Multiple Substitution Strategies toward Tunable Luminescence in Lu2MgAl4SiO12:Eu2+ Phosphors.

The equivalent or heterovalent substitution strategy is an efficient way to stimulate photoluminescence tuning or to optimize the luminescence performances of phosphor materials. Garnet-type compounds receive much attention as phosphor hosts because of their flexible structural frameworks. Herein, a garnet-type Lu2MgAl4SiO12:Eu2+ phosphor with broad-band blue-green emission is first explored with two-site occupation by varying the Eu2+ content. Two host-substitution approaches to controlling the luminescence behavior of Lu2MgAl4SiO12:Eu2+ phosphor are implemented. The cation substitution strategy of Ca2+ for Mg2+ achieves tunable emission from 463 to 503 nm together with broadening emission bands in Lu2Mg1-yCayAl4SiO12:Eu2+ phosphors. Moreover, chemical unit cosubstitution of [Ca2+-Ge4+] replacing [Lu3+-Al3+] results in Lu2-zCazMgAl4-zGezSiO12:Eu2+ phosphors, which induce a red shift of the emission peak of about 60 nm and a broadening in the emission spectra with increasing Ca2+ and Ge4+ concentrations. The possible photoluminescence tuning mechanism is ascribed to the coordination sphere variation in the EuO8 polyhedron depending on the changing neighboring cations. The proposed approaches on equivalent or heterovalent substitution can contribute to the development of Eu2+-activated garnet-type phosphors with regulation of the luminescence performance and further initiate research discovering new phosphors for white-light-emitting diodes.

Local Structure and Spectroscopic Properties of Eu3+-Doped BaZrO3.

Pristine and Eu3+-doped BaZrO3 were synthesized via a solid-state reaction method, and the synthesized samples were systematically characterized. X-ray diffraction confirmed the formation of single and pure phases of cubic-structured BaZrO3. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed the site occupancy of Eu3+ and coordination environment around the different atomic sites. Photoluminescence (PL) excitation and emission spectra revealed the dominant absorption at 275 nm and a broad emission centered at 400 nm due to oxygen vacancies below the conduction band (CB). The PL emission intensity at 597 nm increased with increasing Eu3+ doping concentration; simultaneously, emission from the defect level decreased. This confirmed the efficient energy transfer from oxygen vacancies to Eu3+. Density functional theory was employed to calculate the density of states (DOS) to explain the mechanisms of the PL phenomenon. DOS also showed the presence of impurity states due to Eu3+ doping within the band-gap region. The coincidence of the oxygen vacancy state with Eu f state at the bottom of the CB confirmed the PL energy-transfer mechanisms from the oxygen vacancy to europium. The excited-state lifetime values of the 5D0 state decreased with increasing doping concentration due to the increase of the nonradiative transition rate. The internal quantum efficiency, small excited-state lifetime, and photometric parameters indicated that 3 mol % Eu3+-doped BaZrO3 can be a suitable candidate for the red-light-emitting device applications.

Energy Transfer Mechanisms and Optical Thermometry of BaMgF4:Yb3+,Er3+ Phosphor.

Motivated from our previous studies on the upconversion properties of BaMgF4:Yb3+,Tb3+ phosphor, here we investigated the upconversion properties of BaMgF4:Yb3+,Er3+ phosphor. We demonstrate a two-way versatile approach for the fine-tuning of emission from green to the red region, by varying the dopant concentration and adjusting the pulse width of an infrared laser. The mechanism involved in tuning the emission color by laser power and pulse width variation was illustrated in detail. The temperature dependent upconversion spectra were studied by analyzing the fluorescence intensity ratio of the thermally coupled levels. The maximum sensitivity obtained is 83.29 × 10-4 K-1 at 583 K, which is much higher than the temperature sensitivity reported for other fluoride based materials. Moreover, the influence of the excitation power density on the ability of the phosphor for temperature sensing was also investigated. We obtained a maximum (∼415 K) temperature detection at 2563 mW laser power. The obtained results illustrate the potential use of BaMgF4:Yb3+,Er3+ phosphor in an optical thermometer due to its highly sensitive temperature detection ability.

Calculated Nanocube Vacancy Formation Energy and Cohesion Energy at 0 K.

