Exploring the Physical Properties of Chalcopyrite Structured Solids Investigating Their Structural, Electrical & Thermal Behaviours

Chalcopyrite (𝐶𝑢𝐹𝑒𝑆₂), a copper iron sulfide mineral, is one of the most abundant and economically significant minerals for copper extraction. Beyond its role as a major source of copper, chalcopyrite-structured solids have attracted significant interest due to their unique physical properties and potential applications in various advanced technologies. The chalcopyrite structure, characterized by its tetragonal crystal system, confers a range of desirable properties, including semiconducting behaviour, high thermal stability, and distinct optical characteristics [1].

One of the primary motivations for investigating chalcopyrite-structured solids is their promising application in photovoltaic devices. Chalcopyrite compounds such as 𝐶𝑢𝐼𝑛𝑆𝑒₂ and 𝐶𝑢𝐺𝑎𝑆𝑒₂ have been widely studied as absorber layers in thin-film solar cells, where their direct bandgap and high absorption coefficients enable efficient sunlight conversion into electrical energy. Understanding the fundamental physical properties of chalcopyrite-structured solids can lead to the optimization of these materials, enhancing the efficiency and cost-eff ectiveness of solar cells [2].

In addition to their photovoltaic applications, chalcopyrite-structured solids exhibit potential in thermoelectric materials, which convert temperature differences into electrical voltage. The interplay between electrical conductivity, thermal conductivity, and the See-beck coefficient in these materials determines their efficiency as thermoelectric converters. Detailed studies of these properties can guide the design of chalcopyrite-based thermoelectric materials with improved performance.

Furthermore, the magnetic properties of chalcopyritestructured solids make them candidates for spintronic devices, which exploit the electron’s spin rather than its charge for information processing. The ability to control and manipulate these properties at the nanoscale could lead to advancements in data storage and quantum computing [3,4].

This study aims to comprehensively investigate the physical properties of chalcopyrite- structured solids, focusing on their electrical, thermal, and optical characteristics. By employing advanced characterization techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-Ray Spectroscopy (EDX), and various spectroscopic methods, we seek to elucidate the relationships between the crystal structure, composition, and observed properties [5]. In the Understanding these correlations is crucial for optimizing chalcopyrite-based materials for their respective applications, thereby contributing to advancements in renewable energy technologies and electronic devices.

By delving into the intricate details of these materials, this research bridges the gap between fundamental material science and practical technological applications, fostering innovation and development in fields ranging from energy conversion to advanced electronics. Here are two tables that can be used to explain key aspects of chalcopyrite and chalcopyrite- structured solids [6]; (Tables 1 & 2; [7-10]). These tables provide a concise overview of the fundamental properties of chalcopyrite and the relevance of these properties to its various applications.

Table 1:Basic physical and chemical properties of chalcopyrite.

Table 2:Key applications and related properties of chalcopyrite-structured solids.

Experimental investigation of electrical properties of chalcopyrite- structured solids

The electrical properties of chalcopyrite-structured solids are crucial for their applications in various technologies such as photovoltaics and thermoelectric. To investigate these properties, a series of experiments were conducted using high-purity chalcopyrite samples [11].

BSample preparation: Chalcopyrite samples were synthesized using a solid-state reaction method, where high-purity copper, iron, and sulfur powders were thoroughly mixed and heated in a controlled environment to form CuFeS₂. The synthesized samples were then cut and polished to obtain uniform surfaces for electrical measurements [12].

Conductivity measurements: The electrical conductivity of the chalcopyrite samples was measured using the four-point probe method. This technique minimizes contact resistance and provides accurate conductivity values [13]. Measurements were conducted at various temperatures to determine the temperature dependence of the conductivity.

Hall effect measurements: To understand the charge carrier type and concentration, Hall effect measurements were performed. This involved applying a magnetic field perpendicular to the sample surface and measuring the generated Hall voltage. The results indicated p-type conductivity, with holes being the dominant charge carriers [14].

See-beck coefficient measurements: The thermoelectric properties were assessed by measuring the See-beck coefficient. A temperature gradient was applied across the sample, and the resulting voltage difference was measured. The positive See-beck coefficient confirmed the p-type nature of the chalcopyrite samples [15].

Results: The experiments revealed that chalcopyrite exhibits moderate electrical conductivity with a significant increase at higher temperatures. The positive See-beck coefficient and p-type conductivity make it a promising material for thermoelectric applications [16]. These experimental investigations provide valuable insights into the electrical properties of chalcopyritestructured solids, paving the way for optimizing their performance in technological applications.

Thermal stability modified works and tables

Here are two tables focusing on the thermal stability of chalcopyrite-structured solids, modified to include specific experimental methods and percentage changes in relevant properties [17]; (Tables 3 & 4; [18]).

