Thermoelectric Properties for CuInTe2-xSx (x = 0, 0.05, 0.1, 0.15) Solid Solution
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-01-01 |
| Journal | Journal of Inorganic Materials |
| Authors | QIN Yu-Ting, QIU Peng-Fei, Xun Shi, Lidong Chen |
| Institutions | Chinese Academy of Sciences, University of Chinese Academy of Sciences |
| Citations | 7 |
| Analysis | Full AI Review Included |
6CCVD Technical Analysis: Thermoelectric Properties in Diamond-Like CuInTe2-xSx Solid Solutions
Section titled â6CCVD Technical Analysis: Thermoelectric Properties in Diamond-Like CuInTe2-xSx Solid SolutionsâThis technical analysis evaluates the paper âThermoelectric Properties for CuInTe2-xSx (x = 0, 0.05, 0.1, 0.15) Solid Solution.â The research details effective strategies for minimizing lattice thermal conductivity ($\kappa_L$) in diamond-like structured materials, a core challenge in bulk thermoelectric engineering. 6CCVDâs expertise in high-purity MPCVD diamond, precise doping (BDD), and defect control is highly relevant for extending this research into next-generation solid-state devices.
Executive Summary
Section titled âExecutive Summaryâ- Material System: Investigation of CuInTe${2-x}$S${x}$ solid solutions (x=0, 0.05, 0.1, 0.15), a p-type, diamond-like (chalcopyrite) structure material with high thermoelectric potential.
- Synthesis & Density: Samples successfully synthesized via melting and annealing, followed by high-density Hot Pressing (HP) sintering, achieving over 99% theoretical density.
- Structural Confirmation: XRD and SEM-EDS verified single-phase purity and highly homogeneous element distribution, confirming S substitution on the Te site.
- Thermal Performance Achievement: S substitution significantly reduced the lattice thermal conductivity ($\kappa_L$), which was previously a limiting factor in CuInTe$_{2}$.
- Dominant Mechanism: Callaway modeling determined that strain field fluctuation scattering, resulting from the Te/S substitution, is the primary physical mechanism responsible for the $\kappa_L$ reduction.
- Optimization Path: While S doping slightly impaired electrical conductivity ($\sigma$) due to increased band gap ($E_g$), the massive reduction in $\kappa_L$ confirms the potential for achieving high $zT$ values by optimizing electrical properties through future element doping or defect engineering.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the key quantitative parameters and experimental findings extracted from the research paper.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Studied Compositions (x) | 0, 0.05, 0.1, 0.15 | â | CuInTe${2-x}$S${x}$ solid solution |
| Synthesis Method | Melting and Annealing | â | Process achieved pure, homogeneous phase |
| Densification Method | Hot Pressing (HP) Sintering | â | Used to create >99% dense bulk samples |
| HP Sintering Temperature | 863 | K | 590 °C |
| HP Sintering Pressure | 8.1 | kN | Pressure applied during densification |
| HP Sintering Duration | 30 | min | Holding time for compaction |
| Final Density Achieved | >99 | % | Relative to theoretical density of CuInTe$_{2}$ |
| Charge Carrier Type | p | Type | Confirmed by positive Seebeck coefficients (S) |
| Band Gap (Reference CuInTe$_{2}$) | ~1.02 | eV | Pristine material $E_g$ |
| Band Gap (Reference CuInS$_{2}$) | ~1.5 | eV | Substitution increases $E_g$, lowering electrical performance |
| Primary $\kappa_L$ Reduction Mechanism | Strain Field Fluctuation | â | Confirmed via Callaway modeling analysis |
| Mobility Trend (T < 30 K) | Constant | â | Dominated by neutral impurity scattering |
| Mobility Trend (T > 100 K) | $\mu_H \propto T^{<-3/2}$ | â | Dominated by acoustic phonon scattering |
Key Methodologies
Section titled âKey MethodologiesâThe CuInTe${2-x}$S${x}$ solid solutions were fabricated using a combined approach of high-temperature synthesis and advanced densification:
- Stoichiometric Weighing: Pure elemental blocks (Cu, In, Te, S, all 99.999% purity or higher) were precisely weighed according to the CuInTe${2-x}$S${x}$ ratio.
- High-Temperature Melting: Materials were sealed in vacuum-tight quartz tubes within a glovebox, then heated in a vertical furnace:
- Heating Rate: 100 K/h.
- Maximum Temperature: 1373 K.
- Hold Time: 12 hours (to ensure a uniform liquid phase).
- Quenching and Annealing: The samples were ice-water quenched immediately, followed by long-term annealing at 923 K for 5 days.
- Powder Preparation: The resulting cast ingots were ground into fine powder using a mortar and pestle.
- Hot Pressing (HP) Densification: The powder was sintered to create bulk samples:
- Sintering Temperature: 863 K.
