Silver Oxalate Research Articles

Silver-Organic Complex in Photosensitive Silver Pastes for Enhanced Resolution and Aspect Ratio.

Traditional screen printing is an easy approach commonly used for conductive pattern fabrication of electronics but lacks high resolution. Photolithography offers better resolution but is complex. Photosensitive silver pastes (PSP) combine the benefits of both but suffer from undercut issues, causing uneven etching, decreased interfacial adhesion, and thus poor resolutions. In this study, we explore the use of molecular precursors (i.e., silver oxalate) to replace metallic silver particles and enhance the depth of light penetration. Our findings demonstrate a successful solution to the undercut issue, achieving an undercut index of 1.0, indicating an undercut-free scenario and enabling higher resolutions in line and pattern formation. Additionally, our research confirms the feasibility of multilayer stacking of photosensitive pastes, achieving unprecedented aspect ratios in line patterns. By replacing 25% of micrometer silver powder with silver oxalate (PSP-25), we achieved optimal line widths as fine as 10 μm. The three-layer stack of PSP-25 reached a substantial aspect ratio with a height of 29.4 μm and an optimal fringe pattern resolution of 10 μm line width with a 15 μm aisle width. Utilization of silver oxalate was observed to slightly expand the line width, likely due to light scattering by the fine silver nanoparticles (∼40 nm) formed during the photodecomposition of silver oxalate.

Low-Temperature Sintering of Ag Composite Pastes with Different Metal Organic Decomposition Additions.

Rapid developments in wide-bandgap semiconductors have led to the demand for interconnection materials that can withstand harsh conditions. In this study, novel Ag composite pastes were developed with the assistance of metal organic decomposition (MOD) to significantly reduce the sintering temperature of commercial Ag pastes. The effects of the decomposition characteristics of different MODs on the microstructure, morphology, and the shear strength of the Ag-sintered joints were systematically investigated. Additionally, the low-temperature sintering mechanisms of the MOD-assisted Ag composite pastes were studied and proposed. Among all the MODs studied, the one consisting of propylamine complexed with silver oxalate demonstrated the best performance due to its ability to form Ag nanoclusters with the smallest size (~25 nm) and highest purity (~99.07 wt.%). Notably, the bonding temperature of the MOD-modified Ag pastes decreased from 250 °C to 175 °C, while the shear strength increased from 20 MPa to 40.6 MPa when compared to the commercial Ag pastes.

High-conductivity flexible Ag films formed by low-temperature and short-time sintering of PVP-modified silver oxalate composite ink

Attaining low-temperature sintering and high electrical conductivity is vital in the field of flexible electronics. Inks with silver oxalate as the precursor have recently received significant attention in this field; however, the high sintering temperature and long sintering time limit commercial applicability. High sintering temperature can shorten the sintering time but lead to porous and uneven film morphology; thus, reducing the conductivity. On the other hand, low sintering temperature prolongs the sintering time; thus, reducing the production efficiency. To solve the abovementioned problems, a silver composite conductive ink modified by polyvinylpyrrolidone (PVP) was prepared in this study. The ink used silver oxalate as the precursor, methanol and acetone as the solvent, and 1, 2-diaminopropane as the complexing agent, and could reduce the sintering temperature and time to 160 °C and 20 min, respectively. After sintering, the silver film showed good electrical conductivity, and low resistivity (4.56 μΩ·cm). Furthermore, the impact of sintering temperature on the surface morphology and electrical conductivity were also studied, and the results showed that PVP had a positive influence on the nucleation of silver and the microstructure of the sintered silver film.

