing zinc ammonium carbonate crystals provided in this application involves a solvothermal reaction of a solvent, zinc acetate, and urea. After the reaction, the mixture is cooled and separated to obtain zinc ammonium carbonate crystals. This invention provides an efficient, controllable, and low-cost synthesis route for zinc ammonium carbonate single crystals. It employs a solvothermal method with a specific mixed solvent and utilizes the controlled hydrolysis of urea to achieve the directional growth of crystals with a specific helical chain structure under mild conditions. The crystals exhibit stable, reversible, and linear negative linear compression (NLC) behavior over a wide pressure range of 0-5 GPa, solving the key technical bottlenecks of narrow pressure range and nonlinear response of existing NLC materials. This provides an ideal solid-state molecular spring material for high-pressure precision sensing and actuation. Furthermore, the method is simple, reproducible, and provides a reliable and high-quality material source for subsequent research and applications.

[0025] This application also provides a pressure sensing element that preliminarily realizes the NLC characteristics of the zinc ammonium carbonate crystal. By setting the b-axis of the crystal parallel to the direction of the pressure to be measured, the pressure can be directly and linearly converted into significant axial strain, thereby constructing a basic sensing unit with a wide operating range (0-5 GPa) and high response linearity.

[0026] This application also provides a Fabry-Perot cavity fiber optic pressure sensor, which utilizes the characteristic of linear elongation of the crystal's b-axis under pressure to directly modulate the optical cavity length of the Fabry-Perot cavity, converting minute pressure changes into high-precision optical wavelength signals. Its sensitivity can theoretically be an order of magnitude higher than traditional sensors, making it particularly suitable for fields with extremely high accuracy requirements, such as minimally invasive medical monitoring (e.g., arterial blood pressure).

[0027] This application also provides an adaptive shock absorber that, by setting the crystal's b-axis perpendicular to the impact direction, causes it to expand laterally upon impact, actively dispersing impact energy over a larger area, thereby significantly improving energy absorption efficiency and response speed. This design provides a lighter and more efficient impact protection solution for fields such as aerospace and automotive safety.

[0028] This application also provides a zero Poisson's ratio compression-resistant buffer composite material. By incorporating NLC crystals as functional fillers into an elastic matrix, the opposing Poisson effect of crystal expansion under pressure and matrix contraction cancels each other out, allowing the composite material to maintain lateral dimensional stability or even expand under pressure. This "zero / negative Poisson's ratio" characteristic effectively prevents structural failure due to stress concentration in extreme environments with drastic pressure fluctuations, such as deep sea and deep space, greatly improving the reliability of the equipment.

[0029] This application also provides a deep ultraviolet optical window element that combines the advantages of ultra-wide bandgap (deep ultraviolet transparency) and high-pressure stability of zinc ammonium carbonate crystal. It can maintain excellent optical transmission performance in harsh environments such as high pressure or vacuum, providing key component support for the operation of deep ultraviolet detection, lithography and other equipment under special working conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram illustrating the change of lattice parameters of zinc ammonium carbonate with pressure, as provided in Example 1 of this application. Figure 2 The linear compressibility K of the three lattice parameters a, b, and c of zinc ammonium carbonate provided in Example 1 of this application a K b K c The fitted curve; Figure 3 This is the band structure of zinc ammonium carbonate provided in Example 1 of this application. Detailed Implementation

[0032] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. In the description of this application, it should be understood that the terms "upper", "lower", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified. To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments.

[0033] This application provides a method for preparing zinc ammonium carbonate crystals, comprising the following steps: A solvent, zinc acetate, and urea were subjected to a solvothermal reaction. After the reaction was completed, the mixture was cooled and separated to obtain zinc ammonium carbonate crystals.

[0034] In this embodiment, the solvent is a mixed solvent containing water and N,N-dimethylformamide.

[0035] In this embodiment, the mass ratio of urea, zinc acetate and solvent is 1:7:50-80.

[0036] In this embodiment, the temperature of the solvothermal reaction is 150-155°C.

[0037] In this embodiment, the separation step includes collecting transparent, long needle-like crystals from the reaction products.

[0038] In this embodiment, the method further includes a step of vacuum drying the separated crystals.