Nanoparticles of face-centered cubic Cu are modeled using the Sutton-Chen potential. Shapes ranging from perfect cubes through to octahedrons are modeled and characterized. Bulk properties, surface energies, vacancy formation energy, Ev , and cohesive energies, Ecoh , are investigated for particles simulated to up to 5 nm in diameter. Below the subsurface layers, particles larger than 1 nm diameter are compared well to bulk. Of the different shapes, rhombicuboctahedrons are both more stable and have more reactive surfaces. As Ev is dependent on surface orientation, there is a little correlation with size and Ev is mostly dependent on nanoparticle shape. Ecoh is not as dependent on surface orientation and shows both size and shape dependency.

Spectroscopic Investigation of Up-Conversion Properties in Green Emitting BaMgF4:Yb3+,Tb3+ Phosphor.

In this work we have comprehensively studied the up-conversion (UC) properties of BaMgF4:Yb3+,Tb3+ phosphor for the first time. BaMgF4:Yb3+,Tb3+ phosphors were prepared by a simple and low cost precipitation method. To determine the influence of dopant concentration on luminescence properties, the corresponding UC luminescence spectra of BaMgF4:Yb3+,Tb3+ phosphors were studied under NIR excitation. Emission spectra under NIR excitation reveal the vital role of Tb3+ concentration in spectral tuning from the blue to green region. The UC decay curves were also studied to explore the possible energy transfer (ET) mechanisms between Yb3+ and Tb3+. The results reported here are expected to provide an approach for better understanding ET mechanisms in many Yb3+/Tb3+ codoped UC phosphors. This study will be helpful in applications where precisely defined optical transitions is an essential criterion.

Engineering of Mesoporous Cube-like In2O3 Products as Ethanol Detection Platform at Low Operating Temperature: Effects of Different Transition Metals as Dopant Ions.

Although most semiconductor metal oxides including In2O3 show acceptable sensitivity to volatile organic compounds, it is difficult to detect ethanol effectively at low operating temperatures and detection levels. In this study, pure and Co-, Ni-, and Cu-doped In2O3 products with their doping content maintained at 1 mol % were successfully produced using a hydrothermal approach. Explicit contrast on the structural, microstructural, and textural properties of the synthesized In2O3 products was examined to determine their gas sensing performance. The Cu-doped In2O3 sensor demonstrated improved response of 15.3 to 50 ppm ethanol and has satisfactory selectivity, stability, low detection limit of 0.2, humidity resistance, and decreased working temperature of 80 °C compared to 150 °C of the pure In2O3 sensor. This optimal gas sensing performance is derived from the cube-like morphology assembled with interlinked nanoparticles, which favors trapping more target gas molecules and exposing more active sites, thereby greatly improving its sensing ability. This study showed that the Cu-doped In2O3 sensor with 1 mol % is suitable for monitoring ethanol gas for food safety applications.

Effect of annealing conditions on the luminescence properties and thermometric performance of Sr3Al2O5Cl2:Eu2+ and SrAl2O4:Eu2+ phosphors.

We report on the synthesis, photoluminescence optimization and thermometric properties of Sr3Al2O5Cl2:Eu2+ and SrAl2O4:Eu2+ phosphor powders. The photoluminescence of Sr2.9Al2O5Cl2:0.1Eu2+ phosphors exhibits a blue-shift with an increasing annealing temperature owing to a decrease in the crystal field strength of the host caused by evaporation of Cl from the material. The quenching of the blue band in favour of the red band observed in the luminescence spectra of Sr2.9Al2O5Cl2:0.1Eu2+ with an increased annealing temperature was explained using the mechanism of the Landau-Zener transitions. The quantum yield and the lifetime of the phosphors depend on the annealing temperature. Phosphor samples annealed at 850 °C, 1000 °C, 1200 °C and 1500 °C were found to be potential luminescence thermometers using the luminescence spectral method. For Sr3Al2O5Cl2:Eu2+ annealed at 1000 °C, the temperature-dependent dual-band intensity ratio demonstrated a high-temperature sensitivity of ∼1.47%/°C in the temperature range of 23 °C to 40 °C which is superior to other reported phosphors with a microsecond decay time, suggesting that the material has potential for sensitive thermometry applications at ambient temperatures.

High-contrast multi-surface imaging of latent fingerprints using color-tunable YOF:Tb3+,Eu3+ ultrafine nanophosphors with high quantum yield.

