Phase Of Cu Research Articles

Study Experimental Joining Dissimilar Metal of Cemented Carbide and Carbon Steel under TIG Brazing

In the manufacturing industry, cutting tools are the main component. To produce the best performance of the cutting tool is required high cost. The cemented carbide and steels are joined using brazing. The aim of the work is to investigate the joining of dissimilar metals between cemented carbide and carbon steel using arc brazing. The TIG brazing method has been prepared for the joining of carbide insert and carbon steel. Phenomena that occur in the joint were observed using a scanning electron microscope (SEM). The composition of the constituent elements of the brazed area was characterized by energy dispersive spectroscopy (EDS). Vickers hardness machine is used to hardness test in the brazed area. The results of the microstructure analysis and EDS test composition indicate that solid solution phase enriched Cu is detected in the brazed area. The Fe and C elements are diffusions into the brazed area. The hardness value in the brazed area is 12,16 HVN, greater than based metals especially SS400. Thus, the solid solution phase of Cu and elements of Fe and C affect the hardness value.

In-situ study of the crystallization of amorphous CuInSe2 thin films and the effect of InCl3 treatment

Amorphous CuInSe2 films were deposited by rf-magnetron sputtering onto soda-lime glass and silicon substrates. Some were treated with an InCl3 solution. The films were annealed in a nitrogen environment and studied using in-situ high-temperature x-ray diffraction. CuInSe2 recrystallization began at ∼x223C270 °C and all samples showed increasing crystallinity up to ∼x223C380 °C. The onset and completion temperatures for crystallization varied minimally between samples. The as-deposited films (no InCl3) showed CuSe phase formation at intermediate temperatures (180–250 °C). Na2O from the soda-lime glass increased net rate of crystallization. InCl3 resulted in an even greater increase to crystallization rate and largely improved the final crystalline quality.

Computational study of mechanical properties in [formula omitted][formula omitted

The mechanical properties of the bcc β phase in Cu−Al−Zn alloys are investigated by means of first-principles calculations. Several bcc-based superstructures are considered, with compositions along three different lines. Elastic constants, Young’s and shear moduli, Zener’s anisotropy, sound velocities and Debye temperatures are determined and analyzed as a function of composition. The calculated results are compared with the available experimental data, and general trends are identified. For the line of compositions with electron concentration e/a=1.5 (Cu3Al to CuZn line), a decrease of the elastic constants with the Zn content is obtained. Elastic constants for this line are in the range C11≈ 120–140 GPa, C12≈ 110–130 GPa and C44≈ 85–100 GPa, in general good agreement with the experiment. Values of the anisotropy and Debye temperatures are also comparable with the measured ones.

Influence of Cu content on the phase composition and thermoelectric properties of deposited Cu-Se films

In this study, the p-type Cu-Se films with different Cu contents were prepared on SiO2/Si substrates by magnetron sputtering using targets with different atomic ratio ([Cu]/[Se]) of Cu to Se. The relation of Cu content and phase composition in Cu-Se films was systematically studied. The deposited films took place phase transformation from p-CuSe2 to p-CuSe2+γ-CuSe, to γ-CuSe, to γ-CuSe+β-Cu2-xSe, to β-Cu2-xSe, to α-Cu2Se+unknown, to α-Cu2Se+unknown+Cu phase with increasing [Cu]/[Se] in the deposited films from 0.49 to 5.74. At room temperature, the carrier concentration decreases in the order of the CuSe2, CuSe and β-Cu2-xSe phase; but the carrier mobility exhibits an opposite trend. In the studied temperature range, the Seebeck coefficient and the power factor decreases in the order of β-Cu2-xSe, CuSe2 and CuSe phase. The [Cu]/[Se] in deposited films with single β-Cu2-xSe phase exceeds 2.0 of stoichiometric lattice and Cu-rich β-Cu2-xSe phase films forms. The deposited Cu-rich β-Cu2-xSe phase film with [Cu]/[Se]=2.65 has an optimum Seebeck and resistivity value, reaching a high power factor of 2.88 mW·m−1·K−2 at RT and 5.91 mW·m−1·K−2 at 320°C. It is of the guidance meaning for the further study the thermoelectric properties of Cu-Se films in the future.