[0039] Mechanistically, the synthetic route described in this invention can specifically obtain zinc ammonium carbonate single crystals with a ZnOCO-ZnOCO helical network structure. This structure is the fundamental reason why it exhibits wide compressibility, stability, reversibility, and linear-negative linear compression (NLC) behavior. The following is a step-by-step mechanism analysis: This embodiment uses a mixed solvent of water and DMF, instead of pure water. DMF is a polar aprotic solvent with strong coordination ability. In the reaction system, DMF molecules can react with Zn... 2+ Weak coordination occurs, forming [Zn(DMF)x] 2+ Intermediate. This coordination effect moderately reduces the Zn content. 2+ Its reactivity was reduced, thus avoiding its interaction with rapidly released CO3. 2- Instead of immediately forming an amorphous precipitate (such as basic zinc carbonate), the reaction is guided towards a slow, orderly crystallization process.

[0040] Urea undergoes slow hydrolysis under high-temperature hydrothermal conditions of 150-155℃, gradually releasing NH3 and CO2 (which in turn generates CO3). 2- NH3 molecules, as strong-field ligands, preferentially bind to Zn²⁺. + Coordination occurs, forming [Zn(NH3)] 2+ This unit exhibits a clear tetrahedral coordination tendency; simultaneously, CO3 2- The ions connect two different [Zn(NH3)] ions in a bidentate bridging mode. 2+ unit.

[0041] Driven by thermodynamics, [Zn(NH3)] 2+ Unit and CO3 2- Alternating connections spontaneously assemble to form one-dimensional infinitely long chains extending along the b-axis, with the basic unit being -Zn(NH3)-OCO-Zn(NH3)-, i.e., ZnOCO-ZnOCO chains. These one-dimensional chains are not arranged in a straight parallel line. Due to the steric hindrance of the Zn(NH3) units within the chains and the interactions of inter-chain hydrogen bonds (NH…O) and van der Waals forces, adjacent ZnOCO chains stack in a spiral-like, intertwined manner in space. This stacking pattern is crystallographically locked into an orthorhombic crystal system. Pna The 21-space group forms a stable three-dimensional network with chiral helical channels. The b-axis is the main direction of extension of these helical chains.

[0042] It is understandable that the mixed solvent provides a mild environment, urea hydrolysis provides structural units, and finally, through coordination chemistry and supramolecular interactions, a ZnOCO-ZnOCO helical network oriented along the b-axis is precisely constructed from the bottom up.

[0043] When external hydrostatic pressure or uniaxial pressure along the b-axis is applied to this crystal, the pressure does not directly compress the covalent bonds (Zn-O and CO bond lengths are extremely difficult to compress), but rather acts first on the weaker non-covalent interactions between chains (hydrogen bonds and van der Waals forces). The pressure forces adjacent helical chains closer together. To accommodate this proximity and release stress, the entire helical chain network undergoes synergistic structural relaxation: the radius of the elliptical helix (the helix diameter parallel to the ab plane) decreases slightly, the helix tilts relative to the ac plane, forcing its helical radius along the b-axis to increase. In this process, the elongation of the b-axis compensates for the significant pressure of the helical spring along the c-axis, ultimately maintaining the geometrical continuity of the helix and minimizing the total energy of the system. In the crystal, the macroscopic manifestation of the b-axis lattice parameter is an increase, i.e., negative linear compression.

[0044] Furthermore, within the moderate pressure range of 0-5 GPa, the aforementioned deformation mechanism is primarily dominated by the elastic bending of the helical chains and changes in bond angles. This is a continuous, gradual process. The helical network is a highly redundant and flexible topology. Pressure energy is uniformly distributed across countless helical cycles and the entire three-dimensional network, avoiding sudden structural collapse caused by localized stress concentration. As long as the deformation remains within the elastic range, the elongation of the b-axis (Δb) approximately conforms to Hooke's Law with the applied pressure (P), exhibiting an excellent linear relationship. This makes the material highly suitable for linear pressure sensors.

[0045] Furthermore, within the 0-5 GPa range, the basic topology and connectivity of the helical network remain unchanged, and no irreversible structural phase transitions that disrupt covalent bonds occur. The deformation mainly involves the bending of hydrogen bonds and the adjustment of van der Waals distances, which are fully recovered after pressure removal. The entire compression-elongation process is almost an elastic energy storage and release process with minimal hysteresis, ensuring the stability and reliability of cyclic use.

