Resistivity Ρs Research Articles

Effect of atomic layer deposition process parameters on TiN electrode for Hf0.5Zr0.5O2 ferroelectric capacitor

Abstract Hf0.5Zr0.5O2 (HZO), as a novel and outstanding ferroelectric material, exhibits an extremely high sensitivity, rendering it quite susceptible to electrode effect. Titanium nitride (TiN) is a commonly employed as electrode material in the complementary metal-oxide-semiconductor (CMOS) process. Adjusting the process parameters of preparing TiN film can alter matching degree with HZO, so as to find the optimal parameters of TiN process to improve ferroelectric property of HZO. In this study, the impact of key process parameters in atomic layer deposition (ALD) TiN, including cycle number, TiCl4 and NH3 pluse time, process temperature (Tp) on film thickness, crystalline phases of TiN, square resistivity (Rs), surface average roughness (Ra) and the root-mean-square roughness (Rq) of TiN film are comprehensively investigated. Through optimization, ~10nm ALD TiN film can achieve excellent uniformity of 0.43%, low Rs of 286.9Ω/sq, improved Ra and Rq of 1.82Å and 2.28Å. The results show that the maximum 2 times remnant polarization (2Pr) of the HZO ferroelectric capacitor with optimized TiN electrodes can reach 36.34µC/cm2, and the switching cycle endurance exceeds 1E7.

High thermal conductivity regenerated cellulose/carboxylated carbon nanotubes composite films with semi-insulating properties prepared via ionic coordination and hydrothermal synthesis of zinc oxide

With the rapid development of miniaturization and integration of electronic products, its heat dissipation has become the focus of research. In order to improve the heat dissipation efficiency of electronic components, flexible thermal conduction materials are constantly studied. Cellulose has good flexibility and load capacity, which is often used in the preparation of thermal conduction materials. In this paper, carboxylated multi-walled carbon nanotubes (C-MWCNTs) were modified by metal ion coordination and hydrothermal synthesis of zinc oxide (ZnO) to prepare semi-insulating thermal conduction fillers, which were dispersed into regenerated cellulose (RC) to cast to be composite films. The results show that the two modification methods can reduce the probability of phonon scattering and block the electron transport path, so as to improve the thermal conductivity (TC) and electrical insulation properties of the composite films. Especially for the RC/C-MWCNTs@ZnO composite films, when the total filler content is 20 wt%, the in-plane TC can reach 11.89 ± 0.19 (W/(m·K)), and the surface electrical resistivity (ρs) is (5.24 ± 0.17) × 106 Ω. Compared with the RC/C-MWCNTs composite films, the in-plane TC and ρs of the RC/C-MWCNTs@ZnO composites films are increased by about 94.92 % and 555 %, respectively. Therefore, the developed RC-based composite film has broad application prospects in thermal management.

Size effect configuration modeling for the high-performance hybrid Fe-Si directional alloyed soft magnetic material (DASMM)

This work presents a novel hybrid gas/water atomized Fe-Si directional alloyed soft magnetic materials (DASMM), they have a combination of low core loss (Pcv), constant permeability (μ) and high compatibility. The particle size has a big influence upon the Fe-Si DASMP magnetic properties, the study result revealed that the coarse powder DASMM merely have a steady permeability of 60 in the frequency range between 10 and 100 kHz; while the fine particle (≥200 meshes) DASMM could maintain its constant permeability of 40 in the whole range between 10 and 500 kHz. The Pcv of Fe-Si DASMM rapidly decreased as the consisting powder particle size decrease, dramatically decreased from 277.36 W/kg for the 100 mesh to 62.00 W/kg for the 300 mesh Fe-Si DASMM. While the resistivity (Rs) sharply increased, it increased 9 times from 5.93 mΩ·cm for the 100 mesh to 54.33 mΩ·cm for the 300 mesh Fe-Si DASMM.