Graphene@Metal Sulfide/Oxide Nanocomposites as Novel Photo‐Fenton‐like Catalysts for 4‐Nitrophenol Degradation

AbstractHerein, S‐doped graphene flakes‐based composites with Fe3O4 and/or CuS nanoparticles (NPs) are reported as photo‐Fenton catalysts for the 4‐nitrophenol (4‐NP) degradation. The S‐doped graphene flakes (S‐GF) were prepared using a thermal treatment approach, and the nanocomposites by the in situ growth of Fe3O4 and/or CuS onto the S‐GF scaffold. The characterization methods confirmed the formation of two‐ and three‐components nanocomposites. The Fe3O4 NPs presented a cubic inverse spinel structure and the CuS phases a covellite structure, both with smaller crystallite sizes in the nanocomposites. The new nanocomposites showed higher ability to catalyze the photo‐Fenton 4‐NP degradation than the individual components. The S‐GF@CuS−Fe3O4 nanocomposite exhibited the best catalytic activity: 95.2 % of 4‐NP degradation, a kinetic of pseudo‐first order (k=0.016 min−1), high photo‐Fenton catalytic stability and catalyst's composition/structure preservation. The CuS NPs showed an important role in the photo‐Fenton‐like catalytic activity improvement.

Effects of rare earth Ce addition on the microstructure and shear property of Cu/In-50Ag/Cu composite solder joint

The microstructure and shear property of Cu/In-50Ag-xCe/Cu (x = 0, 0.3, 0.6, 1.2, 2 wt%) composite solder joints fabricated by transient liquid phase (TLP) bonding were investigated. The results showed that the appropriate amount of Ce particles refined the microstructure in the Cu/In-50Ag/Cu solder joint, and inhibited Cu2In phase formation at the Cu/solder interface. The refined Ag2In phases contribute to suppressing the formation of microstructural defects. The Ce particles can improve the microstructure uniformity of composite solder joint, the porosity of Cu/In-50Ag-0.6Ce/Cu solder joint is only 1.05%, and the excessive (1.2–2 wt%) Ce particles are harmful to the composite solder joints. Doping 0.3–0.6 wt% Ce particles can improve the shear strength of composite solder joints by reducing microstructural defects, refining Ag2In phases and improving the phase boundaries strength. The maximum shear strength value of the Cu/In-50Ag-0.6Ce/Cu composite solder joint reaches 17.58 MPa. The fracture mechanism is mainly brittle fracture, which occurs near the in-situ reaction zone. The Cu/In-50Ag-0.6Ce/Cu composite solder joint fabricated by TLP bonding with finer microstructure and higher mechanical properties is acceptable.

Impact of substrate temperature during NaF and KF post-deposition treatments on chemical and optoelectronic properties of alkali-free Cu(In,Ga)Se2 thin film solar cell absorbers

The substrate temperature TPDT during the alkali fluoride post-deposition treatment (PDT) of Cu(In,Ga)Se2 (CIGSe) thin-film solar cell absorbers is a critical process parameter. So far, TPDT is optimized empirically for a particular alkali distribution, and literature only reports on the effects of high TPDT (300–350 °C). To better understand the influence of TPDT and to close the gap for TPDT below 300 °C, a temperature series from 100 to 315 °C was studied. Furthermore, most studies on KF PDTs are performed with alkali-containing soda-lime glass substrates, in which the electrical effects of alkalis from the substrate and the PDT on the final device cannot be separated. To circumvent this obstacle, we use alkali-free substrates in our study and compare electrical and chemical effects of NaF and KF PDTs at different TPDT using current-density-voltage and capacitance-voltage measurements, as well as time-of-flight secondary-ion mass spectrometry and ultraviolet photoelectron spectroscopy. The alkali concentrations are quantified as a function of TPDT and discussed in relation to the respective cell parameters. Both, NaF and KF PDTs, improve the cell efficiency significantly, with the highest conversion efficiency of 16.3% obtained for a NaF PDT at TPDT = 315 °C. A given TPDT leads to a larger K concentration (after KF PDT) than Na concentration (after NaF PDT). For TPDT above 150 °C, similar conversion efficiencies are achieved for NaF and KF PDTs. In contrast, the KF PDT results in a significant decrease of the conversion efficiency at TPDT = 105 °C, likely caused by the formation of a Cu-Se secondary phase at the CIGSe surface, which is accompanied by a shift of the valence band maximum towards the Fermi energy.