[0046] It is understood that the synthesis path of this invention precisely constructs a ZnOCO-ZnOCO helical network oriented along the b-axis through coordination regulation and slow reaction. Under pressure, this structure resembles a microscopic "spring array," converting axial pressure into lateral elongation through a unique geometric-mechanical coupling mechanism of decreasing helical radius and pitch followed by helical tilt elongation. Because its deformation is based on elastic bond angle changes and weak interaction adjustments, and because the structure itself is robust and redundant, it achieves stable, reversible, and linear negative linear compression behavior within a wide pressure range of 0-5 GPa. This provides near-ideal intrinsic material properties for high-pressure precision sensing and actuation.

[0047] This application provides a method for preparing zinc ammonium carbonate crystals, offering an efficient, controllable, and low-cost synthesis route for single crystals. Employing a solvothermal method using a specific mixed solvent and controlled hydrolysis of urea, the method achieves directional growth of crystals with a specific helical chain structure under mild conditions (150-155℃). This method is simple, reproducible, and provides a reliable and high-quality material source for subsequent research and applications.

[0048] This application also provides a zinc ammonium carbonate crystal, prepared by the aforementioned method, ensuring that the obtained crystal has high purity, high crystal quality, and a unique long needle-like morphology imparted by the above-mentioned optimization method, which facilitates device processing (such as directional cutting).

[0049] This application also provides a zinc ammonium carbonate crystal, wherein the crystal is orthorhombic and the space group is [space group number missing]. Pna 21 has a helical network structure composed of ZnOCO-ZnOCO chains; and, within a pressure range of 0-5 GPa, the crystal exhibits stable and reversible negative linear compression behavior in the b-axis direction, and its b-axis lattice parameter increases linearly with increasing pressure.

[0050] It is understandable that the "ZnOCO-ZnOCO helical network structure" of the aforementioned zinc ammonium carbonate crystal is the root cause of its unusual mechanical behavior. The stable, reversible, and linear negative linear compression (NLC) behavior exhibited in the wide pressure range of 0-5 GPa solves the key technical bottleneck of narrow pressure range and nonlinear response of existing NLC materials, and provides an ideal solid-state "molecular spring" material for high-pressure precision sensing and actuation.

[0051] In this embodiment, the optical band gap of the crystal is greater than or equal to 5.8 eV.

[0052] It is understandable that zinc ammonium carbonate crystals reveal that this material also possesses excellent optical properties, and its ultra-large band gap of ≥5.8 eV makes it a high-performance deep ultraviolet transparent material. This breaks through the limitation of small band gaps in traditional helical structure materials, achieving a unity of excellent mechanical and optical properties.

[0053] This application also provides a pressure sensing element comprising the zinc ammonium carbonate crystal described in any one of the above applications.

[0054] In this embodiment, the zinc ammonium carbonate crystal is configured such that its b-axis direction is parallel to the direction of the pressure to be measured, in order to provide a linear strain response in the pressure range of 0-5 GPa.

[0055] It is understood that this embodiment preliminarily realizes the NLC characteristics of the crystal into a device. By setting the b-axis of the crystal parallel to the direction of the pressure to be measured, the pressure can be directly and linearly converted into significant axial strain, thereby constructing a basic sensing unit with a wide operating range (0-5 GPa) and high response linearity.

[0056] This application also provides a Fabry-Perot cavity fiber optic pressure sensor, comprising: An optical resonant cavity, and a pressure-sensitive element disposed within the optical resonant cavity; The pressure-sensitive element includes the zinc ammonium carbonate crystal, and the b-axis of the crystal is parallel to the direction of change of the cavity length of the optical resonant cavity. When external pressure is applied to the sensor, the zinc ammonium carbonate crystal elongates linearly along the b-axis, causing a corresponding change in the cavity length of the optical resonant cavity, which in turn leads to a shift in the interference spectrum.

[0057] This embodiment demonstrates a high-sensitivity, electromagnetic interference-resistant precision pressure sensor. Utilizing the characteristic of linear elongation of the crystal's b-axis under pressure, the optical cavity length of the Fabry-Perot cavity is directly modulated, converting minute pressure changes into high-precision optical wavelength signals. Theoretically, its sensitivity can be an order of magnitude higher than traditional sensors, making it particularly suitable for fields with extremely high precision requirements, such as minimally invasive medical monitoring (e.g., arterial blood pressure).