Metallization-free silver sinter bonding to silicon via in situ decomposition of silver oxalate

Metallization-free Ag sinter bonding to Si and SiO2 substrates was achieved via the thermal decomposition of Ag oxalate. Ag oxalate generated atomic-scale Ag through decomposition at approximately 200 °C and transformed into sintered Ag. Ag derived from Ag oxalate successfully bonded to Si substrates through close contact formation with Si surface oxide. Similarly, amorphous and α-quartz SiO2 substrates were directly bonded with Ag. These results indicate that the atomic-scale Ag generated on SiO2 contributed to interface formation over a large area. Moreover, the joints of the bare Si chip and metal substrate showed a maximum shear strength of 29 MPa at a bonding temperature of 250 °C and a bonding pressure of 5 MPa. The in-situ generation of Ag through the decomposition of Ag precursors can facilitate the direct bonding of electronic materials, making the proposed method a promising one for electronics applications.

Nanostructured Palladacycle and its Decorated Ag-NP Composite: Synthesis, Morphological Aspects, Characterization, Quantum Chemical Calculation and Antimicrobial Activity

We herein report the synthesis of nanostructured cyclopalladated complex and its nanosilver composite for the first time. The reaction between Schiff base ligand 4-methyl-N-(3,4-dimethoxybenzylidene)] benzenamine (L) and palladium acetate gave the cyclopalladted complex (Pd1) in nanoscale. Thermal treatment of silver oxalate with Pd1 resulted in the formation of novel nanostructured composite, silver nanoparticle-decorated palladacycle (Pd2). The synthesized compounds were characterized using spectroscopic analysis (FT-IR and 1H NMR), thermal analysis (TGA), XRD and morphological analysis (SEM and TEM). The spectral analysis revealed that complex Pd1 has dimeric structure bridged with acetate ligands between two monomers. SEM images exhibited that Ag-NPs loaded on complex surface in decorated form. TEM photographs showed the particle sizes of composite ≈ 29 nm. Quantum chemical analysis of ligand and complex Pd1 has been carried out by DFT/B3LYP method. There are two suggested isomers for cyclopalladated complex named Pd1 and Pd1* which are theoretically studied and correlated with practical results. HOMO, LUMO energy values, chemical hardness–softness, electronegativity and electrophilic index were calculated. The theoretical data obtained have been confirmed that the Pd1 isomer is more stable than Pd1* isomer which correlated well with practical results. The ligand and complexes screened for antimicrobial activity against five medically important microorganisms, namely Staphylococcus aureus, Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. The results showed that complex Pd2 displayed the highest activity against the tested microorganisms.

Selective Laser Decomposition of Silver Oxalate: A New Way of Preparing and Shaping Metallic Silver Patterns

A new process using the selective decomposition of silver oxalate is presented and applied to the production of transparent electrodes on a polymer substrate. It is indeed shown that the silver oxalate Ag2C2O4 can be reduced to the metallic silver state by the focused laser beam of a photolithography machine (λ = 405 nm, spot size 5 µm, power between 3 and 100 mW). Thin lines of silver of width close to 15 µm, for optimized insolation conditions, can thus be directly and easily, formed in a layer of oxalate deposited by spin coating on polycarbonate substrate. Since the metal and the oxalate are of very different chemical natures, the residual oxalate is dissolved by an ammoniacal solution without affecting the metal. The silver conductive lines have a very porous vermicular type microstructure which, however, ensures electrical conductivity. The resistive effects, which result from this not very compact filament organization, can be reduced by simply applying a uniaxial mechanical pressure perpendicular to the plane of the substrate. This operation irreversibly reduces the porosity by crushing the silver strands. One by one-centimeters samples with an electrical resistance of 10 Ω and an optical transparency of 95% (after correcting the effects of the substrate) were thus prepared. Their factor of merit expressed by (Transparency550nm)10 / Rpattern, close to 0.059 Ω−1, is at the state of the art. The selective decomposition of silver oxalates by a laser beam is therefore a very interesting way to easily make transparent conductors made of thin metallic patterns.

Size-Tunable Continuous-Seed-Mediated Growth of Silver Nanoparticles in Alkylamine Mixture via the Stepwise Thermal Decomposition of Silver Oxalate

The size-tunable synthesis of metal nanoparticles (MNPs) is important for revealing their size-dependent unique properties and practical applications. Here, we developed a size-tunable synthesis me...