Electrically conductive crystalline polylactide nonwovens obtained by electrospinning and modification with multiwall carbon nanotubes

Polylactide nonwovens were electrospun from solutions and then crystallized, one in α-form, and another, S-PLA, made of poly(l-lactide) and poly(d-lactide) 1:1 blend, in scPLA crystals with high melting temperature, close to 220 °C. To make the nonwovens electrically conductive, they were coated with multiwall carbon nanotubes (MWCNT) by padding and dip-coating with an aqueous dispersion of MWCNT. The electrical conductivity evidenced the formation of the electrically conductive MWCNT network on the fiber surfaces. Depending on the coating method, the surface resistivity (Rs) of S-PLA nonwoven of 1.0 kΩ/sq and 0.09 kΩ/sq was reached. To study the effect of surface roughness, before the modification the nonwovens were etched with sodium hydroxide, which additionally made them hydrophilic. The effect of etching depended on the coating method and led to an increase or decrease of Rs, in the case of padding or dip-coating, respectively. All MWCNT-modified nonwovens, unetched and etched, were hydrophobic with water contact angles of 138–144°. Scanning electron microscopy corroborated the presence of MWCNT on the fiber surfaces. Impedance spectroscopy confirmed the dominant role of the network of MWCNT direct contacts on the electrical properties of MWCNT-modified nonwovens in a broad frequency range.

Combined Application of Hydrogeological and Geoelectrical Study in Groundwater Exploration in Karst-Granite Areas, Jiangxi Province

Drinking water shortage is a major concern in villages across southern Jiangxi, and this has impacted economic and social development. In order to address this challenge, groundwater prospecting was carried out in the villages under the support of Drinking Water Safety Project of China Geological Survey. In this study, we present two example sites in Ningdu County selected to demonstrate the combined hydrogeological survey, and the direct current electrical resistivity method was utilized for the present study for groundwater exploration in karst-granite distribution areas. First, a hydrogeological study was effectively used to delineate shallow severely weathered structural fissures as prospective target water-bearing beds. Then, a direct current electrical resistivity survey was used to confirm the distribution, thickness scale, and water-bearing features. The structural fractured zone whose distribution and trend were first established through hydrogeological surveys and whose development characteristics and water-richness were investigated by the direct current electrical resistivity method is the target layer for water exploration in the karst-granite rock areas. The water-bearing fracture zone shows a groove or strip-shape low resistivity anomaly and can be identified in its aquifer position according to its IP half decay time (Th), apparent polarizability (ηs), and apparent resistivity (ρs). The findings demonstrate that the above methods were successful in locating water potential areas, providing information for comparison and accurate borehole positioning. The results of the subsequent drilling and pumping tests supported the interpretation of the geophysical exploration data, and the water output from both boreholes met the objectives of this study. This groundwater search might serve as a guide for future exploration projects in similar areas.

A Conductive Bamboo Fabric with Controllable Resistance for Tailoring Wearable Sensors.

Force-sensitive textile sensors are becoming a research hotspot as a part of wearable devices. The core research topic is the method to obtain the sensing property, which decides the sensitivity and service performance of the sensors. Here, we introduce a new sensing mechanism based on a statistical change of contact resistance that exhibits an exponential decay upon strain or pressure, where a novel conductive bamboo fabric is prepared and the dependence of electric conductivity on the fabric structure is discovered. The fabric surface resistivity (ρs) is anisotropic with respect to the measuring directions and the warp, weft, and linear densities. The surface resistance (Rs) decreases rapidly under pulling force, especially in diagonal directions, making it available in designing strain sensors. The volume resistivity (ρv) decreases with increasing weft and linear densities, too. The vertical resistance (Rv) decays exponentially under pressure, and the rule is retained even if the fabric is coated with a polymer, leading to diverse possible pressure sensors with a good service performance (e.g., waterproof). Finally, the conductive fabric could be facilely tailored to various wearable sensors with a fast response time, e.g., sensing finger sleeves and sensing insole, which could be used to operate the manipulator's fingers or to monitor human walking gestures, respectively.

Optical and electrical properties of ITO/Metal/NiO triple-layer grown by PVD method: An experimental study

In this work, transparent conducting oxides (TCOs) comprising an ITO/Metal/NiO sandwich structure grown by sputtering and thermal evaporation in a vacuum are investigated. By exploiting the four-point probe measurements and optical spectrometry both optical and electrical characteristics of the fabricated ITO/Metal/NiO trilayers for diverse metals such as Au, Ag, and Cu are studied. Moreover, through X-ray diffraction and high-resolution scanning electron microscopy method the structural characteristics are fully examined. The results reveal that the type of innermost metal plays the main role in the optical and electrical behavior of the trilayers structure. An average transmittance of 73-62% range at visible wavelength and small resistivity of 2 × 10−4 Ω cm are achieved for a 10 nm thick Au interlayer. The sheet resistivity (Rs) of NiO drops drastically from 200 Ω (single NiO layer) to 1.2Ω for ITO/Cu/NiO structure. Moreover, an increase in sputtering power and film thickness increases the optical bandgap. The obtained results prove that physical vapor deposition (PVD) is a good method for producing par excellence TCO films with beneficial characteristics such as high transmittance and low resistivity.