[0058] This application also provides an adaptive damper, comprising: An energy dissipation core layer comprising any one of the zinc ammonium carbonate crystals described above; wherein the zinc ammonium carbonate crystals are oriented with their b-axis direction perpendicular to the expected main impact force direction; when subjected to impact, the crystals expand significantly perpendicular to the impact direction to disperse and absorb impact energy.

[0059] This embodiment demonstrates an intelligent shock absorption mechanism based on the negative Poisson's ratio effect. By setting the crystal's b-axis perpendicular to the impact direction, it expands laterally upon impact, actively dispersing impact energy over a larger area, thereby significantly improving energy absorption efficiency and response speed. This design provides a lighter and more efficient impact protection solution for fields such as aerospace and automotive safety.

[0060] This application also provides a zero Poisson's ratio compression buffer composite material, comprising: An elastic polymer matrix; and zinc ammonium carbonate crystals dispersed in the elastic polymer matrix; wherein, when the composite material is subjected to pressure, the negative linear expansion behavior of the zinc ammonium carbonate crystals along the b-axis offsets or partially offsets the positive Poisson contraction of the elastic polymer matrix, thereby causing the composite material to exhibit a macroscopically close to zero or negative Poisson's ratio.

[0061] It is understood that this embodiment provides a novel composite material with unique macroscopic mechanical properties. By incorporating NLC crystals as functional fillers into an elastic matrix, the opposing Poisson effect of crystal expansion under pressure and matrix contraction cancels each other out, allowing the composite material to maintain lateral dimensional stability or even expand under pressure. This "zero / negative Poisson ratio" characteristic effectively prevents structural failure due to stress concentration in extreme environments with drastic pressure fluctuations, such as deep sea and deep space, greatly improving the reliability of the equipment.

[0062] This application also provides a deep ultraviolet optical window element comprising the aforementioned zinc ammonium carbonate crystal. The deep ultraviolet optical window element is used in deep ultraviolet optical detection equipment operating under extreme high-pressure or vacuum environments.

[0063] It is understood that this embodiment develops a deep ultraviolet optical window material suitable for extreme environments. This element combines the dual advantages of ultra-wide bandgap (deep ultraviolet transparency) and high-pressure stability of zinc ammonium carbonate crystals, and can maintain excellent optical transmittance performance under harsh environments such as high pressure or vacuum, providing key component support for the operation of deep ultraviolet detection, photolithography and other equipment under special working conditions.

[0064] This application provides a unique multifunctional material, zinc ammonium carbonate crystal, exhibiting stable, linear negative compressive response over a wide pressure range of up to 5 GPa, and also possessing deep ultraviolet transparency. Based on this material, a series of devices and solutions have been developed for high-value fields such as precision sensing (medical, industrial), intelligent vibration damping (aerospace, transportation), special composite materials (deep sea, deep space), and advanced optics (deep ultraviolet detection). It effectively solves key technical challenges of existing NLC materials, such as narrow pressure range, nonlinear response, limited functionality, and insufficient environmental adaptability of deep ultraviolet window materials. This results in a comprehensive patent portfolio covering materials, devices, and systems, laying a solid technical foundation for future industrial applications in high-end manufacturing, biomedicine, and defense technology.

[0065] This invention utilizes zinc acetate and urea powder as raw materials. Through a hydrothermal reactor heated using a urea hydrolysis and solvothermal method, the zinc acetate and urea powder are placed within a suitable temperature and pressure range, achieving a structural transformation to obtain zinc ammonium carbonate single crystals. The raw materials for preparing the zinc ammonium carbonate single crystals provided by this invention are inexpensive and readily available, the reaction temperature and pressure are easily controlled, the preparation method is simple, and the preparation cycle is short. The synthesis approach of this invention for zinc ammonium carbonate single crystals can also be extended to the controllable preparation of other metallic ammonia carbonate functional materials. The zinc ammonium carbonate of this invention exhibits extremely rare negative linear compressibility properties, showing great application potential in fields such as biomimetic engineering, smart wearables, extreme environment detection, and high-voltage energy storage.