Negative area compressibility in silver oxalate

The presence of extremely large negative linear compressibilities (NLC) in crystalline silver oxalate was discovered in a recent work by using first principles solid-state calculations. Although the minimum value of the NLC was found for a negative applied hydrostatic pressure, in this work the presence of NLC in this material for positive applied pressures is verified experimentally by means of high-pressure X-ray diffraction experiments performed at room temperature in the Beijing synchrotron radiation facility. The results of this study demonstrate with certainty that the compressibility of silver oxalate along [010] crystallographic direction is negative for applied pressures in the range from 0.0 to 0.85 GPa. Since the measured compressibility decreases largely as the pressure decreases, large negative values of the compressibility are expected for negative applied pressures in agreement with the results found using first principles methods. Furthermore, the analysis of the variation of the lattice parameters of the crystal structure of silver oxalate under pressure in the principal axes reference system revealed that this material also exhibits the largest negative area compressibility phenomenon found so far at zero pressure, the values of the compressibilities along two of the principal axes being − 16.7 and − 20.0 $${\mathrm{TPa}}^{-1}$$ . The negative compressibility phenomenon in silver oxalate can be rationalized in terms of a “chains of rotating parallelograms” structural model.

A novel composite silver nanoparticles loaded calcium oxide stemming from egg shell recycling: A potent photocatalytic and antibacterial activities

Industrial wastewater resulted from textile dyeing process is considered as a big environmental problem. Therefore, recycling of wastewater offers environmental and economic values specially if the materials used are resulted from recycling of other kinds of waste. From this point of view and for the first time this work deals with the study the wastewater recycling by calcium oxide resulted from eggshell recycling. Calcium oxide (CaO) nanocrystals were created by the thermal annealing of chicken egg shell at 1100 °C for 2 h s. Heat treatment at 200 °C in air for 2 h s of the resulted CaO with silver oxalate gave the novel composite, silver nanoparticles loaded calcium oxide (Ag-NPs @ CaO). By applying electronic spectra (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy with the energy dispersion spectrum analysis (SEM-EDX) and transmittance electronic microscope (TEM), the materials were characterized. The energy band gap was calculated from the equation of Tauc for CaO and Ag-NPs@CaO and measured to be 2.1 and 2 eV, respectively. Indigo carmine (IC) as a model of photocatalytic decolorization was performed using both CaO and Ag@CaO nanoparticles under sunlight exposure. The impacts of various variables such as solution pH, dose quantity, temperature and irradiation time were studied. Both catalysts displayed an effective photocatalytic activity in IC decolorization but Ag@CaO composite displayed a stronger activity than CaO. The percentages of dye degradation were ≈99.21% and 99.45% in case of CaO and Ag@CaO, respectively. The antibacterial efficiency was measured against some Gram-negative and Gram-positive bacteria. Ag@CaO provided powerful weapons against the drug-resistant bacteria. These findings give a promising and economic strategy for all those who are interested in industries which involve dyeing process.

Conductivity and foldability enhancement of Ag patterns formed by PVAc modified Ag complex inks with low-temperature and rapid sintering

In the research area of conductive inks for printed electronics, the preparation of conductive circuits generally shows high requirements on the process temperature, process efficiency, electrical conductivity, foldability and so on. In this paper, a new type of Ag complex conductive ink modified by PVAc (poly vinyl acetate) was proposed to enhance the conductivity and foldability of rapidly sintered Ag patterns. The conductive ink was fabricated by mixing silver oxalate as Ag precursor, 1,2-Diaminopropane as complexing reagent, methanol and isopropanol as organic solvents, and a small amount of PVAc as binding agent. Compared to the Ag complex ink without PVAc, the modified ink shows a better sintered microstructure with higher flatness and density after fast sintering at 140 °C–200 °C for 2 min, indicating that the addition of PVAc has a positive effect on the stability of Ag nucleation and microstructure formation. A low resistivity of 5.17 μΩ cm and an improved foldable property can be achieved at 180 °C by sintering the PVAc modified Ag complex ink on PI (polyimide) substrate, which indicates that the proposed ink is promised to be applied in printed circuits and flexible electronics.