Effects of alloying, heat treatment and nanoreinforcement on mechanical properties and damping performances of Cu–Al-based alloys: A review

Abstract Cu–Al-based alloys are a kind of new functional material. Due to their unique thermoelastic martensite structure, they have excellent damping performance, which has become a research hotspot in the field of materials science and engineering in recent years. However, the elastic anisotropy and large grain size easily cause a brittle fracture, which is harmful to the mechanical properties of the material. In order to meet the practical needs of engineering, it is an important choice to design Cu–Al-based alloys with excellent mechanical properties and damping performances from the perspective of refining the grain size. When the grain size is small, the effect of fine grain strengthening and interfacial damping can play a role simultaneously to obtain Cu–Al-based alloys with excellent comprehensive properties. In this paper, several common preparation methods of Cu–Al-based alloy are introduced firstly. Then the contributions of researchers in refining grain size from alloying and heat treatment are summarized. Meanwhile, nanomaterials can be used as the reinforcing phase of Cu–Al based alloy, and play a superb role in mechanical properties and damping performances. The purpose of this study is to provide a reference for the further research of structure-function integrated materials with high strength and high damping simultaneously. Finally, the development of Cu–Al-based alloy from the aspects of 3D printing and numerical simulation is prospected.

Synthesis of a novel ZnAl2O4/CuS nanocomposite and its characterization for photocatalytic degradation of acid red 1 under UV illumination

ZnAl2O4/CuS nanocomposite micro-flakes were prepared using a hydrothermal method. The as-prepared catalyst was investigated using X-ray diffraction, Fourier transform infrared spectra, scanning electron microscopy and UV–vis diffusive reflectance spectroscopy. X-ray diffraction analysis revealed the presence of CuS phase as a major phase (70%) in the prepared catalyst. The results indicated that the combination of ZnAl2O4 with CuS ameliorate potentially its photocatalytic efficiency during the degradation of acid red 1 (95% within 150 min) under ultraviolet illumination compared to ZnAl2O4 or CuS alone. The effect of catalyst mass, dye concentration and pH solution were investigated using ZnAl2O4/CuS. On the other hand, the reuse tests of ZnAl2O4/CuS displayed high-performance stability after five cycles. Additionally, the activity of hydroxyl radicals (OH.) and superoxide ions (O2·-) as the spices responsible for AR1 dye degradation was confirmed by the free radicals scavenging tests.

Effect of sintering temperature on lightweight aggregates manufacturing from copper contaminated soil

Manufacturing lightweight aggregate (LWA) at high temperature is an effective way to immobilize heavy metals in solid waste. This work investigated the performance and solidification mechanism of LWA prepared from copper contaminated soil. The volume expansion of LWA could reach a maximum of 28%, and its lowest density accounted of 1.5 g/cm3, which met the standard requirements. Optical microscope and micro-CT test illustrated that the addition of Cu leaded to obvious phase separation in LWA. The Cu leaching result of LWA first increased and then dropped with the temperature. The XRD test found that the main formation phase of Cu in LWA were t-CuFe2O4 and amorphous phase that they had different acid resistance ability. XPS revealed that the main cause of the agglomeration of liquid phase in LWA was the chain broken reaction between Cu and Si–O tetrahedron. SEM-EDS results showed that the distribution of Cu and Si had a strong correlation, which meant that Cu mostly formed amorphous phase. This work showed the uniqueness of Cu in the high temperature immobilization and pointed out the best immobilization target phase.

Temperature Controlled Evolution of Pure Phase Cu9S5 Nanoparticles by Solvothermal Process

Copper sulphides are one of the most explored semiconductor metal sulphides because of their stoichiometric and morphological dependent optical and electrical properties, which makes them tunable for numerous optoelectronic applications. Stoichiometrically, copper sulphides exist in numerous structures which varies from the copper-rich phase (Cu2S) to the copper-deficient phase (CuS). Within these extreme stoichiometric phases lies numerous non-stoichiometric phases with interesting optical properties. Different solvothermal techniques have been explored for the synthesis of copper sulphides; however, the thermal decomposition of single source precursors provides a facile and tunable route to the synthesis of pure phase copper sulphides of different stoichiometries. In this study, copper (II) dithiocarbamate have been explored as a single source precursor compound to study the evolution of pure phase Cu9S5. Below 240°C, mixed phase of CuS and Cu9S5 were obtained, and as the temperature was increased beyond 240°C, keeping other reaction condition unchanged, the precursor yielded pure phase of Cu9S5. This phase selectivity at high temperature was attributed to the increased reducing ability of oleylamine (used as solvent) which enhance the evolution of the copper rich phase at high temperature. Optical and morphological studies of the pure phase Cu9S5, showed properties that varied considerably with the temperature of synthesis.