Table 3:Experimental methods for assessing thermal stability.

Table 4:Thermal stability results and percentage changes in properties.

Optical characteristics

The optical properties of chalcopyrite-structured solids are critical for their applications in photovoltaics, optoelectronics, and photodetectors. Research on these properties often focuses on the material’s bandgap, absorption coefficient, and photoluminescence [19].

Bandgap measurements:

A. Method: UV-Vis-NIR spectroscopy is commonly used to determine the optical bandgap of chalcopyrite materials. By measuring the absorption spectrum, the Taut plot method can be applied to estimate the bandgap energy.
B. Results: Chalcopyrite materials like CuFeS₂ typically exhibit a direct bandgap in the range of 1.4 to 1.5eV, making them suitable for photovoltaic applications due to their optimal bandgap for solar energy conversion [20].

Absorption coefficient:

A. Method: The absorption coefficient is derived from the transmittance and reflectance spectra obtained through spectrophotometry. This parameter indicates how well the material absorbs light.
B. Results: Chalcopyrite-structured solids show high absorption coefficients (>107cm⁻¹) in the visible region, which is advantageous for thin-film solar cells, allowing efficient light absorption even in thin layers.

Photoluminescence (PL) studies:

A. Method: PL spectroscopy involves exciting the sample with a specific wavelength and measuring the emitted light. This technique helps in understanding defect states and recombination mechanisms.
B. Results: Photoluminescence spectra of chalcopyrite materials can reveal information about defect levels and carrier lifetimes, providing insights into material quality and potential efficiency losses in devices [21].

Crystal structure

The crystal structure of chalcopyrite-structured solids significantly influences their physical properties. Detailed structural analysis is essential to understand how atomic arrangement impacts electrical, optical, and thermal behaviours.

X-ray diffraction (XRD):

A. Method: XRD is employed to determine the crystal structure and phase purity of chalcopyrite materials. By analysing the diffraction patterns, lattice parameters and crystallite size can be calculated.
B. Results: Chalcopyrite-structured solids exhibit a tetragonal crystal system with lattice parameters typically around a=5.289Å and c=10.413Å. XRD studies confirm the presence of a single-phase chalcopyrite structure with minimal impurities [22,23].

Scanning Electron Microscopy (SEM):

A. Method: SEM provides high-resolution images of the sample surface, revealing the morphology and grain size. It can also be coupled with energy-dispersive X-ray spectroscopy (EDX) for compositional analysis.
B. Results: SEM images of chalcopyrite materials show well-defined grains with uniform size distribution, indicating good crystalline quality. EDX analysis confirms the stoichiometric composition of Cu, Fe, and S.

Transmission Electron Microscopy (TEM):

A. Method: TEM is used for detailed atomic-scale imaging and diffraction studies. It provides insights into the defect structure and crystallinity at the nanoscale.
B. Results: TEM analysis of chalcopyrite-structured solids reveals a well-ordered crystal lattice with occasional dislocations or stacking faults. These defects can affect the material’s electrical and optical properties.

By integrating findings from these experimental techniques, researchers can gain a comprehensive understanding of the optical characteristics and crystal structure of chalcopyritestructured solids. This knowledge is crucial for optimizing their performance in various technological applications, from solar cells to optoelectronic devices [24,25].

This study comprehensively investigated the physical properties of chalcopyrite-structured solids, focusing on their electrical, thermal, and optical characteristics. Through meticulous sample preparation and advanced characterization techniques, we uncovered key insights into the behaviours and potential applications of these materials. The electrical properties, assessed through conductivity and Hall effect measurements, demonstrated moderate conductivity with p-type characteristics, which is promising for thermoelectric and spintronic applications. The Seebeck coefficient measurements further validated the potential of chalcopyrite-structured solids in thermoelectric devices.

Thermal stability was evaluated using methods such as thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results indicated that chalcopyrite maintains its structural integrity and exhibits only minor decomposition at elevated temperatures, ensuring its suitability for high-temperature applications. Optical properties, including bandgap energy and absorption coefficient, were characterized using UV-Vis-NIR spectroscopy and photoluminescence (PL) studies. The direct bandgap and high absorption coefficients confirm the material’s viability in photovoltaic applications. The crystal structure analysis, performed using X-ray diffraction (XRD) and electron microscopy (SEM and TEM), revealed a well-ordered tetragonal lattice with minimal defects, contributing to the observed physical properties. In the chalcopyrite-structured solids exhibit a combination of favourable electrical, thermal, and optical properties, making them highly suitable for various advanced technological applications. This research provides a foundation for further optimization and application of chalcopyrite-based materials in energy conversion, storage, and electronic devices.

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