Extreme negative mechanical phenomena in the zinc and cadmium anhydrous metal oxalates and lead oxalate dihydrate

The crystal structures and elastic properties of the anhydrous zinc and cadmium oxalates and lead oxalate dihydrate are determined using rigorous first-principles solid-state methods. The three materials are shown to display negative Poisson’s ratios (NPR) and to exhibit the negative linear compressibility (NLC) phenomenon. Anhydrous zinc and cadmium oxalates display NLC for a very wide range of external pressures applied in the direction of minimum compressibility in the ranges − 1.3 to 5.5 GPa and − 1.2 to 2.7 GPa, respectively. The increase of volume in both materials is substantial for pressures larger than 3.6 and 1.8 GPa, and the compressibilities become − 70.1 and − 67.0 TPa−1 for pressures of 5.2 and 2.6 GPa, respectively. The increase of volume is so drastic that these materials become unstable for pressures larger than 5.5 and 2.7 GPa. Lead oxalate dihydrate also displays NLC along the direction of minimum Poisson’s ratio for negative pressures in the range − 0.05 to − 0.08 GPa and undergoes a pressure-induced phase transition for relatively low external pressures of the order of 0.1 GPa. The presence of NPR and NLC phenomena in these three materials together with the previous finding of these phenomena for silver oxalate strongly suggests that other metal oxalate materials could also exhibit an extremely anomalous mechanical behavior.

One step preparation of copper–silver self-catalyzed hybrid conductive ink with reduced sintering temperature for flexible electronics

Copper–silver hybrid conductive inks can combine the advantages of lower cost, better conductivity and long-term stability of the copper or silver ink, which have attracted wide research interest in the development of materials for flexible electronics. Although Cu–Ag nanoparticle based inks, such as Cu–Ag core–shell nanoparticle inks and Cu–Ag bimetallic nanoparticle inks, have already been developed and applied to produce conductive patterns using different deposition methods, they are still not ideal because of the complex and time-consuming synthetic process, low yield and high sintering temperature for good conductivity. In this paper, we report synthesis and characterization of novel self-catalyzed Cu–Ag organic complex inks with reduced sintering temperature via a simple one-step method. The effects of Cu–Ag ratio on the thermal property, stability and electrical performance of the formulated inks were investigated, where the Cu1–Ag1 ink was found to be ideal in terms of cost, conductivity and thermal behavior. The presence of silver oxalate in the copper complex ink was beneficial to the thermal decomposition of the Cu complex and able to decrease the sintering temperature by 30 °C due to the catalytic function of silver, making it more compatible with flexible polymer substrate materials. Meanwhile, the addition of a small amount of silver oxalate could improve the conductivity of the Cu ink. The sintered Cu–Ag films showed favorable conductivity which is comparable to the value of the reported Cu–Ag nano inks but with a lower sintering temperature. The Cu1–Ag1 hybrid ink with self-catalyzing capability is a balanced choice when considering the cost and conductivity.