RapidET: a MEMS-based platform for label-free and rapid demarcation of tumors from normal breast biopsy tissues

The rapid and label-free diagnosis of malignancies in ex vivo breast biopsy tissues has significant utility in pathology laboratories and operating rooms. We report a MEMS-based platform integrated with microchips that performs phenotyping of breast biopsy tissues using electrothermal sensing. The microchip, fabricated on a silicon substrate, incorporates a platinum microheater, interdigitated electrodes (IDEs), and resistance temperature detectors (RTDs) as on-chip sensing elements. The microchips are integrated onto the platform using a slide-fit contact enabling quick replacement for biological measurements. The bulk resistivity (ρB), surface resistivity (ρS), and thermal conductivity (k) of deparaffinized and formalin-fixed paired tumor and adjacent normal breast biopsy samples from N = 8 patients were measured. For formalin-fixed samples, the mean ρB for tumors showed a statistically significant fold change of 4.42 (P = 0.014) when the tissue was heated from 25 °C to 37 °C compared to the adjacent normal tissue, which showed a fold change of 3.47. The mean ρS measurements also showed a similar trend. The mean k of the formalin-fixed tumor tissues was 0.309 ± 0.02 W m−1 K−1 compared to a significantly higher k of 0.563 ± 0.028 W m−1 K−1 for the adjacent normal tissues. A similar trend was observed in ρB,ρS, and k for the deparaffinized tissue samples. An analysis of a combination of ρB, ρS, and k using Fisher’s combined probability test and linear regression suggests the advantage of using all three parameters simultaneously for distinguishing tumors from adjacent normal tissues with higher statistical significance.

On the limiting efficiency for silicon heterojunction solar cells

Silicon heterojunction (SHJ) solar cell, as one of the promising technologies for next-generation passivating contact solar cells, employs an undiffused and n-type mono-crystalline silicon (c-Si) substrate and two amorphous-silicon-based selective contacts with opposite polarities. In this work, a numerical model based on Richter's theory has been developed to simulate the performances of a 25.11 % efficiency SHJ solar cell obtained recently. Analyses on series resistivity (Rs) explicit that the upper bound for the sum of contact resistivities for p-type (ρc,p) and n-type (ρc,n) contacts is 0.073 Ω cm2. With the updated contact resistivities, the theoretical limiting efficiency estimated by Brendel's formulation is therefore 28.5 % for SHJ solar cells, which is comparable to 28.7 % for bi-facial tunneling-oxide passivating contact (TOPCon) solar cells. A hybrid structure consisting of p-type contact from SHJ and n-type contact from TOPCon is feasible to reach 28.9 % limiting efficiency in principle, showing potential of solar cells with hybrid structures.

Durability Performance Indices for Cement-Based Mortars.

Corrosion-induced damaged structures are generally repaired using locally available materials. Nevertheless, determining the durability of the repair materials to be used is necessary to forecast its service life after being placed on the damaged structure. In previous investigations, the most commonly used durability indices are saturated electrical resistivity (ρS), ultrasonic pulse velocity (UPV), total void content (TVC), water capillary absorption (WCA), rapid chloride permeability (RCP), and compressive strength (fc). Four repair mortar types were evaluated. For each mortar type, 5 × 5 cm2 cubes, 5 × 10 cm2 (small) cylinders, and 10 × 20 cm2 (large) cylinders were made from each mortar evaluated. On the basis of the present results, the durability design of mortars should consider not only the mechanical strength, but also the durability index values to define its durability performance. According to the empirical correlations obtained between all durability indices, ρS vs. RCP, TVC vs. WCA, and RCP vs. WCA were the ones with higher correlation coefficient. These correlations could be used for mortar mixture durability forecasting.