Visualization of latent fingerprints (LFPs) using conventional powders has faced challenges on multicolor surfaces. However, these challenges are addressed by the advent of fluorescent powders in LFP detection, and they have redefined the effectiveness of the powder dusting method. In this study, color-tunable YOF:Tb3+,Eu3+ nanophosphors were examined for LFP recognition and were evaluated for their practicality on different types of surfaces. Under 254 nm UV irradiation, the LFPs developed using these nanophosphors showed clear and distinct ridge patterns with level 1, 2, and 3 details. The ultrafine particles of these nanophosphors adhered to the ridge patterns and replicated the minutiae of the LFPs. Meanwhile, the variation of the Tb3+/Eu3+ ratio demonstrated multicolor fluorescence emission from the nanophosphors, which provided better contrast between the ridge patterns on complex surfaces. Furthermore, the high luminescence quantum yield of the nanophosphors ensured high-resolution fluorescence images of the LFPs with a well-defined pattern that was recognizable even without any microscope or sophisticated instrumentation.

The "firing cannons" of Dipodascopsis uninucleata var. uninucleata.

According to literature, the elongated ascospores of Dipodascopsis uninucleata var. uninucleata exhibit smart movement when forcefully ejected from bottle-shaped asci. This type of movement is defined as the unique patterns of non-random movement of ascospores with specialized morphology thereby facilitating release from asci. Smart movement is required to actively release ascospores individually through the narrow ascus neck, without causing an obstruction and blocking ascospore release. However, little is known about the propulsion mechanism of this cannon-type release system. We show that asci of this yeast contain a central channel (barrel) filled with ascospores. These are surrounded by a sheath-like structure that lines the inner surface of the ascus wall. We found that this sheath is responsible for forcing the naked ascospores out of the ascus by exerting turgor pressure from the bottom towards the tip of the ascus. This cannon firing system is in contrast to that found in Dipodascus geniculatus, where no sheaths lining the ascus interior were observed. Instead, sheaths were found enveloping each ascospore.

High Quantum Yield Shortwave Infrared Luminescent Tracers for Improved Sorting of Plastic Waste.

More complete recycling of plastic waste is possible only if new technologies that go beyond state-of-the-art near-infrared (NIR) sorting are developed. For example, tracer-based sorting is a new technology that explores the upconversion or down-shift luminescence of special tracers based on inorganic materials codoped with lanthanide ions. Specifically, down-shift tracers emit in the shortwave infrared (SWIR) spectral range and can be detected using a SWIR camera preinstalled in a state-of-the-art sorting machine for NIR sorting. In this study, we synthesized a very efficient SWIR tracer by codoping Li3Ba2Gd3 (MoO4)8 with Yb3+ and Er3+, where Yb3+ is a synthesizer ion (excited near 976 nm) and Er3+ emits near 1550 nm. Fine-tuning of the doping concentration resulted in a tracer (Li3Ba2Gd(3-x-y)(MoO4)8:xYb3+, yEr3+, where x = 0.2 and y = 0.4) with a high photoluminescence quantum yield for 1550 nm emission of 70% (using 976 nm excitation). This tracer was used to mark plastic objects. When the object was illuminated by a halogen lamp and a 976 nm laser, the three parts could be easily distinguished based on reflectance and luminescence spectra in the SWIR range: a plastic bottle made of polyethylene terephthalate, a bottle cap made of high-density polyethylene, and a label made of the tracer Li3Ba2Gd3(MoO4)8:Yb3+, Er3+. Importantly, the use of the tracer in sorting may require only the installation of a 976 nm laser in a state-of-the-art NIR sorting system.

Persistent luminescent nanophosphors for applications in cancer theranostics, biomedical, imaging and security.

The extraordinary and unique properties of persistent luminescent (PerLum) nanostructures like storage of charge carriers, extended afterglow, and some other fascinating characteristics like no need for in-situ excitation, and rechargeable luminescence make such materials a primary candidate in the fields of bio-imaging and therapeutics. Apart from this, due to their extraordinary properties they have also found their place in the fields of anti-counterfeiting, latent fingerprinting (LPF), luminescent markings, photocatalysis, solid-state lighting devices, glow-in-dark toys, etc. Over the past few years, persistent luminescent nanoparticles (PLNPs) have been extensively used for targeted drug delivery, bio-imaging guided photodynamic and photo-thermal therapy, biosensing for cancer detection and subsequent treatment, latent fingerprinting, and anti-counterfeiting owing to their enhanced charge storage ability, in-vitro excitation, increased duration of time between excitation and emission, low tissue absorption, high signal-to-noise ratio, etc. In this review, we have focused on most of the key aspects related to PLNPs, including the different mechanisms leading to such phenomena, key fabrication techniques, properties of hosts and different activators, emission, and excitation characteristics, and important properties of trap states. This review article focuses on recent advances in cancer theranostics with the help of PLNPs. Recent advances in using PLNPs for anti-counterfeiting and latent fingerprinting are also discussed in this review.