Massive Intracellular Remodeling of CuS Nanomaterials Produces Nontoxic Bioengineered Structures with Preserved Photothermal Potential.

Despite efforts in producing nanoparticles with tightly controlled designs and specific physicochemical properties, these can undergo massive nano-bio interactions and bioprocessing upon internalization into cells. These transformations can generate adverse biological outcomes and premature loss of functional efficacy. Hence, understanding the intracellular fate of nanoparticles is a necessary prerequisite for their introduction in medicine. Among nanomaterials devoted to theranostics is copper sulfide (CuS), which provides outstanding optical properties along with easy synthesis and low cost. Herein, we performed a long-term multiscale study on the bioprocessing of hollow CuS nanoparticles (CuS NPs) and rattle-like iron oxide nanoflowers@CuS core-shell hybrids (IONF@CuS NPs) when inside stem cells and cancer cells, cultured as spheroids. In the spheroids, both CuS NPs and IONF@CuS NPs are rapidly dismantled into smaller units (day 0 to 3), and hair-like nanostructures are generated (day 9 to 21). This bioprocessing triggers an adaptation of the cellular metabolism to the internalized metals without impacting cell viability, differentiation, or oxidative stress response. Throughout the remodeling, a loss of IONF-derived magnetism is observed, but, surprisingly, the CuS photothermal potential is preserved, as demonstrated by a full characterization of the photothermal conversion across the bioprocessing process. The maintained photothermal efficiency correlated well with synchrotron X-ray absorption spectroscopy measurements, evidencing a similar chemical phase for Cu but not for Fe over time. These findings evidence that the intracellular bioprocessing of CuS nanoparticles can reshape them into bioengineered nanostructures without reducing the photothermal function and therapeutic potential.

Correlation between structural and optical characteristics upon changing the composition ratio of CuS@MnS nanocomposites

Nanocomposite (1 − x)CuS/(x)MnS samples (x = 0, 0.25, 0.5, 0.75, 1) were prepared by a simple thermolysis procedure at low temperature (250 °C). HighScor plus program and Rietveld profile method revealed that CuS crystallized in hexagonal phase, while MnS crystallized in hexagonal and cubic phases. The intermediate alloying ratios (x = 0.5, 0.75) have a cubic phase of MnS and a hexagonal phase of CuS, while sample with x = 0.25 has a hexagonal phase of CuS only. The phase percentage of MnS phase in the nanocomposite samples is always less than the nominal value proposed during the sample’s preparation. The MnS phase in the intermediate alloying ratios (x = 0.5, 0.75) has a larger crystallite size than the CuS phases. Composite samples (x = 0.5, 0.75) revealed two optical band gaps while sample with x = 0.25 showed only one optical band gap. The photoluminescence intensities for CuS@MnS nanocomposites were decreased as compared with either CuS or MnS samples. Nanocomposite (1 − x)CuS/(x)MnS samples emitted UV, violets, blue, green and yellow colors depended on the ratio between CuS and MnS mounts in the composite samples and the excitation wavelengths uses. The different kinds of defects in different samples were investigated also in detail.

Synthesis and characterization of CuAlS2 nanoparticles by mechanical milling

CuAlS2 chalcopyrite nanocrystalline was successfully synthesized by high energy mechanical milling followed by a homogenization annealing at argon atmosphere. The stoichiometric mixture of elemental Cu, Al, and S powders was mechanically alloyed under argon atmosphere using a high energy ball milling device. The X-ray diffraction patterns indicated that the CuS phase with a hexagonal crystal lattice and interconnected plane morphology forms in the early stage of milling. The Main phase begins at 1 h. With increasing milling time, crystallite size decreased and microstrain increased. The X-ray diffraction patterns of annealed powder at different times and temperatures show increased crystallite size and c/a, and decreased microstrain. The optical direct bandgap values of CuAlS2 nanoparticles were calculated to be about 3.1–3.4 eV. The positive Seebeck coefficient indicates that the dominant carrier holes. The maximum Seebeck coefficient 11.5 μV/K was obtained at 377 ℃.