Depth profile study on Ti/Al bilayer Ohmic contacts to AlGaN/GaN

The electrical performance of double layered Ohmic contacts not only depends on layer thicknesses, annealing temperatures and annealing time etc. but also Ohmic contact metals and reactions with substrates and each other. Furthermore, oxidation tendency of Ohmic contact metals is highly important for contact quality and stability. In this study, we have investigated Ti/Al Ohmic contact formation on undoped AlGaN substrates by X-ray photoelectron spectroscopy (XPS) depth profile analysis. We aimed to reveal the oxide compounds and reaction products of metals and dependencies to the contact depth. In survey mode and depth profile mode five atoms core level (Ga 3d, Al 2p, N 1 s, Ti 2p and O 1 s) was observed and the XPS core level peaks were convoluted with Gaussian profiles to identify the origin of the peaks. Our results show that Ohmic contact metals strongly incorporated with oxygen, leading to high specific contact resistivity (ρs) confirmed by the TLM measurement. Also it is found that thermal treatments cause a TiAl3 metallic alloy in the Ti/Al interface and the presence of excess Ga and TiN indicates that out diffusion of N atoms at the metal semiconductor (MS) interface.

Durability health monitoring during construction of concrete structures in marine environment

A new methodology for durability health monitoring for a bridge structure during construction was developed by monitoring concrete's saturated electrical resistivity (ρS), rapid chloride permeability (RCP), and the apparent chloride diffusion coefficient (DAP) indices. Results were compared with same durability indices collected previously from in-service bridges located along the Gulf of Mexico (Florida, USA, and Yucatan, Mexico). Excellent correlations were found between ρS versus RCP, ρS versus DAP, and RCP versus DAP from present and previous investigation data. Empirical models obtained corroborate that ρS test is feasible to use, instead of more complicated and expensive testing, for structural health monitoring for quality control/assurance during construction.

Thermally Conductive and Insulating Epoxy Composites by Synchronously Incorporating Si-sol Functionalized Glass Fibers and Boron Nitride Fillers

Glass fibers (GFs)/epoxy laminated composites always present weak interlaminar shear strength (ILSS) and low cross-plane thermal conductivity coefficient (λ⊥). In this work, silica-sol, synthesized from tetraethyl orthosilicate (TEOS) and KH-560 via sol-gel method, was employed to functionalize the surface of GFs (Si-GFs). Together with a spherical boron nitride (BNN-30), the thermally conductive BNN-30/Si-GFs/epoxy laminated composites were then fabricated. Results demonstrate that Si-sol is beneficial to the improvement of mechanical properties for epoxy laminated composites (especially for ILSS). The BNN-30/Si-GFs/epoxy laminated composites with 15 wt% BNN-30 fillers display the optimal comprehensive properties. In-plane λ(λ//) and λ⊥ reach the maximum of 2.37 and 1.07 W·m−1·K−1, 146.9% and 132.6% higher than those of Si-GFs/epoxy laminated composites (λ// = 0.96 W·m−1·K−1 and λ⊥ = 0.46 W·m−1·K−1), respectively, and also about 10.8 and 4.9 times those of pure epoxy resin (λ// = λ⊥ 0.22 W·m−1·K−1). And the heat-resistance index (THRI), dielectric constant (e), dielectric loss (tanδ), breakdown strength (E0), surface resistivity (ρs) as well as volume resistivity (ρv) are 197.3 °C, 4.95, 0.0046, 22.3 kV·mm−1, 1.8 × 1014Ω, and 2.1 × 1014Ω·cm, respectively.

Concrete durability enhancement from nopal (opuntia ficus-indica) additions

Durability criteria were used to evaluate concretes containing Opuntia Ficus Indica (OFI, also called nopal) derivatives: exudate nopal mucilage (eNm), cooked nopal mucilage (cNm), and dehydrated nopal powder (dNp). Concrete containing eNm and cNm was fabricated using 4%, 8%, 15%, and 30% concentrations by water mass replacement. The dNp was added at 1%, 2%, and 4% (per cement weight) by sand mass replacement. Concrete’s physical and mechanical performance was monitored for the nopal derivative treatments and the control (without nopal derivatives), to quantify any possible durability improvements.The durability tests included: saturated electrical resistivity (ρS); total voids percentage (TV%), capillary absorption (effective porosity, εEF); compressive strength (fc); rapid chloride permeability (RCP); and SEM micrograph analysis. Because nopal derivatives have an apparently slow reaction time, the tests were evaluated at 30, 90, 180, and 400 days.Addition of dehydrated nopal powder (dNp) did not improve substantially concrete durability performance, except chloride transport: additions <2% decreased RCP index values up to 10%. Exudate nopal mucilage (eNm) exhibited improved durability index values up to 20% (TV%/εEF decrease and ρS/fc increase), and RCP index was improved up to 30%. Cooked nopal mucilage (cNm), at all four tested ages, produced results superior to the control mixture (between 20% and 40% improvements). In summary, nopal derivatives may act as clogging sponge-like biopolymer within the cement matrix pores, stopping water and chloride transport into concrete.