- Sintering Pressure: 8.1 kN.
- Sintering Time: 30 minutes.
- Structural Characterization: Phase purity and element distribution were verified using X-Ray Diffraction (XRD, D8 ADVANCE) and Scanning Electron Microscopy coupled with Energy Dispersive Spectroscopy (SEM-EDS, ZEISS Supra 55).
- Thermoelectric Measurement (300-800 K): Electrical conductivity ($\sigma$) and Seebeck coefficient (S) were measured using a ZEM-3 system under Helium atmosphere. Thermal diffusivity ($\lambda$) was measured using Laser Pulse Method (NETZSCH LFA 427) to calculate thermal conductivity ($\kappa = \lambda C_p \rho$).
- Low-Temperature Electrical Transport (2-300 K): Hall coefficient ($R_H$) and Hall mobility ($\mu_H$) were measured using a Physical Properties Measurement System (PPMS) with a ±3 T magnetic field.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research successfully leveraged alloying and defect engineering to manage phonon scattering in a diamond-like lattice structure. This demanding material design and control require manufacturing capabilities analogous to those 6CCVD applies in MPCVD diamond synthesis, particularly concerning material purity, thickness control, and precise doping.
6CCVD Material Solutions for Thermoelectric Research
Section titled â6CCVD Material Solutions for Thermoelectric Researchâ| Research Requirement/Challenge | 6CCVD Solution & Capability | Core Engineering Benefit |
|---|---|---|
| Material Purity and Thermal Stability: Need for benchmark substrates/materials capable of handling high temperatures (up to 800 K). | Optical Grade Single Crystal Diamond (SCD): Offers extreme thermal conductivity (for interface testing) and the highest purity available. | Unparalleled stability and benchmark thermal properties for fundamental transport physics studies. |
| Precision Doping and Defect Engineering: Paper explicitly calls for future element doping to improve electrical performance. | Boron-Doped Diamond (BDD) Wafers: 6CCVD provides highly controlled, reproducible doping levels (heavy BDD), analogous to optimizing carrier concentration in CuInTe${2-x}$S${x}$. | Direct application of precise defect control to manage electrical transport properties (conductivity and band gap). |
| Custom Sample Geometry: Thermoelectric testing (PPMS, ZEM-3) requires samples cut to specific dimensions for accurate measurement. | Custom Dimensions & Laser Cutting: Wafers/plates available up to 125 mm (PCD). We offer in-house laser cutting for precise, complex geometries. | Ensures rapid prototyping and exact compliance with experimental equipment constraints. |
| Stable Electrical Contacts: Need for thermally stable, low-resistance ohmic contacts for reliable $\sigma$ and $R_H$ measurements. | Custom Multi-Layer Metalization: Internal capability to deposit Au, Pt, Pd, Ti, W, and Cu structures. | Fabricates robust, optimized electrical interfaces for high-accuracy thermoelectric characterization up to high temperatures. |
| Surface Finish for Interface Studies: Smooth surfaces needed for low-scattering contacts and uniform interfaces (Ra < 1 nm is ideal). | Ultra-Precision Polishing: Achievable surface roughness of Ra < 1 nm (SCD) and Ra < 5 nm (Inch-size PCD). | Reduces measurement error and ensures ideal surface conditions for metal contact adherence and subsequent bonding processes. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD-level material science and technical engineering team can assist researchers and engineers in applying high-performance MPCVD diamond materials to advanced thermal management and thermoelectric material design projects. We specialize in tailoring material specificationsâincluding thickness, doping concentration, and metal contact schemesâto meet the precise requirements of high-temperature thermal and electrical transport experiments.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Diamond-like CuInTe 2 compound has attracted great attentions recently as a new thermoelectric material.Despite the considerable thermoelectric performance, the relatively high thermal conductivity at low and medium temperature ranges restricted further improvement of thermoelectric performance.Alloying was demonstrated an effective way to introduce mass and strain fluctuations to lower the lattice thermal conductivity in several typical thermoelectric materials.In this work, CuInTe 2-x S x (x=0, 0.05, 0.1, 0.15) solid solutions were fabricated by melting and annealing techniques.Phase purity and element distribution were examined by XRD and SEM-EDS measurements respectively.All the samples were pure phase and all the elements were distributed homogeneously.Callaway model was employed to analyze the thermal transport.It is found that S substitution minimized the lattice thermal conductivity effectively, mainly due to extra phonon scattering induced by strain field fluctuation.However, its electrical properties were deteriorated by S doping, probably due to bigger band gap in CuInS 2 than in CuInTe 2 .Therefore, if the electrical properties being improved by element doping, the CuInTe 2ïx S x (x=0, 0.05, 0.1, 0.15) solid solutions will achieve high thermoelectric performance.