The effects of S, Cl and oxygen fugacity on the sublimation of volatile trace metals degassed from silicate melts with implications for volcanic emissions

Volatile trace metals emitted to the atmosphere by volcanism can be complexed with ligands in a gas phase that undergoes large changes in temperature (T) and oxygen fugacity (fO2). To study this effect, a modified vertical tube gas-mixing furnace was used to investigate the role of S and Cl on the degassing and sublimation of volatile trace metals from silicate melt at 100 kPa over a range of fO2 from FMQ+5 to FMQ−4.6 at the melt-gas interface (where FMQ is the fayalite-quartz-magnetite buffer). Analogue phonolitic melt compositions in the Na2O-Fe2O3-Al2O3-SiO2 systems containing trace metals (Li, V, Fe, Cu, Ni, Zn, As, Y, Mo, Cd, Sn, Yb, Rb, Cs, Ag, Pb and Bi) are degassed at 950 °C and form sublimates along a temperature gradient (25–900 °C) in a suspended silica glass tube. Silica polymorphs are ubiquitous sublimates at all temperatures; halite is common below 600 °C with other less-easily identified oxides, sulfides, sulfates, chlorides and molybdates in trace quantities. The trace metal concentrations in the sublimates show trends used to infer their transport and deposition with temperature, fO2 and ligand identity. The sublimation of metals is mainly controlled by T. Monovalent Rb, Cs, and Ag sublime in halides at 350 ± 50 °C with transport dominated by Cl. The effect of fO2 is only observed for Zn, As, Pb, Cd, Bi, Fe, and Ni below ∼FMQ−3, where they change their sublimation host from sulfates or sulfides at 500 ± 50 °C to halides at 350 ± 50 °C. Molybdates subliming at 600 ± 50 °C host Li and Mo. No discernible host phase for Cu and Sn is observed with decreasing temperature. The experiments suggest different suites of trace metals in volcanic systems are transported with either S (Zn, As, Pb, ±Cd, ±Bi) or Cl (Rb, Cs, Ag, Fe, Ni, ±Cd, ±Bi) depending on T and fO2. Eruptions rich in Cl make halide sublimates a likely significant source of volatile trace metals to the environment.

CeO2 and TiO2 support material effects on NH3 decomposition pathway mechanism over Cu–Zn catalysts

The decomposition of NH3 over Cu–Zn catalysts, supported on ceria and titania, was investigated, producing carbon (di)oxide-free H2. The rate of the H2 formation at the exposed metallic Cu atoms (cumulative turnover frequency) for dispersed Cu–Zn depended strongly on the type of metal oxide support, indicating that the pathway active sites of Cu–Zn nano-catalysts were not identical in quantity. The investigation of the associative desorption process of atomic nitrogen moieties formed by the NH3 scission over Cu–Zn alloy revealed that N2 interface evolution temperature was affected by the nature of substrates. The characterization of the nanomaterials before the catalyzed splitting reactions of NH3 was carried out by XRD, N2 physisorption, N2O chemisorption, H2 TPD, CO2 TPD, NH3 TPD and H2 TPR. TEM and XPS were conducted on both fresh and used composites. Cu–Zn dispersion increased in the presence of TiO2. These spinel forms exhibited a strong Cu0.5Zn0.3Ti0.2O2–x (x = 0–1) structure interaction. Cu–Zn/CeO2 showed a 79% conversion of ammonia at 600 °C, whereas Cu–Zn/TiO2 demonstrated 63% at comparative operating conditions. A high catalytic activity, reflected in almost total consumption of ammonia at 700 °C with the hydrogen reactive production of 33.2 mmol g−1 min−1, was achieved over Cu–Zn/TiO2. No reactivity loss considering the NH3 depletion under applied reactor runs was detected, implying that materials had excellent time-on-stream stability. By scanning and transmission electron microscopy, bimetallic Cu–Zn was also observed, displaying a uniform TiO2 particle distribution on a structured sample surface. Impregnated zinc and copper species were uniformly distributed over Cu–Zn/TiO2. In the case of higher precursor content, a slight Cu domain agglomeration was noted. A heterogeneous mixed phase of Cu and Cu2O was present in all examined powders, as exposed by Cu L-edge spectra ratios.