Phase change, band gap energy and electrical resistivity of Mg doped TiO2 multilayer thin films for dye sensitized solar cells applications

Magnesium doped Titanium dioxide (Mg: TiO2) thin films with 1, 3, 5 and 7 layers are deposited on FTO-glass substrates. XRD shows that the phases of TiO2 are changed by changing the number of coating layers. The 7th layered film has larger grain size than other layered films. The absorption is shifted towards the visible region when numbers of stacked layersare increased, according to the absorption spectra taken with UV–Vis spectrometer. The optical band gap energy (Eg) of 1, 3, 5 and 7 layers films is 3.48, 3.34, 3.14 and 2.98 eV, respectively.The average sheet resistivity (Rs)measured by four point probe technique of 1, 3, 5 and 7 layered film is 5.68 x 105, 1.67 x 105, 3.99 x 104 and 6.34 x 102 (Ω-cm), respectively. The efficiency of 7 layered based DSSC is 1.68% which is nearly 65% improved as compared with single layered based DSSC (i.e. 1.10%). This improvement in efficiency is due to increase in grain size and decrease in Eg.

Electrical resistivity, remote sensing and geographic information system approach for mapping groundwater potential zones in coastal aquifers of Gurpur watershed

Electrical resistivity method and RS & GIS techniques are very much useful in identification of potential aquifer zones for exploitation, management and recharge of groundwater. Vertical Electrical Soundings are conducted at 35 locations in Gurpur watershed using Schlumberger array. The thematic layers like porosity, transmissivity and hydraulic conductivity are prepared using electrical resistivity data. Total of 13 thematic layers are used for vector integration and identification of Groundwater Potential Zones (GWPZ). The numerical weights and ranks are assigned to the themes based on their relationship with groundwater. The findings shows that the depth to bedrock varies from 9.1 to 44.4 m and most of the mid land and low land region shows moderate to high depths of about 25–44 m. The GWPZ are classified into five classes namely, Very Good (≈21.02 km2), Good (≈231.35 km2), Moderate (≈420.76 km2), Poor (≈185.05 km2) and Very Poor (≈19.56 km2). The Good and Moderate categories cover ≈75% of total area.

Mineral resource estimation using a combination of drilling and IP&amp;Rs data using statistical and cokriging methods

The aim of this research is the mineral resource estimation using a combination of drilling and IP-Rs data. Therefore the approach of this paper is to study the correlation of induced polarization (IP) and Electrical resistivity (Rs) data with drilling data in order to grade estimation and mineral resource estimation. Reducing the boreholes number and optimization of the boreholes location is another aim of this research. The Abassabad copper mine located in Miami-Sabzevar mineralization belt northeast Iran was chosen as a case study. Within the borehole locations, geophysical profiles were designed and surveyed. After IP-Rs data inversion, 2D sections were prepared. The 3D block models of IP-Rs were constructed by geostatistical methods. The correlation between IP-Rs and drilling data were examined by statistical and geostatistical methods using regression, multivariate regression analysis, and cokriging. Based on the mentioned methods copper grade was estimated and the 3D block models of Cu grade were constructed. Obtained models were checked and compared with real Cu model compiled according to drilling data which was done after geophysical measurements. Results showed that the regression between IP data and Cu grade was more appropriate with least error. Rs data are not suitable for Cu estimation, due to changing intervals which led to increasing estimation error. Based on the suggestions of this paper, we could reduce the number of boreholes to 30% of the initial number and optimize the boreholes locations.