Gas bubble formation in the cytoplasm of a fermenting yeast.

Current paradigms assume that gas bubbles cannot be formed within yeasts although these workhorses of the baking and brewing industries vigorously produce and release CO(2) gas. We show that yeasts produce gas bubbles that fill a significant part of the cell. The missing link between intracellular CO(2) production by glycolysis and eventual CO(2) release from cells has therefore been resolved. Yeasts may serve as model to study CO(2) behavior under pressurized conditions that may impact on fermentation biotechnology.

Spectroscopy and calculations for 4f(N) → 4f(N-1)5d transitions of lanthanide ions in K3YF6.

In the present work, we report on the combined experimental and theoretical studies of the 4f-5d spectra of Ce(3+), Pr(3+), Nd(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), and Er(3+) ions in a newly synthesized K3YF6 matrix. The low temperature experimental 4f-5d excitation spectra have been analyzed and compared with the results of the energy-level and intensity calculations. For this theoretical analysis, the extended phenomenological crystal-field model for the 4f(N-1)5d configuration (i.e., the extended f-shell programs, developed by Prof. M. F. Reid) and exchange charge model (developed by Prof. B. Z. Malkin) have been used together to estimate the crystal field parameters and implement the spectral simulations. On the basis of the results of the performed theoretical analysis, we suggest the most probable positions occupied by optically active ions. Although the spectra of only eight lanthanide ions have been studied, the Hamiltonian parameters of the 4f(N-1)5d configuration have been evaluated for the whole lanthanide series and reported here for the first time, to give a complete and unified description of the spectroscopic properties of the trivalent rare earth ions in the chosen host. In addition to the studies of the 4f-5d transitions, various possible competitive excitation channels overlapping with 4f-5d ones have also been discussed, where a theoretical scheme giving rudiments to understand 4f-6s spectra are proposed for the first time. An excellent agreement between the calculated and measured excitation spectra shapes confirms validity of the performed analysis. The obtained parameters of the crystal field Hamiltonians for different ions and various electron configurations can be used in a straightforward way to generate the energy level positions and calculate the particular transition intensities for any rare earth ion in any particular spectral region. With the aid of the obtained parameters, the positions of the lowest energy levels of the 4f(N), 4f(N-1)5d ,and 4f(N-1)6s configurations of rare earth ions and 4f(N+1)(np)(5) configuration of rare earth ions and ligands (corresponding to the ligand-impurity ion charge transfer transitions) in the band gap of K3YF6 have all been estimated. The obtained Hamiltonian parameters and energy levels diagrams, which include the electronic structure of a host material, can be used as a starting point for analysis of spectroscopic properties of trivalent lanthanides in similar fluorides.

Crystal phase modified blue upconversion on Tm3+/Yb3+:BCZT ceramic phosphor benefits multifunctionality in white-light applications.

Rare earth (RE) doped perovskite oxide hosts especially titanates, are promising phosphor materials in terms of white-light emission owing to their extraordinary properties such as an exceptional hosting environment for RE-ions and a switchable crystal phase near the phase boundary. Here, we report a new strategy of crystal phase modification to enhance the blue upconversion (UC) efficiency to such an extent that the combinational mixing of blue and green/red-emitting phosphor gives intense white emission. The Lead free (Ba0.85Ca0.15)(Zr,Ti)O3 ceramics were synthesised at different sintering temperatures by incorporation of Tm3+/Yb3+ ions as dopants. The UC quantum efficiency of the Tm3+/Yb3+:BCZT sample sintered at 1300 °C was recorded at different excitation power densities. It was observed that the crystal phase transformation from tetragonal to rhombohedral symmetry in the sample near the phase boundary plays a cruicial role in improving the quantum efficiency. White-light emission applications were demonstrated by preparing biphasic samples with powder mixing of a BCZT:Tm3+/Yb3+ (blue-emitting) + BCZT:Er3+/Yb3+ (green/red-emitting) phosphor, and their composition were optimised at a mixed ratio. Thereafter, photometric characterization (CIE chromaticity, colour purity and corelated colour temperatures) was performed, and it indicated the suitability of the current biphasic samples in direct white-light (cooler) applications on an industrial scale. Crystal phase modified blue emission efficiency enhancement is a key feature of this work, which helps to generate approximately pure white-light with ideal chromacity (∼0.333, 0.343) emission when Tm3+/Yb3+:BCZT is mixed with a green emitting BCZT:Er3+/Yb3+ phosphor.