Metal–Organic Framework-Derived CuS Nanocages for Selective CO 2 Electroreduction to Formate

Electroreduction of CO2 to target products with high activity and selectivity has techno-economic importance for renewable energy storage and CO2 utilization. Herein, we report a hierarchical CuS h...

Comparative study between pure and manganese doped copper sulphide (CuS) nanoparticles

The pure CuS and Mn2+ doped CuS nanoparticles are synthesized by wet chemical route. The CuS phase and hexagonal crystal structure is confirmed by the powder X-ray diffraction and Raman analysis. The vibrational bonds present in the respective synthesized samples are confirmed by Fourier transformed infra-red spectroscopy. The spherical shapes of the nanoparticles are validated by the electron diffraction in scanning and transmission mode. The thermal analysis showed the Mn2+ doped CuS nanoparticles to be more stable than pure CuS nanoparticles. The thermal parameters determined using Coats-Redfern relation stated thermal activation energy and enthalpy change values are highest in the higher temperature range. The Seebeck coefficient variation with temperature and ambient condition Hall effect measurements showed the synthesized nanoparticles to be semiconducting and p-type in nature. The magnetic properties study by Gouy method showed the nanoparticles to be paramagnetic.

Scalable synthesis of Cu\u2013Sb\u2013S phases from reactive melts of metal xanthates and effect of cationic manipulation on structural and optical properties

We report a simple, economical and low temperature route for phase-pure synthesis of two distinct phases of Cu–Sb–S, chalcostibite (CuSbS2) and tetrahedrite (Cu12Sb4S13) nanostructures. Both compounds were prepared by the decomposition of a mixture of bis(O-ethylxanthato)copper(II) and tris(O-ethylxanthato)antimony(III), without the use of solvent or capping ligands. By tuning the molar ratio of copper and antimony xanthates, single-phases of either chalcostibite or tetrahedrite were obtained. The tetrahedrite phase exists in a cubic structure, where the Cu and Sb atoms are present in different coordination environments, and tuning of band gap energy was investigated by the incorporation of multivalent cationic dopants, i.e. by the formation of Zn-doped tetrahedrites Cu12−xZnxSb4S13 (x = 0.25, 0.5, 0.75, 1, 1.2 and 1.5) and the Bi-doped tetrahedrites Cu12Sb4−xBixS13 (x = 0.08, 0.15, 0.25, 0.32, 0.4 and 0.5). Powder X-ray diffraction (p-XRD) confirms single-phase of cubic tetrahedrite structures for both of the doped series. The only exception was for Cu12Sb4−xBixS13 with x = 0.5, which showed a secondary phase, implying that this value is above the solubility limit of Bi in Cu12Sb4S13 (12%). A linear increase in the lattice parameter a in both Zn- and Bi-doped tetrahedrite samples was observed with increasing dopant concentration. The estimated elemental compositions from EDX data are in line with the stoichiometric ratio expected for the compounds formed. The morphologies of samples were investigated using SEM and TEM, revealing the formation of smaller particle sizes upon incorporation of Zn. Incorporation of Zn or Bi into Cu12Sb4S13 led to an increase in band gap energy. The estimated band gap energies of Cu12−xZnxSb4S13 films ranges from 1.49 to 1.6 eV, while the band gaps of Cu12Sb4−xBixS13 films increases from 1.49 to 1.72 eV with increasing x.

Megahertz dynamics in skyrmion systems probed with muon-spin relaxation

We present longitudinal-field muon-spin relaxation (LF $\mu$SR) measurements on two systems that stabilize a skyrmion lattice (SkL): Cu$_2$OSeO$_3$, and Co$_x$Zn$_y$Mn$_{20-x-y}$ for $(x,y)~=~(10,10)$, $(8,9)$ and $(8,8)$. We find that the SkL phase of Cu$_2$OSeO$_3$ exhibits emergent dynamic behavior at megahertz frequencies, likely due to collective excitations, allowing the SkL to be identified from the $\mu$SR response. From measurements following different cooling protocols and calculations of the muon stopping site, we suggest that the metastable SkL is not the majority phase throughout the bulk of this material at the fields and temperatures where it is often observed. The dynamics of bulk Co$_8$Zn$_9$Mn$_3$ are well described by $\simeq~2$ GHz excitations that reduce in frequency near the critical temperature, while in Co$_8$Zn$_8$Mn$_4$ we observe similar behavior over a wide range of temperatures, implying that dynamics of this kind persist beyond the SkL phase.