[0066] Example 1: (1) Preparation of zinc ammonium carbonate: The cadmium sulfate material proposed in this invention has negative linear compressibility along the b-axis and is an orthorhombic crystal system with the corresponding space group being Pn twenty one m The unit cell parameters are a = 9.1413 Å, b = 7.5912 Å, and c = 5.4978 Å. The preparation method is as follows: First, urea powder is dissolved in N,N-dimethylformamide (DMF) and a small amount of water is added, subsequently releasing NH3 and CO3. 2- Ions, and NH produced by hydrolysis 4+ The DMF solution acts as a buffer, stabilizing the system pH between 8 and 11, which is the critical window for the formation of the target product. Zinc acetate dissolved in DMF is then added dropwise to the system to form an initial precipitate. A solvothermal reaction at 150°C for 24 hours promotes the growth of large single crystals. Finally, the product is washed repeatedly with DMF to completely remove organic residues. The key to the success of this method lies in the strict control of reactant concentration and pH value, thus achieving a balance between crystal nucleation and growth. High-purity reagents and deionized water must be used during the synthesis, and thorough washing and solvent exchange steps must be ensured to obtain materials with intact structures and excellent adsorption properties. This method is not only simple to operate and highly reproducible, but its synthetic approach can also be extended to the controllable preparation of other metal ammonia carbonate functional materials.

[0067] The zinc ammonium carbonate crystal provided in Example 1 of this application has the theoretically calculated elastic constant matrix as follows: Cij = 43.3749816.9432516.660820.000000.000000.00000 16.9432541.2056421.440710.000000.000000.00000 16.6608221.4407128.021620.000000.000000.00000 0.000000.000000.0000014.377600.000000.00000 0.000000.000000.000000.0000011.402480.00000 0.000000.000000.000000.000000.000006.71205 Please see Figure 1 The figure shows the change of lattice parameters of zinc ammonium carbonate with pressure as provided in Example 1. The black squares, black circles, and black triangles in the figure represent the relative change rates of the three lattice parameters a, b, and c of zinc ammonium carbonate, respectively.

[0068] Please see Figure 2, is the fitting curve of the linear compressibility Ka, Kb, Kc of the three lattice parameters a, b, c of zinc ammonium carbonate provided in Example 1.

[0069] Please see Figure 3 The diagram shows the band structure of zinc ammonium carbonate in Example 1, with a band gap of 5.897 eV.

[0070] As can be seen from the above, zinc ammonium carbonate exhibits a rare negative linear compression phenomenon on the b-axis, that is, the lattice parameter of the b-axis increases with increasing pressure.

[0071] The ammonium carbonate zinc provided in this application has the potential to become an excellent energy storage material and an excellent deep-ultraviolet optical window material. When combined with an elastic matrix, it becomes a zero-compression, pressure-resistant buffer material that can maintain its structure in pressure fluctuation environments, avoiding structural failure caused by stress impact. It can be applied to deep space exploration, deep-sea equipment, and other scenarios. By utilizing the specific pressure softening properties of ammonium carbonate zinc in the b-axis direction, the application scenarios of pressure-induced softening materials are expanded.

[0072] Based on zinc ammonium carbonate, a helical-configured negative linear compressible material, a high-precision fiber optic Fabry-Perot pressure sensor can be developed. This sensor utilizes the significant lateral expansion characteristics of the material under pressure (Poisson's ratio as high as 1.31) to accurately convert external pressure into changes in optical signals. When pressure is applied to the sensor's optical cavity, the material's negative linear compressibility causes a small but measurable deformation in the cavity length (the bulk modulus B0 is only 23.4, making it extremely sensitive to pressure). By detecting the shift in the interference spectrum, it achieves highly sensitive capture of micropascal-level pressure changes, with a sensitivity more than 10 times higher than traditional fiber optic sensors. It is particularly suitable for real-time minimally invasive monitoring of arterial blood pressure in the medical field, providing breakthrough technical support for precise health diagnosis.

[0073] In the realm of pressure applications, zinc ammonium carbonate can be used to construct intelligent adaptive damping systems. Its massive negative linear compressibility (lateral expansion up to 16.08‰ under pressure) enables the damper to actively disperse energy under impact, and its response to pressure is extremely rapid (bulk modulus B0 is only 23.4). When an external impact occurs, the material first compresses along the direction of force, then expands significantly in the vertical direction, efficiently dispersing the impact force over a larger area, thereby greatly improving energy absorption efficiency and shortening response time. This adaptive mechanism allows the system to maintain a lightweight and compact design while significantly optimizing damping performance in aerospace vehicles, high-end automotive safety systems, and high-performance sports equipment, providing a safer and more efficient protection solution for dynamic load scenarios.