Power-dependent upconversion luminescence properties of self-sensitized Er2WO6 phosphor.

A Yb3+ free self-sensitized Er2WO6 phosphor has been synthesized via a solid-state reaction method. The phosphor material, Er2WO6, has a monoclinic crystal structure with space group P2/c (13). The deconvoluted high-resolution X-ray photoelectron spectra of all the core elements in the Er2WO6 phosphor material were explored. The highly resolved absorption peaks in the ultra-violet, visible and near-infra-red (NIR) regions of the diffuse reflectance spectrum were due to the Stark-splitting of the 4f energy levels of the Er3+ ions. Under 980 nm NIR laser excitation, the Er2WO6 phosphor showed an intense up-converted red emission at 677 nm due to the 4F9/2→4I15/2 transitions of the Er3+ ions. The cross-relaxation and resonance energy transfer process involved in the key intermediate 4F3/2 and 4F5/2 levels of the Er3+ and their role in generating red emissions were investigated. The laser pump power versus upconversion intensity plot showed a slope with an n value <1 and the possible reasons behind this behavior were investigated. The photoluminescence properties of the Er2WO6 phosphor in the visible and NIR region were further analyzed. The potential application of the phosphor as a marker in latent fingerprint detection was also evaluated.

Review on recent progress in metal-organic framework-based materials for fabricating electrochemical glucose sensors.

Diabetes is a type of disease that threatens human health, which can be diagnosed based on the level of glucose in the blood. Recently, various MOF-based materials have been developed as efficient electrochemical glucose sensors because of their tunable pore channels, large specific surface area well dispersed metallic active sites, etc. In this review, the significance of glucose detection and the advantages of MOF-based materials for this application are primarily discussed. Then, the application of MOF-based materials can be categorized into two types of glucose sensors: enzymatic biosensors and non-enzymatic sensors. Finally, insights into the current research challenges and future breakthrough possibilities regarding electrochemical glucose sensors are considered.

Luminescent MoS2 Quantum Dots with Tunable Operating Potential for Energy-Enhanced Aqueous Supercapacitors.

Wide band gap luminescent MoS2 quantum dots (QDs) and MoS2 nanocrystals (NCs) have been synthesized by using laser-assisted chemical vapour deposition and used as an electrode material in supercapacitors. Size-dependent properties of the MoS2 QDs and NCs were examined by UV-vis absorption, photoluminescence, and Raman spectroscopy. The morphological evolution of the NCs and QDs were characterized by using field emission scanning electron microscopy, high-resolution transmission electron microscopy, and atomic force microscopy. The as-synthesized uniform QDs with a size of ∼2 nm exhibited an extended electrochemical potential window of 0.9 V with a specific capacitance value of 255 F/g, while the NCs values were 205 F/g and 0.8 V and the pristine MoS2 with values of 105 F/g and 0.6 V at a scan rate of 1 mV s-1. A shorter conductive pathway and 3D quantum confinement of MoS2 QDs that exhibited a higher number of active sites ensure that the efficient charge storage kinetics along with the intercalation processes at the available edge sites enable significant widening of operating potential window and enhance the capacitance. The symmetric device constructed with the QDs showed a remarkable device capacitance of 50 F/g at a scan rate of 1 mV s-1 with an energy density of ∼5.7 W h kg-1 and achieved an excellent cycle stability of 10,000 consecutive cycles with ∼95% capacitance retention.

Synthesis of biocompatible chitosan functionalized Ag decorated biocomposite for effective antibacterial and anticancer activity.