3D model construction of induced polarization and resistivity data with quantifying uncertainties using geostatistical methods and drilling (Case study: Madan Bozorg, Iran)

Madan Bozorg is an active copper mine located in NE Iran, which is a part of the very wide copper mineralization zone named Miami-Sabzevar copper belt. The main goal of this research work is the 3D model construction of the induced polarization (IP) and resistivity (Rs) data with quantifying the uncertainties using geostatistical methods and drilling. Four profiles were designed and surveyed using the CRSP array based on the boreholes. The data obtained was processed, 2D sections of IP and Rs were prepared for each profile by inverting the data, and these sections were evaluated by some exploratory boreholes in the studied area. Based on the geostatistical methods, 3D block models were constructed for the 2D IP and Rs data, and the uncertainties in the prepared models were obtained. The mineralization location was determined according to the geophysical detected anomalies. In order to check the models, some locations were proposed for drilling in the cases that the borehole data was unavailable. The drilling results indicated a high correlation between the identified anomalies from the models and mineralization in the boreholes. The results obtained show that it is possible to construct 3D models from surveyed 2D IP & Rs data with an acceptable error level. In this way, the suggested omitted drilling locations were optimized so that more potentials could be obtained for copper exploration by the least number of boreholes.

Calcined Mussel Shell Powder (CMSP) via Modification with Surfactants: Application for Antistatic Oil-Removal.

Biomass is known to efficiently adsorb pollutants from wastewater. In this paper, we demonstrated that a new antistatic oil-cleaning material can be prepared and assembled by using two surfactants, alkyl polyglucosides (APG) and dimethyl octadecyl hydroxy ethyl ammonium nitrate (SN), to modify calcined mussel shell powder (CMSP) through a two-step hydrotherm-assisted adsorption. The pore size and structure of CMSP was measured by BET and a contact angle meter was used to characterize the surface wetting ability. XRD, FTIR, XPS, SEM, TEM, and HRTEM were employed to determine the surface structure of CMSP modified by surfactants APG and SN (MMO). In order to further characterize properties of the surface morphology and crystal structure, the HRTEM was employed to show that the MMO surface had a single crystal structure: calcite, with a crystal plane spacing of 0.2467 nm. The surface of MMO appeared to be fluffy and disperse. The antistatic and degreasing ability of as-prepared samples (MMO) was evaluated by a ZC-36 high resistance meter and BD-457 whiteness meter. The results showed that when the calcination temperature of CMSP reached 1000 °C, and the addition amount of APG and SN was 0.8 g and 0.16 g, it had an optimum antistatic effect with a surface resistivity (Rs) of 1.35 × 108 Ω, and a detergency rate to oil of 17.35%. This study aims to embrace a green solution to reduce environmental pressure and make use of waste, which is of great significance to environmental protection.

Detailed investigation of thermal and electron transport properties in strongly correlated compound Ce6Pd12In5 and its nonmagnetic analog La6Pd12In5

An in-depth study of thermal and electron transport properties including thermal conductivity κ(T), thermoelectric power S(T), and electrical resistivity ρ(T) of the heavy fermion Kondo lattice Ce6Pd12In5 and its nonmagnetic reference compound La6Pd12In5 is presented. The absolute κ(T) value of Ce6Pd12In5 is smaller that than of La6Pd12In5, which indicates that conduction electron–4f electron scattering has a large impact on the reduction of thermal conductivity. The isolated 4f electron contributions to the electrical resistivity ρ4f(T), electronic thermal resistivity displayed in the form Wel,4f(T)·T, and thermoelectric power S4f(T) reveal a low- and high-temperature –lnT behaviour characteristic of Kondo systems with strong crystal-electric field (CEF) interactions. The analysis of phonon scattering processes of lattice thermal conductivity κph(T) in (Ce, La)6Pd12In5 was performed over the whole accessible temperature range according to the Callaway model. In the scope of a theoretical approach based on the perturbation type calculation, we were able to describe our experimental data of ρ4f(T) and Wel,4f(T)·T by using the model incorporating simultaneously the Kondo effect in the presence of the CEF splitting, as it is foreseen in the framework of the Cornut-Coqblin and Bhattacharjee-Coqblin theory. Considering the fact that there are not many cases of similar studies at all, we also show the numerical calculations of temperature-dependent behaviour of spin-disorder resistivity ρs(T), magnetic resistivity ρ4f(T), and occupation number ⟨Ni⟩ due to the various types of degeneracy of the ground state multiplet of Ce3+ (J = 5/2).