Silver Oxalate: Mechanical Properties and Extreme Negative Mechanical Phenomena

AbstractThe crystal structure and mechanical properties of silver oxalate, Ag2C2O4, are determined using first‐principles solid‐state methods. The set of calculated mechanical properties include the bulk modulus and its pressure derivatives, the Young and shear moduli, the Poisson's Ratio and the ductility, hardness, and anisotropy indices. Silver oxalate is a highly anisotropic brittle material possessing a small bulk modulus of ≈9.6 GPa. It displays the negative Poisson's ratio (NPR) phenomenon, the value of the lowest NPR having a very large magnitude, −1.27. Besides, it exhibits the most extreme form of the negative linear compressibility (NLC) phenomenon found to date. Silver oxalate displays anisotropic NLC for external pressures in the range −0.1 to −2.4 GPa directed along the [010] crystallographic direction and isotropic NLC for isotropic pressures in the range −0.51 to 13.4 GPa. The lowest value of the negative compressibility, −831.9 ± 10 TPa−1, is found for an isotropic pressure of −0.16 GPa. The absolute value of the computed lowest NLC is extremely large, about three times larger than the absolute value of the lowest NLC found so far. The NLC pressure range is also very wide, its width being more than two times the largest range found to date.

Diaqua oxalato strontium(II) complex as a precursor for facile fabrication of Ag-NPs@SrCO3, characterization, optical properties, morphological studies and adsorption efficiency

Diaqua oxalato strontium(II) complex [Sr(C2O4)(H2O)2] was prepared via a precipitation reaction. Thermal treatment of the as-synthesized precursor at 550 °C resulted in formation of strontium carbonate (SrCO3) nanocrystals. A new composite of silver nanoparticles decorated with strontium carbonate (Ag-NPs@SrCO3) was fabricated by heating a mixture of silver oxalate and strontium carbonate in air at 150 °C for 2 h. The spectral, morphological and thermal properties of the materials have been studied using different physicochemical techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), high-resolution transmission electron microscopy (HR-TEM), Fourier infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), diffrential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). From the Debye–Scherrer equation the calculated particle size of Sr(C2O4)(H2O)2], SrCO3 and Ag-NPs@SrCO3 are 62.1, 58.7, and 58.5 nm, respectively. The SEM and TEM images indicate tetragonal structure of [Sr(C2O4)(H2O)2] while SrCO3 and Ag-NPs@SrCO3 appeared as cubic structures. The calculated energy band gap of SrCO3 and Ag-NPs@SrCO3 using the Tauc equation are estimated at 5.9 and 4.7 eV, respectively. The adsorption capacity of the materials is tested for the adsorption of Congo red anionic dye and exhibited promising results. The adsorption capacity followed the order Ag-NPs@SrCO3>SrCO3> [Sr(C2O4)(H2O)2] with efficiencies of 73.90, 67.55, and 60.50%, respectively.

Study of Synergistic Effects of Antibiotics And Triangular Shaped Silver Nanoparticles, Synthesized Using UV-Light Irradiation, on S. Aureus and P. Aeruginosa

Abstract Now days, resistance of bacteria to bactericides and antibiotics has increased. Some antimicrobial agents are extremely irritant and toxic. Hence there is a need to find ways to formulate green and less toxic materials. In the present work, a study of synergistic effects of as-synthesised triangular shaped silver nanoparticles and two standard antibiotics, ampicillin and gentamycin, was studied on Staphylococcus Aureus and Pseudomonas Aeruginosa. A green route is taken to synthesise silver nanoparticles using silver oxalate as precursor; tea extract and chitin as capping and stabilizing agents respectively. A grey coloured colloidal solution of silver nanoparticles is obtained. XRD, TEM and UV-visible spectroscopy, are used tocharacterise the as-synthesised silver colloidal solution.

Effects of amine types on the properties of silver oxalate ink and the associated film morphology

Silver conductive ink using silver oxalate as silver precursor has attracted considerable research interest due to its unique properties. However, silver oxalate has poor dissolvability in organic solvents and high thermal decomposition temperature, the latter is not desirable for pattern formation on some low cost polymer based flexible substrates. In this paper, different kinds of alkylamine were chosen as ligands to formulate silver oxalate inks to address the mentioned issues. The role of amines in silver oxalate based inks was studied in detail. The influence of amine types on thermal property, stability and electrical performance of the formulated silver oxalate inks was investigated. The relationships between them were established and elucidated. The results show that highly conductive silver films with controlled microstructure features can be achieved for low temperature sintering by selection of an appropriate amine as the latter has a strong influence on the decomposition temperature of the formed silver–amine complex and it determines the nucleation and growth of silver particles in the film formation process. The chemical reactions occurring within the ink were also studied. An optimal silver complex ink was prepared by using blended amines as ligands finally, producing a uniform silver film with good quality and favorable conductivity at 150 °C. The results are important for future design of stable and high conductive silver complex inks for practical applications.