[0074] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A method for preparing zinc ammonium carbonate crystals, characterized in that, Includes the following steps: A solvent, zinc acetate, and urea were subjected to a solvothermal reaction. After the reaction was completed, the mixture was cooled and separated to obtain zinc ammonium carbonate crystals.

2. The method for preparing zinc ammonium carbonate crystals as described in claim 1, characterized in that, The solvent is a mixed solvent containing water and N,N-dimethylformamide.

3. The method for preparing zinc ammonium carbonate crystals as described in claim 1, characterized in that, The mass ratio of urea, zinc acetate and solvent is 1:7:50-80.

4. The method for preparing zinc ammonium carbonate crystals as described in claim 1, characterized in that, The temperature of the solvothermal reaction is 150-155℃.

5. The method for preparing zinc ammonium carbonate crystals as described in claim 1, characterized in that, The separation step includes collecting transparent, long needle-like crystals from the reaction products.

6. The method for preparing zinc ammonium carbonate crystals as described in claim 1, characterized in that, It also includes the step of vacuum drying the separated crystals.

7. A zinc ammonium carbonate crystal, characterized in that, It is prepared by any one of claims 1 to 6.

8. A zinc ammonium carbonate crystal, characterized in that, The crystal is an orthorhombic crystal system with space group . Pna 21 has a helical network structure composed of ZnOCO-ZnOCO chains; and, within a pressure range of 0-5 GPa, the crystal exhibits stable and reversible negative linear compression behavior in the b-axis direction, and its b-axis lattice parameter increases linearly with increasing pressure.

9. The zinc ammonium carbonate crystals as described in claim 8, characterized in that, The optical band gap of the zinc ammonium carbonate crystal is greater than or equal to 5.8 eV.

10. A pressure sensing element, characterized in that, It comprises zinc ammonium carbonate crystals as described in any one of claims 7 to 9.

11. The pressure sensing element as claimed in claim 10, characterized in that, The zinc ammonium carbonate crystals are configured such that their b-axis direction is parallel to the direction of the pressure to be measured, in order to provide a linear strain response in the pressure range of 0-5 GPa.

12. A Fabry-Perot cavity fiber optic pressure sensor, characterized in that, include: An optical resonant cavity, and a pressure-sensitive element disposed within the optical resonant cavity; The pressure-sensitive element comprises a zinc ammonium carbonate crystal as described in any one of claims 7 to 9, wherein the b-axis of the crystal is parallel to the direction of change of the cavity length of the optical resonant cavity; when external pressure is applied to the sensor, the zinc ammonium carbonate crystal elongates linearly along the b-axis, causing a corresponding change in the cavity length of the optical resonant cavity, thereby resulting in a shift in the interference spectrum.

13. The Fabry-Perot cavity fiber optic pressure sensor as described in claim 12 is responsive to micropascal-level pressure changes and is suitable for real-time minimally invasive monitoring of arterial blood pressure.

14. An adaptive shock absorber, characterized in that, include: An energy dissipation core layer comprising zinc ammonium carbonate crystals as described in any one of claims 7 to 9; wherein the zinc ammonium carbonate crystals are oriented with their b-axis direction perpendicular to the expected main impact force direction; when subjected to impact, the crystals expand significantly perpendicular to the impact direction to disperse and absorb impact energy.

15. The shock absorber as described in claim 12 is applied to aerospace structures, automotive safety systems, or high-performance sports equipment.

16. A zero Poisson's ratio compression-resistant buffer composite material, characterized in that, include: Elastic polymer matrix; And zinc ammonium carbonate crystals of any one of claims 7 to 9 dispersed in the elastic polymer matrix; wherein, when the composite material is subjected to pressure, the negative linear expansion behavior of the zinc ammonium carbonate crystals along the b-axis offsets or partially offsets the positive Poisson contraction of the elastic polymer matrix, thereby causing the composite material to exhibit a macroscopically close to zero or negative Poisson's ratio.

17. The zero Poisson's ratio compression-resistant composite material as described in claim 16 is used as a structural stabilizing component in the pressure fluctuation environment of deep-sea exploration equipment or deep-space probes.

18. A deep ultraviolet optical window element, characterized in that, It comprises zinc ammonium carbonate crystals as described in any one of claims 7 to 9.

19. The deep ultraviolet optical window element as described in claim 18 is used in deep ultraviolet optical detection equipment operating in extreme high-pressure or vacuum environments.

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