The transition-metal dichalcogenides (TMDCs) like MoS2 and WS2 are a new and interesting class of materials and show considerable promise for use in a wide variety of fields, including nanomedicine for cancer. The eco-friendly, biodegradability, toxicity, and antimicrobial activity remain an open issue. Herein, we focused on the current demands of two dimensional (2D) TMDCs and produced high-quality, few-layered MoS2 nanosheets. Noble metal Ag incorporated into the 2D-CS/MoS2 NC by the liquid exfoliated process. The manufactured CS/MoS2/Ag hybrid NC showed excellent antibacterial activity against two microorganisms such as Gram-positive (21, 27, and 33 mm) and Gram-negative bacteria (23, 30, and 39 mm). The CS/MoS2/Ag hybrid NC was designed to have significant antibacterial activity against E.coli bacteria than S.aureus. Furthermore, the hybrid NC has a 74.18% cell inhibition against MCF-7 cancer cells. According to the literature relevant, it is the first extensive experimental analysis on the nano-bio interaction of 2D TMDCs nanomaterials in MCF-7 breast cancer cells.

The effects of palm oil breakdown products on lipid turnover and morphology of fungi.

The oleaginous fungi Cryptococcus curvatus and Mucor circinelloides were used to determine the effect of palm oil breakdown products, measured as polymerized triglycerides (PTGs), on lipid turnover and on fungal growth and morphology. In M. circinelloides, we found after 7 days of growth, a decrease in biomass and in lipid utilization and accumulation at increased PTG levels, both at low and neutral pH. In C. curvatus, there was also a decrease in lipid utilization and biomass production at increased PTG levels, at both low and neutral pH. However, an increase in oil accumulation was observed at low pH while it remained similar at neutral pH for all PTG levels tested. Hairy and warty protuberances on the cell surface were observed when C. curvatus was grown on oils with 15% and 45% PTGs, respectively. Using nano scanning Auger microscopy, we found no evidence to suggest a difference in elemental composition of the surfaces of the warty protuberances compared with the rest of the cell wall surface. We conclude that the warty protuberances are outgrowths of cell walls and that the changes observed in lipid turnover in both fungi are due to the presence of palm oil breakdown products.

Electronic and Simple Oscillatory Conduction in Ferrite Gas Sensors: Gas-Sensing Mechanisms, Long-Term Gas Monitoring, Heat Transfer, and Other Anomalies.

The early detection and warning of the presence of hazardous gases have been well studied. We present a study that focuses on some fundamental properties of gas sensors for liquefied petroleum gas (LPG) using spinel nanoferrites, namely, CoSm0.1Fe1.9O4, CoCe0.1Fe1.9O4, MgCe0.1Fe1.9O4, and MgFe2O4. A highly sensitive and selective response of 846.34 at 225 °C toward 10,000 ppm concentration of LPG was recorded. Other flammable gases tested were hydrogen, methane, propane, and butane. Electronic conduction of LPG sensors near saturation showed simple electrical oscillations that can be attributed to the self-dissociation of water molecules physically adsorbed on the surface of the chemisorbed oxygen species due to proton transfer. The oscillatory behaviors follow fluctuations in the operating temperature attributed to heat transfer between the physisorbed water molecules and the hot sensor surface. This depends on the LPG concentration because higher LPG concentration gives rise to greater heat transfer from the sensors. The adsorption and desorption of these water molecule multilayers take a few hundreds of seconds at low concentrations, while the adsorption formation process takes longer at higher concentrations. Other parameters such as LPG exposure time, bias voltage, relative humidity, ambient conditions, operating temperatures, and temperature of the gas not only affect electrical oscillations and thermal fluctuations but also switch the dominant charge carriers from p- to n-type or vice versa. The type of sensor surface, either p- or n-type, did not appear to affect the oscillatory behavior, while the exposure time, short or long, determined the appearance and further behavior of the oscillations. The long-time exposure to 10,000 ppm concentration resulted in the resistance gradually decreasing due to the lack of oxygen supply, while at 5000 ppm, this was constant, stable, and oscillated indefinitely. Changing the dry air to argon gas as a carrier and for dilution of the hazardous gas prevented the electrical oscillations and thermal fluctuations and significantly lowered the response values. Both the inert ambient (argon gas) and changing operating temperature flipped the dominant charge carriers of these sensors. The concentration of these chemisorbed oxygen species governs the charge space and depletion layers. In addition, the spinel nanoferrites used contained higher oxygen vacancies than the lattice oxygen and chemisorbed oxygen. When using dry air, the oscillations were observed at 3000 ppm concentration, while using argon gas, they were observed at 7000 ppm concentration. The room-temperature LPG responses were about 35 and 80 under 45% relative humidity using dry air and argon gas, respectively. These room-temperature measurements showed electrical oscillations but did not show any thermal fluctuations or heat transfer phenomena. This study presents a deeper insight into the fundamentals of gas-sensing mechanisms and energy costs involved.