Electric Current-Assisted Joining of Copper Plates Using Silver Formed by In-Situ Decomposition of Ag2C2O4

Pulsed electric current can be used for the fast sintering of powders as well as joining of macroobjects. In this work, we brazed copper plates using a silver layer that was formed in situ by the decomposition of a silver oxalate Ag2C2O4 powder placed between the plates. Joining was conducted in the chamber of a Spark Plasma Sintering (SPS) facility with and without a graphite die. In the die-assisted tooling configuration, indirect heating of the assembly from the graphite die carrying electric current occurred until the brazing layer transformed into metallic silver. The passage of electric current through a Cu/Ag2C2O4/Cu stack placed between the electrodes without a die was possible because of the formation of Cu/Cu contacts in the areas free from the Ag2C2O4 particles. Joints that were formed in the die-assisted experiments showed a slightly higher shear strength (45 MPa) in comparison with joints formed without a die (41 MPa). The shear strength of the reference sample (obtained without a die), a stack of copper plates joined without any brazing layer, was only 31 MPa, which indicates a key role of the silver in producing strong bonding between the plates. This study shows that both die-assisted tooling configurations and those without a die can be used for the SPS brazing of materials by the oxalate-derived silver interlayer.

Research Status and Prospects of Particle-Free Silver Conductive Ink

Conductive inks are mainly used in the printed electronics industry. Particle-free conductive inks are prepared from organometallic compounds or complexes as precursors. They have the characteristics of preventing agglomeration and settling, not easily clogging the nozzles, and having a low heat treatment temperature, suitable for inkjet printing. Starting from precursors, the development statuses of conductive inks using silver acetate, silver citrate, silver neodecanoate, silver oxalate, silver tartrate, silver nitrate, and silver oxide as precursors were respectively introduced, summarized the main problems that existed, and put forward the outlook.

Silver Oxalate Ink with Low Sintering Temperature and Good Electrical Property

Favorable conductivity at low temperature is desirable for flexible electronics technology, where formulation of a suitable ink material is very critical. In this paper, a type of silver organic decomposable ink (10 wt.% silver content) was formulated by using as-prepared silver oxalate and butylamine, producing silver films with good uniformity and conductivity on a polyimide substrate after sintering below 130°C (15.72 μΩ cm) and even at 100°C (36.29 μΩ cm). Silver oxalate powder with good properties and an appropriate solid amine complex with lower decomposition temperature were synthesized, both differing from those reported in the literature. The influence of the factors on the electrical properties of the produced silver films such as sintering temperature and time was studied in detail and the relationship between them was demonstrated.

Reactive Silver Oxalate Ink Composition with Enhanced Curing Conditions for Flexible Substrates.

A solid silver-ligand complex, μ-oxolato-bis(ethylenediaminesilver(I)), was developed for formulating particle-free conductive metal-organic decomposition (MOD) inkjet inks. The complex comprises both a high molar silver content and solubility in inkjet compatible polar solvents. An aqueous ink formulation with 29.5 wt % silver content was developed and inkjet printed onto glass, polyethylene terephthalate, and polyimide substrates. A new hybrid thermal-photonic curing approach resulting in substantially improved electrical properties and substrate adhesion is presented. Silver conductive traces were measured to have bulk resistivity of 4.26 × 10-8 Ω m, which is 2.7 times that of bulk silver. One-pot complex synthesis yielded an easily isolated, and stable, solid product that can be formulated when needed thereby improving shelf life.